Supporting structure of road foundation pit and construction method of supporting structure

Abstract

The invention discloses a supporting structure of a road foundation pit and a construction method of the supporting structure, relates to the field of foundations, and aims to shorten the occupation time of a road and quickly recover road traffic. According to the technical scheme, the supporting structure of the road foundation pit comprises an open caisson located in the foundation pit, the open caisson comprises vertically-arranged side plates and a horizontally-arranged top plate, the side plates and the top plate are prefabricated reinforced concrete and define an open caisson inner cavity with the bottom open, the bottoms of the side plates are blade feet, at least one of the side plates and the top plate is provided with a soil sampling hole, and the open caisson inner cavity is provided with a soil sampling hole. The outer surfaces of the side plates abut against the side wall of the foundation pit, the bottom of an inner cavity of the open caisson is a bottom plate constructed at the bottom of the foundation pit, and the top of the open caisson is flush with an existing road or a pavement structure flush with the existing road is laid on the top of the open caisson. The construction method of the supporting structure of the road foundation pit is used for construction of the supporting structure of the road foundation pit. And after the foundation pit is excavated, traffic can be recovered at the top of the open caisson in time, and the road occupation construction time is shortened.

Description

Technical Field

[0001] The invention relates to the foundation field, in particular to a supporting structure of a road foundation pit and a construction method of the supporting structure. Background Art

[0002] In urban underground engineering construction, the commonly used foundation pit excavation methods are open cut, dark cut and covered cut. The open cut method occupies a large area and will have a serious impact on the construction area and surrounding traffic. The deformation of the foundation pit and the surface settlement are difficult to control, which will affect the safety of surrounding buildings and underground pipelines, and will also affect the safety of surrounding vehicles. The dark cut and covered cut methods have high construction costs and are not economical for small and medium-sized underground projects. During construction, they will still have a certain impact on urban traffic and the safety of the foundations of surrounding buildings. When the foundation pit is located on the driving lane of the road, the open cut method will also occupy the road for a long time and cannot quickly restore traffic, which is unacceptable for busy sections of the road. Summary of the invention

[0003] The present invention firstly provides a supporting structure for a road foundation pit, the purpose of which is to shorten the occupation time of the road and quickly restore road traffic.

[0004] The technical solution adopted by the present invention is: a supporting structure for a road foundation pit, including a caisson located in the foundation pit, the caisson including vertically arranged side panels and a horizontally arranged top panel, the side panels and the top panel are both prefabricated reinforced concrete and surround an inner cavity of the caisson with an open bottom, the bottom of the side panels are blade feet, and at least one of the side panels and the top panel is provided with a soil sampling hole, the outer surface of the side panels abuts the side wall of the foundation pit, the bottom of the inner cavity of the caisson is a bottom plate constructed at the bottom of the foundation pit, the bottom plate is fixedly connected to the side panels of the caisson, the top of the caisson is flush with the existing road or the top of the caisson is paved with a pavement structure flush with the existing road.

[0005] The caisson can be a whole or prefabricated in sections and assembled on site. Specifically: the side panels and top panels of the caisson are prefabricated as a whole; or, the caisson is divided into at least two parts, and the parts are spliced ​​and connected.

[0006] After the bottom plate is constructed, it becomes a whole with the caisson. Specific: The bottom plate is cast-in-place reinforced concrete.

[0007] The shape of the caisson is generally a rectangular parallelepiped. Specifically: the outer contour of the caisson and the shape of the inner cavity of the caisson are both rectangular parallelepiped, and any one of the four side panels of the caisson or any two opposite panels are provided with a soil taking hole.

[0008] In order to improve the inherent strength of the caisson, further: an internal support is provided in the inner cavity of the caisson.

[0009] The present invention also provides a construction method for a supporting structure of a road foundation pit, the purpose of which is also to shorten the occupation time of the road and quickly restore road traffic. The technical solution adopted by the present invention is: a construction method for a supporting structure of a road foundation pit, comprising the following steps:

[0010] S1. Prefabricated caisson, the caisson includes vertically arranged side plates and horizontally arranged top plates, both of which are prefabricated reinforced concrete and enclose an inner cavity of the caisson with an open bottom, the bottom of the side plate is a blade foot, and at least one of the side plate and the top plate is provided with a soil taking hole.

