A support coupling construction method for a foundation pit at a negative corner of an existing foundation pit

Abstract

The present invention discloses a support coupling construction method for a foundation pit at a negative corner of an existing foundation pit. The support structure comprises a double-row pile group 1 for the existing foundation pit, a double-row pile group 2 for the existing foundation pit, a ground-connected wall for the existing foundation pit, a row of piles for the existing foundation pit, a crown beam for the double-row piles for the existing foundation pit, a crown beam for the double-row pile group 2 for the existing foundation pit, a connecting beam 1 for the double-row pile group 1 for the existing foundation pit, a connecting beam 2 for the double-row pile group 1 for the existing foundation pit, a connecting beam 2 for the double-row pile group 2 for the existing foundation pit, a wall-wall connecting beam, and a row of piles-wall connecting beam. The double-row piles at the two locations transform the force of the support form connected to the existing ground-connected wall and anchor cables to ensure the structural stability of project B. U-shaped crown beams are respectively arranged on the tops of the double-row piles at the two locations, and the crown beams are respectively connected to the crown beams at the two locations of project B through connecting beams to form a spatial grid structure, so that the anchor cables of project B can be cut to realize force conversion, thereby ensuring the safety and stability of all supports, and realizing it when two projects are urgently needed to be constructed simultaneously.

Description

Technical Field

[0001] The invention belongs to the field of foundation pit support, and in particular relates to a support coupling construction method for a foundation pit at a negative corner of an existing foundation pit. Background Art

[0002] Foundation pit support is to ensure the stability of the soil around the foundation pit and meet the requirement of sufficient space for basement construction. It is a necessary condition for earth excavation and basement construction. At present, conventional single foundation pit support forms are relatively mature, including pile rows or ground-connected walls, cement soil walls, soil nail walls, slope support and other support methods.

[0003] However, in actual construction, the following construction conditions are often encountered: construction project A is located near project B, and project B is in the shape of an L-shaped inner corner. Project A needs to be connected to one side of project B, but there is a distance between it and the other side. Due to the constraints of the excavation of the foundation pits of the two projects, there are no conditions for the construction of the underground continuous wall at the connection position. In order to ensure the stability of the foundation pit structure of B, it is necessary to wait until the construction of the foundation pit structure of project B is completed before excavating the foundation pit of A, resulting in a delay of at least 2 months in the construction period. Summary of the Invention

[0004] The present invention provides a support coupling construction method for a foundation pit at a negative corner of an existing foundation pit, so as to solve the technical problems mentioned in the background technology.

[0005] To achieve the above-mentioned object, the present invention adopts the following technical solution: a support coupling construction method for a foundation pit at a negative corner of an existing foundation pit, comprising a support structure and a support process, wherein one end of the existing foundation pit is connected to a connecting foundation pit, one side of the existing foundation pit is parallel to and spaced apart from the separated foundation pit, the side of the connected foundation pit close to the existing foundation pit is provided with a connecting foundation pit ground diaphragm and an anchor cable, the top of the connecting foundation pit ground diaphragm wall is provided with a connecting foundation pit ground diaphragm crown beam, the side of the separated foundation pit close to the existing foundation pit is provided with a separated foundation pit ground diaphragm wall, the top of the separated foundation pit ground diaphragm wall is provided with a separated foundation pit ground diaphragm crown beam;

