Field of the invention

The present invention relates to an underground vibration shield element for damping and/or absorbing underground vibrations. The present invention further relates to an underground vibration shield system and to a method for shielding an object from underground vibrations.

Background of the invention

Underground vibrations are omnipresent and may for example be caused by a wide range of human activities. Industries, construction works and (heavy) traffic are important causes of underground vibrations.

Underground vibrations may cause nuisance, noise pollution, equipment failure and damage. Therefore, governments are increasingly limiting vibration loads in accordance with the Dutch SBR-guidelines, German DIN 4150 and ISO 2631/2 standards.

An underground vibration may propagate through underground media, such as soil and groundwater. Foundations, infrastructural works and buildings may be affected by vibrational waves. Monumental buildings in inner cities are especially vulnerable, given their traditional construction method, older construction materials, and, often, a location close to a road. Such constructions may already have a reduced integrity in view of their age, and are particularly vibration-prone if built without foundation piles on a weak subsoil, such as loam or clay, as is common in the Netherlands. Older buildings are usually not designed to withstand vibrations caused by the increasing amount of heavy traffic on nearby roads. Therefore, even light vibrations can lead to long-term damage, for example to foundations and masonry.

Additionally, in order to increase road safety, local authorities are taking an increasing number of measures to enforce speed limits. For example, chicanes and speed bumps are installed on roads, which force traffic to change direction and therewith achieve a speed reduction. However, when traffic passes through a chicane or over a speed bump, these direction changes cause additional vibrations.

NL2020761 B1 discloses an underground vibration barrier of at least one shield element comprising a substrate of man-made vitreous fibres (MMVF), wherein the at least one shield element is arranged underground in such way that vibrations in the ground are substantially reduced and/or absorbed. It has, however, been found that such a barrier is vulnerable during handling.

Other methods used to damp vibrations from road traffic and rail traffic, for example, consist of deep concrete walls between the vibration source and the building. These are extremely expensive, require a relatively large amount of space in the ground and are especially difficult to fit into existing situations. As a result, it is normally not possible to use a concrete deep wall in residential areas or city centres. Due to the depth and watertightness of a deep concrete wall, such constructions may influence groundwater flows.

In addition, the vibration damping effect of known is relatively limited, in particular of traffic vibrations.

The invention is partly based on the discovery that vibration-damping systems made of polystyrene are difficult to apply due to their buoyancy, especially in weaker and moist soils, and have a tendency to float on the groundwater. In addition, a stable concrete foundation or subsoil is often required, and known systems are typically unsuitable for application in a softer soil that may be subject to (uneven) settling. Plastic foam materials as polystyrene may be relatively fragile and may rupture, especially in softer soils.

The applicant has found that due to the presence of groundwater, a limited available space in the soil and/or due the possible unevenly distributed traffic loads, especially underneath roads, current systems are often not usable and often not effective.

Furthermore, it has been found that the vibration damping properties of known barriers may decrease over time.

Object of the invention

It is therefore an object of the present invention to provide an underground vibration shield element that may provide high vibration damping properties that are retained throughout its service life, or at least to provide a usable alternative for example a relatively durable alternative that can be used in relatively weak soils and/or an alternative that can be used when groundwater is present.

Detailed description

The present invention provides an underground vibration shield element according to claim 1. The underground vibration shield element according to the present invention is configured to be positioned in a shielding orientation in the ground, such that underground vibrations, for example traffic vibrations, can be damped by the shield element, for example by absorption of the underground vibrations, before the vibrations reach other objects. By damping substantially all and/or a portion of the underground vibrations, nuisance and noise pollution may be reduced and failure and damage of equipment and buildings may be avoided.

The underground vibration shield element is configured to be positioned in a shielding orientation in the ground. The shield element may be arranged in a path along which the underground vibrations to be dampened propagate, for example a path between a vibration source, such as a road surface or road foundation, and an object that is to be protected from underground vibrations, such as a building. This way, vibrational waves will come in contact with the shield element, and the shield element will at least partially absorb the vibrational energy. The vibrational wave will therefore be dampened by the shield element before reaching the object.

The underground vibration shield element may for example be used in one of two types of shielding orientations, or a combination of them. Firstly, the vibration energy may be reduced in a shielding orientation close to the vibration source, e.g. under a roadway. As a second option, the vibration may be reduced in a shielding orientation near the object to be protected. Various embodiments of the invention may provide benefits in one or both of these shield orientations.

The advantage of the underground vibration shield element according to the present invention is that the underground vibration damping properties of the main body of mineral fibres are enhanced by a pressure distribution layer and at least one channel. In particular, vibration damping of groundwater and water drainage through the at least one channel and protection of the structure of the main body through the pressure distribution layer.

The pressure distribution layer is arranged along a top surface, bottom surface and/or side surface the main body, and is configured to distribute ground pressure forces and/or vibration forces over the top, bottom and/or side surface, respectively. Therewith, the main body may be compressed evenly. Mineral fibres may be poorly resistant to point loads as an uneven load may damage the fibre structure, potentially affecting dimensions, stability and vibration-absorbing properties of the main body. The pressure distribution layer at least partially distributes point loads.

Underground vibrations propagate through the ground by vibrational waves, such as longitudinal and/or transversal waves, which comprise local pressure variations in the ground, transferred through ground forces by solid ground material, i.e. soil, such as clay and sand, and by ground water. The local pressure variations comprise an increase in grain tension of the solid ground material, respectively an increase in water tension of the ground water. According to the present invention, the pressure variation transferred by ground material may be relieved by subsequent compression and expansion of the main body, thereby providing vibration damping. The at least one channel improves vibrational damping as the at least one channel creates an empty space, and therefore increases the amount of air in the main body, which provides isolation and allows compression and expansion of the shield element for absorbing grain tension.

In railways, a relatively large thickness of ballast material having an open structure is often used underneath the track. On the one hand, this raises the railway above ground level, so that water can easily flow away sideways to avoid water tension in the ballast material. On the other hand, the ballast material spreads pressures and therewith prevents uneven loading of a vibration shield. However, in the case of roads, neither is often the case: The road may lie at ground level, or even below and the surrounding soil may drain water relatively poorly.. As a result, there may be relatively little space between a groundwater level and ground level for positioning a shield element and vibrations may also be transferred via local increases in water tension

In contrast with other vibration damping systems, the underground vibration shield element may be partially positioned underneath a ground water level and thereby also absorb pressure variations transferred by ground water, commonly referred to as increased water tension. By allowing ground water to flow relatively freely towards open spaces in the main body, in particular to rise in the at least one channel, the water tension may be reduced. This way, increased water tension may be relieved by the rising of the water in the at least one channel and it may be prevented that ground water flows around and/or through the main body, whereby the vibrational wave would be transferred.

Additionally, the at least one channel provides an open space into which water may flow and exert a pressure on main body around the at least one channel for absorbing water tension. For example, the water may flow freely into the open spaces, and vibration forces may be exerted on the main body through the at least one channel, such that pressure variations in ground water are relieved.

Thereby, water may be drained through the at least one channel in the main body by means of gravity, instead of around the main body. In doing so, water may be drained downwardly and a negative effect of the underground vibration dampening element on the moisture balance in surrounding soil may at least partially be mitigated, such that effects on stability of a road or building may be avoided. Additionally, a relatively good water drainage may be achieved without an additional drainage layer on top of the main body to drain water sideways around the main body. This may be advantageous as additional drainage layers can be relatively weak due to their open structure, or relatively heavy when a coarse crushed stone is used, such as basalt pebble. Lack of drainage could cause a water layer to form on top of the shield element, which could make a structure above it, such as a road, unstable, for example due to resulting quicksand.

It seems that this combined effect of damping both vibrations propagating trough soil grains and trough groundwater contributes to the improved vibration damping of an underground vibration shield element according to the invention.

This effect may even be achieved when the vibrational waves reach the pressure distribution layer from another direction with respect to the at least one channel. For example, vibrational waves coming from an inclined or diagonal direction may also be damped. As a result, less underground vibrations will reach the object and the vibrations that will still reach the object may have a lower amplitude, such that the object to be protected may be subject to less and less severe vibrations. This way, the shield element provides shielding to the object, and nuisance, noise pollution, equipment failure and damage due to underground vibrations may be prevented or at least reduced.

