Frequently, overfilled arch structures formed of precast or cast-in-place reinforced concrete are used in the case of bridges to support one pathway over a second pathway, which can be a waterway, a traffic route, or in the case of other structures, a storage space or the like. The terms"overfilled arch"or"overfilled bridge"will be understood from the teaching of the present disclosure, and in general as used herein, an overfilled bridge or an overfilled arch is a bridge formed of arch elements that rest on the ground or on a foundation and has soil or the like resting thereon and thereabout to support and stabilize the structure and in the case of a bridge provide the surface of the second pathway. The arch form is generally arcuate such as cylindrical in circumferential shape, and in particular a prolate shape; however, other shapes can be used. Examples of overfilled bridges are disclosed in US Patents 3,482, 406 and 4,458, 457, the disclosures of which are incorporated herein by reference.

Presently, reinforced concrete overfilled arches are usually constructed by either casting the arch in place or placing precast elements, or a combination of these. These arched structures rest on prepared foundations at the bottom of both sides of the arch. The fill material, at the sides of the arch (backfill material) serves to diminish the outward displacements of the structure when the structure is loaded from above. As used herein, the term"soil"is intended to refer to the normal soil, which can be backfill (e. g. soil brought to and placed in location) or in situ (e. g. soil in its original location), located at a site used for a bridge structure, and which would not otherwise adequately support an arch. The terms"backfill," and"in situ"will be used to mean such"soil"as well.

Such soil is not adequate to support the concentrated loads at the ends of a flat arch or conventional arch without load distribution through the use of arch footings and/or reinforced foundation blocks.

Soil is usually not mechanically strong enough to adequately support bridge structures of interest to this invention. Thus, prior art bridge structures have been constructed to transfer forces associated with the structure to walls of the structure and/or large concrete foundations at the base of the wall. Such walls have to be constructed in a manner that will support such forces and thus have special construction requirements. As will be discussed below, such requirements present drawbacks and disadvantages to such prior art structures.

For the prior art structures, the overfilled arches are normally formed such that the foundation level of the arch is at the approximate level of a lower pathway or floor surface of an underground structure over which the arch spans. Referring to Figures lA-1C, it can be understood that prior art systems S1 and S2 include sides or sidewalls SW1 and SW2 which transfer loads from tops T1 and T2 of the arch to foundation Fl and F2. The sides of arch systems Sl and S2 must be sufficiently thick and contain sufficient reinforcement in order to be able to carry these loads and the thereby induced bending moments.

Furthermore, as it is necessary to limit the normal forces, arch loading and bending actions in the top and sides of prior art overfilled arch systems to an acceptable level, the radius of the arch is in practice restricted. This restriction in arch radius leads to a higher"rise"R1 and R2 (vertical dimension between the top of clearance profile Cl and C2 of lower pathway surface LSI or LS2 and crown CR1 and CR2 of the arch) in the arch profile than is often desirable for the economical and practical arrangement of the two pathways and formation of the works surrounding and covering the arch. This results in a lost height LH1 and LH2 which can be substantial in some cases.

Beams or slabs, while needing a larger thickness than arches, do not require this"rise"and, therefore, can be used for bridges accommodating a smaller height between the top of the clearance profile of the lower pathway and the top of the upper pathway. Arches, despite their economical advantage, often cannot compete with structures using beams or slabs for this reason especially for larger spans.

However, the larger thickness may result in an expensive structure whose precast elements may be difficult unwieldy and heavy to transport to a building site. Thus, many of the advantages of this structure may be offset or vitiated.

Furthermore, as indicated in Figures lA-1C, foundations Fl and F2 for the prior art overfilled arch systems must be substantial in order to carry the arch loading indicated in Figure 1C as AL, and require additional excavation at the base of the arch (generally beneath the lower pathway) to enable their construction. As will be understood from the present disclosure, forces AL can be considered as being circumferential forces, and forces AV can be considered as being vertical forces with forces AH being considered as horizontal forces. Loading forces on the system are a combination of these forces.

Furthermore, the foundations for the prior art overfilled arch systems must be substantial in order to carry the arch loading and will require additional excavation at the base of the arch (generally beneath the lower pathway) to enable their construction.

For overfilled arches made of precast construction, the incorporation of the required height of the sides or sidewalls of the arch result either in a tall-standing precast element which is difficult and unwieldy to transport and to place or in the requirement of pedestals, such as pedestals Fla shown in Figure 1A.

As discussed above, transportation and handling of precast arch elements of some arch structures are difficult. However, precast elements have certain advantages including the ability to support their own self-weight and all of the advantages associated with pre-casting of such structural elements. However, precast elements also have certain disadvantages, including the transportation issues mentioned above.

Therefore, it would be helpful to retain as many of the advantages associated with precast structural elements as possible while eliminating, or at least substantially reducing, as many of the disadvantages associated with precast structural elements as possible.

Likewise, cast-in-place structural elements have many advantages, including the ability to be customized on site and the elimination of the transportation problems associated with precast structural elements. However, cast-in-place structural elements also have certain disadvantages, including a need for a formwork support structure, as well.

Therefore, it would be expedient to retain as many of the advantages associated with cast-in-place structural elements as possible while eliminating, or at least substantially reducing, as many of the disadvantages associated with cast- in-place structural elements as possible.

One aspect of this invention (Figures 1 to 14) teaches a means and method of forming an arch structure system that overcomes problems associated with the mechanical inadequacy of normal soil to support bridge and other structures of interest to that, and to this, invention. The advantages associated with this means and method are substantial. Therefore, it would be valuable to utilize these teachings in a manner which also realizes the advantages associated with the retention of the advantages associated with both precast and cast-in-place overfilled arch structures while reducing, or possibly eliminating, many of the disadvantages associated with such precast and cast-in-place structures.

While the advantages associated with the means and method this aspect of the invention (Figures 1 to 14) are substantial, it would be extremely beneficial if further advantages in support could be realized.

Bending moments applied to an overfilled bridge structure are induced by the overfill and loads, such as traffic, carried by the bridge structure. These bending moments must be accommodated by the bridge structure. Prior overfilled structures counter these bending moments by increasing structural thickness, providing larger amounts of steel reinforcement and/or by increasing the size and stiffness of the arch supports. These measures may be costly and may not be as efficient as possible.

Therefore, there is a need for a means for efficiently minimizing bending moments induced in an overfilled arch structure.

The technology of the first aspect of the invention (Figures 1 to 14) significantly improves the efficiency of an overfilled bridge structure in accommodating such loading over prior art structures. However, it would be helpful if these load accommodating efficiency advantages could be further improved.

Overfilled arch structures, in particular overfilled flat arches, are sensitive to outward displacement of the arch ends. This outward displacement leads to increased bending movements in the arch. Prior overfilled structures counter these bending moments by increasing structural thickness, providing larger amounts of steel reinforcement and/or by increasing the size and stiffness of the arch supports.

These measures may be costly and may not be as efficient as possible.

Therefore, there is a need for a means for efficiently reducing the outward displacements, and particularly the sensitivity of an overfilled arch to outward displacements, of arch footings.

The technology disclosed and taught in the Figures 1 to 14 significantly improves the efficiency of an overfilled bridge structure in preventing such footing outward displacement as compared to prior art structures. However, it would be helpful if these resistances to arch footing outward displacement are further improved.

The novel system disclosed with reference to Figs 1 to 14 of the present application solves a number of the above problems by having foundation blocks located behind or near the top of the side walls and against which the arch of the structure bears. The arch delivers all or at least most of its support forces into the foundation blocks.

This is an extremely effective system and accomplishes a number of the objects hereof.

However, the effectiveness of this structure can be further enhanced by improving the methods used to erect the structure. Therefore, there is a need for a means and a method for building the structure disclosed with reference to Figs 1 to 14 hereof.

While the cast-in-place (cip) mode of constructing an arch system is suitable for many situations due to its economy and speed, there are certain commercial and technical (site) conditions for which a totally precast structure is preferred. Some of these conditions are: time restrictions for on-site installation; weather conditions, especially low temperatures; the absence of shuttering and crew suited/trained for the cip construction procedure; * a need to limit the specialist contractors'duties to supplying (and, perhaps mounting) precast elements, in contrast to providing total contractor's services (and responsibility); * limited clear space, not allowing the use of a shuttering (such as with live train lines at the lower pathway); special requirements (aesthetic, etc).