[0006] The supporting structure includes the first group of double-row piles in the excavated foundation pit, the second group of double-row piles in the excavated foundation pit, the ground-connected wall of the excavated foundation pit, the row of piles in the excavated foundation pit, the first crown beam of the first group of double-row piles in the excavated foundation pit, the second crown beam of the second group of double-row piles in the excavated foundation pit, the first connecting beam of the first group of double-row piles in the excavated foundation pit, the second connecting beam of the first group of double-row piles in the excavated foundation pit, the second connecting beam of the second group of double-row piles in the excavated foundation pit, the wall-wall connecting beam, the row of piles-wall connecting beam, the deep hole grouting water-stop curtain and the grouting reinforcement. The first group of double-row piles in the excavated foundation pit is set at one end of the excavated foundation pit close to the connected foundation pit and close to the side of the separated foundation pit. The second group is set at one end of the existing excavated foundation pit close to the connected foundation pit and away from the side of the separated foundation pit. The two rows of piles in the existing excavated foundation pit double row pile group one are arranged perpendicular to the connected foundation pit ground connection wall and have a distance from the connected foundation pit ground connection wall. The tops of the two rows of piles of the existing excavated foundation pit double row pile group one are provided with the existing excavated foundation pit double row pile one crown beam and are connected to the connected foundation pit ground connection wall crown beam through the existing excavated foundation pit double row pile group one connecting beam one. The existing excavated foundation pit double row pile one crown beam is also provided between the two rows of piles away from the connected foundation pit ground connection wall. The existing excavated foundation pit double row pile one crown beam is connected to the separated foundation pit. A connecting beam 2 of the existing excavated foundation pit double-row pile group 1 is set between the foundation pit ground-connecting walls. The two rows of piles in the existing excavated foundation pit double-row pile group 2 are arranged perpendicular to the connected foundation pit ground-connecting walls and have a distance from the connected foundation pit ground-connecting walls. A crown beam of the existing excavated foundation pit double-row pile group 2 is set on the top of the two rows of piles of the existing excavated foundation pit double-row pile group 2 and is connected to the crown beam of the separated foundation pit ground-connecting wall through the connecting beam of the existing excavated foundation pit double-row pile group 2. A crown beam of the existing excavated foundation pit double-row pile group 2 is also set between the two rows of piles of the existing excavated foundation pit double-row pile group 2 away from the connected foundation pit ground-connecting wall. An excavated foundation pit diaphragm wall is respectively set in the middle of one end away from the connecting foundation pit diaphragm wall, and an excavated foundation pit row pile is respectively set at one end of the excavated foundation pit diaphragm wall away from the connecting foundation pit diaphragm wall. A double row of deep hole grouting water stop curtain is set on the side of the excavated foundation pit double row pile group one close to the separated foundation pit diaphragm wall, a double row of deep hole grouting water stop curtain is set on the side of the excavated foundation pit double row pile group two close to the separated foundation pit diaphragm wall, grouting reinforcement is set between the excavated foundation pit double row pile group one and the separated foundation pit diaphragm wall, and grouting reinforcement is set on the side of the excavated foundation pit double row pile group two away from the separated foundation pit diaphragm wall;

[0007] The construction process includes the following steps:

[0008] Step 1: Construction of load-transfer piles in the excavated foundation pit double-row pile group 1 and the excavated foundation pit double-row pile group 2, including drilling and pouring;

[0009] Step 2: Double-row deep hole grouting water-stop curtain and grouting reinforcement construction, including drilling and grouting. The grouting adopts the backward deep hole grouting process. According to the excavation and backfilling of the adjacent foundation pit that has been constructed, the soil layer is exposed. The drilling and grouting equipment uses two grouting equipment to perform skipping holes every 2m and drill and grouting at the same time. The grouting pressure is strictly controlled. The drilling and grouting sequence is in the direction of the long side, and the holes are skipped from the middle to both sides.

[0010] Step 3: construct the first crown beam of the double-row piles in the excavated foundation pit, the second crown beam of the double-row pile group in the excavated foundation pit, the first connecting beam of the double-row pile group in the excavated foundation pit, the second connecting beam of the double-row pile group in the excavated foundation pit, and the second connecting beam of the double-row pile group in the excavated foundation pit;

[0011] Step 4: Cut off the anchor cables on the ground connection wall connected to the foundation pit;

[0012] Step 5: Construct the ground-connected wall of the excavated foundation pit;

[0013] Step 6: Dig the foundation pit and arrange the piles during construction.

[0014] As a preferred solution of this embodiment, a vertical shaft spraying section is further provided between the existing excavated foundation pit double row pile group one and the existing excavated foundation pit double row pile group two and the connected foundation pit ground connection wall respectively, and the vertical shaft spraying section is arranged on a row of piles of the existing excavated foundation pit double row pile group one or the existing excavated foundation pit double row pile group two close to the connected foundation pit ground connection wall, one end of the vertical shaft spraying section is connected to the connected foundation pit ground connection wall, and the other end of the vertical shaft spraying section is connected to the existing excavated foundation pit double row pile group one or the existing excavated foundation pit double row pile group two.

[0015] As a preferred solution of this embodiment, the spacing between the two rows of piles of the double-row pile group 2 of the existing excavated foundation pit is greater than the spacing between the double-row pile group 1 of the existing excavated foundation pit, and the middle connecting piles of the double-row pile group 2 of the existing excavated foundation pit are set away from the middle of the connecting wall of the foundation pit.

