The first and most important phase of starting on building is ensuring the proper foundation of the buildings. It happens more and more often with the increase of the area of cities, that building becomes necessary on soils of weak physical conditions, soils unsuitable for plane foundation. It often happens, that foundations must be made on boggy, marshy, waterlogged, muddy, sodden areas, in old river-beds, or on place of old waste deposits. It also occurs, that various works, for example railways, roads, power lines, utility lines have to be built on soils with unfavorable conditions.

Solution for making foundations and building on such areas was applying various pile-drivers. Earlier it was made by wooden piles, nowadays beside well-spread technologies various concrete piles and pile-driving methods are used, for example "Franki"pile-driving, prefabricated pile-driving, slot-wall building technologies, vibratory pile drivers.

In the state of art Hungarian patent application P 92 03358 dated 28/11/1995, published under number H 3766, makes known renewable pipe or closed profile suitable particularly for making in-site piles. The pipe or closed profile is hollow, respectively blank along its lengthwise axle and there are at least two recyclable closing elements placed in arrow shape, which are preferably clams joining like beaks. In the inside of the pipe there are one or more non-return valves functioning as valves. Furthermore the patent makes known recyclable pipes or closed profiles, which are also hollow, respectively blank along their lengthwise axle and the hollow inside the pipe is shaped funnel-like from the top and narrowing arch-like from the bottom at the end close to the part joining the soil or at a certain distance from the end.

Hungarian patent application number P 92 03359 dated 28/11/1995, published under number H 3766 H 3760, makes known a method for soil-zones of great load- bearing capacity. With this method zones suitable for foundation and building can be created on the surface, respectively under the surface of slack soils or grounds of low load-bearing capacity. Depending on the type of works these zones can be made separated from each other at certain points, or next to each other as stripes, or in case of slabs covering the whole area. When applying the method the local soil which is in given case sodden or waterlogged is compacted with an in-site soil- compacting method and solid grainy or lumpy additive material is added at the time of compacting. The additive is jammed to the soil during compacting and this way a soil-zone consolidated with the local soil is created and this soil-zone is mechanically working together with the local soil. Way of compacting can be stamping and/or vibrolithic and/or tamping and/or exploding. The applied additive can preferably be sized or ungraded detritus, coarse gravel, rock-waste, pebble stone, concrete refuse or sand or crushed gravel or slag of fine grains, preferably of 3-5 mm diameter.

The solutions already known suffer from a limitation, that stamping does not ensure proper stability in case of certain types of soil, for example moor lands, it does not ensure integral restructuring with the soil, so especially in case of sodden, muddy soils does not ensure the proper working together of the pile and the soil. Pile- driving and slot-wall building are expensive technologies requiring special machinery with high operational costs resulting in end-products of high price-level.

When working out the solution according to the invention we aimed to elaborate a method, which is suitable for increasing value of physical parameters and load- bearing capacity of soil as well as decreasing time of consolidation and expectable settlement and makes possible plane foundation and building on soft or less set soils.

When working out the solution according to the invention we realized, that in case we apply a method, during which a hollow is created by ramming or vibropressing in the soil and a grainy additive, preferably coarse gravel is put into the hollow, then this additive is compacted into the soil by ramming, during the ramming the additive compacted into the soil breaks down the original structure of soil and the additive is restructured with the local soil, then additional additive is put into the hollow by additional ramming and this process is started over until the soil is filled with additive, by this an outer compacted local soil-zone and an inner compacted soil- zone consisting of a mixture of the additive and the local soil are created, then the set aim can be achieved.

The invention relates to a method for increasing value of physical parameters and load-bearing capacity of soil as well as decreasing consolidation time and expectable settlement, during which a hollow is created by ramming or vibropressing in the soil and a grainy additive, preferably coarse gravel is put into the hollow, then this additive is compacted into the soil by ramming, which is characterized by that, during the ramming the additive compacted into the soil breaks down the original structure of soil and the additive is restructured with the local soil, then additional additive is put into the hollow by additional ramming and this process is repeated until the soil is filled with additive, by this an outer compacted local soil-zone and an inner compacted local soil-zone consisting of a mixture of the additive and the local soil are created, and on said soil a plane basement of a building is made.

In a preferred application of the method according to the invention forming of the hollow takes place on the ground surface in the beginning of the method.

In another preferred application of the method according to the invention before forming the hollow a pre-grabbed hollow is formed and ramming and putting in additive take place on the bottom of said pre-grabbed hollow making deeply located soil or soil unsuitable for plane foundation or soil of low load-bearing capacity, for example moor lands, slobs, loose replenishments, river-beds suitable for load- bearing.

In a further preferred application of the method according to the invention during ramming and putting in additive the pre-grabbed hollow is filled in as well and in the side of said filled-in pre-grabbed hollow an outer compacted soil-zone is formed, as well as an inside compacted soil-zone consisting of a mixture of the additive and the local soil.