Therefore, there is a need for a means and a method for building a fully precast overfilled shallow arch structure.

The precast arch elements in many prior systems are cast on their sides.

This requires forms which have walls and also may require special handling of the forms to ensure proper formation of the arch elements. Still further, these elements are generally shipped in the side-on orientation. The elements are then lifted off the transporting vehicle, turned in the air to be oriented in the use orientation (as used herein, the use orientation is an orientation shown in Figure 32 herein as well as in Figures 2A to 2C, and a side-on orientation will have the elements rotated 90° with respect to the orientation shown in these same figures).

Side-on formation and shipping has several drawbacks: complicated formwork ; special transportation problems; and lifting problems associated with lifting and turning such elements.

Therefore, there is a need for a means and a method for forming and shipping a precast arch element.

In the case of relatively large overfills, no connection may be required between adjacent arch elements because the overfilled soil spreads the loads on the overfill surface so that no differential displacements between adjacent elements occur. Differential displacements are caused by loads, such as traffic loads, placed only on one arch element, then on the adjacent arch element, and so on. Such deformations may lead to so called deflection cracking (cracks that propagate from the top of the arch element to the pavement surface). Such deformations should be avoided.

For shallow arch applications, shallow overfills are more frequent than high overfills since the shallow arch is preferably used where lost height needs to be minimized. In such a case, with only one or two feet or even only inches of overfill or almost zero overfill in some situations, the live loads may act on individual elements before being transferred to the next one causing the relative vertical displacements that can be such that the pavement of the system will be cracked due to these relative displacements.

Therefore, there is a need for a means and a method for forming an arch system that avoids differential displacements between adjacent arch elements of the system.

Still further, there is a need for a means and a method for forming an arch system in a manner that avoids differential displacements between adjacent arch elements of the system even in the situation of a shallow, or even a zero, overfill.

It is a main object of the present invention to provide an economical and expeditiously erected overfilled arch structure system and method of forming an overfilled arch structure system.

It is another object of the present invention to provide an arch structure system and method of forming an arch structure system that utilizes soil to create a foundation for the arch structure.

It is another object of the present invention to provide an arch structure and system and method of forming an arch structure and system that does not transfer forces associated with an arch element directly to walls of the arch structure and system whereby the walls are not required to support a significant amount of these forces.

It is another object of the present invention to provide an overfilled arch bridge or other structure and method of construction therefor which enables a minimal arch curvature to be adopted.

It is another object of the present invention to minimize the rise of the arch and hence extend the scope of application of the arch while still maintaining a structural arching action in the arch of the overfilled structure.

It is another object of the present invention to provide an overfilled arch bridge structure and method of construction therefor which enables the sides/sidewalls of the overfilled structure to be of a lighter and therefore more economical design and faster methods of construction as compared to the prior art.

It is another object of the present invention to provide an overfilled arch bridge structure which enables such a structure to be constructed using poor quality backfill material.

It is another object of the present invention to provide an overfilled arch bridge structure and method of construction therefor which enables the footings at the base of the overfilled structure to be smaller than the prior art.

It is another object of the present invention to provide an overfilled arch bridge structure and method of construction therefor which enables the footings at the base of the overfilled structure to be omitted.

It is another object of the present invention to provide an overfilled arch bridge structure and method of construction therefor which enables the footings at the base of the overfilled structure to be reduced to very small dimensions serving only for the erection of sidewalls.

It is another object of the present invention to provide an overfilled arched bridge and method of construction therefor which reduces dependence on large and unwieldy element transportation and reliance on heavy erection cranes as compared to the prior art.

It is another object of the present invention to provide an overfilled arched bridge which is expeditious to produce.

It is a further main object of the present invention to provide an overfilled arch structure which is easier to handle and transport than presently-available arch structures.

It is another object of the invention to provide overfilled arch structure elements which are easier to handle and transport than presently-available arch structure elements yet which yield as strong and stable structures as presently- available arch structures.

It is a specific object of the present invention to provide an overfilled arch structure which includes a composite section of precast and cast-in-place concrete.

It is another object of the present invention to provide an overfilled arch structure which includes a means for efficiently counteracting bending moments induced in the overfilled arch structure.

It is another object of the present invention to provide an overfilled arch structure which includes a means for efficiently reducing the sensitivity of an overfilled arch to outward displacements of arch footings.

It is another object of the present invention to provide an overfilled arch which is prestressed to induce moments therein which counteract moments induced therein by overfill and loads on the arch structure.

It is another object of the present invention to provide an overfilled arch which has an arch end that is customized to induce eccentricities between an arch thrust reaction and a centerline of the arch.

It is another object of the present invention to provide an overfilled arch has a sensitivity to outward displacement of arch footings that is reduced as compared to presently-available arches.

It is another object of the present invention to provide an overfilled arch which utilizes treated soil to create a foundation for the arch.

It is another object of the present invention to provide an overfilled arch which includes a composite section of precast concrete and cast-in-place concrete and which utilizes soil to create a foundation for the arch, a foundation that not only reduces (vertical) settlements, but also (horizontal) displacements.

It is a another object of the present invention to provide an overfilled arch which consists of a composite of precast concrete and cast-in-place concrete layers and which utilizes the technology disclosed and taught in the aspect of Figures 1 to 14.

It is another object of the present invention to provide an overfilled arch which uses support geometry to automatically counteract the moments induced therein by overfill and loads on the arch and which utilizes the technology disclosed and taught in the aspect of Figures 1 to 14.

It is another object of the present invention to provide an overfilled arch which uses prestressing to automatically counteract the moments induced therein by overfill and loads on the arch and which utilizes the technology disclosed and taught in the aspect of Figures 1 to 14.

It is another object of the present invention to provide an overfilled arch which retains many of the advantages associated with precast overfilled bridge structures while eliminating, or at least substantially reducing, many of the disadvantages associated with a precast overfilled bridge structure.

It is another object of the present invention to provide an overfilled arch which retains many of the advantages associated with cast-in-place overfilled bridge structures while eliminating, or at least substantially reducing, many of the disadvantages associated with a cast-in-place overfilled bridge structure.

It is another object of the present invention to further improve the advantages realized by the technology disclosed and taught in the aspect of Figures 1 to 14.

It is another main object of the present invention to provide a means and a method for building structures.

It is another object of the present invention to provide a means and a method for building a fully precast overfilled shallow arch structure such as disclosed in Figures 1 to 14.

It is another object of the present invention to provide a means and a method for forming, stacking and shipping a precast arch element such as disclosed Figures 1 to 14 in a use orientation.

It is another object of the present invention to provide a means and a method for forming an arch system such as disclosed in Figures 1 to 14 in a manner that avoids differential displacements between adjacent arch elements of the system.

It is another object of the present invention to provide a means and method for forming an arch system such as disclosed in Figures 1 to 14 in a manner that avoids differential displacements between adjacent arch elements of the system even in the situation of a shallow, or even a zero, overfill.

Various ways of describing the features of the invention are set out in the independent claims. Various optional features are mentioned in the dependent claims. Some of the above objects are achieved by an arched overfilled and/or backfilled structure which includes a shallow arch spanning over a clear space.

The sides of the clear space are formed by curved or planar walls. Solidified zones of the backfill material or previously existing (in situ) ground against the footings at the springs, also referred to as ends, of the arch and/or behind the walls form foundation blocks which are in intimate contact with the footings at the arch springs and/or with the upper part of the walls in such a way that the arch delivers all or at least most of its support forces into the aforementioned foundation blocks, drastically reducing the normal forces, shear forces and bending moments in the walls and wall foundations. The arch structure contacts the foundation blocks in a manner that the support forces of the arch are transferred to the foundation blocks rather than to the sidewalls of the system. The resulting advantages of transferring such forces to the foundation blocks rather than to the sidewalls will be understood from the teaching of the present disclosure.

The arched structure system which is formed using precast concrete, or cast-in-place concrete, or a combination of both comprises either: A plain concrete or reinforced concrete arch resting on arch footings which in turn rest on foundation blocks, the latter being a solidified portion of the backfill or of in situ material located outside of the wall beneath either side of the concrete arch. The concrete arch may be precast, cast-in- place (cip) or a combination. The walls can be formed using mechanically stabilized earth (MSE) or any other type of earth retaining wall system, including but not limited to sheet piles, bored piles, diaphragm walls or an excavated cip, precast or sprayed (shotcrete) concrete wall with or without nails/anchors; or A continuous, one-piece monolithic frame whereby the top of the frame comprises an arch, and the sides of the frame consist of curved or planar walls, in which the outside surfaces of the arch and top of the walls are shaped such that the arch loads are directed into foundation blocks, the latter being solidified portions of the backfill material or in situ material, located outside the frame sidewalls.