[0016] As a preferred solution of this embodiment, the double-row pile group 1 of the excavated foundation pit has four piles, with two piles in each row, and the double-row pile group 2 of the excavated foundation pit has five piles, with two piles in each row and an intermediate connecting pile in the middle.

[0017] As a preferred solution of this embodiment, the pile diameter of the double-row pile group 1 and the double-row pile group 2 of the excavated foundation pit is 800mm, the pile depth is 32m, and the steel cage is provided with 18 28mm main bars. The cross-sectional dimensions of the connecting beam 1 of the double-row pile group 1, the connecting beam 2 of the double-row pile group 1, and the connecting beam of the double-row pile group 2 of the excavated foundation pit are 600*600mm. The main steel bars are 18 B25 in diameter, the stirrups are A8@200mm, the protective layer is 70mm, and the concrete pouring is C30.

[0018] As a preferred solution of this embodiment, the hole spacing of the double-row deep hole grouting water-stop curtain is 300 mm, and the diffusion radius is 150 mm.

[0019] As a preferred solution of this embodiment, embedded reinforcement is provided at the outer ends of the crown beams of the connecting walls of the foundation pit and the crown beams of the connecting walls separated by the foundation pit.

[0020] As a preferred solution of this embodiment, internal supports are provided between the double-row pile group 1 and the double-row pile group 2 of the existing excavated foundation pit, and steel purlins and steel supports are used. Internal supports are provided between the ground-connected walls of the existing excavated foundation pits on both sides. The two internal supports close to the ground-connected walls connecting the foundation pits are concrete supports, and the rest are steel supports. Internal supports are provided between the rows of piles of the existing excavated foundation pits on both sides, and steel supports are used.

[0021] The beneficial effects of the present invention are as follows: for the construction project A located near the project B, and the project B is in the shape of an L-shaped inner corner, and the project A is to be connected to one side of the project B, but there is a distance between it and the other side. The construction conditions are restricted by the excavation of the foundation pits of the two projects, and the underground continuous wall at the connecting position has no construction conditions. Compared with the conventional method of waiting for the completion of the foundation pit structure of project B before excavating the foundation pit of A, first, the present application creates a unique double-row pile in two places to transform the force of the support form of the connected existing ground-connected wall plus anchor cable, ensuring the structure of project B. In order to ensure the stability and support of Project A, U-shaped crown beams are set on the tops of the two double-row piles, and the crown beams are connected to the crown beams of Project B through connecting beams to form a spatial grid structure, so that the anchor cables of Project B can be cut to achieve force conversion, ensuring the safety and stability of all supports. It can be carried out under limited space and can be realized when the two projects are urgently needed to be constructed simultaneously, shortening the construction period and improving efficiency. In addition, the double-row pile group of the existing excavated foundation pit close to the separated foundation pit adopts the form of four arrangements, far away The double-row pile group 2 of the existing excavated foundation pit is arranged in the form of five piles, which further ensures the overall safety and stability; third, the double-row pile group 1 of the existing excavated foundation pit is set with a double row of deep hole grouting water-stop curtain on the side close to the ground connection wall of the existing excavated foundation pit, and the double-row pile group 2 of the existing excavated foundation pit is set with a double row of deep hole grouting water-stop curtain on the side close to the ground connection wall of the existing excavated foundation pit. Grouting reinforcement is set between the double-row pile group 1 of the existing excavated foundation pit and the ground connection wall of the existing excavated foundation pit, and grouting reinforcement is set on the side of the double-row pile group 2 of the existing excavated foundation pit away from the ground connection wall of the existing excavated foundation pit; fourth, the double-row pile group 1 of the existing excavated foundation pit and the double-row pile group 2 of the existing excavated foundation pit are respectively A vertical shaft spraying section is also provided between the connecting foundation pit ground connection wall and the vertical shaft spraying section is provided on a row of piles of the existing excavated foundation pit double row pile group one or the existing excavated foundation pit double row pile group two close to the connecting foundation pit ground connection wall. One end of the vertical shaft spraying section is connected to the connecting foundation pit ground connection wall, and the other end of the vertical shaft spraying section is connected to the existing excavated foundation pit double row pile group one or the existing excavated foundation pit double row pile group two to ensure the strength of the connection and better overall cost. The above four points cooperate with each other and the structures support each other to achieve safe, stable and synchronous construction of foundation pits A and B, saving at least two months of construction period, which is a good progress.

