Supporting coupling construction method for foundation pit at internal corner of existing foundation pit

Abstract

The invention discloses a supporting coupling construction method for a foundation pit at an internal corner of the existing foundation pit. The supporting structure comprises a first on-site excavation foundation pit double-row pile set, a second on-site excavation foundation pit double-row pile set, an on-site excavation foundation pit diaphragm wall, on-site excavation foundation pit row piles, a top beam of the first on-site excavation foundation pit double-row pile set, a top beam of the second on-site excavation foundation pit double-row pile set, a first connecting beam of the first on-site excavation foundation pit double-row pile set, a second connecting beam of the first on-site excavation foundation pit double-row pile set and a connecting beam of the second on-site excavation foundation pit double-row pile set. The wall-wall connecting beam, the row pile-wall connecting beam and the double-row piles at the two positions conduct stress conversion on the supporting mode of communicating existing diaphragm walls and anchor cables, the structural stability of a project B is guaranteed, U-shaped top beams are arranged at the tops of the double-row piles at the two positions correspondingly, and the top beams at the two positions of the project B are connected through the connecting beams correspondingly. And a spatial grid structure is formed, so that the anchor cable of the project B can be cut off to realize stress conversion, the safety and stability of all supports are ensured, and the operation is realized under the condition that two projects urgently need synchronous construction.

Description

Technical Field

[0001] The present invention belongs to the field of foundation pit support, and particularly relates to a coupling construction method for the support of a foundation pit at the internal corner of an existing foundation pit. Background Technique

[0002] Foundation pit support is to ensure the stability of the soil around the foundation pit and at the same time meet the requirement of sufficient space for basement construction, which is a necessary condition for earth excavation and basement construction. At present, conventional single foundation pit support forms are relatively mature, including support methods such as row piles or diaphragm walls, cement soil walls, soil nail walls, and slope protection.

[0003] However, in actual construction, construction conditions often occur as follows: Construction project A is located adjacent to project B, and project B has an L-shaped internal corner, and project A is to be connected to one side of project B but has a spacing from the other side. Restricted by the excavation of the foundation pits of the two projects, there is no construction condition for the diaphragm wall at the connection position. To ensure the structural stability of foundation pit B, it is necessary to wait until the construction of the foundation pit structure of project B is completed before excavating foundation pit A, resulting in a construction period delay of at least 2 months. Summary of the Invention