Where precast concrete is used, adjacent precast arch spans may be structurally connected along all or part of the circumferential length.

The foundation blocks of the present invention comprise a material exhibiting sufficient stiffness and strength such that the thrust reactions of the arch can be distributed via the arch footings through the foundation block to the adjacent soil material, such that the displacements of the arch springs are within acceptable limits. Shallow arches, as in the present invention, are particularly susceptible to horizontal outward displacements of the springs. The structure of the present invention ensures that the solid foundations, which are essential for such an arch, can be provided economically.

By enabling a load transfer from the springs of the arch via the arch footings into the foundation blocks, the arch support forces do not need to be transferred into the sidewalls of the earth overfilled system. This characteristic of the system embodying the present invention enables the backfilling of the sidewalls to be combined with the construction of the foundation blocks because all or part of the solidified backfill of the sidewalls or the solidified in situ ground directly constitutes the arch foundation blocks. This also enables more efficient construction procedures to be adopted for construction of the walls, which can be made considerably lighter than prior art systems.

Furthermore, by enabling direct transfer of the arch support forces into the foundation blocks at the top of the sidewalls, it is possible to adopt a flatter arch than is possible and economic for the conventional state of the art. This is because the loads and bending moments transferred into the sidewalls of a conventional overfilled arch are significantly larger for a flatter arch than for a higher (less flat) arch. A flatter arch (smaller arch rise) has the advantage that for a given clearance beneath the sides of the arch, the lost height (see lost height LH1 and LH2 in Figures 1A and 1B) can be reduced, and the distance between the lower and upper paths of the overfilled arch system can be reduced, thereby increasing the scope of arch structure application. Thus, the total lost height LH1 or LH2 will be considerably reduced from those values indicated in Figures 1A and 1B.

The present invention also includes a cover-and-cut method of such a system.

While a bridge system is discussed herein, it is to be understood that the present invention can be applied to other systems as well without departing from the scope of the present disclosure and invention. For example, any type of underground space (including, but not limited to, shelters, warehouses, storage spaces, backfilled and overfilled, or only backfilled or built into existing in situ ground) can be within the scope of the present invention and disclosure and it is intended that the present invention as defined by the teaching of this disclosure and the claims associated therewith will cover such structures as well.

Other objects are achieved by an overfilled bridge arch that includes both precast and cast-in-place layers. The overfilled bridge arch can also be prestressed in an efficient and effective manner, or the ends of the arch arranged in such a way, such that bending moments induced by loading are efficiently and effectively accommodated and sensitivity of the arch to arch footing outward displacement is also reduced.

The overfilled arch bridge structure embodied in the aspect of Figures 15 to 31 of the present invention can be used in conjunction with the technology disclosed and taught in the aspect of Figures 1 to 14 hereof to thereby realize additional advantages for each technology.

The composite overfilled bridge structure embodied in the aspect of Figures 15 to 31 of the present invention thus realizes advantages for both precast and cast-in-place structures as well as reducing, or even eliminating, many disadvantages associated with such precast and cast-in-place arches. Additional advantages are also realized due to the composite nature of the structure of the present invention, including the ability to efficiently waterproof the structure as well as to include efficient joint seals.

The overfilled bridge and elements thereof embodying Figures 15 to 31 of the present invention make an overfilled bridge efficient to transport, handle and erect, yet will produce a stable and efficiently waterproofed structure.

Further objects are achieved by a means and method (Figures 32 to 51) for forming an arch system such as disclosed in Figures 1 to 14 in which the arch elements are fully precast in a use orientation, then stacked and shipped in a use orientation. It is noted that the term"fully precast"is used herein to mean that the arch element is fully precast and with the exception of some cast-in-place concrete in the footings and in some cases cast-in-place concrete in the crown joints. The arch elements are placed on the foundation blocks in a manner which distributes forces associated with the arch elements to the foundation blocks, as taught in the disclosure of the aspect of Figures 1 to 14.

The form work is very simple and no counter forms are usually required.

Furthermore, there is no need to turn the elements in the air while hanging from a crane.

The arch elements can be pre-stressed by pre-deformation either during movement from the shipping vehicle to the in place location, or in another manner.

The pre-stressing will partly or wholly compensate for the influence of possible outward yield (deformation) of the abutments (foundation blocks). The elements are placed in their pre-deformed shape and come back to their intended and optimal shape when overfilled.

The width of arch elements may be limited by the geometric transportation limitations and the weight. The lying down or use orientation has several advantages over the standing way or the side on orientation including the advantages associated with longer elements. For the shallow arches of the present invention, longer elements can be transported (even with footings attached) than with other arch geometries.

It is noted that the means and method disclosed herein (e. g. Figures 32 to 51) can be applied to skew arch structures as well as to spans which do not allow one element solutions but which require a crown joint to connect two halves together. Therefore, spans can range from about twelve feet to eighty-four feet or more.

The invention may be carried out in various ways and a number of preferred examples of embodiments will now be described with reference to the accompanying drawings, in which: Figures 1 A and 1 B illustrate cross sectional views of prior art systems.

Figure 1 C illustrates forces associated with overfilled arches, as characteristic of a prior art system.

Figure 2 shows the typical cross section for the basic embodiment of the present invention using a flat arch resting on foundation blocks.

Figure 3 shows the typical cross section for the basic embodiment of the present invention using a continuous frame supported by foundation blocks in which the arch and the sidewalls are integral and continuous, the embodiment shown includes a stepped outer surface.

Figure 4 shows the typical cross section for the basic embodiment of the present invention using a continuous frame supported by foundation blocks in which the arch and the sidewalls are integral and continuous, the embodiment shown includes a protruding corner.

Figure 5 is a flow chart for a cover-and-cut method embodying the present invention.

Figure 6 shows a system produced by a cover-and-cut method.

Figure 7 is a flow chart showing the overall method of forming an arch support system embodying the present invention.

Figure 8 is a top plan view of an alternative form of the present invention in which the overall system includes a dome and an arcuate sidewall.

Figure 9 illustrates a multi-arch section bridge form of the present invention.

Figure 10 illustrates the present invention as embodied in a skewed arch bridge.

Figure 11 illustrates the present invention incorporating a battered slope at the ends of the structure to conform with a battered (sloped) fill embankment.

Figure 12 illustrates a method step included in the method embodying the present invention in which an arch structure is prestressed.

Figure 13 illustrates a method of forming several different arch spans using the same mould or formwork, by blocking off the mold or formwork.

Figure 14 illustrates a method of forming several different arch spans using the same mould or formwork by connecting extensions to the mould or formwork.

Figure 15 shows a basic overfilled bridge structure as disclosed in Figures 1 to 14.

Figure 16 is an elevational view of a composite overfilled bridge structure embodying the present invention.

Figure 17 is a view taken along line A-A of Figure 16.

Figure 18 shows detail B of Figure 17.

Figure 19 is an elevational view of an overfilled arched bridge structure of the present invention illustrating arch footing elements.

Figure 20 is a detail view of one form of a bearing forming an arch spring to arch footing interface.

Figure 21 shows a concentric support reaction of the prior art.

Figure 22 is a diagram illustrating moment distribution in an arch for a conventional arch support such as shown in Figure 21.

Figure 23 shows an eccentric arch support reaction according to the teaching of the present invention.

Figure 24 is a diagram illustrating the moment induced by support reaction eccentricity.

Figure 25 is a diagram illustrating the resultant moment distribution for a customized end geometry such as shown in Figure 23.

Figure 26 is a diagram illustrating moment optimization obtained by prestressing an arch.

Figure 27 is a diagram illustrating moment distribution in an arch for a prior art arch support.

Figure 28 is a diagram illustrating moment induced by prestressing load placed on an arch.

Figure 29 is a diagram illustrating a resultant moment distribution for a prestressed arch.

Figure 30 is a detail view from Figure 19 of a bearing interposed between an arch spring and an arch footing in which the arch will be prestressed.

Figure 31 is a diagram illustrating use of a tie in order to prestress the arch.