[0022] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or may be understood by practicing the present invention; the main purpose and other advantages of the present invention can be realized and obtained through the solutions particularly pointed out in the description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural plan view of an embodiment of the present invention;

[0024] Figure 2 This is an enlarged view of the double-row piles in the structural plan diagram of an embodiment of the present invention;

[0025] Figure 3 It is a side view of a double-row pile group and a connecting beam in an excavated foundation pit according to an embodiment of the present invention.

[0026] Figure numerals: 1. Crown beam of ground-connected wall of foundation pit; 2. Crown beam of ground-connected wall of separated foundation pit; 3. Double-row pile group one of existing foundation pit; 4. Double-row pile group two of existing foundation pit; 5. Ground-connected wall of existing foundation pit; 6. Row of piles of existing foundation pit; 7. Crown beam of double-row piles one of existing foundation pit; 8. Crown beam of double-row pile group two of existing foundation pit; 9. Connecting beam one of double-row pile group one of existing foundation pit; 10. Connecting beam two of double-row pile group one of existing foundation pit; 11. Connecting beam of double-row pile group two of existing foundation pit; 12. Wall-to-wall connecting beam; 13. Row of piles-to-wall connecting beam; 14. Deep hole grouting water-stop curtain; 15. Grouting reinforcement; 16. Vertical shaft spraying section; 17. Internal support. DETAILED DESCRIPTION

[0027] The technical solutions of the present invention are described in detail below through examples. The following examples are merely exemplary and can only be used to explain and illustrate the technical solutions of the present invention, and cannot be interpreted as limiting the technical solutions of the present invention.

[0028] Combine Figure 1-3 A support coupling construction method for a foundation pit at a negative corner of an existing foundation pit includes a support structure and a support process, wherein one end of the existing foundation pit is connected to a connecting foundation pit, one side of the existing foundation pit is parallel to the separated foundation pit and spaced apart, a connecting foundation pit ground diaphragm and an anchor cable are provided on the side of the connecting foundation pit close to the existing foundation pit, a connecting foundation pit ground diaphragm crown beam 1 is provided on the top of the separated foundation pit ground diaphragm, and a separated foundation pit ground diaphragm is provided on the side of the separated foundation pit close to the existing foundation pit, and a separated foundation pit ground diaphragm crown beam 2 is provided on the top of the separated foundation pit ground diaphragm.

[0029] The supporting structure includes a double-row pile group 1 3 for the existing excavated foundation pit, a double-row pile group 2 4 for the existing excavated foundation pit, a ground-connected wall 5 for the existing excavated foundation pit, a row of piles 6 for the existing excavated foundation pit, a crown beam 7 for the existing excavated foundation pit, a crown beam 8 for the existing excavated foundation pit, a connecting beam 1 9 for the existing excavated foundation pit, a connecting beam 2 10 for the existing excavated foundation pit, a connecting beam 11 for the existing excavated foundation pit, a wall-to-wall connecting beam 12, a row of piles-to-wall connecting beam 13, a deep hole grouting water-stop curtain 14 and a grouting reinforcement 15. The double-row pile group 1 3 for the existing excavated foundation pit is arranged at one end of the existing excavated foundation pit close to the connected foundation pit and close to the side of the separated foundation pit. The double-row pile group 2 4 of the excavated foundation pit is arranged at one end of the existing foundation pit close to the connecting foundation pit and away from the side of the separated foundation pit. The two rows of piles in the double-row pile group 1 3 of the existing foundation pit are arranged perpendicular to the connecting foundation pit ground connection wall and have a distance from the connecting foundation pit ground connection wall. The tops of the two rows of piles of the double-row pile group 1 3 of the existing foundation pit are provided with a crown beam 7 of the existing foundation pit double-row piles and are connected to the crown beam 1 of the connecting foundation pit ground connection wall through a connecting beam 1 of the double-row pile group 1 9 of the existing foundation pit. A crown beam 7 of the existing foundation pit double-row piles is also provided between the two rows of piles away from the connecting foundation pit ground connection wall. The crown beam 7 of the existing foundation pit double-row piles is connected to the corresponding A connecting beam 2 10 of a double-row pile group of existing excavation pits is arranged between the foundation pit ground-connecting walls. The two rows of piles in the double-row pile group of existing excavation pits 24 are arranged perpendicular to the connected foundation pit ground-connecting walls and have a distance from the connected foundation pit ground-connecting walls. A crown beam 2 of the double-row pile group of existing excavation pits 24 is arranged on the top of the two rows of piles and is connected to the crown beam 2 of the separated foundation pit ground-connecting walls through the second connecting beam 11 of the double-row pile group of existing excavation pits 24. A crown beam 8 of the double-row pile group of existing excavation pits 24 is also arranged between the two rows of piles away from the connected foundation pit ground-connecting walls. The double-row pile group 1 3 and the double-row pile group 2 4 are far away from the connected foundation pit ground-connecting walls. An existing excavated foundation pit diaphragm wall 5 is respectively provided at the middle of one end of the connecting foundation pit diaphragm wall, and an existing excavated foundation pit row pile 6 is respectively provided at one end of the existing excavated foundation pit diaphragm wall 5 away from the connecting foundation pit diaphragm wall. A double row of deep hole grouting water-stop curtain 14 is provided on the side of the existing excavated foundation pit double row pile group 1 3 close to the separated foundation pit diaphragm wall, a double row of deep hole grouting water-stop curtain 14 is provided on the side of the existing excavated foundation pit double row pile group 2 4 close to the separated foundation pit diaphragm wall, a grouting reinforcement 15 is provided between the existing excavated foundation pit double row pile group 1 3 and the separated foundation pit diaphragm wall, and a grouting reinforcement 15 is provided on the side of the existing excavated foundation pit double row pile group 2 4 away from the separated foundation pit diaphragm wall;