The advantageous combination of main body of mineral fibres, protective pressure distribution layer and at least one channel allows to obtain a vibration shielding element that drains water relatively well, that can possibly be placed partly under a groundwater level, whereby a relatively good corrosion resistance and vibration damping can be obtained for a relatively long time. In addition, the applicant has found that effective vibration damping may be provided and therefore considers the vibration shielding element to be very well applicable in both existing and new situations, under various soil conditions (such as in a shielding orientation partially underneath a groundwater level, in soft soil types and having a top layer of limited height above the shield element). As such, the shield element may perform well relatively close to a road surface, such as in existing situations where deeper cables or pipelines would obstruct deep walls, and/or in areas with a relatively high groundwater level.

Due to the simple installation of the vibration shield element, relatively little space is required and the amount of necessary adjustments to the subsoil may be lower than in many existing systems.

The main body may have any size and/or shape suitable for damping underground vibrations. The main body may advantageously have a rectangular shape with 6 sides that are substantially flat, as such a shape can be manufactured easily and allows to place multiple shield elements against other, side-by side to form a shield system of vibration shield elements. As such, shield elements may be laid side by side in three orthogonal directions, to create multiple layers of shield elements. The number of shield elements in each of the three directions may be adjusted to form a vibration shield having any desired the width, height and number of layers. This way, the properties of the vibration shield may be adapted regarding strength and desired damping properties, using a single type of shield element.

For example, when the shield element comprises a plate element, a longitudinal axis of the plate element, for example parallel to one of the side surfaces of the main body, may be arranged substantially transverse to the path travelled by the underground vibrations in the shielding orientation, for example transverse, such as perpendicular, to a vibration source. This way, a relatively large surface of the shield element, for example a side surface of the main body, may face the vibration source, such that a large amount of vibrational waves may come into contact with the shield element and be damped therewith. The shield element may for example be a rectangle of 1000x1200x150 mm, however, other dimensions may also be provided.

One of the sides of the main body may also have a special shape that differs from the shape of other sides of the main body. For example, a side may be provided with an inclined shape. An inclined side may be advantageous for the drainage of fluids along the top of the main body. In addition, a special shape can help in the application of top layers. For example, if a road pavement is applied on top of the shield element as a top layer, a camber that may be required on the road surface may already be provided with the main body. In this way, a top layer having a constant layer thickness can be applied on top of the shell element, while still a camber can be created on top of the underground vibration shield element.

The main body comprises a substrate of mineral fibres, forming a type of mineral wool. Mineral wool may also be referred to as mineral fibre or man-made vitreous fibre, and comprise stone wool, slag wool and glass wool. Mineral wools are known to have properties that are advantageous for damping sounds and/or vibrations. It has been found that these properties of mineral wool, for example the compressibility, density and open structure, may contribute to improved vibration absorption that surpasses the vibration absorption of other materials, such as polystyrene, which is commonly available in extruded (XPS) or expanded (EPS). In addition, mineral fibre may be provided with a relatively lower buoyancy, which is an advantage when provided underneath a groundwater level and/or relatively light soil types.

A load rating of the main body may for example be 50-200 kN/m ² , for example 80 kN/m ² when arranged in a shielding position next to a foundation of a building, or 180 kN/m ² when arranged in a shielding position underneath a road surface.

The mineral fibres may be arranged in a particular direction, for example perpendicular to an expected propagation direction of vibrations. This way, a vibration may push fibres of the substrate towards each other, opposed to or in addition to a compression of the fibres themselves, such that vibration damping of the shield element may be enhanced.

In an embodiment, the substrate is hydrophobic. Hydrophobic properties may be advantageous to minimize the amount of water absorbed by the shield element. It has been found that the shield element exhibits improved shielding properties when a lower amount of water is absorbed in the mineral wool structure. Water absorption by the shield element displaces insulating air that is enclosed in the mineral wool. Water transfers vibrations more effectively than air and therefore, the presence of water in the mineral wool decreases the vibration shielding properties of the shield element. In particular when arranged at least partially underneath a groundwater level, hydrophobic properties may advantageously reduce water retention in the main body and therewith improve vibration damping characteristics.

Additionally, when the shield element is arranged on an object to be protected, the presence of water may cause moisture absorption and corrosion in the object, for example the foundation of a building, which is usually not desirable as that may cause inconvenience to users and construction problems.

The pressure distribution layer may have any desirable shape. Advantageously, the shape of an inner side of the pressure distribution layer corresponds to the shape of the respective surface of the main body, such that the pressure distribution layer fits over that respective surface, allowing forces and vibrations to be transmitted evenly. Additionally, an even fit may prevent resonance of the layer due to movement with respect to the main body.

The pressure distribution layer may also be arranged on the inner surface of the at least one channel. When multiple channels are provided, the pressure distribution layer may be arranged on the inner surface of all channels. Therewith, pressure may also distributed within the channel, for example pressure due to ground water.

The pressure distribution layer may comprise any material suitable for distributing vibrations and ground/traffic vibrations and forces over the surface of the main body. Advantageously, the pressure distribution layer is made of a more rigid material than the substrate, such that vibrations may be distributed over the whole surface of the main body by the pressure distribution layer, with less deformation of the layer itself, for example without substantial deformation of the layer. In this way, the vibrations through the layer can be transmitted to the main body, where the vibrations are absorbed by elastic deformation of the substrate. Further, a more rigid material may protect the mineral fibres of the main body.

A load rating of the pressure distribution layer may be higher than a load rating of the main body.

The pressure distribution layer may comprise an elastic material, for example based on natural or synthetic polymers (such as natural rubber, latex and silicones) and/or elastomers (such as synthetic rubber, LDPE, polyurethane, EPDM, neoprene, polyurea) and/or bitumen and/or mixtures thereof.

In particular, the pressure distribution layer has a stiffness that is chosen such that compressive forces are distributed along the surface of the main body, but the pressure distribution layer is sufficiently flexible to adapt gradually to settlement in the subsoil. In particular, in the case of several shielding elements connected together, a relatively large vibration-damping system can thus be created which can adapt to settlement in the soil, possibly without the individual shielding elements being so stiff that excessive forces would occur at connection points between them.

A pressure distribution layer may distribute the ground pressure forces along at least a portion of the respective surface of the main body, such that relatively large local differences may be avoided. The pressure distribution layer may extend through the at least one channel. Advantageously, the pressure distribution layer covers the entire surface of the at least one channel. This way, when multiple vibration shield elements are arranged adjacent to each other, the surfaces of the main body that are adjacent to the soil and/or ground water, may be protected by the pressure distribution layer.

In particular, the pressure distribution layer may be arranged along the top surface, the bottom surface and the side surfaces of the main body, and in the inner surface of the at least one channel, such that the main body is completely covered by the pressure distribution layer.

The pressure distribution layer may be watertight. This way, the pressure distribution layer may reduce the amount of water, such as rain or ground water, and/or the amount of substances suspended and/or dissolved in water that may flow into the main body. As such, blocking of open spaces in the main body may be reduced and watertightness may improve vibration damping.

In particular, watertight sealing of the main body may prevent the main body from being damp for long periods, which can be a risk when arranged in groundwater and may cause vibrations to be transmitted through the water in the main body. Further, a relatively compact or non-hydrophobic mineral wool may potentially be used, as the main body may be protected against capillary effects by the watertight pressure distribution layer.

As such, water may flow through the at least one channel through the main body, whereby water flow into the substrate through the inner surface of the at least one channel may be prevented when the pressure distribution layer is also arranged on the inner surface of the at least one channel.

In an embodiment, the underground vibration shield element comprises multiple pressure distribution layers. The multiple pressure distribution layers may be arranged on opposite sides of the main body. Additionally or alternatively, the multiple distribution layers may be partially or completely stacked on top of each other.

In a further embodiment, at least one of the multiple pressure distribution layers extends through the at least one channel. This way, the at least one channel may be protected by a first one of the multiple pressure distribution layers having different properties from a second one of the multiple pressure distribution layers. In particular, the first pressure distribution layer may be more flexible but less rigid than the second pressure distribution layer.

The pressure distribution layer may be provided as a pressure distribution plate.

The pressure distribution plate may comprise a thickness that is relatively thin compared to the main body, for example form a relatively thin layer, such as a sheet of elastic material The thickness may be substantially uniform. The thickness may for example be less than 5 mm, for example 2 mm. The pressure distribution plate may comprise a single piece and/or a continuous layer of material.