[0011] S2. The prefabricated caisson is transferred to a location on an existing road where a foundation pit needs to be excavated, or the caisson is assembled at a location on an existing road where a foundation pit needs to be excavated.

[0012] The caisson can be a whole or prefabricated in sections and assembled on site. Specifically: in step S1, the side panels and top panels of the caisson are prefabricated as a whole; or, in step S1, the caisson is divided into at least two parts, and in step S2, the parts of the caisson are spliced ​​into a whole at the location where the foundation pit needs to be excavated on the existing road.

[0013] The transfer method of the prefabricated caisson is selected according to the quality of the caisson. Specifically: the caisson is prefabricated as a whole, transported and hoisted to the location where the foundation pit needs to be excavated on the existing road; or, the caisson is prefabricated at the prefabrication site, and a slideway is set up between the prefabrication site and the location where the foundation pit needs to be excavated on the existing road, and the caisson is slid to the location where the foundation pit needs to be excavated by pushing, pulling, or a combination of pushing and pulling.

[0014] In order to improve the inherent strength of the caisson, further: an internal support is provided in the inner cavity of the caisson.

[0015] S3. Start excavating the foundation pit in the inner cavity of the caisson, the caisson sinks synchronously, and the excavated soil is transported out from the soil borrowing hole.

[0016] S4. After the foundation pit is excavated to the designed elevation, a bottom plate is constructed at the bottom of the foundation pit, and the bottom plate is fixedly connected to the side plates of the caisson.

[0017] After the bottom plate is constructed, it becomes a whole with the caisson. Specific: The bottom plate is cast-in-place reinforced concrete.

[0018] S5. Use the top plate of the caisson directly as the road surface, or construct a road surface structure on the top plate, and the road surface structure is flush with the existing road.

[0019] The beneficial effects of the present invention are as follows: the caisson is prefabricated reinforced concrete, and the caisson has high strength, high rigidity, and good stability. The caisson sinks synchronously with the excavation of the foundation pit, and the excavated soil is transported out from the soil borrowing hole. During the excavation of the foundation pit and after sinking to the designed position, the caisson can always balance the water and soil pressure around the foundation pit, eliminate the disturbance of the excavation to the surrounding soil, and prevent foundation settlement. The deadweight of the caisson can resist the uplift of the soil at the bottom of the foundation pit, ensuring the safety of buildings and underground pipelines around the construction area. After the excavation of the foundation pit is completed, the top of the caisson is flush with the road or the pavement structure is laid on the top of the caisson to be flush with the road, so that traffic can be restored on the top of the caisson in time, minimizing the time of road occupation for construction and minimizing the impact of construction on road traffic. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a construction plane schematic diagram of an embodiment of a construction method of a supporting structure for a road foundation pit of the present invention.

[0021] Figure 2 It is a schematic diagram of the vertical section when the caisson of the present invention is placed at a position where a foundation pit needs to be excavated.

[0022] Figure 3 It is a schematic diagram of the vertical section of the caisson after the caisson is sunk into place.

[0023] Figure numerals: caisson 1, side plate 1-1, top plate 1-2, blade foot 1-3, soil hole 1-4, inner support 1-5, bottom plate 2, existing road 3, location where foundation pit needs to be excavated 4, prefabricated site 5, slide 6, traction rope 7, traction device 8. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings.