[0030] The construction process includes the following steps:

[0031] Step 1: Construction of load-bearing transfer piles in the existing excavated foundation pit double-row pile group 1 3 and the existing excavated foundation pit double-row pile group 2 4, including drilling and pouring;

[0032] Step 2: Construction of double-row deep hole grouting water-stop curtain 14 and grouting reinforcement 15, including drilling and grouting. Grouting adopts the backward deep hole grouting process. According to the excavation and backfilling of the adjacent foundation pit that has been constructed, the soil layer is exposed. The drilling and grouting equipment uses two grouting equipment to perform skipping holes every 2m and drill and grouting at the same time. The grouting pressure is strictly controlled. The drilling and grouting sequence is in the direction of the long side, and the holes are skipped from the middle to both sides.

[0033] Step 3: construct the first crown beam 7 of the double-row piles in the existing excavated foundation pit, the second crown beam 8 of the double-row pile group in the existing excavated foundation pit, the first connecting beam 9 of the double-row pile group in the existing excavated foundation pit, the second connecting beam 10 of the double-row pile group in the existing excavated foundation pit, and the second connecting beam 11 of the double-row pile group in the existing excavated foundation pit;

[0034] Step 4: Cut off the anchor cables on the ground connection wall connected to the foundation pit;

[0035] Step 5: Construct the excavated foundation pit ground-connected wall 5;

[0036] Step 6: Excavate the foundation pit and arrange the piles 6.

[0037] As a preferred solution of this embodiment, a vertical shaft spraying section 16 is further provided between the existing excavated foundation pit double row pile group 13 and the existing excavated foundation pit double row pile group 24 and the connected foundation pit ground connection wall respectively, and the vertical shaft spraying section 16 is provided on a row of piles of the existing excavated foundation pit double row pile group 13 or the existing excavated foundation pit double row pile group 24 close to the connected foundation pit ground connection wall, one end of the vertical shaft spraying section 16 is connected to the connected foundation pit ground connection wall, and the other end of the vertical shaft spraying section 16 is connected to the existing excavated foundation pit double row pile group 13 or the existing excavated foundation pit double row pile group 24.

[0038] As a preferred solution of this embodiment, the spacing between the two rows of piles of the double-row pile group 2 4 of the existing foundation pit is greater than the spacing between the double-row pile group 1 3 of the existing foundation pit, and the intermediate connecting piles are set in the double-row pile group 2 4 of the existing foundation pit away from the middle of the connecting wall of the foundation pit.