The pressure distribution plate may have any desirable shape. Advantageously, the shape of an inner side of the pressure distribution plate corresponds to the shape of the respective surface of the main body, such that the pressure distribution plate fits over that respective surface, allowing forces and vibrations to be transmitted evenly. Additionally, an even fit may prevent resonance of the plate due to movement with respect to the main body.

The pressure distribution plate may comprise any material suitable for distributing vibrations and ground/traffic vibrations and forces over the surface of the main body. Advantageously, the pressure distribution plate is made of a more rigid material than the substrate, such that vibrations may be distributed over the whole surface of the main body by the pressure distribution plate, without substantial deformation of the plate itself. In this way, the vibrations through the plate can be transmitted to the main body, where the vibrations are absorbed by elastic deformation of the substrate.

When the shield element is positioned in the ground, ground forces may act on the surfaces of the main body. Ground pressure may occur due to the ground surrounding the shield element in the shielding orientation, but also due to top layers applied on the shield element. If traffic is present around the shield element, the traffic loads and vibrations can cause additional forces. These forces may be unevenly distributed over the main body. It has been found that this may cause differences in the vibration damping properties of the shield element, such as a local decrease of vibration damping. A pressure distribution plate distributes the ground pressure forces along the surface, such that local differences are avoided.

Furthermore, when a road is constructed on a ground layer on top of the shield element, the continuous traffic load may cause gradual rutting in the shield element. It has been found that rutting causes deformations in the substrate, which form an increasingly weak spot that is susceptible to further deformation, causing further progression of the deformation in the substrate, et cetera. Additionally, an underground vibration shield element may even rupture locally, which may cause sagging of the shield element. A deformed road profile due to rutting or sagging of the shield element may then result in additional traffic vibrations. The plate distributes traffic load outside of the average track width of traffic, so that the forces may be spread over the surface of the main body to prevent rutting therein.

The pressure distribution plate offers the additional advantage that, during the construction of a vibration shield, it provides strength to the shield elements. It has been found that the application of the substrate without protective measures may be susceptible to damage, for example causing tears of dimples in the surfaces of the main body. Damage to the shield element may occur while arranging it in the shielding orientation, during handling, or due to unevenness or sharp obstacles in the ground. Damage may be unwanted if a solid construction, for a road or other infrastructure is required. The damage may be such that the structure above, such as the road, can no longer fulfil its purpose. Damage may also result in uneven vibration damping and may hamper water discharge around the shield element. The pressure distribution plate may comprise a higher rigidity and/or surface hardness than the main body. Therewith, the pressure distribution plate protects the surface of the main body, and limits bending or twisting of the main body.

The pressure distribution plate may, for example, be a plate formed of a single layer. In an embodiment, the pressure distribution plate comprises an inner side, arranged along the main body, and an opposite outer side, configured to, in the shielding orientation, be in contact with the ground.

The inner and the outer side may be provided with different surfaces.

In an embodiment, the outer side is provided with a smooth surface. A smooth surface of the outer side may be advantageous in the case of a vertical shielding orientation, as less vertical ground forces may be exerted on the sheet along this surface than would be the case with a structured surface. In particular, a smooth surface of the outer side may be beneficial for avoiding deformation of the main body in case of a vertical shielding orientation of the underground vibration shield element. .

In an embodiment, the inner side is provided with a smooth surface. A smooth surface of the inner side avoids deformation of the main body. This way, local variations in vibration compressibility of the main body are avoided, which may result in improved vibration damping properties of the underground vibration shield element.

In an embodiment, the pressure distribution plate comprises an inner side, arranged along the main body, and an opposite outer side, configured to, in the shielding orientation, be in contact with the ground, wherein the inner and the outer side are provided with different surfaces. This way, the structure and surface roughness of the surface of the inner and the outer side may be optimised for adherence to another surface, such as the main body, a pressure distribution plate, a cover layer or the ground.

In a further embodiment, the outer side comprises a structured surface with elevated elements that extend transversely from the surface. The elevated elements may, for example extend perpendicular to the surface. A structured surface may be advantageous for the application of top layers, such as road paving or sand. The structure prevents movement of the top layer with respect to shield element. The elevated elements may for example have a height of 2 cm or more, such as 4 cm.

The elevated elements may comprise materials such as metal (such as steel) or (fibre- reinforced) plastic such as composite, polypropylene, and/or glass fibre reinforced plastic. The elevated elements may for example form a grating, such as a metal grating or a plastic grating. A grating is advantageous as it may provide a relatively high rigidity compared to weight. The grating may, for example, comprise a square mesh and/or a round, hexagonal or differently shaped mesh.

In an embodiment, the elevated elements are provided with drain openings that extend through the elevated elements from one side towards an opposing side. The drain openings may allow fluids to drain sideways between the elevated elements, such that retention of fluids, for example rain water, in between the elevated elements may be limited.

In an embodiment, the pressure distribution plate is provided with through-going openings in a direction perpendicular to the inner surface. The trough-going openings may be fluid open, such that fluids may drain through the through-going openings towards the main body and through the at least one channel.

In a further embodiment, the pressure distribution plate is arranged on the top and/or bottom surface of the main body, and the through-going openings are arranged in fluid communication with at least one of the top openings and/or bottom openings of the main body. This way, fluids may be drained through the shield element efficiently. In an embodiment, elevated elements are arranged in groups, wherein groups of elevated elements enclose subregions of the structured surface. In this embodiment, at a first portion of the enclosed subregions, the pressure distribution plate may be provided with through-going openings.

In a further embodiment, a second portion of the enclosed subregions is fluidly connected to the first portion of the enclosed subregions with the drain openings. This way, the trough-going openings do not need to be aligned with the elevated elements.

In an embodiment, the underground vibration shield element comprises two pressure distribution plates arranged on opposite sides of the main body.

The pressure distribution plate may comprise a plate element. The plate element may be a pre-formed plate element that is arranged on the main body, for example by glue. In particular, the plate may be pre-formed by injection moulding, stamping or cutting. Drain openings may be pre-formed in the plate element, or alternatively be provided after arranging the plate element on the main body.

The plate element may, for example, be a plate element having a low friction surface. The low friction surface may be a smooth surface. The plate element may be a plastic plate element, for example comprising polyethylene, polypropylene or nylon. A low frictions surface has been found to be advantageous to avoid shear forces in the main body due to settling of the surrounding soil, in particular in sticky soils, such as clay soils.

Additionally or alternatively, the pressure distribution plate may be formed by a coating that is arranged on the main body. The coating may be applied on the main body upon provision of the at least one channel in the main body. This way, the coating may easily be applied on the surface of the at least one channel.

The coating may for example be applied by spraying and/or immersion in a coating fluid. In particular, the main body may be completely submerged in the coating fluid for application of the elastic coating.

The coating may comprise a natural and/or synthetic, polymer and/or elastomer, bituminous substances and/or mixtures thereof.

In an embodiment, the pressure distribution layer comprises a coating arranged on the main body, and at least one plate element arranged on a top, bottom and/or side surface of the main body.

The at least one channel may allow fluids to drain out of the main body, through the channel, into the ground. It has been found that, even in the case of a hydrophobic substrate and/or a pressure distribution plate, relatively small amounts of moisture may present in the main body, in particular when no watertight pressure distribution layer is arranged all sides of the main body and on the inner surface of the at least one channel. For example, due to aging, hydrophobic properties of the main body may decline and due to the capillary phenomenon, ground water may be absorbed by the main body. As a result, small amounts of moisture may fill open spaces in the main body, causing air to be expelled out of the main body and reducing the vibration damping properties thereof. The provision of at least one bottom opening allows this water to drain away, such that the effect of aging of the main body may be overcome or alleviated.

Additionally, water in the underground vibration shield element may freeze, resulting in damage of the substrate, causing breakage of the structure between mineral fibres. Especially in colder climates, and/or open ground layers, for example permeable layers of road surfacing, this may cause an unwanted decline of vibration damping properties of an underground vibration shield element. By draining fluids, the risk of damage due to frost is at least partially relieved.

Water absorbed by the main body may be drained from the inside of the shield element. Especially when multiple shield elements are arranged adjacently to form an underground vibration shield system, drainage of water around the shield elements may be limited and a channel enables efficient drainage.

The at least one channel may for example have a diameter of 20-50 mm, but other dimensions may also be provided. One or more channels may have a different diameter. The channels may be positioned in the centre of the main body or in any other place. The channels may be round, square, rectangular, triangular, hexagonal or any other shape. The at least one channel may also have the shape of a semi-geometric figure, for example a semicircle.