In a further preferred application of the method according to the invention in the first phase of the method forming of the hollow and/or forming of a deep hollow takes preferably place by vibropressing.

In a further preferred application of the method according to the invention additive applied is coarse gravel of grains larger than 60 mm, coarse gravel of maximum 200-250 mm diameter grains, and/or crushed gravel and/or concrete refuse, and/or detritus, and/or pebble stone.

In a further preferred application of the method according to the invention output of ramming is 4-5 tons mass dropped from a height of 6-10 m.

In a further preferred application of the method according to the invention the shape of drop-stamp is ball-shape, or a truncated cone with a flat-end, or a cylinder with a flat-end.

In a further preferred application of the method according to the invention in the upper plane of the soil-zones formed in given distance next to each other, a plane of given thickness compacted and filled in with additive preferably by a drop-stamp of flat-end is formed providing plane foundation for the building together with the load-bearing soil zones.

In a further preferred application of the method according to the invention in the upper part of the compacted soil-zone a spot of hemisphere shape is formed preferably by a ball-shaped drop-stamp and said spot of hemisphere shape is filled in with concrete, then on the upper part of said hemisphere shape spot a reinforced concrete slab is formed providing stabilizing and load-taking. Method according to the invention will be obvious to persons skilled in the art from the foregoing description of examples of application: Example 1 : In a preferred application of the method according to the invention in case of foundation near the surface of soils unsuitable for plane foundation, with depth of 2- 4 m below the surface, forming the hollow and the stamping take place near the soil surface at freezing level. When applying the method a hollow is created by ramming or vibropressing in the soil and a grainy additive, preferably coarse gravel is put into the hollow, and the additive is compacted into the soil by ramming. During the ramming the additive compacted into the soil breaks down the original structure of soil and the additive is restructured with the local soil. Additional additive is put into the hollow created by additional ramming. This process is repeated until the soil is filled with additive. By this an outer compacted local soil-zone and an inner compacted soil-zone consisting of a mixture of the additive and the local soil are created, and the plane foundation of the basement of the building can be made there.

Example 2: In another preferred application of the method according to the invention the method is used in case of soils of low load-bearing capacity, unsuitable for plane foundation, with depth of 4-10 m below the surface, for example marshy, muddy, sodden, waterlogged soils, river-beds. When starting the application, before starting the ramming a hollow of 6-10 m depth is formed below the soil level and ramming and putting in additive take place on the bottom of this pre-grabbed hollow. During the process a grainy additive, preferably coarse gravel is put into the hollow, and this additive is compacted into the soil by ramming. During the ramming the additive compacted into the soil breaks down the original structure of soil and the additive is restructured with the local soil. Additional additive is put into the hollow created by additional ramming. This process is repeated until the soil is filled with additive. By this an outer compacted local soil-zone and an inner compacted soil-zone consisting of a mixture of the additive and the local soil are created. During ramming and putting in additive the pre-grabbed hollow is filled in as well and in the side of the filled-in pre-grabbed hollow an outer compacted local soil-zone is formed as well as an inside compacted soil-zone consisting of a mixture of the additive and the local soil. On the upper part of the compacted soil-zone the plane foundation of the building is made.

The method according to the invention is set forth by the attached figures as follows : Fig 1-6 show a preferred application of the method according to the invention and <BR> <BR> the shape of the foundation made on it in case of foundation near ground level.<BR> rig 7-12 show a preferred application of the method according to the invention in case of making the foundation in a pre-grabbed hollow.

Fig 13-17 show a preferred application of the method according to the invention with creating the surface hollow by vibropressing and ramming of the additive.

Fig 18-20 show a preferred application of the method according to the invention when forming of plane foundations and technique of placing of concrete, reinforced concrete base elements are shown.

Fig 1-6 show a preferred application of the method according to the invention and the foundation made on it in case of foundation near ground level.

Fig 1 shows the phase of the process when the preferably ball-shaped drop-stamp 4 forms a hollow 1 of hemispheric shape in the soil after the first drops, and at the same time as the affect of the strikes an outer compacted local soil-zone 2 is created around the hollow 1. It is followed by filling the hollow 1 of hemispheric shape with additive 3, preferably with coarse gravel. Fig 3 shows the phase of the process, when the hollow 1 filled with additive 3 is further rammed by the drop-stamp 4. In this phase beside creating an additional hollow 1 by dropping the drop-stamp 4 the additional compacting of the additive 3 below and that of the outer compacted local soil-zone 2 is achieved. During this compacting the restructuring of the additive 3 and that of the outer compacted soil-zone 2 take place as well.