[0039] As a preferred solution of this embodiment, the double-row pile group 1 3 of the existing foundation pit has four piles, with two piles in each row, and the double-row pile group 2 4 of the existing foundation pit has five piles, with two piles in each row and an intermediate connecting pile in the middle.

[0040] As a preferred solution of this embodiment, the pile diameter of the double-row pile group 1 3 and the double-row pile group 2 4 of the existing excavated foundation pit is 800mm, the pile depth is 32m, and the steel cage is provided with 18 28mm main bars. The cross-sectional dimensions of the connecting beam 1 9 of the double-row pile group 1, the connecting beam 2 10 of the double-row pile group 1, and the connecting beam 11 of the double-row pile group 2 are 600*600mm. The main steel bars are 18 B25 in diameter, the stirrups are A8@200mm, the protective layer is 70mm, and the concrete pouring is C30.

[0041] As a preferred solution of this embodiment, the hole spacing of the double-row deep hole grouting water-stop curtain 14 is 300 mm, and the diffusion radius is 150 mm.

[0042] As a preferred solution of this embodiment, embedded reinforcement is provided at the outer ends of the crown beam 1 of the connecting foundation pit ground diaphragm wall and the crown beam 2 of the separated foundation pit ground diaphragm wall.

[0043] As a preferred solution of this embodiment, internal supports are provided between the double-row pile group 1 3 of the existing excavated foundation pit and the double-row pile group 2 4 of the existing excavated foundation pit, and steel purlins and steel supports are adopted. Internal supports are provided between the ground-connecting walls 5 of the existing excavated foundation pit on both sides. The two internal supports close to the ground-connecting walls connecting the foundation pit are concrete supports, and the rest are steel supports. Internal supports 17 are provided between the rows of piles 6 of the existing excavated foundation pit on both sides, and steel supports are adopted.

[0044] The beneficial effects of the present invention are as follows: for the construction project A which is located near the project B, and the project B is in the shape of an L-shaped inner corner, and the project A needs to be connected to one side of the project B but has a distance from the other side, the construction condition is restricted by the excavation of the foundation pits of the two projects, and the underground continuous wall at the connecting position has no construction conditions. Compared with the conventional method of waiting for the completion of the foundation pit structure of project B before excavating the foundation pit of A, first, the present application creates a unique double-row pile at two locations to transform the force of the support form of connecting the existing ground-connected wall and anchor cables, thereby ensuring the structural stability of project B and the support of this project A. U-shaped crown beams are respectively set on the tops of the double-row piles at the two locations, and the crown beams are respectively connected to the crown beams at the two locations of project B through connecting beams to form a spatial grid structure, thereby being able to cut the anchor cables of project B to realize force conversion, thereby ensuring the safety and stability of all supports, and being able to be carried out under space limitations, and being able to be realized when the two projects are in urgent need of synchronous construction, thereby shortening the construction period and improving efficiency. Second, in addition, The double-row pile group 13 of the existing excavated foundation pit adopts the form of four piles, and the double-row pile group 24 of the existing excavated foundation pit away from the separated foundation pit adopts the form of five piles, which further ensures the overall safety and stability; 3. The double-row pile group 13 of the existing excavated foundation pit is close to the side of the foundation pit ground connection wall, and the double-row pile group 24 of the existing excavated foundation pit is close to the side of the foundation pit ground connection wall. A double-row deep hole grouting water-stop curtain 14 is set, and a grouting reinforcement 15 is set between the double-row pile group 13 of the existing excavated foundation pit and the foundation pit ground connection wall. Grouting reinforcement 15 is set on the side of group 2 4 away from the ground connection wall separating the foundation pits; fourth, a vertical shaft spraying section 16 is also set between the existing foundation pit double row pile group 1 3 and the existing foundation pit double row pile group 2 4, one end of the vertical shaft spraying section 16 is connected to the connecting foundation pit ground connection wall, and the other end of the vertical shaft spraying section 16 is connected to the existing foundation pit double row pile group 1 3 or the existing foundation pit double row pile group 2 4. The above four points cooperate with each other and the structures support each other, realizing the safe, stable and synchronous construction of foundation pits A and B, saving at least two months of construction time, and making good progress.

[0045] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that a person skilled in the art can conceive within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention.