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

[0005] To achieve the above object, the present invention adopts the following technical scheme: A coupling construction method for the support of a foundation pit at the internal corner of an existing foundation pit, including a support structure and a support process. One end of the currently excavated foundation pit is connected to the connected foundation pit, one side of the currently excavated foundation pit is arranged side by side with the separated foundation pit and has a gap. The side of the connected foundation pit close to the currently excavated foundation pit has a connected foundation pit diaphragm wall and has anchor cables. The top of the connected foundation pit diaphragm wall has a connected foundation pit diaphragm wall capping beam. The side of the separated foundation pit close to the currently excavated foundation pit is provided with a separated foundation pit diaphragm wall, and the top of the separated foundation pit diaphragm wall has a separated foundation pit diaphragm wall capping beam; The retaining structure includes the first double-row pile group of the excavated foundation pit, the second double-row pile group of the excavated foundation pit, the diaphragm wall of the excavated foundation pit, the row piles of the excavated foundation pit, the capping beam of the first double-row piles of the excavated foundation pit, the capping beam of the second double-row pile group of the excavated foundation pit, the first connecting beam of the first double-row pile group of the excavated foundation pit, the second connecting beam of the first double-row pile group of the excavated foundation pit, the connecting beam of the second double-row pile group of the excavated foundation pit, the wall-wall connecting beam, the row pile-wall connecting beam, the deep-hole grouting water-stop curtain and grouting reinforcement. The first double-row pile group of the excavated foundation pit is arranged at one end of the excavated foundation pit close to the connected foundation pit and on one side close to the separated foundation pit. The second double-row pile group of the excavated foundation pit is arranged at one end of the excavated foundation pit close to the connected foundation pit and on the side far from the separated foundation pit. The two rows of piles in the first double-row pile group of the excavated foundation pit are both vertically arranged with the diaphragm wall of the connected foundation pit and have a spacing from the diaphragm wall of the connected foundation pit. The tops of the two rows of piles in the first double-row pile group of the excavated foundation pit are provided with the capping beam of the first double-row piles of the excavated foundation pit and are connected to the capping beam of the diaphragm wall of the connected foundation pit through the first connecting beam of the first double-row pile group of the excavated foundation pit. The capping beam of the first double-row piles of the excavated foundation pit is also arranged between the two rows of piles far from the diaphragm wall of the connected foundation pit. The second connecting beam of the first double-row pile group of the excavated foundation pit is arranged between the capping beam of the first double-row piles of the excavated foundation pit and the diaphragm wall of the separated foundation pit. The two rows of piles in the second double-row pile group of the excavated foundation pit are both vertically arranged with the diaphragm wall of the connected foundation pit and have a spacing from the diaphragm wall of the connected foundation pit. The tops of the two rows of piles in the second double-row pile group of the excavated foundation pit are provided with the capping beam of the second double-row pile group of the excavated foundation pit and are connected to the capping beam of the diaphragm wall of the separated foundation pit through the connecting beam of the second double-row pile group of the excavated foundation pit. The capping beam of the second double-row pile group of the excavated foundation pit is also arranged between the two rows of piles far from the diaphragm wall of the connected foundation pit. Diaphragm walls of the excavated foundation pit are respectively arranged in the middle parts of the ends of the first double-row pile group of the excavated foundation pit and the second double-row pile group of the excavated foundation pit far from the diaphragm wall of the connected foundation pit. Row piles of the excavated foundation pit are respectively arranged at the ends of the diaphragm walls of the excavated foundation pit far from the diaphragm wall of the connected foundation pit. Double-row deep-hole grouting water-stop curtains are arranged on the side of the first double-row pile group of the excavated foundation pit close to the diaphragm wall of the separated foundation pit. Double-row deep-hole grouting water-stop curtains are arranged on the side of the second double-row pile group of the excavated foundation pit close to the diaphragm wall of the separated foundation pit. Grouting reinforcement is arranged between the first double-row pile group of the excavated foundation pit and the diaphragm wall of the separated foundation pit. Grouting reinforcement is arranged on the side of the second double-row pile group of the excavated foundation pit far from the diaphragm wall of the separated foundation pit; The construction process includes the following steps, Step 1, construction of the force-converting piles for the first double-row pile group and the second double-row pile group of the excavated foundation pit, including drilling and pouring; Step 2, construction of the double-row deep-hole grouting water-stop curtain and grouting reinforcement, including drilling and grouting. The grouting adopts the backward deep-hole grouting process. According to the soil layers exposed by the excavation and backfilling of the adjacent foundation pit that has been constructed, two grouting devices are used for the drilling and grouting equipment to drill and grout simultaneously in a skip-hole manner every 2m. The grouting pressure is strictly controlled. The drilling and grouting sequence is carried out in the long-side direction, skipping holes from the middle to both sides; Step 3: Construct the capping beam of the double-row piles in the freshly excavated foundation pit, the capping beam of the second group of double-row piles in the freshly excavated foundation pit, the first connecting beam of the first group of double-row piles in the freshly excavated foundation pit, the second connecting beam of the first group of double-row piles in the freshly excavated foundation pit, and the connecting beam of the second group of double-row piles in the freshly excavated foundation pit; Step 4: Cut off the anchor cables on the diaphragm wall of the connected foundation pit; Step 5: Construct the diaphragm wall of the freshly excavated foundation pit; Step 6: Construct the row piles of the freshly excavated foundation pit.

[0006] As a preferred solution of this embodiment, a shaft shotcrete section is further provided between the first group of double-row piles in the freshly excavated foundation pit and the second group of double-row piles in the freshly excavated foundation pit and the diaphragm wall of the connected foundation pit, and the shaft shotcrete section is arranged on a row of piles of the first group of double-row piles in the freshly excavated foundation pit or the second group of double-row piles in the freshly excavated foundation pit close to the diaphragm wall of the connected foundation pit. One end of the shaft shotcrete section is connected to the diaphragm wall of the connected foundation pit, and the other end of the shaft shotcrete section is connected to the first group of double-row piles in the freshly excavated foundation pit or the second group of double-row piles in the freshly excavated foundation pit.

[0007] As a preferred solution of this embodiment, the spacing between the two rows of piles of the second group of double-row piles in the freshly excavated foundation pit is greater than the spacing of the first group of double-row piles in the freshly excavated foundation pit, and an intermediate connecting pile is arranged in the middle of the second group of double-row piles in the freshly excavated foundation pit away from the diaphragm wall of the connected foundation pit.