[0025] The first subject of the present invention is a supporting structure for a road foundation pit. Figure 3As shown, the supporting structure of the road foundation pit includes a caisson 1 located in the foundation pit, wherein the foundation pit is located on the existing road 3, that is, the foundation pit is completely or partially located on the existing road 3. The caisson 1 includes a vertically arranged side panel 1-1 and a horizontally arranged top panel 1-2, and the side panel 1-1 and the top panel 1-2 are both prefabricated reinforced concrete and surround an inner cavity of the caisson with an open bottom. The side panel 1-1 is generally flat, but can also be a curved surface. For example, the outer contour of the caisson 1 and the shape of the inner cavity of the caisson are both rectangular. The caisson 1 can be a whole, or it can be prefabricated in sections and assembled on site. The side panel 1-1 of the caisson 1 can be a whole, or it can be divided into at least two parts, and the parts are assembled into a whole; the top panel 1-2 of the caisson 1 can be a whole, or it can be divided into at least two parts, and the parts are assembled into a whole. For example, the side panels 1-1 and the top panels 1-2 are an integral prefabricated component, and the caisson 1 is prefabricated and transported as a whole, which is suitable for conditions where the foundation pit is small and the mass of the caisson 1 does not exceed the existing vehicle transportation capacity and the lifting capacity of the lifting equipment. For another example, the caisson 1 is divided into at least two parts, each part is prefabricated and transported separately, and the parts are spliced ​​and connected on site at the location 4 where the foundation pit needs to be excavated on the existing road 3. The bottom of the side panel 1-1 is a blade foot 1-3, which is conducive to the synchronous sinking of the caisson 1 after the foundation pit is excavated. The shape of the foundation pit is consistent with that of the caisson 1, and the outer surface of the side panel 1-1 abuts against the side wall of the foundation pit.

[0026] At least one of the side plate 1-1 and the top plate 1-2 is provided with a soil hole 1-4, which is used to transport the excavated soil out of the foundation pit. The soil hole 1-4 is set on the top plate 1-2 to facilitate vertical soil extraction; the soil hole 1-4 is set on the side plate 1-1, and soil can be extracted from one side of the foundation pit. For example, see Figure 1 to Figure 3 , a soil-taking hole 1-4 is provided at the center of the top plate 1-2. One side or two opposite sides of the foundation pit generally have slope conditions or are connected to the existing foundation pit, so the soil-taking hole 1-4 can also be provided on the side plate 1-1. When the side plate 1-1 is provided with a soil-taking hole 1-4, the soil-taking hole 1-4 can be a hole, that is, it can be a side plate 1-1 of the caisson 1 that is open. For example, the outer contour of the caisson 1 is a rectangular parallelepiped, and the caisson 1 has four side plates 1-1, and any one of the four side plates 1-1 or any two opposite ones are provided with a soil-taking hole 1-4. In order to improve the self-strength of the caisson 1, an internal support 1-5 is also provided in the inner cavity of the caisson. The arrangement of the internal support 1-5 should try to avoid its influence on the construction, and reinforce the weak parts of the caisson 1. The internal support 1-5 can be a steel structure or reinforced concrete.

[0027] The bottom of the inner cavity of the caisson is a bottom plate 2 constructed at the bottom of the foundation pit. The bottom plate 2 is fixedly connected to the side plate 1-1 of the caisson 1. After the construction, the bottom plate 2 becomes a whole with the caisson 1. The bottom plate 2 is generally cast-in-place reinforced concrete. In order to facilitate the stable connection between the bottom plate 2 and the caisson 1, the side plate 1-1 of the caisson 1 can also reserve a connection groove for connecting with the bottom plate 2. The top of the caisson 1 is flush with the existing road 3, so that the top plate 1-2 can be directly used as a road surface; or, the top plate 1-2 of the caisson 1 is lower than the existing road 3, and the top of the caisson 1 is paved with a road surface structure flush with the existing road 3.

[0028] The second subject of the present invention is a construction method of a supporting structure of a road foundation pit, which is used for the construction of the first subject. Figure 1 to Figure 3 The construction method of the supporting structure of the road foundation pit includes the following steps.