Figure 32 is an elevational view of a completed arch structure as disclosed in Figures 1 to 14 and which is formed in accordance with the teaching of the present disclosure.

Figure 33a is a plan view of a system with skew alignment that can be formed in accordance with the teaching of the present disclosure.

Figure 33b is a plan view of a system with curved alignment which can be formed in accordance with the teaching of the present disclosure.

Figure 33C is a plan view of a system with an irregular alignment which can be formed in accordance with the teaching of the present disclosure.

Figure 34a is a plan view of a curved system which can be formed in accordance with the teaching of the present disclosure showing adjacent arch elements.

Figure 34b is a plan view of a skewed system which can be formed in accordance with the teaching of the present disclosure showing adjacent arch elements.

Figure 34c is a plan view of a conventional span system which can be formed in accordance with the teaching of the present disclosure showing adjacent arch elements.

Figure 35 is a plan view of a form used to form arch elements in a use orientation in accordance with the teaching of the present disclosure.

Figure 36 is an end elevational view of the form shown in Figure 35.

Figure 37a shows an arch element that has been formed in the use orientation being moved in the use orientation.

Figure 37b shows a top plan view of the arch element being moved in the use orientation.

Figure 38 shows an arch element having a prestressing element associated therewith.

Figure 39 shows a portion of an arch element in which bores are defined to accommodate tie elements, such as dowel rods or the like.

Figures 40 and 40a show a tie element located in a bore of the arch element.

Figure 41 is a longitudinal section of a plurality of adjacent arch elements.

Figure 42 shows a detail of a connection between adjacent arch elements.

Figure 43 is an elevational view in section of a completed arch system in which adjacent arch elements are connected together in accordance with the teaching of the present disclosure.

Figure 44 is a detail view showing a connection between two adjacent arch elements of a completed arch system in accordance with the teaching of the present disclosure.

Figure 45 is a detail view showing an alternative form of a connection between two adjacent arch elements in accordance with the teaching of the present disclosure.

Figure 46 is an elevational view in section of an arch system showing the arch system during one step in the process of erecting the system in accordance with the teaching of the present disclosure.

Figure 47 is a detail view of an end of an arch element and a portion of a foundation block during one step in the process of erecting the arch system in accordance with the teaching of the present disclosure.

Figure 48 is a detail view of an end of an arch element and a portion of a foundation block during one step in the process of erecting the arch system in accordance with the teaching of the present disclosure.

Figure 49 shows a detail view of one form of an arch element and its footing that is included in the disclosure of the present invention.

Figure 50 shows another detail view of a form of an arch element and its footing that is included in the disclosure of the present invention.

Figure 51 shows another detail view of a form of the arch element and its footing that is included in the disclosure of the present invention.

Other objects, features and advantages of the invention will become apparent from a consideration of the following detailed description and the accompanying drawings.

FIRST ASPECT Dealing with a first aspect of the invention discussed now with reference to Figures 1 to 14, as will be understood from the teaching of the present disclosure, instead of one footing (which may be in reinforced concrete) that distributes the horizontal and vertical support forces, the system embodying the present invention includes a small arch footing at the springs of the arch plus a large foundation block on which the arch footing rests. Thus, the stresses on the soil (ground) are distributed in two stages, which is more effective and less expensive than prior art systems. The foundation block of the present invention, while large in volume, is still relatively inexpensive because the backfill needs to be well compacted anyway, the present invention merely adds stabilizing materials. The present invention can use poor material which otherwise may be unsuitable for backfilling a normal bridge, by making it suitable through adding stabilizing materials, thus creating a foundation block. The arch of the present system contacts the thus- formed foundation blocks via the arch footings, in a manner to transfer all or at least most of the arch support forces to the foundation block. In practice, this reduces or eliminates the forces applied to the sidewall and to the wall footings thereby resulting in concomitant advantages. In most cases, the sidewalls are connected to the foundation blocks and are therefore held in place by the foundation block or blocks. The large dimensions of the foundation block together with its weight allows such an advantageous force/stress distribution, with outward (horizontal) movements/displacements of the arch ends (springs) being minimized in a very economical manner, even where relatively soft soil exits beneath the foundation block. This feature of the invention is especially advantageous for a relatively flat arch. Flat arches are used in conjunction with wide clearances with a minimum of lost height LH (Figures 1A, 1B and 2).

Referring to Figure 2, it can be understood that top-arch arched overfilled and/or backfilled structure 10, which also will be referred to as an arch structure, and method of construction embodying the present invention includes an arch span 12, which also will be referred to as an arch element, or simply an arch, which forms the roof of a void 14 within an earth filled space. Beneath arch span 12, walls 16 and 18, which will also be referred to as side walls or retaining walls, retain backfilled earth 20 or excavation edges 22 and 24 of previously existing (in situ) ground material on either side of open space 14. The arch and retaining walls may or may not be structurally connected. The art and practice of the present invention enables the arch and the walls to be constructed independently, in different construction phases. The purpose and form of the arch, the retaining walls and the means of founding these two key components of the backfilled and/or overfilled structure will be understood from the teaching of the present disclosure.

Structure 10 can be located between first selected area 30 which can be the floor of a void or a lower pathway, and which includes a plane 32, and a second selected area 34 which can be a roof of a void or an upper pathway which includes a plane 36.

The arch span comprises reinforced or unreinforced concrete, which may be manufactured as precast elements or cast in place or a combination of these means.

The arch span is founded via arch footings and foundation blocks 40 and 42 on general earth backfill 20 and/or on in situ soil (the surface of the previously existing (in situ) subsoil having been excavated to that extent). Foundation blocks 40 and 42 are each placed behind corresponding sidewalls 16 and 18 respectively of the overfilled and/or backfilled arch structure during its construction. Arch footings 48 and 50, formed of concrete or reinforced concrete are interposed between springs 44 and 46 which will also be referred to as ends of arch span 12 and the foundation blocks to further distribute forces over a wide area as indicated by arrows 54 thus also reducing the strength and stiffness requirements of the solidified fill material. As can be understood from the figures, especially Figure 2, forces 54 are radially directed forces associated with the springs of the arch span.

As can be understood from Figure 2, the contact between the springs of arch span 12 and the foundation blocks is arranged so that forces associated with the springs of the arch are transferred via the arch footings to the foundation blocks.

Accordingly, the sidewalls do not support the arch structure in any significant manner, at least not in the horizontal direction. In fact, as shown in Figure 2, since the springs of arch span 12 are spaced apart from the top ends 55 of the sidewalls, it can be stated that all or at least most of the forces associated with the springs of the arch span are transferred to the foundation blocks. The foundation blocks comprise a solidified material exhibiting sufficient stiffness and strength such that the thrust reactions of the arch can be distributed through the foundation block to the adjacent soil material. Thus the system embodying the present invention enables three objectives to be achieved with one structural member because the foundation blocks serve both to secure the sidewalls of the structure while at the same time to provide the foundation for the arch structure and to constitute all or part of the backfill.

As indicated by arrows 56 in Figure 2, the foundation blocks distribute the concentrated arch support forces at the springs of the arch via arch footings onto a sufficiently large earth backfill area such that the bearing pressure on the volume of earth to which the arch loads are applied does not cause unacceptable displacements, especially in the horizontal direction. Materials which may be used for creation of the foundation blocks 40 and 42 include cement stabilized earth (soil cement), lime stabilized earth, hardened flowable fill, lightweight hardened flowable fill, jet grouted earth or other such manufactured or treated material.

These materials have a strength and stiffness superior to that of normal earth, but considerably less than that of standard concrete. Thus, foundation blocks 40 and 42 are much more economical to produce than standard concrete. Quite often, earth material not suitable for bridge backfilling can be used for the foundation blocks since it is treated with cement and or lime or other additions. Additionally, material that would need to be deposited in special dumps, since they are environmentally critical, may be used as backfill because when treated with cement, etc, some such materials are no longer critical or dangerous.

Walls 16 and 18 may be constructed independently of, and before, arch 12 and can be designed primarily for the purpose of retaining the backfill soil placed at the outside of the backfilled structure; or as a continuation of the concrete arch span so as to be one-piece and monolithic therewith as indicated by system 10' shown in Figure 3 or system 10"shown in Figure 4.