The channels may arranged in side surface in the main body. In this way, a contact area between the shield element and a building's foundation can be reduced, creating ventilation space with the at least one channel. This way, moisture problems may potentially be reduced through improved ventilation of the foundation through the at least one channel. When the vibration shield element is arranged in the shielding orientation, the at least one channel may extend in a substantially vertical direction.

In an embodiment, a side surface of the main body extends in a first direction parallel to the at least one channel with a first length, and in a second direction perpendicular to the first direction, wherein a top surface and/or bottom surface extends in a third direction perpendicular to the first direction and the second direction with a second length, wherein the second length is smaller than the first length. As such, the at least one channel may extend in a vertical longitudinal direction of the plate. This way, a relatively large surface of a building foundation may be covered by a side surface, when arranged in a shielding position near a building foundation.

In an embodiment, the at least one channel has a top opening in the top surface of the main body, such that the at least one channel runs through the main body from the bottom opening to the top opening. This way, water may be drained from the top surface of the main body through the at least one channel.

In a further embodiment, the top opening and bottom opening are of equal size and shape. This allows placement multiple shield elements adjacent to each other, with adjacent top and bottom openings being aligned with each other.

The cross-sectional surface area of each channel may be constant over a length of the channel. A constant cross-sectional surface area may be beneficial as it provides constant vibration damping properties throughout the shield element.

In an embodiment, a surface area of a cross section of the at least one channel is at least 1 %, for example at least 5%, such as 10%, of a surface area of the main body in a direction of the cross-section of the at least one channel. The cross section may, for example, be an average cross section of the at least one channel in an axial direction of the at least one channel. By having a larger surface area, less vibrations may be transferred by the main body, fluid flow through the channels may be enhanced and/or vibration damping of the underground vibration shield element may be improved.

In an embodiment, a volume of the at least one channel is at least 1%, for example at least 5%, such as 10% of a volume of the underground vibration shield element. The surface areas and/or volumes mentioned above have been found to provide the shield element with advantageous vibration damping properties. Open spaces in the main body may be formed by the structure of the mineral fibres in the main body, and/or by the at least one opening. Therefore, an open structure of mineral fibres in the main body may also contribute to vibration damping and/or absorbing properties of the shield element.

In an embodiment, the underground vibration shield element comprises multiple channels. By providing multiple channels, the number, position and orientation of the multiple channels may be optimised for the vibrations to be damped. The compression strength of the main body varies with these properties. For example, application under a road may require a higher strength to withstand traffic loads.

In a further embodiment, the multiple channels are arranged, in the shielding orientation, vertically parallel to each other. Whereas horizontal channels could, in the shielding orientation, reduce the vertical stiffness, vertical channels may provide vertical stiffness of the underground vibration shield element, which may be advantageous for withstanding traffic loads when a road is to be built above an underground vibration shield element.

The multiple channels may be arranged in a pattern, for example a regular pattern in which the multiple channels are evenly distributed over the main body. An even distribution may provide constant vibration damping properties and water drainage properties throughout the underground vibration shield element. Alternatively, multiple channels or groups of multiple channels may be spaced at equal distances from each other. The multiple channels may be arranged in a pattern over the whole main body or in a particular area of the main body, for example nearby an outer edge of the main body, at two opposite outer edges of the main body, et cetera.

By having multiple channels arranged next to each other, for example in a row, two sides of the main body may be separated from each other by the multiple channels. In particular, the multiple channels may be arranged in between two side surfaces of the main body. This way, a certain degree of mechanical decoupling of the respective side surfaces may be obtained, in particular when multiple channels are arranged in a row, which may advantageously contribute to the vibration damping. As an example, a row of 10-20 channels may be provided.

In an embodiment, the multiple channels may also be arranged in multiple rows in between two side surfaces of the main body. The multiple rows may be shifted with respect to each other, for example in a honeycomb-like pattern. This may further contribute to vibration damping.

In an embodiment, the underground vibration shield comprises a cover layer that covers at least the bottom opening and/or the top opening. The cover layer may prevent and/or limit ingress of material into the at least one channel, such that the at least one channel remains substantially open. The cover layer may be a layer arranged on top of the bottom opening and/or the top opening to cover the bottom opening and/or the top opening, respectively, or be arranged in an outer end of the at least one channel, to form a recessed cover in the channel. This way, ingress of material, for example ground material such as sand or clay, or the intrusion of pollution or organisms into the at least one channel may be prevented and the at least one channel remains substantially open. This way, water and air may flow therein, contributing to the advantageous properties of the present invention.

The cover layer may be soil-retaining but water-permeable.

The cover layer may comprise a separate layer, or may be integrally formed in the pressure distribution layer and/or the main body. The cover layer may comprise the main body material, the pressure distribution layer material, and/or another material, for example a natural, sustainable material.

The cover layer may partially or completely surround the main body. In this way, entire sides of the main body can be covered by the covering layer. The cover layer may be attached to the main body by wrapping the main body, without the need for additional fixation means. The cover layer may also be applied locally around the bottom opening and/or the top opening.

In addition or as an alternative, the cover layer may be bonded to the main body, for example be glued thereto. An advantage of bonding is that the movement of the main body in relation to the covering layer may be limited therewith. This way, for example, a shape of the main body may be maintained by the covering layer, and/or alignment of the covering layer may be guaranteed, for example with respect to the at least one channel. As such, creep deformation of the main body and/or misalignment of the covering layer due to traffic or ground forces may be prevented.

In case of a pressure distribution layer that is applied as a liquid, the cover layer may be embedded in the liquid before curing, such that the cover layer is bonded to the pressure distribution layer upon curing of the pressure distribution layer.

The cover layer may provide protection to the main body, in particular when the pressure distribution layer is not arranged on all sides of the main body and when the main body has a softer, less coherent and/or less tear-resistant structure than the covering layer. For example, rupturing or disintegration of the main body, e.g. of a rock wool main body due to rough handling, can be limited as the main body is at least partially held together by the covering layer. In an embodiment, the cover layer is a fluid-permeable cover layer. An advantage of having a fluid-permeable cover layer is that it may allow water to flow through the cover layer, such that water may flow into and/or be drained out of the main body. The cover layer may comprise synthetic or organic material, for example woven or non-woven textiles, jute or recycled material such as clothing.

For example, the cover layer may be a geotextile fabric layer. A geotextile fabric is readily available and has been found to offer advantageous properties in terms of durability, water permeability and tear resistance.

The fluid-permeable cover layer may at least partially be arranged in between the between the pressure distribution layer and the main body.

The cover layer and/or the pressure distribution layer may over its full surface be attached to the main body. This may ease fabrication or processing of the shield element (e.g. cutting a recess for a cable or pipe) easier than with a loose cover layer, respectively pressure distribution layer.

In an embodiment, the underground vibration shield element comprises one or more connectors to connect the underground vibration shield element to an adjacent vibration shield element. This way, the shield elements may cooperate to form a vibration shield such that leaking of vibrations between adjacent vibration shield elements, in particular between pressure distribution layers thereof, may be avoided or at least reduced. In addition, connecting prevents the movement of a shield element by ground and/or traffic forces may at least partially be prevented.

The connectors may rigidly connect the underground vibration shield element to an adjacent vibration shield element

In a further embodiment, the pressure distribution layers are connected by the one or more connectors. As such, the pressure distribution layers may cooperate to distribute ground forces and vibrations along multiple shield elements. Therewith, an even and advantageous vibration damping may be achieved.

In an embodiment, the connectors extend through the underground vibration shield element in a direction perpendicular to the pressure distribution layer, such that the connectors do not limit movement of the underground vibration shield element.

In an additional or alternative embodiment, the connectors do not extend though the main body.

In an embodiment, the connectors connect adjacent elevated elements of the pressure distribution layer. The connectors may for example comprise bolts, rivets or pins.

In an embodiment, the connectors have dimensions corresponding to trough-going openings in the pressure distribution layer. This way, connectors may be attached to and/or detached from the pressure distribution layer through the through-going openings. This may be advantageous, as the amount of connectors required for a solid connection may depend on circumstances as soil type, groundwater level, and expected pressure loads, such as traffic loads. The connectors may also have different dimensions.

In an embodiment, the connectors may connect underground vibration shield elements by providing a clamping force between adjacent underground vibration shield elements. This way, a strength of the connection may be further improved.