Claims

1. A support coupling construction method for a foundation pit at a negative corner of an existing foundation pit, characterized by: The invention comprises a support structure and a support process, wherein one end of the existing foundation pit is connected to the connecting foundation pit, one side of the existing foundation pit is parallel to the separated foundation pit and has a gap therebetween, the side of the connected foundation pit close to the existing foundation pit is provided with a connecting foundation pit ground diaphragm and an anchor cable, the top of the connecting foundation pit ground diaphragm wall is provided with a connecting foundation pit ground diaphragm crown beam (1), the side of the separated foundation pit close to the existing foundation pit is provided with a separated foundation pit ground diaphragm, the top of the separated foundation pit ground diaphragm wall is provided with a separated foundation pit ground diaphragm crown beam (2); The supporting structure includes a double-row pile group (3) for the existing excavated foundation pit, a double-row pile group (4) for the existing excavated foundation pit, a ground-connected wall (5) for the existing excavated foundation pit, a row of piles (6), a crown beam (7) for the existing excavated foundation pit, a crown beam (8) for the existing excavated foundation pit, a connecting beam (9) for the existing excavated foundation pit, a connecting beam (10) for the existing excavated foundation pit, a connecting beam (11) for the existing excavated foundation pit, a wall-wall connecting beam (12), a row of piles-wall connecting beam (13), a deep hole grouting water-stop curtain (14) and a grouting reinforcement (15). The double-row pile group (3) for the existing excavated foundation pit is arranged at one end of the existing excavated foundation pit close to the connected foundation pit and close to the separated foundation pit. On one side of the pit, the existing excavated foundation pit double row pile group 2 (4) is arranged at one end of the existing excavated foundation pit close to the connected foundation pit and away from the side of the separated foundation pit, the two rows of piles in the existing excavated foundation pit double row pile group 1 (3) are arranged vertically to the connected foundation pit ground connection wall and have a distance from the connected foundation pit ground connection wall, the existing excavated foundation pit double row pile one crown beam (7) is arranged on the top of the two rows of piles of the existing excavated foundation pit double row pile group 1 (3) and is connected to the connected foundation pit ground connection wall crown beam (1) through the existing excavated foundation pit double row pile group one connecting beam (9), the existing excavated foundation pit double row pile one crown beam (7) is also arranged between the two rows of piles away from the connected foundation pit ground connection wall, the existing excavated foundation pit double row pile one crown beam (7) is arranged between the two rows of piles A connecting beam (10) of the existing excavated foundation pit double row pile group 1 is set between the foundation pit ground connection wall. The two rows of piles in the existing excavated foundation pit double row pile group 2 (4) are arranged vertically to the connected foundation pit ground connection wall and have a distance from the connected foundation pit ground connection wall. A crown beam (8) of the existing excavated foundation pit double row pile group 2 (4) is set on the top of the two rows of piles and is connected to the crown beam (2) of the foundation pit ground connection wall through the connecting beam (11) of the existing excavated foundation pit double row pile group 2. A crown beam (8) of the existing excavated foundation pit double row pile group 2 (4) is also set between the two rows of piles away from the connected foundation pit ground connection wall. The existing excavated foundation pit double row pile group 1 (3) and the existing excavated foundation pit double row pile group 2 (4) are far away from the connected foundation pit ground connection wall. A newly excavated foundation pit diaphragm wall (5) is respectively provided at the middle of one end of the connected foundation pit diaphragm wall, a newly excavated foundation pit row pile (6) is respectively provided at one end of the newly excavated foundation pit diaphragm wall (5) away from the connected foundation pit diaphragm wall, a double row of deep hole grouting water-stop curtain (14) is provided on the side of the newly excavated foundation pit double row pile group (3) close to the separated foundation pit diaphragm wall, a double row of deep hole grouting water-stop curtain (14) is provided on the side of the newly excavated foundation pit double row pile group (4) close to the separated foundation pit diaphragm wall, a grouting reinforcement (15) is provided between the newly excavated foundation pit double row pile group (3) and the separated foundation pit diaphragm wall, and a grouting reinforcement (15) is provided on the side of the newly excavated foundation pit double row pile group (4) away from the separated foundation pit diaphragm wall; The construction process includes the following steps: Step 1: Construction of load-transfer piles of double-row pile group 1 (3) and double-row pile group 2 (4) in the existing excavated foundation pit, including drilling and pouring; Step 2: Construction of double-row deep hole grouting water-stop curtain (14) and grouting reinforcement (15), including drilling and grouting. Grouting adopts the backward deep hole grouting process. According to the excavation and backfilling of the adjacent foundation pit that has been constructed, the soil layer is exposed. The drilling and grouting equipment uses two grouting equipment to perform skipping holes every 2m and drill and grout simultaneously. The grouting pressure is strictly controlled. The drilling and grouting sequence is in the direction of the long side, and the holes are skipped from the middle to both sides. Step 3: construct the first crown beam (7) of the double-row piles in the existing excavated foundation pit, the second crown beam (8) of the double-row pile group in the existing excavated foundation pit, the first connecting beam (9) of the double-row pile group in the existing excavated foundation pit, the second connecting beam (10) of the double-row pile group in the existing excavated foundation pit, and the second connecting beam (11) of the double-row pile group in the existing excavated foundation pit; Step 4: Cut off the anchor cables on the ground connection wall connected to the foundation pit; Step 5: construct the excavated foundation pit ground-connected wall (5); Step 6: Excavate the foundation pit and arrange the piles (6).