Independently constructed sidewalls may comprise mechanically stabilized earth (MSE) using precast wall panels or any other type of earth retaining wall, including but not limited to sheet piles, bored piles or an excavated cast-in-place (cip), precast or sprayed (shotcrete) concrete wall with or without nails/anchors.

The independence of sidewall and arch construction enables the construction process to be staged as independent activities i. e. construction of the sidewalls and solidified backfill, and subsequent placement of the arch and overfill of the structure.

Since all or at least most of the arch support forces are directed onto the foundation blocks, wall foundations 57 and 58 respectively can be designed to be very small as compared to wall foundations F1 and F2, or omitted completely.

As can be understood by comparing Figures 1C and 2, the system embodying the present invention has several advantages over prior art systems. By locating the foundation blocks behind the wall or walls a number of advantages become associated with the system embodying the present invention.

Normal foundations below the walls, which usually require significant cuts into the ground and which can be expensive and environmentally disadvantageous especially in the case of river beds (wetlands act prohibits the interference with river beds) or when deposited wastes have to be removed prior to foundation construction, can be significantly reduced.

Since the foundation blocks of the present system are located behind the sidewalls, they are less at risk when scour problems are present, than the footings of prior art systems.

The foundation blocks of the present invention are simpler, cheaper and can be faster to build than prior art footings. An additional advantage is that general earthworks machinery may be used for their construction rather than specialist equipment used for placing concrete.

Earth material unsuitable for backfill in prior art systems can be made suitable for the system of the present invention even for the solidified backfill zones (foundation blocks), by using cement, lime or other solidifying materials and/or treatment.

The foundation blocks are unreinforced (except by anchors, mostly synthetic anchors in some forms of the invention) and therefore are more durable and long-lasting compared to prior art systems. In the case of cement or lime treatments, the foundation blocks actually become harder over time; they cannot deteriorate.

Because the system of the present invention primarily uses earth material available at the site, the system of the present invention has several ecological advantages, including less transportation (less air pollution), and less exploitation of valuable gravel resources. There is even the possibility of backfilling the wall with environmentally hazardous materials which in some cases become harmless when mixed with cement, lime or other additive.

Furthermore, by comparing the system shown in Figure 2 to the system shown in Figure 1B, it can be understood that the system embodying the present invention has an advantageously reduced lost height LH required to achieve the same clearance profile as compared to prior art systems.

There are many alternative forms of the present invention. One form of the invention is the case where the upper pathway plane 36 (in Figure 2) coincides with the top surface of the arch span 12, thus omitting the earth overfill which is a normal characteristic of the present art. As mentioned above, two forms of the invention are shown in Figures 3 and 4 as systems 10'and 10"respectively. The flat arch form of the invention may rest on foundation blocks which simultaneously serve to support the sidewalls, or may comprise a continuous frame supported laterally by foundation blocks as shown in Figures 3 and 4.

Figure 3 shows system 10'which includes steps 60 in the upper sides of the arch structure 12'as well as elements 62, such as pipes or the like, which are used to grout the contact zone between the structure itself and the foundation block, thereby additionally securing the intimate contact and force transfer from the arch structure 12'of system 10'to foundation blocks 40'and 42'. Forces from arch structure 12'are distributed to the foundation blocks as above described and as identified by arrows 63. Figure 4 shows an embodiment 10"of the flat arch using a continuous one-piece monolithic frame whereby protruding corner 64 is used (instead of the stepped upper side of the arch structure 12'to ensure the force transfer from the structure to the foundation block. In order to ensure a secure connection between arch structure 12"and foundation blocks 40"and 42", a channel 65 can be defined through each protruding corner. Cement or concrete or the like can be placed through channel 65 and/or pipes can be used as in the other embodiments of the invention to improve the intimacy of the contact between protruding corner 64 and foundation blocks 40"and 42".

Also, as shown in Figures 2 and 3, the sidewalls of the system of the present invention can be planar and extend perpendicularly with respect to plane 32 contained in first selected area 30 or can be inclined at an oblique angle 8 with respect to plane 32 with angle 8 being an acute angle whereby the sidewalls incline toward each other. Furthermore, as indicated in Figure 4, the sidewalls can be curved in the manner indicated at area 68 with respect to a plane 69 which is upright with respect to plane 32. In some cases, plane 69 can be perpendicular to plane 32. In other cases, as will be discussed below, the curved nature of the sidewall will make that sidewall cylindrical in nature.

Furthermore, any or all of the systems of the present invention can include reinforcing elements RE in either or both the arch and/or the sidewalls as indicated in Figures 2 and 4. The foundation block as such is unreinforced with the exception of the mostly synthetic anchors used to tie the MSE (mechanically stabilized earth) walls back into the backfill (for the case where this type of wall is used).

The system of the present invention can also be used in conjunction with a cover-and-cut technique. As indicated in Figure 5, a cover-and-cut method embodying the present invention includes forming sidewalls by the use of sheet, soldier, driven or bored piles, diaphragm walls or other similar materials in step 70; constructing foundation blocks from soil in step 72; creating the foundation blocks adjacent to a selected area in step 74; placing an arch element in a position to span adjacent foundation blocks and to rest on the foundation blocks in step 76; covering the arch element with soil in step 78 (if soil cover is required); and removing soil from between the sidewalls in step 80. The final product of such a method is shown in Figure 6 as system 90. System 90 includes sidewalls 92 and 94 which have been first constructed using sheet, soldier, driven or bored piles, diaphragm walls, etc. , subsequently foundation blocks 96 and 98 are constructed by manufacturing soil cement with the excavated material or by shallow soil mixing techniques where possible or by other means of solidification; next, shallow arch span 100 is placed or constructed, and in the final step the arch is covered to natural grade 104 and the soil material 102 located between the sidewalls is removed. Where permissible, the"cover-and-cut"method can be used without first placing the sidewalls if the excavation walls can be secured using shotcrete and/or nails and anchors subsequent to and/or during removal of the material beneath the flat arch. It is noted that foundation blocks 96 and 98 can be created by excavating and replacing material with soil cement or the like, or by using a solidification process from the top such as"shallow soil mixing"or grouting or other manner to solidify the material. It is also noted that sidewalls 92 and 94 can include sheet piles, or soldier piles, or driven piles or bored piles or diaphragm walls or excavation protected by shotcrete and nails/anchors or any other practical means of creating a retaining wall appropriate for this application.

As shown in Figure 6, springs 106 and 108 of arch span 100 bear via arch footings on the foundation blocks.

As indicated in Figure 7, the present invention includes a method of forming an arch system which comprises defining a first selected area in step 120; defining a second selected area spaced above the first selected area in step 122; placing two sidewalls (vertical, upright or inclined) between the first and second selected areas in step 124; forming foundation blocks near the sidewalls in step 126; placing an arch span over the sidewalls in step 128; abutting ends of the arch span against the foundation blocks in step 130 (via arch footings); and transferring arch structure support forces from the arch span to the foundation blocks in step 132. The method can further include a step 134 of spacing the arch span apart from the sidewalls. The method can further include a step 136 of providing soil material near the sidewalls and the step of forming foundation blocks includes stabilizing the soil material. The step of stabilizing the soil material can also include solidifying the soil material in step 138. The method can further include inclining the sidewalls toward each other in step 140, and further include spreading the forces between the arch structure and the foundation blocks over an area larger than the ends of the arch span in step 142. As indicated in step 144, the step of placing two sidewalls can include casting the sidewalls in place, or as shown as step 146, the step of placing an arch span can include casting the arch span in place. The step of placing two sidewalls can include precasting the sidewalls in step 148, and the step of placing an arch span can include precasting the arch span in step 150. The method defined can further include reinforcing the arch span in step 152, and can further include reinforcing the sidewalls in step 154.

The above disclosure has been directed to a straight bridge structure; however, the above-disclosed means and methods can be applied to curved or angular shapes in plan view or in longitudinal section as well without departing from the scope of the present disclosure.

As discussed above, the present invention can also be embodied in a domed structure. As shown in plan view in Figure 8, a system 10"'includes a dome 160 which corresponds to arch 12 and which spans a void area therebeneath. An arcuate sidewall, which can be circular or elliptical in plan view (cylindrical) or the like identified as sidewall 161 is located beneath dome 160. A dome footing and foundation block 162 are located to abuttingly engage the spring 164 of dome 160 in the manner described above. Since the only difference between system 10" and system 10 is the dome shape of system 10"', no further discussion of system 10"'will be presented. It is also noted that while a spherical dome shape has been discussed, those skilled in the art will understand that the arcuate shape of the present invention can also be other arcuate shapes as well, including elliptical or other such arcuate shape. Such arcuate shapes are intended to be included in the scope of the present disclosure as well.

