A METHOD FOR BUILDING A ROAD BED AND THE USE OF THE SAME

Abstract: The invention relates to a method for building a road bed (96) and the use of the same. Shotcreting is used to provide a road bed (96) with one or a plurality of vaulted concrete casings (6) with respective vaulted cavities (92) remaining thereinside. This can be assisted by using a mesh or a profiled shaped plate set in a vaulted shape, and shotcreting is effected onto the surface of said mesh or profiled shaped plate.

Description: A METHOD FOR BUILDING A ROAD BED AND THE USE OF THE SAME The present invention relates to a method as set forth in claim 1 for building a road bed. Our earlier Patent application FI 894535 discloses a method for producing a joint structure as a combination of a shaped plate, generally a profiled steel plate, and concrete by shotcreting the shaped plate. An expanded sheet metal mesh manufactured from thin steel sheet by elongation is prior known from US Patents 1 864 598 and 3 034 197. A wider- meshed diagonal screen grid manufactured from thicker sheet metal by cutting' and elongation is known e.g. from US Patent 3 570 086. Α drawback in the current road-building methods is e.g. that a road bed requires heavy soil masses, which often lead to undesired depressions in soft ground underneath. The elimination of those requires expensive ground reinforce¬ ments. Indeed, the construction on soft basic grounds generally incurs major extra costs. Building passages in road-bed structures by the application of the prior known methods is expensive and inconvenient. Particularly, the casting of concrete into an arched vaulted shape is difficult and tedious. Carrying great masses of soil to a road-construction site requires a lot of time and causes environmental problems. The soil materials suitable for road-building are nearly exhausted in many places and must often be excavated in areas valuable in terms of environmental protection. Carrying out the construction on soft grounds may take several years as the reinforcement of subsoil is a tedious procedure. The road surfaces do not often remain flat but the roads develop traffic-disturbing depressions. At present, road beds are in useless form as some sort of soil storages. In downtown areas, for example, the street sections are highly valuable areas. Those should be in service more useful than e.g. the storage of sand. An object of this invention is to alleviate the above drawbacks and that is achieved by means of a method of the invention by the application of shotcreting to provide a road bed with one or a plurality of vaulted cavities inside a concrete casing. The invention can be used in a great number of applications. The accompanying figures are only intended to serve as examples and to illustrate the way of carrying out the invention. In this specification, the term "roadway" refers to highways, walking paths, railroads, and streets as well as like passages. The term "vaulted" refers in specification to arched vaults, vaulted shapes consisting of arched and straight sections, circles, egg shape and its sections, as well as parabolic and hyperbolic segments. A vaulted structure is often dominated by compression stresses but also flexural stresses may exist. Compression stresses are preferred since in that case the concrete does not require many steel reinforcements to take up tensile stresses. Thus, the structure will be inexpensive as expensive steel can be saved. Fig. 1 shows in principle a cross-section of a presently used general road bed. Fig. 2 shows in principle a visualization of an archedly bent mesh and plate section prior to concreting. Fig. 3 shows a section of an elongated mesh structure following the addition of a first concrete layer. Fig. 4 shows a principle of carrying out shotcreting by means of two nozzles behind steel members. Fig. 5 shows a concrete casing sprayed on top of an expanded sheet metal mesh braced with reinforcement corrugations. Fig. 6 shows an expanded sheet metal mesh shotσreted on both sides. Fig. 7 shows a visualization of the lifting of a prevaulted shotcreted surface element on top of a foundation. Pig. 8 shows a visualization of two parallel-set vaulted concreting surfaces. Pig. 9 shows a visualization of carrying out shotcreting by means of a remote-controlled heavyduty machine on top of a mesh element. Fig. 10 illustrates vaulted and profiled thin sheets on top of a foundation prior to concreting. Fig. 11 shows a visualization of a. finished road struc¬ ture obtained according to the invention. Fig. 12 shows a visualization of a finished road struc¬ ture built on top of piles. Fig. 13 shows a visualization of an alternative road structure with passages extending crosswise relative to the direction of a road. Fig. 14 shows a divided roadway based on top of piles. Fig. 15 shows a visualization of a street obtained according to the invention. Fig. 16 shows a visualization of a pedestrian street obtained according to the invention. Fig. 17 shows a visualization of a roadway obtained according to the invention with a parking lot provided in its bed structure. Fig. 18 shows a visualization of a roadway with another traffic route provided in its bed structure. Fig. 19 shows in cross-section a principle of carrying out shotcreting against the ground into an egg shape. Fig. 20 shows the spraying of the top portion of an egg-shaped cross-section on top of the structure shown in fig. 19. Fig. 21 shows a cross-section of a road structure set on top of an egg-shaped void. Fig. 1 illustrates an available road structure with a great amount of soil material underneath a cover structure 55. In a way, the road bed is in useless service and heavy. In fig. 2, an arched mesh 86 has been mounted on top of an arched and profiled thin sheet 1. Mesh 86 is shaped into an apexed form for increased rigidity. The diagonal strands of mesh 86 retain well the dimensional stability prior to concreting. In fig. 3, a first shotcrete layer 6 is applied to cover the lower section of mesh 86. In order to prevent the passage of shotcrete, it is possible to employ some sort of a backing member 27 temporarily or permanently. Through mesh apertures the concrete mass 6 works its way also inside a ribbed mesh portion. A double nozzle as shown in fig. 4 can be used for spraying concrete to the same spot from different directions for filling possible shadow regions caused by steel members 86 with shotcrete mass 4 from the other nozzle 5. It is also possible to employ a plurality of nozzles to spray concrete from different directions to a common spot. Nozzles 5 can be secured to support arms 82 that can be linked with a pivot 89 for adjusting the angle of incidence between various nozzles 5. If desired, the concrete mass 4 can be ricocheted from backing member 27 into spaces behind steel members 86. In fig. 5, the shotcreting is effected on top of an expanded sheet metal mesh 10 reinforced with corrugations 49. In an embodiment shown in fig. 6, an expanded sheet metal mesh 10 is shotcreted on both sides. This is to increase the vault strength with increased thickness. At the same time, a mesh made of e.g. steel is protected against corrosion. In fig. 7, a crane 52 is used for lifting a vaulted mesh element 10 on top of pre- ade foundations 45, said element being provided with reinforcement corrugations 49. The mutually tied foundations 45 are preset on ground 23. In fig. 8, the mesh elements are provided with reinforcement braces 100 which can be e.g. mesh troughs. Those can be first shotcreted full of concrete at the beginning of a concreting operation when the structure is still light. The structurally reinforcing braces are developed upon setting of the concrete. The diagonal reinforcement braces 100 are used to readily transfer the loads on a vault e.g. to piles 60 on soft ground. In fig. 9, shotcreting is carried out effectively from a remote-control equipped machine onto parallel mesh elements. Concreting can be effected in layers in a manner that structural strength increases gradually as the preceding concrete layers are setting. The weight and strength of the structure are increased at the same rate. In an embodiment shown in fig. 10, shotcreting can be effected e.g. onto a profiled metal sheet 1. In a case shown in fig. 11, a road construction 96 is provided by shotcreting with two vaulted cavities 92 side by side. The horizontal stresses of concrete casings 6 on the level of foundations can be directed oppositely to each other at the center. In an embodiment shown in fig. 12, e.g. shotcreting is used to provide a vaulted casing structure 6 with a noise barrier and upper-structure supporting ribs. In an embodiment shown in figs. 13 and 14, cavities or passages 92 are placed side by side and thus, on the level of foundations, the horizontal forces substantially neutralize each other. The passages extending crosswise to a roadway can serve e.g. as underpasses or bridges, storages etc. In figs. 15 and 16, a void space 92 is provided underneath a street area e.g. for traffic, pipelines 26, 26a or other equipment. In figs. 17 and 18, the road bed is also adapted to the requirements of traffic e.g. in crowded downtown areas with no available space for large parking lots or multi-lane roadways. In figs. 19, 20 and 21, an egg-shaped void space 92 is formed in the bed of a road 55. The egg-shaped form is preferable in terms of stresses. At the beginning, concreting can be effected e.g. against the ground 23. The necessary mesh or plate elements are used as a shotcreting foundation for the top section. Necessary extensions can also be readily made by shotcreting. If desired, it is also possible to employ a circular form or some other shape instead of an egg shape in cavity 92. An essential object of this invention is to make a hollow road bed as light as possible and by minimum labour. A method of the invention can be applied to produce structures having a great load-carrying capacity and flexural strength.