2. The support coupling construction method for a foundation pit at a negative corner of an existing foundation pit according to claim 1, characterized in that: A vertical shaft spraying section (16) is further provided between the existing excavated foundation pit double-row pile group 1 (3) and the existing excavated foundation pit double-row pile group 2 (4) and the connected foundation pit ground connection wall, and the vertical shaft spraying section (16) is provided on a row of piles of the existing excavated foundation pit double-row pile group 1 (3) or the existing excavated foundation pit double-row pile group 2 (4) close to the connected foundation pit ground connection wall, one end of the vertical shaft spraying section (16) is connected to the connected foundation pit ground connection wall, and the other end of the vertical shaft spraying section (16) is connected to the existing excavated foundation pit double-row pile group 1 (3) or the existing excavated foundation pit double-row pile group 2 (4).

3. The support coupling construction method for a foundation pit at a negative corner of an existing foundation pit according to claim 2, characterized in that: The spacing between the two rows of piles in the second double-row pile group (4) of the existing excavated foundation pit is greater than the spacing between the first double-row pile group (3) of the existing excavated foundation pit, and the second double-row pile group (4) of the existing excavated foundation pit is provided with an intermediate connecting pile away from the middle of the connecting wall of the foundation pit.

4. The support coupling construction method for a foundation pit at a negative corner of an existing foundation pit according to claim 3, characterized in that: The double-row pile group 1 (3) of the excavated foundation pit has four piles, with two piles in each row, and the double-row pile group 2 (4) of the excavated foundation pit has five piles, with two piles in each row and an intermediate connecting pile in the middle.

5. The support coupling construction method for a foundation pit at a negative corner of an existing foundation pit according to claim 4, characterized in that: The pile diameter of the double-row pile group 1 (3) and the double-row pile group 2 (4) of the excavated foundation pit is 800mm, the pile depth is 32m, 18 28mm main bars are set in the steel cage, the cross-sectional dimensions of the connecting beam 1 (9) of the double-row pile group 1, the connecting beam 2 (10) of the double-row pile group 1, and the connecting beam 11 of the double-row pile group 2 are 600*600mm, 18 main bars of steel bar are B25 in diameter, stirrups are A8@200mm, the protective layer is 70mm, and C30 is used for pouring concrete.

6. The support coupling construction method for a foundation pit at a negative corner of an existing foundation pit according to claim 5, characterized in that: The hole spacing of the double-row deep hole grouting water-stopping curtain (14) is 300 mm, and the diffusion radius is 150 mm.

7. The support coupling construction method for a foundation pit at a negative corner of an existing foundation pit according to claim 6, characterized in that: Planting bars are provided at the outer ends of the connecting foundation pit ground connection wall crown beam (1) and the separated foundation pit ground connection wall crown beam (2).

8. The support coupling construction method for a foundation pit at a negative corner of an existing foundation pit according to claim 7, characterized in that: Internal supports are provided between the first double-row pile group (3) and the second double-row pile group (4) of the existing excavated foundation pit, and steel purlins and steel supports are used. Internal supports are provided between the ground-connected walls (5) of the existing excavated foundation pit on both sides. The two internal supports close to the ground-connected walls of the foundation pit are concrete supports, and the rest are steel supports. Internal supports (17) are provided between the rows of piles (6) of the existing excavated foundation pit on both sides, and steel supports are used.

Images