The present invention further provides an underground vibration shield system, comprising a plurality of underground vibration shield elements arranged in the shielding orientation in the ground to form a row of underground vibration shield elements, for damping and/or absorbing vibrations. By having a plurality of underground vibration shield elements, larger objects may be shielded from vibrations and/or objects may be shielded from larger vibration sources, multiple vibration sources or moving vibration sources. Additionally, vibrations may be damped and/or absorbed more effectively by a plurality of underground vibration shield elements.

In an embodiment, the plurality of underground vibration shield elements are connected to each other to form a row of connected underground vibration shield elements. As such, transfer of vibrations in between adjacent underground vibration shield elements may be reduced. Additionally, movements of the underground vibration shield elements with respect to each other may be prevented.

In a further embodiment, the pressure distribution layers of the respective connected underground vibration shield elements are connected to each other, for example by a connector. As such, the pressure distribution layers may cooperate to distribute ground forces and vibrations along multiple shield elements. Therewith, a more even and advantageous vibration damping may be achieved.

The multiple underground vibration shield elements may be connected such that vertical movement of the shield elements with respect to each other is constrained by the connection, such that the chances of a single shield element being pressed into the soil can be reduced.

Additionally or alternatively, underground vibration shield elements may be connected such that horizontal movement of the shield elements with respect to each other is constrained by the connection, such that the chance of horizontal gaps between underground vibration shield elements can be reduced.

It has been found that if the pressure distribution layers of different shield elements can move individually from one another, tipping movements of an individual pressure distribution layers may potentially occur due to traffic loads, which may cause damage to the main body. By fixing the pressure distribution layers of the shield elements to each other, the tilting movement may at least partially be prevented. In an embodiment, underground vibration shield elements at outer edges of the row of underground vibration shield elements extend perpendicular to the other underground vibration shield elements of the row of underground vibration shield elements. The other underground vibration shield elements of the row of underground vibration shield elements may, for example, be arranged substantially horizontally, while underground vibration shield elements at outer edges of the row of underground vibration shield elements are arranged vertically to damp vibrations that propagate sideways, such as superficial vibrations.

In an embodiment, a second row of underground vibration shield elements is stacked on the row of underground vibration shield elements. By having multiple rows, vibration absorbing and/or damping properties of the underground vibration shield system may be improved.

In a further embodiment, top openings of the row of underground vibration shield elements are in fluid connection with bottom openings of the second row of underground vibration shield elements. This way, continuous channels, for example vertical continuous channels may be formed through which water may flow freely to be drained and/or for vibration damping. This is different from water infiltration, wherein water flows may be slowed down in order to infiltrate the soil gradually.

The underground vibration shield system may, in an embodiment, further comprise a mounting bracket, configured to mount the underground vibration shield elements in a shielding orientation on an object, such as a building. The mounting bracket prevents movement of the shield element with respect to the object due to ground movements. This may be especially advantageous in areas where the ground can move through creep, such as with soft clay or peaty soil. Additionally, a mounting bracket allows the shield elements to be placed in a vertical shield orientation, in which there is relatively little support from the soil.

A further advantage of mounting the underground vibration shield elements to a abuilding, is that it enables the shield elements to function as sheet piling. Usually, a foundation of a building comprises an open space or crawl space for maintenance. As a result of creep of the soil, precipitation and vibrations, the crawl space may fill up with soil material over time. As a result, the paving around the building may sag and the crawl space becomes less accessible. A mounted vibration shield element may act as a sheet pile wall around the foundation of the building, which separates the crawl space from the soil, and therewith prevents soil material from entering to keep the foundation and/or crawl space accessible and avoid sagging of for example pavement around the building.

In an embodiment, the mounting bracket comprises mounting elements, such as pins and/or clamps, extending around a part of the shield element, and configured to mount the underground vibration shield elements in the shielding orientation by delimiting movement of the part of the shield element with respect to the mounting bracket. In an embodiment, the mounting elements have a predefined thickness, such as less than 30% of the thickness of the main body in a cross section perpendicular to the shielding orientation, for example less than 20%, such as less than 10%. As a thick mounting element may limit compressibility of the main body, a thin mounting element has been found to be advantageous for vibration damping. The mounting elements may, for example, have a thickness of less than 15 mm, such as an M8 bolt.

Additionally, a mounting bracket and/or mounting element surrounding the underground vibration shield element may not be desired as it may transfer underground vibrations. The mounting bracket may have a thickness, in particular in a direction perpendicular to the mounting surface, of less than 60% of the thickness of the main body in a cross section perpendicular to the shielding orientation, for example less than 40%, such as less than 30%. This seems to be able to achieve a good fixation of the shield element with adequate vibration damping.

In an alternative embodiment, the underground vibration shield element may comprise a main body and a pressure distribution layer, without at least one channel. In this embodiment, there is provided an underground shielding element, configured to be arranged in a shielding orientation in the ground for damping and/or absorbing underground vibrations, comprising: a main body comprising a substrate of mineral fibres with a bottom surface to be arranged downwards in the shielding orientation of the shield element, and a pressure distribution layer, arranged along a top surface, bottom surface and/or side surface of the main body, configured to distribute ground pressure forces and/or vibration forces over the top, bottom and/or side surface respectively.

In this alternative embodiment, the underground vibration shield element may be treated to be water repellent, and/or a water repellent foil may be provided on the underground vibration shield element.

Additionally or alternatively, the pressure distribution layer may have dimensions slightly larger than the respective top surface, bottom surface and/or side surface of the main body along which it is arranged such that when multiple underground vibration shield elements are arranged adjacent to each other, the respective pressure distribution layers of the adjacent underground vibration shield elements may come in contact, while a gap remains the respective adjacent main bodies. Water may be drained through the remaining gap.

According to another aspect of the invention, a method for shielding an object from underground vibrations, for example traffic vibrations, is provided, comprising the step of arranging a plurality of underground vibration shield elements according to any of the claims 1-14 in a shielding orientation in the ground, for example in the ground in between an object and a vibration source. This method enables shielding the object from underground vibrations, by damping and/or absorbing vibrations caused by the vibration source, such as a vehicle driving on the road surfacing, with the shield elements.

The combination of channels and pressure distribution layers may provide sufficient vibration damping of traffic vibrations such that no expensive concrete deep wall is required around the object to be shielded from vibrations, such as a building.

In addition, at least one channel may provide water drainage, such that relatively little or no water remains on the vibration shield element.

In an embodiment, the method further comprises the step of connecting the underground vibration shield elements to form a vibration absorbing and/or damping shield system of connected underground vibration shield elements. As such, vibration damping and/or absorption may be improved.

The step of arranging the plurality of shield elements in the shielding orientation may, for example, be followed by a step of covering the plurality of underground vibration shields with a top layer of ground, covering material and/or road surfacing. This way, an existing vibration source, such as a road, may be provided with advantageous vibration shielding.

In an embodiment, underground vibration shield elements are arranged in row as a underlayer for a road. Shield elements of the row of underground vibration shield elements may be arranged , while underground vibration shield elements at outer edges of the row of underground vibration shield elements are arranged vertically to damp vibrations that propagate sideways, such as surficially propagating vibrations.

Vibration shield elements may be arranged horizontally to form a horizontal surface wherein the at least one channels are arranged vertically in the horizontal surface. In addition, shield elements may be positioned vertically on the outer edges of the horizontal surface to form a vertical surface adjacent to the horizontal surface, for example, wherein the at least one channel in the respective shield elements in also runs vertically.

In an embodiment, the method comprises the steps of attaching a mounting bracket to an object, such as a building, and positioning the underground vibration shield elements in the mounting bracket for fixing the underground vibration shield elements in a shielding orientation on the object. By fixing to the object, movement with respect to the object may be prevented. The underground vibration shield elements may be mounted to the object, for example be suspended thereon. Alternatively, the underground vibration shield elements may be supported in the soil, while the fixing on the object prevents movement of the underground vibration shield element in the soil. In a further embodiment, the underground vibration shield element may be fixed on a mounting surface of the object, such that the underground vibration shield element, in the shielding orientation, is oriented with a longitudinal axis parallel to the mounting surface.

By fixing the vibration shield element to an existing surface, such as a building's foundation, the building can be protected from vibrations, so that an existing situation, for example with existing, older houses, can easily be shielded from vibrations. Particularly attractive is the possibility of attenuating traffic vibrations for existing buildings and/or buildings nearby a road.

In addition, fixation prevents the shield element from deformation and/or movement in relation to its surroundings due to subsidence of surrounding soil or varying groundwater levels, such that vibration damping may also be provided in areas with subsidence or varying groundwater.