Claims: Claims 1. A method for building a road bed (96), c h a r a c ¬ t e r i z e d in that shotcreting (4) is used to provide a road bed (96) with one or a plurality of vaulted cavities (92) inside a concrete casing (6). 2. A method as set forth in claim 1, c h a r a c t e r ¬ i z e d in that a mesh (10) or a profiled shaped plate (1) is set in a vaulted form and shotcreting is effected onto the surface of mesh (10) or profiled shaped plate (1). 3. A method as set forth in claim 1 or 2, c h a r a c ¬ t e r i z e d in that said mesh (10) comprises a socalled expanded sheet metal mesh, made of thin metal sheet and pro¬ vided with reinforcement corrugations (49). 4. A method as set forth in any of claims 1 - 3, c h a r a c t e r i z e d in that said mesh (10) or profiled shaped plate (1) used as a concreting foundation is bent by prefabriσation into a vaulted shape. 5. A method as set forth in any of claims 1 - 4, c h a r a c t e r i z e d in that said mesh (10) or profiled shaped plate (1) used as a concreting foundation is reinforced by means of a trussed bracing (86). 6. A method as set forth in any of claims 1 - 5, c h a r a c t e r i z e d in that behind said mesh (10) is placed a concreting backing (27). 7. A method as set forth in any of claims 1 - 6, c h a r a c t e r i z e d in that said mesh (10) or profiled shaped plate (1) used as a concreting foundation is made substantially impervious to concrete. 8. A method as set forth in any of claims 1 - 7, c h a r a c t e r i z e d in that said vaulted cavity (92) is shotcreted both on the outside and on the inside. 9. A method as set forth in any of claims 1 - 8, c h a r a c t e r i z e d in that said casing structure (6) is provided with one or a plurality of reinforcement braces (100). 10. A method as set forth in any of claims 1 - 9, c h a r a c t e r i z e d in that said casing structure (6) is made at least partially corrugated. 11. A method as set forth in any of claims 1 - 10, c h a r a c t e r i z e d in that two or more vaulted cavities (92) are provided side by side for setting the horizontal stresses of concrete casings (6) at least partially to oppose each other. 12. The use of a road bed manufactured by the application of a method as set forth in any of claims 1 - 11, c h a r a c t e r i z e d in that the road bed is used as a traffic tunnel; a parking lot; a service passage; a cable canal; a public shelter, a storage; a water passage or a bridge.

Inventors: RYYNAENEN SEPPO, RYYNAENEN, SEPPO
Applicants: GESERTEK OY
Application year: 1991
Main classification: E01C3
IPC codes: E01C3, E02D29