Fig 4 shows the repeated embankment of the hollow 1 with additive 3, below which the outer compacted local soil-zone 2 can already be found. The composition of the inner compacted local soil-zone 5 is in 70% additive 3, preferably coarse gravel and in 30% local soil, which is mixed with the additive 3 due to minor irruption of the soil during ramming. This is necessary to a certain extent for the application of the method, as the local soil fills in the gaps of the additive 3 and the required compactness can be jointly achieved together with the affects of ramming.

The process shown in Fig 1-4 that is the compacting with the drop-stamp 4 is started over until the compacted additive 3 gets to the side of the building level and during the ramming the additive 3 starts to break down. When this state is achieved, that is the soil is not able to take in any more additive 3 it is fill with additive 3. By this the aim of the process is achieved, that is the maximum value of the physical property and load-bearing capacity of the soil. This case the hollow 1 is not filled in with additive 3, but with concrete as shown in Fig 5.

Fig 5 shows a preferred application of the load-bearing structure of the method according to the invention in which the base element 6 made of concrete and provided with bonding reinforcement 7 is formed in the inner compacted local soil- zone 5 consisting of additive 3 compacted to the proper strength. On the upper part of the base element 6 the reinforced concrete base element 8 taking up the load is formed, which increases the load-bearing of the foundation and secures the load- bearing structure made against shifting. Fig 6 shows the top view of the foundation made where the border of the outer compacted soil-zone 2 is marked by a broken line. The concrete base element 6 of hemispheric form is placed below the reinforced concrete base element 8, from which the bonding reinforcement 7 protrudes in given case.

Fig 7-12 show a preferred application of the method according to the invention in case of foundation into a pre-grabbed hollow 9. It is actual, when the thickness of the soil unsuitable for local foundation reaches 4-10 m. This case firstly a deepened pre-grabbed hollow 9 seen in Fig 7 is formed with the help of an excavator. The additive 3 is put into this pre-grabbed hollow 9 as it can be seen in Fig 8. The additive 3, preferably coarse gravel is rammed with the drop-stamp 4 as it can be seen in Fig 9. Fig 9 shows the phase of the process when the additive 3 in the pre- grabbed hollow 9 creates an inner compacted local soil-zone 5 as the affect of the ramming 4 and at the same time the outer compacted soil-zone 2 is created in the local soil below. At the same time the additive 3 is compacted into the soil by ramming which breaks down the original structure of soil and the additive is restructured with the local soil. Fig 10-11 show the repeating of this process several times during which additional additive 3 is put into the pre-grabbed hollow 9 in sections, which is compacted into the soil by ramming, and this process is started over until the soil is filled with additive 3. During the process an outer compacted local soil-zone 2 and an inner compacted soil-zone 5 consisting of a mixture of the additive and the local soil are created. During stamping and putting in the additive the pre-grabbed hollow 9 is continuously filled in during which we get to the state shown in Fig 12, when in the side of the pre-grabbed hollow 9 an outer compacted local soil-zone 2 and an inner compacted local soil-zone 5 consisting of the mixture of the additive 3 and that of the local soil are formed.

Fig 13-17 show the forming of the surface hollow by vibropressing and the stamping of the additive 3. This method is suitable for forming a hollow 1 near the surface, or in a medium depth of preferably 4-6 m below the surface. Fig 13 shows that phase of the process when a hollow 1 of preferably cone or truncated pyramidal shape hollow 1 is formed by vibropressing in the soil. This is followed by the filling of the hollow 1 by additive 3 preferably by coarse gravel as it can be seen in Fig 14. Fig 15 shows the phase of the process when the hollow 1 is filled with additive 3 by the ramming 4, during which the outer compacted local soil-zone 2 is formed in the side of the hollow 1 as well as the inner compacted local soil-zone 5 consisting of the mixture of the additive 3 and the local soil. in Fig 16 additional filling and stamping of the hollow 1 can be seen, during which the additive 3 is compacted by the stamp-drop 4 and the further compacting of the outer compacted local soil-zone 2 is achieved as well. During this compacting the restructuring of the additive 3 and that of the outer compacted local soil-zone 2 takes place as well. Fig 17 shows the final phase of the process when the hollow 1 is completely filled with reaching the upper soil level and the outer compacted local soil-zone 2 is formed as well as the inner compacted local soil-zone 5 consisting of the mixture of the additive 3 and the local soil.

Fig 18-20 show the forming of the plane foundations and technique of placing of the concrete, reinforced concrete base elements.

It can be seen in Fig 18, that during preparing the foundation of a building several load-bearing zones consisting of outer compacted local soil-zones 2 and inner compacted local soil-zones 5 are formed below the plane foundation next to each other. The upper part of these load-bearing zones are reduced by a thickness of preferably 0,3-0, 5 cm and with a ramming of flat-surface a continuous plane compacted surface layer 10 is formed and the reinforced concrete base element 15 taking the load of the building is put onto it. Resulting from this the complete surface of the soil becomes suitable for plane foundation.