The dome embodiment of the present invention has an advantage that the solidified backfill (foundation block) avoids the need for circumferential tie rods (at the spring level of the dome) because of the rigidity of the foundation block.

It is also noted that the scope of the present disclosure also includes not solely bridges with pathways on top and under it, but also any kind of underground space, with one or several openings for access, exit, etc.

Still further, the system embodying the present invention can be used in connection with other forms of bridges as well, such as a multi-arch structure 200 shown in Figure 9, a skewed arch structure 300 shown in Figure 10 and disclosed in US Patent application Serial Number 09/520, 636, filed on 03/07/2000 by the same inventor and titled"Overfilled, Precast Skewed Arch Bridge, "the disclosure of which is fully incorporated herein by reference or an arch structure 400 shown in Figure 11 with battered ends whereby the ends of the arch structure are sloped to match the gradient of the sides of the overfill embankment through with the arch structure passes. It is noted that systems 200,300 and 400 all have arches, such as arches 202,302 and 402 which abuttingly engage foundation blocks 204, 304 and 404 respectively in the manner discussed above. In the case of the multi- arch system, foundation blocks can replace the sidewalls that would otherwise be interposed between adjacent arch sections, such as indicated by foundation blocks 206. Foundation blocks 304 and 404 may be extended beyond the length of the arch elements 302 and 402. As shown in Figure 10, skewed bridge 300 has a skew angle a, with angle (x<90°. The methods of the present invention can be modified to include the above-mentioned arch system forms. These modifications are indicated in Figure 7 as defining a skewed arch system in step 700 and defining an arch system with battered ends in step 800. Reference is made to the incorporated disclosure for such steps.

It is noted that the contact between the arch structures and the foundation blocks in systems 200,300 and 400 is identical to the contact between the arch structures and the foundation blocks discussed above. Accordingly, such contact will not be discussed in detail, but reference is directed to the above discussion.

Furthermore, as indicated in Figure 12, flat (shallow) arches 12A are susceptible to outward displacement 12A'of their springs/abutments. Therefore, the present invention contemplates prestressing the arch by pressing (jacking) the arch on one side and thus producing the opposite of what would happen if there were an outward displacement. This prestressing is indicated in Figure 12 by arrow 12A". The susceptibility to outward displacement, by this token, is considerably reduced. Accordingly, the method of the present invention can further include a step 900 of prestressing the arch structure.

As illustrated in Figures 13 and 14, one of the variants of the present invention is that arch section 12D can be circular (of constant radius of curvature).

Such an alternative has several advantages, including the ability to be precast in which case a single mould can be used both to form large span arches, and by blocking off part of the mould, to form smaller arch spans as indicated in Figure 13 at areas 12B; or cast in place, in which case formwork 12F can be extended as indicated at 12FE with a circular arch shape as indicated in Figure 14 by extension 12FE on basic formwork 12F. The method embodying the present invention can be modified to include this step as well and is indicated in Figure 7 by step 950 of using a common mould to create more than one form of the arch structure.

SECOND ASPECT Broadly dealing now with a second aspect of the invention discussed with reference to Figures 15 to 31 which have their own reference number sequence for the figures which overlaps with the sequence for Figures 1 to 14, the overfilled arch bridge structure and the elements thereof embodying the present invention can be independently used or used in conjunction with the overfilled bridge disclosed in Figures 1 to 14. While the present aspect will be disclosed in combination with that structure, it should be understood that the present aspect can be used independently of such structure and no limitation is intended by the disclosure of this invention in combination with the invention disclosed in the aspect of Figures 1 to 14. The basic structure disclosed in the first aspect is shown in Figure 15 as structure 10. As disclosed in the aspect of Figures 1 to 14, earth overfilled arched structure 10 includes a shallow arch 12, which is concrete in Figures 1 to 14, spanning a clear space 14. Sides of the clear space are formed by curved or straight walls, such as wall 16, and solidified zones of earth material (backfill or in situ) bear against the springs of the arch and/or behind the walls and form foundation blocks, such as foundation block 18 which are in intimate contact via arch footings, such as footing 20, and with the springs of the arch and/or with the upper part of the sidewalls in such a way that the arched structure delivers most or all of its support forces into the foundation blocks. These, due to their size and weight, transfer and spread the support forces to the subsoil, such as subsoil 22, which can be backfill and/or in situ material, so that displacements, especially in the horizontal directions, are minimal. Overfill, such as earth overfill 24 is placed on top of arch 12. The disclosure of this structure will not be further presented with reference to Figures 15 to 31, with reference to the aspect of Figures 1 to 14 made for such disclosure.

As discussed above, the overfilled bridge structure embodying the present invention combines precast and cast-in-place advantages and also stabilizes the arch structure.

Referring first to Figures 16-18, it can be seen that the present invention is embodied in an overfilled bridge structure 28 comprising an arch 30 which has a lower layer 32 which is precast and an upper layer 34 which is cast-in-place. As shown in Figure 15, the arch layers contact footings, such as footing 18, at arch ends, such as arch end 20, when used in conjunction with the structure disclosed Figures 1 to 14. Precast elements form the initial arch shape and cast-in-place concrete is poured over the precast elements to complete an overfilled arch of a shape and thickness that is similar to the shape and thickness of prior structures.

As can be understood from Figures 16,17, and 18, layers 32 and 34 can be reinforced concrete with longitudinal rebars, such as rebar 36, and arch rebars, such as rebar 38, therein. Joint seals, such as joint seal 40, can be included as well and a waterproofing, such as waterproofing 42, can also be included between layers 32 and 34. Shrinkage crack inducers, such as shrinkage crack inducer 46, can also be included in cast-in-place layer 34 to induce shrinkage cracks, such as shrinkage crack 44, within the cast-in-place concrete, adjacent to the gaps between precast elements. As can be seen in Figure 18, the thickness of the cast-in-place layer 34 may be locally increased adjacent to the gaps between precast elements, in order to increase the depth of the concrete section at this location. This has the inherent advantage of increasing the longitudinal moment carrying capacity of these locations, thereby maintaining the longitudinal load-sharing advantage of the cast-in-place previous art.

The precast layer of the arch forms the complete arc of the arch span, but is thinner, and therefore lighter to transport and handle than prior art precast arches.

The precast arch elements are sized to be able to support their own self-weight during transportation and placement, as well as to be sufficiently strong to enable casting layer 34 of cast-in-place concrete over the precast layer 32. Those skilled in the art will understand how to size and form precast layer 32 based on the teaching of this disclosure. The composite section of precast and cast-in-place concrete thus formed has the thickness and strength of previous structures which are exclusively precast or exclusively cast-in-place arches.

The main advantages of the composite arch system embodying the present aspect of Figures 15 to 31 include: the weight of the transported elements is lower, and can be lower by half, than prior precast elements (or alternatively the elements can be made wider such that fewer elements need to be transported); and the cast- in-place layer 34 facilitates load sharing longitudinally along the arch to distribute concentrated loads. Furthermore, placement of waterproofing between precast elements is better facilitated than in prior structures. Thus, the composite system embodying the second aspect hereof has advantages over either a fully precast arch. No formwork or formwork support structure is required to form the arch embodying the second aspect of Figures 15 to 31. The elimination of formwork or formwork support structures will result in considerable saving in costs associated with the formwork, and the clearance below the arch will not be reduced during construction since a temporary support structure is not required. Thus, the structure embodying the aspect of Figures 15 to 31 of the present invention also has advantages over cast-in-place arches.

As also mentioned above, the overfilled bridge structure of the present invention includes means for reducing the bending moments within the overfilled arches, as well as reduces the arch's sensitivity to any outward displacement of the arch footings. Reducing the bending moments also reduces the structural depth and steel reinforcement required with the advantages concomitant to such reduction.

Broadly, the means include either customized arch end geometry or prestressed arches, with the prestressing occurring either prior to or during loading.

Referring to Figures 19 and 20, a basic arch footing 50 of a concrete arch CA is shown as including a cast-in-place arch footing 52 located between arch CA and wall 16 and foundation block 18. A bearing 54 is interposed between the arch spring and the arch footing. Overfill 24 is positioned above the arch CA.