[0029] S1. Prefabricated caisson 1. Caisson 1 includes vertically arranged side panels 1-1 and horizontally arranged top panels 1-2. Both the side panels 1-1 and the top panels 1-2 are prefabricated reinforced concrete and enclose an inner cavity of the caisson with an open bottom. The bottom of the side panels 1-1 is a blade foot 1-3. At least one of the side panels 1-1 and the top panel 1-2 is provided with a soil sampling hole 1-4. Caisson 1 can be a whole or prefabricated in sections and assembled on site. The size of caisson 1 is determined according to actual needs on site, taking into account economy and construction efficiency. For the structure of caisson 1, please refer to the description of the first topic.

[0030] S2. Transfer the prefabricated caisson 1 to the location 4 on the existing road 3 where a foundation pit needs to be excavated, or assemble the caisson 1 at the location 4 on the existing road 3 where a foundation pit needs to be excavated.

[0031] The prefabricated caisson 1 is transferred in a manner according to the mass of the caisson 1. When the foundation pit is small, the caisson 1 can be prefabricated at a long distance, and then transported and hoisted to the location 4 where the foundation pit needs to be excavated. When the foundation pit is large, a prefabrication site 5 can be constructed in an area near the location 4 where the foundation pit needs to be excavated and does not affect traffic. A slideway 6 is set up between the prefabrication site 5 and the location 4 where the foundation pit needs to be excavated on the existing road 3. The caisson 1 slides to the location 4 where the foundation pit needs to be excavated by pushing, pulling, or a combination of pushing and pulling. For example, the caisson 1 slides to the location 4 where the foundation pit needs to be excavated by a traction rope 7 and a traction device 8. When the total mass of the caisson 1 is too large, the caisson 1 can also be split into several parts, each of which is prefabricated and transported separately, and assembled into a whole at the location 4 where the foundation pit needs to be excavated on the existing road 3. In order to improve the self-strength of the caisson 1, especially to compensate for the reduction in strength of the side plate 1-1 caused by the opening of the soil-taking holes 1-4, an internal support 1-5 is also provided in the inner cavity of the caisson.

[0032] S3. The foundation pit is excavated in the inner cavity of the caisson, and the caisson 1 sinks synchronously, and the excavated soil is transported out from the soil holes 1-4.

[0033] After the caisson 1 is positioned, the slide 6, the traction rope 7 and the traction device 8 are removed, the pavement structure of the existing road 3 below the blade foot 1-3 is removed, and soil excavation and sinking begin. The soil in the foundation pit can be transported out from the soil excavation holes 1-4 located on the top plate 1-2 or the soil excavation holes 1-4 on the side plate 1-1 of the caisson 1. The excavation of the foundation pit adopts the construction technology of the caisson in the water supply and drainage structure, and mechanical excavation and sinking are used to sink the caisson 1 to the designed elevation.

[0034] S4. After the foundation pit is excavated to the designed elevation, a bottom plate 2 is constructed at the bottom of the foundation pit, and the bottom plate 2 is fixedly connected to the side plate 1 - 1 of the caisson 1 .

[0035] After the caisson 1 sinks to the designed elevation, the bottom is immediately sealed, that is, the bottom plate 2 is immediately constructed. The bottom plate 2 is fixedly connected to the side plate 1-1 of the caisson 1. After the bottom plate 2 is constructed, it becomes a whole with the caisson 1. The bottom plate 2 is generally cast-in-place reinforced concrete. In order to facilitate the stable connection between the bottom plate 2 and the caisson 1, the side plate 1-1 of the caisson 1 can also reserve a connection groove for connecting with the bottom plate 2.

[0036] S5, the top plate 1-2 of the caisson 1 is directly used as the road surface, or a road surface structure is constructed on the top plate 1-2, and the road surface structure is flush with the existing road 3, and the road traffic can be restored. After the road traffic is restored, the main structure of the underground project is constructed in the caisson cavity.