Due to the convenient handling of the main body, it may be possible to position the shield element against or around existing house connections and foundation penetrations, such as cables or pipes, of the building. Fixing the shield element may prevent deformation of these pipe penetrations in the event of subsidence or varying groundwater.

In particular, if the pressure distribution layer is watertight, the risk of water penetrating into the main body is relatively low, even in the long term, so that direct installation against the foundation may be possible without the need for additional measures such as a waterproof layer on the foundation.

In an embodiment, the bottom side of the main body is, in the shielding orientation, arranged on approximately the height of a foundation foot or foundation beam of the object, or slightly below the foundation, such as 30 cm below the foundation foot or foundation beam. This way, a relatively large part of the object may be shielded from vibrations.

In a further or alternative embodiment of the method, the underground vibration shield elements are, in the shielding orientation, at least partially positioned below a groundwater level in the ground. The underground vibration shield elements may for example be arranged at a depth just below the ground surface, up to a depth of less than 2,5 m below the ground surface, for example less than 1,5 m underneath the ground surface.

By arrangement at least partially below a groundwater level, the shielding element may also be used in relatively humid environments and/or weaker soil types, such as in the Netherlands. The bottom side of the main body may be positioned at least 5 cm, for example approximately 10 cm underneath a ground water level.

In case of high groundwater levels and/or the transmission of vibrations through both the soil and the groundwater, it was difficult in the past to dampen vibrations, particularly traffic vibrations. With the invention, vibrations may be attenuated by open spaces in the underground vibration shield element, and transmission via ground water may be attenuated by allowing the groundwater to rise within the channels of the respective vibration shield elements, in particular the water may rise in the channel at a relatively low resistance.

In an embodiment, the methods further comprises the step of determining a groundwater level in the ground, a maximum pressure load on the underground vibration shield elements in the shielding orientation, and/or characteristics of the vibrations to-be- damped, such as traffic vibrations; and selecting a shielding orientation in the ground for the plurality of underground vibration shield elements in dependence of the determined ground water level, soil type, maximum pressure load and/or vibration characteristics.

In an embodiment, the method comprises the step of selecting a number of channels in dependence of the determined ground water level, maximum pressure load, soil type and/or vibration characteristics, wherein the step of arranging a plurality of underground vibration shield elements in a shielding orientation in the ground is performed using vibration shield elements having the selected number of channels. In addition or alternative to the number of channels, a shape, size and positioning thereof may be selected and optimised to the specific circumstances.

Brief description of drawings

Further characteristics and advantages of the invention will now be elucidated by a description of the embodiments of the invention, with reference to the accompanying drawings, in which:

Figure 1 A schematically depicts a disassembled perspective view of an underground vibration shield element according to an embodiment of the invention;

Figure 1 B schematically depicts a disassembled perspective view of an underground vibration shield element according to another embodiment of the invention; Figure 2A schematically depicts a side view of the main body of the underground vibration shield element of Figure 1A, along cross section A-A;

Figure 2B schematically depicts a top view of the underground vibration shield element of Figure 1A, along cross section B-B;

Figure 2C schematically depicts a side view of a main body of the underground vibration shield element according to another embodiment the invention, using a similar view as in Figure 2A;

Figure 2D schematically depicts a side view of a main body of the underground vibration shield element according to another embodiment the invention, using a similar view as in Figure 2A;

Figure 3A schematically depicts a partial perspective view of the pressure distribution plate of Figure 1A; Figure 3B schematically depicts a partial perspective view of the pressure distribution plate according to another embodiment of the invention;

Figure 4 schematically depicts a disassembled perspective view of an underground vibration shield element according to an embodiment of the invention;

Figure 5A schematically depicts a perspective view of the underground vibration shield element of Figure 1A, further comprising multiple connectors;

Figure 5B schematically depicts a side view of the underground vibration shield element of Figure 5A, along cross section C-C, wherein the underground vibration shield element is connected to adjacent vibration shield elements to form a row of connected underground vibration shield elements;

Figure 6 schematically depicts a perspective view of an underground vibration shield system according to an embodiment of the invention;

Figure 7 schematically depicts a side view of detailed section S of the pressure distribution plate of Figure 6, when arranged next to an adjacent pressure distribution plate;

Figure 8A schematically depicts a side view of a disassembled underground vibration shield element positioned in a shielding orientation in the ground;

Figure 8B schematically depicts a side view of the disassembled underground vibration shield element of Figure 8A, when subject to a vibrational wave;

Figure 9A schematically depicts a perspective view of an underground vibration shield system according to an embodiment of the invention;

Figure 9B schematically depicts a side view of the underground vibration shield system of Figure 9A;

Figure 9C schematically depicts a side view of an underground vibration shield system according to an embodiment of the invention, when subject to a vibrational wave;

Figure 9D schematically depicts a side view of an underground vibration shield system according to another embodiment;

Figure 10A schematically depicts a perspective view of a disassembled underground vibration shield system according to an embodiment of the invention;

Figure 10B schematically depicts a perspective view of a disassembled underground vibration shield system according to an embodiment of the invention;

Figure 11 schematically depicts a perspective view of the underground vibration shield system of Figure 10A in a shielding orientation in the ground, when mounting brackets are attached to a building.

Figure 12 schematically depicts a top view of a cross section of embodiments of the main body of the underground vibration shield system of Figure 10A. Throughout the figures, the same reference numerals are used to refer to corresponding components or to components, which have a corresponding function.

Detailed description of embodiments

Figures 1A, 1B, 2A, 2B and 3A schematically depict an underground vibration shield element 1 according to an embodiment of the invention, partially or in its entirety.

The underground vibration shield element 1 is configured to be arranged in a shielding position in the ground for damping and/or absorbing underground vibrations and comprises a main body 2, two pressure distribution plates 3 and at least one channel 4 extending through the main body 2.

The main body 2 comprises a substrate of mineral fibres with a bottom surface 21, a top surface 22 and side surfaces 23. The bottom surface 21 is configured to be arranged downwards in direction D in the shielding orientation. The main body 2 may have a rectangular shape and comprises a substrate of mineral fibres, for example stone wool, such as hydrophobic stone wool.

The pressure distribution plates 3 are arranged on opposite surfaces of the main body 2, along the top 22 and bottom 21 surfaces. The pressure distribution plates 3 are configured to distribute ground pressure forces and/or vibration forces over the respective surfaces, and comprise a relatively rigid material, for example a plastic, such as polypropylene or steel.

The pressure distribution plate 3 comprises an inner side 31 arranged along the main body 2. An opposite outer side 32 is configured to, in the shielding orientation, be in contact with the ground, and is provided with a surface that is different from the surface of the inner side 31. The outer side 32 comprises a surface that is structured on a macroscopic scale. The structured surface comprises elevated elements 33, 34 that extend transversely from the surface 21, in particular perpendicular from the surface 21. The elevated elements 33, 34 comprise a set of walls 33 arranged perpendicularly to another set of walls 34. The elevated elements 33 34 are made of metal strips which form a square mesh grating. The elevated elements 33 34 have a height of 4 cm.

The elevated elements 33, 34 enclose subregions of the outer surface 32. Alternatively, the elevated elements 33, 34 may also be arranged at a distance from each other, to allow water flow between them and/or may extend under an angle as to improve and or decrease resistance of the surface in the ground. The elevated elements 33, 34 have a constant wall thickness, but may also have a varying wall thickness. The elevated elements 33 34 improve stability of the underground vibration shield element 1 in the ground, and may also improve stability of top layers, such as sand or gravel applied on top of the underground vibration shield element. The elevated elements form a grating comprising a square mesh. The embodiment of Figure 1 B comprises multiple pressure distribution layers 3 3’, two pressure distribution plate elements 3 stacked on top of another distribution layer 3’ comprising an elastic coating, such as a natural and/or synthetic polymer and/or elastomer. . In the Figure, the another distribution layer 3’ is shown separately, but surrounds the main body in an assembled state.

The surfaces 31 32 may also be structured on a microscopic scale, such as having a structure that increases surface roughness, which may improve adhesion of the pressure distribution plate 4 on the main 2, for example when glued thereto.

Trough-going openings 35 are provided in the pressure distribution plate 3, in a direction transverse to the inner side 31, in particular perpendicular. The trough-going openings allow water to flow away from the outer side 32 towards the inner side 31 and the at least one channel 4 in the main body 2.