Fig 19 shows the receiving platform formed on the load-bearing soil-zone 13 created according to the method of the invention. On the bottom the outer compacted local soil-zone 2 formed in the soil, and the inner compacted local soil- zone 5 consisting of the mixture of the additive 3 and the local soil. On the top of this the compacted surface layer 10 is formed and the reinforced concrete base element 11 is placed on it. Next to the reinforced concrete base element the compacted filling 12 can be found, the side of which is closed by a splay 14.

Fig 20 shows load-bearing soil-zones 13 formed in different forms during plane foundation, supporting reinforced concrete base elements 11. The load-bearing soil- zones 13 are formed separately, or next to each other, linked with each other depending on the spacing of the structural elements of the building.

In a possible preferred application of the method according to the invention resulting from the ramming the solid additive, in given case coarse gravel is mixed with the local soil and restructures. The settlement under the building resulting from the building during years takes place during the many-fold overloading during the ramming. Overloading occurs during the ramming and the loads of the building are considerably smaller than loads of ramming. During ramming the material stamped consists of 70% coarse gravel, 30% soil tumbling, filling in the gaps of additive. In case the quantity of the local soil falling in from the side of the hollow is insufficient, or its quality is not suitable, then an additive of fine grains must be added.

Compacting of the soil on the sides and mixing with the additive increases with the filling of the hollow. When reaching the upper layer a certain thickness of the compacted additive is taken away and then the surface ramming follows. Then additive is spread on the places in between and rammed by a plane stamp, so the whole surface under the building is treated.

In given case deep ramming is needed, which is a little more expensive, but there is no other solution. The diameter of the hollow necessary for the method according to the invention is in given case 1. 5 m and the diameter of the ball-pointed stamp is 0. 9- 1. 0 m. The shape of the soil-zone formed by the method according to the invention can be circle, L shaped, T shaped, X shaped, rectangular. In case of deep foundation when a thick soil layer unsuitable for foundation must be improved and made suitable for plane foundation, the depth of the soil-zone is 7-8-10 m. In case of plane foundation, when only a smaller depth soil must be improved, the depth of the soil-zone is 4-5-6 m.

The concrete base element of hemispheric shape can be formed with or without a separating plane. In the inside of the concrete base element of hemispheric shape <BR> <BR> 0. 5-0. 6 m3 concrete can be found with load-bearing of 400-500 KN, which equals<BR> one,, Franki" pile. Resulting from the ramming the local soil is restructured, its load- bearing capacity increases and becomes suitable for plane foundation. In essence the stress onion created during the foundation is filled in with the additive, in given case with coarse gravel.

The separating plane further increases the load-bearing capacity of the foundation. It offers several benefits, it links a bigger part of the soil into load-bearing and in case an additional sheet is put in, this pushes back the protrusions of the soil and prevents turning of the block. The shape of the stamp is preferably ball-pointed, because it makes possible striking into the same track as the previous strike and does not tilt.

Stamping does not damage already existing building, because the strike occurs seldom, one strike per minute, so the speed, amplitude and resonance of the wave created this way is not dangerous.

With the application of the method according to the invention the load-bearing capacity of the soil can be increased from 50 KN/m2 to 600 KN/m2 with the proper choosing of the height of drop, mass of ramming and the quality of the additive.

The advantage of the method according to the invention is, that it accelerates the restructuring of poor soils from the point of view of foundation for example below waterlogged soils of motor-ways, works are made possible during winter-time as well, because frozen zones can be broken through. It is also environment-friendly making possible recycling of building refuse, concrete refuse, respectively ensures environment-friendly materials to get back to the soil. With the method according to the invention decrease of contamination of contaminated soils is possible on top of local reinforcement of the soil.

The method according to the invention can be advantageously applied in wide range of buildings, transportation works, power-line posts, dams, runways, bridges, because it is possible to achieve greater degrees of compacting and load-bearing. Its resonance properties are also better than in case of, Franki" piles. Compared with traditional technologies it does not require complex, expensive preparations, devices, it is of greater load-bearing capacity. It does not depend on the weather, can be used during winter as well.

The applied additive, coarse gravel is a cheap, environment-friendly material, which is not suitable for other technologies. The soil-zone formed, restructured, reinforced by this method is not watertight, does not harm the water regime of the soil, does not close possibility of moving of groundwater.

The method according to the invention makes possible foundation above groundwater level and it can be applied in case of presence of groundwater aggressive for concrete as well. With elevating the level of foundation concrete foundation can be made without protection in case of aggressive ground waters as well. The lateral and vertical compacting of the soil and restructuring of the additive result in decreasing of the gap volume and keeping off water and organic materials in the soil.

It requires a little raw material, in mass production only cheap additive is needed, no cement, steel bars and formwork of big quantities are necessary, thus saving living labor as well.