[0008] As a preferred solution of this embodiment, the first group of double-row piles in the freshly excavated foundation pit has four piles, with two piles in each row, the second group of double-row piles in the freshly excavated foundation pit has five piles, with two piles in each row, and there is an intermediate connecting pile in the middle.

[0009] As a preferred solution of this embodiment, the pile diameter of the first group of double-row piles in the freshly excavated foundation pit and the second group of double-row piles in the freshly excavated foundation pit is 800 mm, the pile depth is 32 m, the steel cage is provided with 18 main bars of 28 mm, the cross-sectional dimensions of the first connecting beam of the first group of double-row piles in the freshly excavated foundation pit, the second connecting beam of the first group of double-row piles in the freshly excavated foundation pit, and the connecting beam of the second group of double-row piles in the freshly excavated foundation pit are 600*600 mm, the main steel bars of the reinforcement are 18 with a diameter of B25, the stirrups are A8@200 mm, the protective layer is 70 mm, and the concrete pouring is C30.

[0010] 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.

[0011] As a preferred solution of this embodiment, planting bars are arranged at the outer ends of the capping beam of the diaphragm wall of the connected foundation pit and the capping beam of the diaphragm wall of the separated foundation pit.

[0012] As a preferred solution of this embodiment, an internal support is provided between the first row of double-row piles in the currently excavated foundation pit and the second row of double-row piles in the currently excavated foundation pit. The steel collar beam + steel support is adopted. An internal support is provided between the diaphragm walls of the currently excavated foundation pits on both sides. The two internal supports close to the diaphragm wall of the connected foundation pit are concrete supports, and the rest are steel supports. An internal support is provided between the rows of piles in the currently excavated foundation pits on both sides, and the steel support is adopted.

[0013] The beneficial effects of the present invention are reflected in: For the construction project A near the location of project B, and project B has an L-shaped internal corner shape, and project A is to be connected to one side of project B, but there is a spacing from the other side. In the construction condition where the diaphragm wall at the connection position has no construction conditions due to the excavation constraints of the foundation pits of the two projects. Compared with the conventional method of waiting for the completion of the foundation pit structure construction of project B and then excavating the foundation pit of A, first, the present application creates a unique form of force transformation for the support of the existing diaphragm wall plus anchor cable by two rows of double-row piles at two places, ensuring the structural stability of project B and the support of project A. The top parts of the two rows of double-row piles are respectively provided with U-shaped capping beams, and the capping beams at the two places of project B are respectively connected by connecting beams to form a spatial grid structure, so as to cut off the anchor cables of project B to realize force conversion, ensuring the safety and stability of all supports, and being able to be carried out under the condition of space limitation and realizing it when the two projects are in urgent need of synchronous construction, shortening the construction period and improving the efficiency. Second, in addition, the first row of double-row piles in the currently excavated foundation pit close to the separated foundation pit is arranged in a form of four rows, and the second row of double-row piles in the currently excavated foundation pit far from the separated foundation pit is arranged in a form of five rows, further ensuring the overall safety and stability. Third, a double-row deep-hole grouting water-stop curtain is provided on the side of the first row of double-row piles in the currently excavated foundation pit close to the diaphragm wall of the separated foundation pit, and a double-row deep-hole grouting water-stop curtain is provided on the side of the second row of double-row piles in the currently excavated foundation pit close to the diaphragm wall of the separated foundation pit. Grouting reinforcement is provided between the first row of double-row piles in the currently excavated foundation pit and the diaphragm wall of the separated foundation pit, and grouting reinforcement is provided on the side of the second row of double-row piles in the currently excavated foundation pit far from the diaphragm wall of the separated foundation pit. Fourth, a shaft shotcrete section is also provided between the first row of double-row piles in the currently excavated foundation pit and the second row of double-row piles in the currently excavated foundation pit and the diaphragm wall of the connected foundation pit, and the shaft shotcrete section is arranged on the row of piles in the first row of double-row piles in the currently excavated foundation pit or the second row of double-row piles in the currently excavated foundation pit close to the diaphragm wall of the connected foundation pit. One end of the shaft shotcrete section is connected to the diaphragm wall of the connected foundation pit, and the other end of the shaft shotcrete section is connected to the first row of double-row piles in the currently excavated foundation pit or the second row of double-row piles in the currently excavated foundation pit to ensure the strength of the connection and better comprehensive cost. With the above four points cooperating with each other and the structures supporting and connecting with each other, the safe and stable synchronous construction of foundation pits A and B is realized, saving at least two months of construction period and having good progress.