The structure embodying the second aspect of the present invention (Figures 15 to 31) improves over the basic arch footing shown in Figures 19 and 20. The structure of the Figures 15 to 31 of the present invention includes two main means by which the bending moments and thus the structural depth and steel reinforcement are reduced. The means embodying Figures 15 to 31 of the present invention include a customized arch end geometry (Figures 23,24 and 25) and prestressing the arch prior to or during loading (Figures 26, and 27-31).

Referring to Figures 21 and 22, a prior art arch support PS is shown in conjunction with an arch C having a centerline CL. As shown in Figure 21, arch support PS is located to provide arch support reaction at centerline CL. The resulting moment distribution is indicated in Figure 22 by dotted line IM and in which negative bending moments NM are defined adjacent to the shoulders of the arch and a positive (sagging) bending moment BM1 is defined at the crown of the arch.

The means embodying the aspect of Figures 15 to 31 of the present invention is illustrated in Figure 23 includes an eccentric arch support 60. As shown in Figure 23, eccentric arch support 60 is located to create arch support reaction 62 spaced apart from centerline CL of arch C, with the eccentricity being indicated in Figure 23 by reference number 64. The moment induced by support reaction eccentricity is indicated in dotted line HM shown in Figure 22. As can be understood from Figure 22, the reaction due to the reaction eccentricity induces a constant negative"hogging"moment BM2 in the arch.

Referring next to Figure 23, it can be understood that adding the constant negative moment BM2 to the negative/positive moment shown in Figure 22 for moment distribution in the arch yields a resultant moment distribution RM shown as a dotted line in Figure 25. As can be understood from Figure 25, resultant moment distribution RM has increased negative bending moments RMN located near the shoulders and a decreased positive (sagging) bending moment SM near the crown. Bending moment SM is a moment addition of bending moments BM1 + BM2, with the total of (BM1 + BM2) being less than BM1 due to the signs of the bending moments. This can also be visualized using the absolute value of the total of (BM1 + BM2). Thus, the peak positive moments in the arch crown are reduced over the prior art (non-eccentric) form of arch support.

Prestressing can also be used to reduce the bending moments within an earth overfilled arch. Prestressing is illustrated in Figures 26-31. As shown in Figure 27, loading L on an arch will induce a bending moment IM'which, as discussed in relation to Figure 22, includes negative bending moments NM'at the shoulders and a positive (sagging) bending moment BM1'at the crown. Figure 27 is similar to Figure 22, but is included here to better explain the prestressing embodiment of the aspect of Figures 15 to 31 of the present invention.

As shown in Figure 26, prestressing loads PL are applied to an arch to displace the arch by a distance DPL prior to or during loading of the arch. Figure 28 illustrates the moment IMS induced in the arch as a result of prestressing load PL. As shown in Figure 28, induced bending moment IMS is a variable negative "hogging"moment which has a negative portion BM2'near the crown of the arch.

During prestressing, a (hogging) moment is induced and then is locked into the arch. This moment is opposite to the peak (sagging) moment in the crown of a conventionally supported arch.

Figure 29 illustrates the arch bending moment RMM which results by adding bending moment IMS associated with prestressing to bending moment IM' associated with the arch support. As above, as a result of the signs of the bending moments, bending moment RMM includes a negative bending moment NBM at the shoulders of the arch which is greater than the negative moments NM'at the shoulders but a reduced positive (sagging) bending moment SM'at the crown of the arch. As discussed above, due to the signs of the moments, the total of (BM1'+ BM2') is less than BM1'. Prestressing the arch also reduces the sensitivity of the arch to outward displacement of the arch footings.

Figure 30 illustrates one means for prestressing the arch. As shown in Figure 30, an element 80 is interposed between the arch footing and the arch.

Element 80 prestresses the arch as discussed above. One form of element 80 includes an inflatable element, such as a hose or other means. Such hose may be inflated and pressurized with a setting substance such that compression is induced and locked into the arch. As shown in Figure 30, bearing 82 is an arch spring to arch footing interface and has a low friction interface 86 between the arch and bearing 82. The arch can be the arch as discussed in the aspect of Figures 1 to 14 hereof or the composite arch disclosed in the aspect of Figures 15 to 31 hereof. As will be understood from the teaching of the present disclosure of Figures 15 to 31, the arch end arrangement shown in Figure 23 could be applied to both arch ends such that the arch can be prestress from both ends.

Figure 31 illustrates another means of prestressing the arch whereby a tie (or ties) is attached to each end of the arch, and tensioned in order to compress the arch (analogous to the string on a bow used for launching arrows in archery).

THIRD ASPECT With reference to a third aspect of the invention now discussed with reference to Figures 32 to 51 which have their own reference number sequence which may overlap with those of Figures 1 to 31, shown in Figure 32 is an arch support system such as disclosed Figures 1 to 14. Reference is made to the discussion of Figures 1 to 14 for a full disclosure of the system shown in Figure 32. However, by way of reference, shown in Figure 32 is a system 10 which includes an arch span 12, which also will be referred to as an arch element, or simply an arch, which forms the roof of a void or open space 14 within an earth filled space. Beneath arch span 12, walls 16 and 18, which will also be referred to as side walls or retaining walls, retain backfilled earth 20 or excavation edges 22 and 24 of previously existing (in situ) ground material on either side of void or open space 14 above arch space 12, overfill (earth) material OV is placed to create the plane 36. The arch and retaining walls may or may not be structurally connected. The art and practice of the present invention enables the arch and the walls to be constructed independently, in different construction phases. The purpose and form of the arch, the retaining walls and the means of founding these two key components of the backfilled and/or overfilled structure will be understood from the teaching of Figures 1 to 14.

Structure 10 can be located between first selected area 30 which can be the floor of a void or a lower pathway, and which includes a plane 32, and a second selected area 34 which can be a roof of a void or an upper pathway which includes a plane 36. Arch span 12 and overfill (earth) material OV is placed to create the plane 36.

The arch span is founded via arch footings 48 and 50 and foundation blocks 40 and 42 on general earth backfill 20 and/or on in situ soil (the surface of the previously existing (in situ) subsoil having been excavated to that extent).

Foundation blocks 40 and 42 are each placed behind corresponding sidewalls 18 and 16 respectively of the overfilled and/or backfilled arch structure during its construction. Arch footings 48 and 50, formed of concrete and/or reinforced concrete are interposed between springs 44 and 46 which will also be referred to as ends of arch span 12 and the foundation blocks to distribute forces over a wide area thus also reducing the strength and stiffness requirements of the solidified fill material of the foundation blocks.

As discussed relative to Figures 1 to 14, the foundation blocks distribute the concentrated arch support forces at the springs of the arch via arch footings onto a sufficiently large earth backfill area such that the bearing pressure on the volume of (in situ or backfill) earth to which the arch loads are applied does not cause unacceptable displacements, especially in the horizontal direction.

As is also shown in Figure 32, a roadway R can be located above the system and can include pavement P with pavement P'located beneath the system.

Shown in Figures 33a-33c are examples of the type of systems that can be formed using the teaching of the present disclosure. As shown in Figure 33a, the system can include skew elements SB. As shown in plan view Figure 33b, the system can include a round bridge RB having a plurality of trapezoidal arch elements 12T or an angled system AB with one trapezoidal element 12T'. Plan views of different arch structures are shown in Figures 34a, 34b and 34c as curved elements CB, skew elements SE and straight elements STE.

As discussed above, the method embodying the present aspect of Figures 32 to 51 forms the arch elements in a use orientation. The use orientation for arch element 12 is shown in Figure 32; whereas, a side on orientation would have arch element 12 oriented at a 90° angle with respect to the orientation shown in Figure 32. As also discussed above, forming the arch elements in the use orientation produces several advantages over forming the arch element in a side-on orientation. A formwork 60 is shown in Figure 35 in plan view and can be used to form the straight elements STE, and/or the skew elements SE and/or the trapezoidal elements TE. The skew elements can include an angle a. Formwork 60 can include walls, such as 62, to define the desired shapes as well as outer perimeter walls 64. Materials and procedures suitable for forming the arch elements are carried out using the formwork and suitable procedures. The formwork is very simple and no counter forms are usually required. The formwork can be lifted up or down on one side of the form as indicated by double-headed arrow 66 in Figure 36 to help in placing and vibrating the concrete in the formwork, and to prevent the flow of vibrated concrete by changing the gradient/slope. The lifting can be performed using a suitable jack. The formwork, itself, can be vibrated, and when using the lifting system with suitable jacks, the vibration of the formwork can be done in halves or thirds of the arch element.