The underground vibration shield element 1 comprises multiple channels 4 that extend through the main body and run from the top surface 22 to the bottom surface 21. The channels 4 comprise a bottom opening 41 in the bottom surface 21 and a top opening 42 in the top surface 22. The bottom opening 41 and top opening 42 are of equal circular shape and size.

The channels 4 are arranged, in the shielding orientation, vertically parallel to each other, such that they run in direction D. The channels 4 are evenly distributed over the main body 2 and a surface area of a cross-section of the channels 4 is more than 1 %, in particular more than 2%, more in particular more than 4% of the surface area of the main body 2 a direction of the cross-section of the channels 4 and a volume of the at least one channel is more than 1%, in particular more than 2%, more in particular more than 4% of a volume of the underground vibration shield element 1.

In Figures 2C and 2D, the pressure distribution layer 3 is also arranged on the surfaces 44 of each the at least one channel 4, extends through the at least one channel 4 and covers the entire surface 44 of each channel 4. The pressure distribution layer 3 is arranged on the main body 2, on the top surface 22 and on the bottom surface 21, and extends through the at least one channel 4 to form a single continuous surface. The pressure distribution layer 3 comprises an elastic material, in this embodiment a rubber mixture. The pressure distribution layer 3 has a stiffness that is chosen such that compressive forces are distributed along the surface of the main body, but the pressure distribution layer is sufficiently flexible to adapt gradually to settlement in the subsoil.

As such, the pressure distribution layers 3 3’ are made of a more rigid material than the substrate. A load rating of the pressure distribution layers 3 3’ is higher than a load rating of the main body 2. In Figure 2C, the pressure distribution layer 3 is arranged along the top surface 22, the bottom surface 21 and the side surfaces 23 of the main body, and in the inner surface 44 of the at least one channel 4, such that the main body 2 is completely covered by the pressure distribution layer 3. The pressure distribution layer comprises a continuous layer of material that forms a pressure distribution plate comprising a thickness that is substantially uniform along the top surface 22 and bottom surface 21.

When produced, the channels 4 are cut in the main body 2 and the pressure distribution layer of the vibration shield element 1 is applied by immersion of the main body 2 in a coating fluid, such that the main body 2 is completely submerged and the coating is provided on the inner surface 44 of all channels 4. This way, the pressure distribution layer 4 is over its full surface attached to the main body 2.

The pressure distribution layer is relatively thin having a thickness of less than 5 mm.

In Figure 2D, a first pressure distribution layer 3 and a second pressure distribution layer 3’ are provided. The second pressure distribution layer 3’ is provided stacked on top of the first pressure distribution layer 3. The first pressure distribution layer 3 comprises a coating that is applied by immersion of the main body 2 in a coating fluid and the second pressure distribution layer 3’ comprises a plate element arranged on the top side 22 of the main body. The first pressure distribution layer 3 is more flexible but less rigid than the second pressure distribution layer 3’. The elevated elements have a height of 2 cm or more, in particular 4 cm.

Figure 3B schematically depicts a partial perspective view of the pressure distribution plate 3 according to another embodiment of the invention. The pressure distribution plate 3 is provided with elevated elements 33 that extend perpendicular from the outer surface 32. The elevated elements 33 are provided with drain openings 36 that extend through the elevated elements 33 from one side 37 to an opposing side 38 thereof.

Trough-going openings 35 are provided in the outer surface 32, distributed over the outer surface 32, such that at least one of the trough-going openings 35 is provided in at least one first subregion 39. The through-going openings 35 therefore allow for water drainage out of the at least one first subregion 39. Furthermore, the at least one subregion 39 is fluidly connected to at least one second subregion 39’ via the drain openings 36, such that water may be drained out from a second subregions 9’ via a first subregion 39.

Figure 4 schematically depicts a disassembled perspective view of an underground vibration shield element according to an embodiment of the invention, shown horizontally and not in the vertical shielding orientation wherein the channel 4 would extend vertically. When arranged in the shielding orientation, the at least one channel may extend in a substantially vertical direction.

A side surface 23’ extends in a first direction D1 parallel to the at least one channel 4 with a first length, and in a second direction D2 perpendicular to the first direction, wherein a top surface 22 and/or bottom surface 21 extends in a third direction D3 perpendicular to the first direction D1 and the second direction D2 with a second length, wherein the second length is smaller than the first length.

The underground vibration shield element 1 comprises a water-permeable cover layer 5, that covers at least the bottom opening and the top opening 42. The cover layer is at least partially arranged in between the pressure distribution plate 3 and the main body 2. The cover layer is soil-retaining thus prevents ingress of ground material and/or cover layers through the top opening 42 into the at least one channel 4.

The fluid-permeable cover layer 5 is wrapped around main body 2, such that the cover layer surrounds the main body 2 completely, and extends along the whole top surface 22, bottom surface 21 and along the side surfaces 23. In this embodiment, the main body 2 is held together by the cover layer 5, such that a loose or less-coherent substrate may be used in the main body 2.

The pressure distribution layer is provided as a pressure distribution plate 3 that forms a plate element having an inner side 31 , arranged along the main body, and an opposite outer side 32, configured to, in the shielding orientation, be in contact with the ground. The pressure distribution plate is formed by a relatively thin layer of polyethylene, having a substantially uniform thickness may of 2 mm. The plate element is a pre-formed plate element. The pressure distribution plate 3 has, on the outer side 32, a low friction surface. The outer side 32 is provided with a smooth surface without a microscopically or macroscopically structured surface.

Figure 5A schematically depicts a perspective view of the underground vibration shield 1 element of Figure 1 , further comprising multiple connectors 61 for connection to adjacent vibration shield elements 1. The connectors 61 extend through the underground vibration shield element 1 in a direction perpendicular to the pressure distribution plate 3.

The connectors 61 are U-shaped, comprising a base 62 and two legs 63 that extend perpendicularly from the base 62. The legs 63 have a length sufficiently large to protrude through both sides of the underground vibration shield element 1. The legs 63 may be provided with a thread, for example around their respective free outer ends, such that a swivel or nut 64 can be provided thereon to clamp the connectors 61 on the respective adjacent vibration shield elements 1. A connectors 61 may have dimensions corresponding to the trough-going opening 35 in the pressure distribution plate, such that connectors 61 may be attached and/or detached by sliding through the through-going openings 35. For example, depending on soil type, groundwater level, and expected pressure loads, the number of required connectors 61 may vary. In use, additional connectors 61 may easily be provided by insertion through a troughgoing opening 35.

Upon insertion, the connectors 61 may be fixed by providing a fixation element, for example a washer 64 and a nut 65, on the free outer ends of the legs 62, as shown along cross section C-C in Fig. 5B.

The legs 63 may also extend non-perpendicularly from the base 62, for example at an angle larger than 90 degrees, away from each other. This way, insertion of a leg 63 in an adjacent vibration shield element 1 with another leg 63 already inserted in a vibration shield element 1 may be eased. Furthermore, a washer 64 may be provided with two openings corresponding to the two outer ends of the legs 63 of a connector 61. A distance between the two openings of the washer 64 may be predetermined to correspond to a distance between the two outer ends. Alternatively, the distance between the two openings may be smaller, such that the two outer ends of the legs 63 may be pulled towards each other upon application of the washer 64 over the outer ends. Thus, upon application of the washer, 64, the legs 63 provide a clamping force between adjacent underground vibration shield elements 1. A predetermined clamping force between the adjacent underground vibration shield elements 1, in particular between the pressure distribution plates 3 thereof, may be achieved by selection of distance between the openings in washer 64.

The multiple underground vibration shield elements 1 may be connected such that vertical movement of the shield elements 1 with respect to each other is constrained by the connection.

By connecting multiple underground vibration shield elements 1, a row of connected underground vibration shield elements may be formed, which reduces leaking of vibrations between adjacent plates. Additionally, by connecting the pressure distribution plates 3, vibrations and ground pressure forces may be spread along multiple pressure distribution plates 3 of multiple vibration shield elements 1, such that a more even vibration damping may be obtained.

Additionally, underground vibration shield elements may be connected to other objects, such as foundations of buildings or other infrastructural elements.

Figures 6 and 7 schematically depict embodiments of an underground vibration shield system 7 according to an embodiment of the invention. Figure 6 schematically shows two vibration shield elements 1 stacked on top of each other to form a stacked underground vibration shield system of stacked underground vibration shield elements. Top openings of a lower first underground vibration shield element are in fluid connection with bottom openings of a second upper underground vibration shield element. Similarly, a second row of underground vibration shield elements may be stacked on a row of underground vibration shield elements, such that top openings of the row of underground vibration shield elements are in fluid connection with bottom openings of the second row of underground vibration shield elements.