Claims

1. The supporting structure of the road foundation pit is characterized by: The invention comprises a caisson (1) located in a foundation pit, wherein the caisson (1) comprises a vertically arranged side plate (1-1) and a horizontally arranged top plate (1-2), wherein the side plate (1-1) and the top plate (1-2) are both prefabricated reinforced concrete and enclose an inner cavity of the caisson with an open bottom, wherein the bottom of the side plate (1-1) is a blade foot (1-3), and at least one of the side plate (1-1) and the top plate (1-2) is provided with a soil taking hole (1-4), wherein the outer surface of the side plate (1-1) is in contact with the side wall of the foundation pit, and the bottom of the inner cavity of the caisson is a bottom plate (2) constructed at the bottom of the foundation pit, and the bottom plate (2) is fixedly connected to the side plate (1-1) of the caisson (1), and the top of the caisson (1) is flush with an existing road (3) or the top of the caisson (1) is paved with a road surface structure flush with the existing road (3).

2. The supporting structure for a road foundation pit as claimed in claim 1, characterized in that: The side plates (1-1) and the top plate (1-2) of the caisson (1) are an integral prefabricated component; or, the caisson (1) is divided into at least two parts, and the parts are spliced ​​and connected.

3. The supporting structure for road foundation pit according to claim 1, characterized in that: The bottom plate (2) is cast-in-place reinforced concrete.

4. The supporting structure for a road foundation pit as claimed in claim 1, characterized in that: The outer contour of the caisson (1) and the shape of the inner cavity of the caisson are both rectangular parallelepiped, and any one of the four side plates (1-1) of the caisson (1) or any two opposite sides are provided with soil taking holes (1-4).

5. The road foundation pit support structure according to any one of claims 1 to 4, characterized in that: An inner support (1-5) is also provided in the inner cavity of the caisson.

6. A construction method for a supporting structure of a road foundation pit, characterized in that: The steps include: S1, a prefabricated caisson (1), the caisson (1) comprising a vertically arranged side plate (1-1) and a horizontally arranged top plate (1-2), the side plate (1-1) and the top plate (1-2) are both prefabricated reinforced concrete and enclose an inner cavity of the caisson with an open bottom, the bottom of the side plate (1-1) is a blade foot (1-3), and at least one of the side plate (1-1) and the top plate (1-2) is provided with a soil taking hole (1-4); S2, transferring the prefabricated caisson (1) to a location (4) on the existing road (3) where a foundation pit needs to be excavated, or assembling the caisson (1) at a location (4) on the existing road (3) where a foundation pit needs to be excavated; S3, starting to excavate the foundation pit in the inner cavity of the caisson, the caisson (1) sinks synchronously, and the excavated soil is transported out from the soil holes (1-4); S4. After the foundation pit is excavated to the designed elevation, a bottom plate (2) is constructed at the bottom of the foundation pit, and the bottom plate (2) is fixedly connected to the side plate (1-1) of the caisson (1); S5. The top plate (1-2) of the caisson (1) is directly used as a road surface, or a road surface structure is constructed on the top plate (1-2), and the road surface structure is flush with the existing road (3).

7. The construction method of the supporting structure of the road foundation pit according to claim 6, characterized in that: In step S1, the side plates (1-1) and the top plate (1-2) of the caisson (1) are an integral prefabricated component; or, in step S1, the caisson (1) is divided into at least two parts, and in step S2, the parts of the caisson (1) are spliced ​​into a whole at a location (4) where a foundation pit needs to be excavated on an existing road (3).

8. The construction method of the supporting structure of the road foundation pit according to claim 6, characterized in that: The caisson (1) is prefabricated as a whole, transported and hoisted to a position (4) on an existing road (3) where a foundation pit needs to be excavated; or, the caisson (1) is prefabricated at a prefabrication site (5), a slideway (6) is set up between the prefabrication site (5) and the position (4) on the existing road (3) where a foundation pit needs to be excavated, and the caisson (1) is slid to the position (4) where a foundation pit needs to be excavated by pushing, pulling, or a combination of pushing and pulling.

9. The construction method of the supporting structure of the road foundation pit according to claim 6, characterized in that: An inner support (1-5) is also provided in the inner cavity of the caisson.

10. The construction method of the supporting structure of a road foundation pit according to any one of claims 6 to 9, characterized in that: In step S4, the base plate (2) is cast-in-place reinforced concrete.

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