Once the concrete is poured and has hardened, the elements are moved, in the use orientation, from the formwork to a yard for stacking and from there to a transportation vehicle using a crane or the like. As shown in Figures 37a and 37b, an element 12X is attached to a crane (not shown) by a harness 68 which includes two cables 70 and 72 attached to a first surface 74 of element 12X. As element 12X is lifted from the formwork, it will flex under its own weight from an unflexed configuration 12xi as shown in solid line in Figure 37a to a flexed configuration 12X2 shown in dotted lines in Figure 37a. This flexing can be used to obtain the desired pre-deformation to prestress the arch to partly or wholly compensate the influence of a possible outward yield (deformation) of the foundation blocks when the arch is subjected in its final position to loading. The arch elements are placed in their pre-deformed shape (indicated in dotted line in Figure 37a) and return to their original shape (indicated in solid line in Figure 37b) when overfilled. When the elements with the dotted line shape are placed onto the foundation blocks, the foundation blocks will hardly move under the dead weight of the arches only.

When all elements have been placed, the overfill is placed which then has a total weight greater than that of the elements alone. This loading condition, the overfill plus the arch dead weight, produces a considerable horizontal thrust are on the foundation blocks. If the foundation block, or blocks, is/are not as stiff as desirable, this loading may push the foundation blocks out by a small amount.

Even small movements result in the activation of the earth resistance to a considerable degree preventing further movement of the foundation block. Ideally, the foundation block will move out about as much as the ends of the arch elements have been drawn together by the pre-deformation before installation. If this is the case, the moments introduced by the drawing together of the ends and the opposite moments caused by the outward deformations of the foundation blocks will largely cancel each other out so that the elements-before traffic loads are applied - are in a state of very little moments. This helps to overcome disadvantages created by a certain amount of yielding of the foundation blocks. Should the foundation blocks not yield, the prestressing or pre-deformation is not harmful because it is done only to a degree which is within the allowable limits of the arch design. Furthermore, the moments generated by prestressing are opposite in direction to the majority of moments generated by traffic and are therefore not detrimental to the load carrying capacity of the arch.

Prestressing of the arch element can also be effected by structural elements, such as tie rod 80 shown for arch element 12X2. Tie rod 80 can include a turnbuckle 82 or the like to set the desired amount of camber, or pre-deformation on the arch element.

As discussed above, in some instances differential displacement can occur between adjacent arch elements in a system having a plurality of arch elements.

This differential deformation can be prevented, or at least minimized, by connecting adjacent arch elements together once they have been put in place. The connection can transfer shear forces between elements and thereby reduce the relative displacements to zero or almost zero. Additionally, the load carrying capacity is increased since two or more adjacent elements carry the imposed loads in unison.

The method embodying the aspect of Figures 32 to 51 of the present invention includes connecting adjacent elements in one of several different ways.

The first connection is via post-tensioning one or several of the tie elements. This can be effected by introducing tension braces to the tie elements.

The post-tensioning force creates friction between the adjacent elements which in turn provides shear resistance. The shear resistance prevents and counteracts differential deformation between adjacent arch elements.

A second form of connection is by bolting. Bolting is indicated in Figures 39 through 44. Holes, such as hole 90 are provided through each arch element.

The holes can be defined by placing pipes in the formwork during formation of the arch element. The holes can have a counterbore 92 on each end thereof. The holes in each arch element are located so that the holes in one arch element will be aligned with the holes in an adjacent arch element as shown in Figure 41 for adjacent arch elements 12Xal and 12Xa2. A relatively thick steel rod or dowel bar 94 (reinforcement bar) is positioned in the aligned holes such that it extends through the holes in at least two adjacent arch elements. To ensure centricity of the rod, support elements 96 can be located in the arch elements inside the holes. To guarantee a tight fit and proper load transfer, the rod has a sheath 98 surrounding it which can be a thin but tough plastic sheathing. After placement of the rod the sheath is filled with grout (cement plus the sand (or filler) plus water) under pressure. The grout fills the interspace between the rod and the arch element adjacent to the holes. The grout prevents play between the rod and the arch element. The rod or dowel bar becomes, after hardening of the grout, an integral part of the arch element. A space 99 exists between the sheath and the arch element adjacent to the hole and is filled when the sheath expands after insertion of grout under pressure. At ring joints, such as ring joint RJ (see Figures 34a to 34c), the bar or rod continues between elements. Here also it is surrounded by grout which protects it against corrosion. Since the sheath extends for the entire length of the rod or dowel bar, the grout will not leak out of the sheath before setting. The sheath will expand to snugly fit the hole (or holes). At the joints between the elements, such as joint 102, the sheath prevents the grout from leaking out. Additionally, as shown in Figure 13, caulking 104 can be applied at the joints to make the structure watertight.

It is also noted that in order to produce a bridge from precast elements, it has to be done in several pieces which are each smaller than the entire bridge.

These pieces (elements) can be tied together on site using the dowel and grouting system discussed above.

It is also noted that due to the rods or dowels the precast arch bridge of Figures 32 to 51 performs almost as well, deformation and resistancewise, as if the joint (the ring joint) didn't exist as would be the case with a cast-in-place structure. The whole bridge acts as a homogeneous vault and not a number of individual arch elements, one next to the other. Thus, the rods or dowel bars are an effective means to overcome the drawbacks of precast structures which are separated by joints instead of being homogeneous structures like cast-in-place structures.

Still further means can be used to connect adjacent arch elements. Such a further means is indicated in Figure 45 and includes a cam 110 in one arch element and a corresponding depression 112 in an adjacent arch element. Each arch element contains both cams and depressions. A cam on one elements is accommodated in an associated depression on an adjacent element to connect the two adjacent elements together. Adhesive can also be applied to the cam and/or to the depression to provide a permanent connection free of play.

The foundation of the precast arch element (Figures 32 to 51) is, in principal, the same as the foundation disclosed in the figures 1 to 14. The foundation will include the foundation block. The arch elements can include an arch footing such as indicated in Figure 32 as arch footings 48 and 50. In the means and method embodying the present invention, the arch footings can be precast together with the arch element as indicated for arch footing 50p in Figure 49 which rests directly on the foundation block. Another form of the arch footing is shown in Figure 50 as arch footing 50p, which is cast in place and connected to the arch element which does not contain precast footings. Yet another form of the arch footing is shown in Figure 51 as arch footing 50p2. Arch footing SOp2 includes a small footing 50p2'that is precast with the arch element and a layer of cast-in- place concrete 5°p2 between the precast footing and the foundation block. This procedure allows the precast footing to be designed quite small (thus adding only little weight to the precast element) while the concrete (preferably unreinforced) which is cast-in-place between the precast element and the foundation block spreads the footing forces sufficiently to be borne by the solidified earth material of the foundation block. This cast-in-place concrete would be poured after the precast elements are installed in their final position, the latter being provisionally supported on locally protruding parts of the arch element LPP in Figures 3a to 3c or element 124 of Figure 16. This ensures that the final support will be between the larger part of the arch element and the foundation block via the cast-in-place concrete.

This process of placing cast-in-place concrete between the arch element and the foundation block is indicated in Figures 46 to 48 in which arch element 120 has an end area 122. An element 124 extends out of the end area of the arch element and engages the foundation block when the arch element is initially installed. Reinforced or unreinforced concrete 126 is then cast in place around the arch element end and the foundation block and overfill 128 is subsequently placed on the cast-in-place concrete once this has hardened. Concrete can also be located between the end of the arch element and the foundation block as indicated in Figure 36 by cast-in-place concrete 130.

As used herein with reference to Figures 32 to 51, the term"prestressing" refers to the condition of an arch element such as shown in Figures 37a and 38 prior to placement of the arch element in the system; and the term"post- tensioning"refers to a condition of an arch element after it has been placed. Thus, the elements shown in Figures 37a and 38 are prestressed; whereas, adjacent arch elements 12 can be post-tensioned by the action of the dowel rods or by the action of friction of one arch element on an adjacent arch element or by the interlocking action of the elements shown in Figure 45.

It is understood that while certain forms of the invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangements of parts described and shown.