Figure 7 shows section S of the pressure distribution plate 3 in more detail, when two vibration shield elements 1 are arranged next to each other. As shown in Figure 6, one or multiple of the channels 4 may be arranged in a different position, for example diagonally. This may allow to drain water away from the underground vibration shield element 1. Additionally, the cross section of the channels 4, the top opening 42 or bottom opening may vary, and may for example be square or have any other shape advantageous for vibration damping. Some of the top openings of a lower underground vibration shield element 1 are in fluid connection with bottom openings of an upper underground vibration shield element 1.

The underground vibration shield elements 1 comprise connectors 66, 67 for connection with an adjacent underground vibration shield element 1. The connectors 66, 67 are arranged in the pressure distribution plate 3. Connectors may additionally or alternatively also be arranged in the main body 2 or elsewhere shield element 1. The connectors are shaped as rectangular protrusions 66 and slots 67 arranged in the surfaces of the shield element. Additionally or alternatively, the protrusions 66 and slots 67 may be shaped like snap-fit connectors, dovetail joints, hook-and-loop type fasteners, pin-hole connections or other form-fitted connections. The connectors may also comprise wedges, bolts or other force-fitted connections.

Figures 8A and 8B schematically depict a side view of a disassembled underground vibration shield element positioned in a shielding orientation in the ground 94 before and during a vibrational wave. The underground vibration shield elements are partially positioned below a ground water 95 level in the ground 94. For clarity, the pressure distribution plate 3 and the main body 2 are shown separately in the figures, but may form one integral piece.

The shielding orientation in the ground may be determined before arranging the underground vibration shield element 1 in the ground 94, for example by determining influence of orientation on vibration damping properties.

Additionally, a groundwater level, maximum pressure load on the underground vibration shield elements, for example due to the weight of traffic and/or characteristics of the vibrations to be damped may be determined before arranging the underground vibration shield elements 1 in the shielding orientation in the ground. The shielding orientation, comprising the inclination, location and height of an underground shielding element, a number of channels 8 a number of pressure distribution plates 3, and a number of underground vibration shield elements 1 to be arranged in the ground adjacent to each other, side by side or on top of each other, may be selected in dependence of the properties determined above.

A vibration may cause a local pressure increase P in the ground 94. The pressure P is transferred to the pressure distribution plate 3 by the ground 94, after which the pressure P is distributed evenly along the top surface of the main body 2 as distributed pressure Q. The pressure P is also transferred to the ground water 95, causing local variations in the ground water 95 level. The channels 4 allow water to rise locally, reducing the pressure P, such that the vibration is damped. Additionally, the rising ground water 95 level in the channels 4 of the main body 2 cause a force F into the substrate of the main body. The distributed pressure Q is directed downward and compresses the main body 2, providing further damping of vibrations.

Figures 9A, 9B and 9C schematically depict a perspective view of an underground vibration shield system 7 according to an embodiment of the invention, comprising multiple underground vibration shield elements 1 , T arranged in a shielding orientation underneath a road 90. The pressure distribution plates of the plurality of underground vibration shield elements 1 in a row of underground vibration shield elements 1 form a horizontal surface wherein the channels 4 of the shield elements 1 are arranged vertically in the horizontal surface.

Underground vibration shield elements T at outer edges of the row of underground vibration shield elements are positioned vertically and extend perpendicular to the other underground vibration shield elements 1 of the row of underground vibration shield elements to form a vertical surface adjacent to the horizontal surface. The channels 4’ in the respective shield elements T in also run vertically.

. The other underground vibration shield elements 1 of the row of underground vibration shield elements are arranged substantially horizontally, while underground vibration shield elements at outer edges of the row of underground vibration shield elements are arranged vertically to damp vibrations that propagate sideways.

A load rating of the main body is 50-200 kN/m ² , in particular 180 kN/m ² .

In the embodiment of Figure 9D, the pressure distribution layers 3 of adjacent vibration shield elements 1” T” are not connected to each other. In this case, a tilting movement of an pressure distribution layer 3’ may potentially occur, which is shown here in aggravated form. This effect may be reduced by connecting the pressure distribution layers of adjacent shield elements 1” T” to each other. By having perpendicular vibration shield elements T, vibrations may be damped sideways. The underground vibration shield elements are covered with top layers of ground, covering material and road surfacing.

After arranging in the ground, for example between the object and a vibration source, such as underneath a road surface, the underground vibration shield elements may be connected to form a vibration absorbing and/or damping shield system 7 of connected underground vibration shield elements 1.

When a vehicle 91 acts as a source of vibrations V, the vibrations V may be damped before reaching an object, such as a vulnerable building.

Figures 10A, 10B and 11 schematically depict a perspective view of an underground vibration shield system 7 according to an embodiment of the invention. The underground vibration shield system 7 comprises a mounting bracket 8 configured to fix a vibration shield elements 1, for example from the embodiment of Fig. 4, in the shielding orientation to an object, such as a building 92.

A load rating of the main body is 50-200 kN/m ² , in particular 80 kN/m ² . The underground vibration shield elements 1 are arranged at a depth just below the ground surface, up to a depth of less than 2,5 m below the ground surface, in particular less than 1,5 m underneath the ground surface, and at least partially underneath a groundwater level 95. The bottom side of the main body is positioned at least 5 cm, for example 10 cm underneath the groundwater level 95.

A vibration shield element 1 according to Figure 4 may be advantageous as a smooth pressure distribution plate 3 is provided on one side of the main body 2. On another side of the main body 2, no pressure distribution plate 3 is provide, such that the shape of the main body 2 may adapt to the foundation 93 and fit snugly against the foundation 93, even if there are unevenness on the surface of the foundation 93.

The mounting bracket 8 comprises mounting elements 81 , arranged to extend around a part of the underground vibration shield elements 1, configured to mount the underground vibration shield elements 1 in the shielding orientation by delimiting movement of the part of the underground vibration shield element 1 with respect to the mounting bracket 8.

The mounting elements 81, can be pins and/or clamps. The mounting bracket 8 comprises a lower rail part and an upper rail part. The mounting elements 81 are configured to extend between the lower and upper rail parts, and may be movable and or removable therefrom. As such, underground vibration shield elements 1 may be provided in between the lower and upper rail parts, after which they may be mounted by the mounting elements 81, extending around a part of the shield elements 1 and configured to mount the underground vibration shield elements 1 in the shielding orientation by delimiting movement of the part of the shield element 1 with respect to the mounting bracket 8.

As an alternative to an upper and lower rail part, as shown in Figure 10A, a stop plate 8’ may be provided at the end of a mounting element 81 and only an upper rail part 8 of the mounting bracket 8 may be provided, or vice versa.

The mounting elements 81 are M8 bolts that have a diameter of lesss than 15 mm and thus have a thickness less than 30% of the thickness of the main body 2 in a cross section perpendicular to the shielding orientation, for example less than 20%, such as 10%.

In use, the mounting bracket 8 may first be attached to a mounting surface, such as a foundation 93 of a building 92, after which the underground vibration shield elements 1 may be positioned in the mounting bracket 8 in the shielding orientation, for example in a direction parallel to the mounting surface. The mounting bracket has a thickness perpendicular to the mounting surface of less than 60% of the thickness of the main body in a cross section perpendicular to the shielding orientation, for example less than 40%, in particular less than 30%.

When the building 92 is arranged nearby a road 90, vibrations V may be transferred via the foundation 93 of the building. By attaching the vibration shield system 7, vibrations may be damped before reaching the foundation 93. With the mounting bracket 8, vibration shield elements may be attached to the foundation 93. This method may be easier to install as no repaving of the road surface itself is necessary. Additionally, in the case of a soft soil layer, sinking of the underground vibration shield elements 1 into the ground may be prevented.

Figure 12 schematically depicts a top view of a cross section of embodiments of the main body 2 of the underground vibration shield system of Figure 10A. The at least one channel 4 has a diameter of 10-50 mm, but other dimensions may also be provided. Multiple channels 4 may be arranged in a row 43, for example having 5-30 channels, such as 11 channels. Channels 4 may be arranged in a side surface 23”of the main body 2. Channels 4 may be arranged in multiple rows 43 shifted with respect to each other in a honeycomb-like pattern.