[0014] Other features and advantages of the present invention will be set forth in the following description, and will be partly obvious from the description, or will be understood by implementing the present invention; the main objectives and other advantages of the present invention can be achieved and obtained through the solutions specifically pointed out in the description. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic plan view of the structure of an embodiment of the present invention; Figure 2 is an enlarged view of the double-row piles at the structure plane of an embodiment of the present invention; Figure 3 is a side view of a continuous beam on one side of the double-row pile group in the currently excavated foundation pit of an embodiment of the present invention.

[0016] Reference numerals: 1, connecting foundation pit diaphragm wall capping beam; 2, separated foundation pit diaphragm wall capping beam; 3, first double-row pile group in the currently excavated foundation pit; 4, second double-row pile group in the currently excavated foundation pit; 5, currently excavated foundation pit diaphragm wall; 6, currently excavated foundation pit row piles; 7, first capping beam of the double-row piles in the currently excavated foundation pit; 8, second capping beam of the double-row pile group in the currently excavated foundation pit; 9, first continuous beam of the first double-row pile group in the currently excavated foundation pit; 10, second continuous beam of the first double-row pile group in the currently excavated foundation pit; 11, continuous beam of the second double-row pile group in the currently excavated foundation pit; 12, wall-wall connecting beam; 13, row pile-wall connecting beam; 14, deep-hole grouting water-stop curtain; 15, grouting reinforcement; 16, shotcrete section of the shaft; 17, internal support. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The technical solutions of the present invention will be described in detail below through embodiments. The following embodiments are merely exemplary and can only be used to explain and illustrate the technical solutions of the present invention, and cannot be construed as a limitation of the technical solutions of the present invention.

[0018] Combined with Figures 1-3 , a coupling construction method for the support of the foundation pit at the internal corner of an existing foundation pit, including a support structure and a support process. One end of the currently excavated foundation pit is connected to the connecting foundation pit, and one side of the currently excavated foundation pit is arranged side by side with the separated foundation pit with a gap. The side of the connecting foundation pit close to the currently excavated foundation pit has a connecting foundation pit diaphragm wall and has anchor cables. The top of the connecting foundation pit diaphragm wall has a connecting foundation pit diaphragm wall capping beam 1. A separated foundation pit diaphragm wall is provided on the side of the separated foundation pit close to the currently excavated foundation pit, and the top of the separated foundation pit diaphragm wall has a separated foundation pit diaphragm wall capping beam 2; The supporting structure includes the first double-row pile group 3 of the currently excavated foundation pit, the second double-row pile group 4 of the currently excavated foundation pit, the diaphragm wall 5 of the currently excavated foundation pit, the row piles 6 of the currently excavated foundation pit, the capping beam 7 of the first double-row pile of the currently excavated foundation pit, the capping beam 8 of the second double-row pile group of the currently excavated foundation pit, the first connecting beam 9 of the first double-row pile group of the currently excavated foundation pit, the second connecting beam 10 of the first double-row pile group of the currently excavated foundation pit, the connecting beam 11 of the second double-row pile group of the currently excavated foundation pit, the wall-wall connecting beam 12, the row pile-wall connecting beam 13, the deep-hole grouting water-stop curtain 14 and the grouting reinforcement 15. The first double-row pile group 3 of the currently excavated foundation pit is arranged at one end of the currently excavated foundation pit close to the connected foundation pit and on one side close to the separated foundation pit. The second double-row pile group 4 of the currently excavated foundation pit is arranged at one end of the currently excavated foundation pit close to the connected foundation pit and on the side far from the separated foundation pit. The two rows of piles in the first double-row pile group 3 of the currently excavated foundation pit are both vertically arranged with the diaphragm wall of the connected foundation pit and have a spacing from the diaphragm wall of the connected foundation pit. The tops of the two rows of piles in the first double-row pile group 3 of the currently excavated foundation pit are provided with the capping beam 7 of the first double-row pile of the currently excavated foundation pit and are connected to the capping beam 1 of the diaphragm wall of the connected foundation pit through the first connecting beam 9 of the first double-row pile group of the currently excavated foundation pit. The capping beam 7 of the first double-row pile of the currently excavated foundation pit is also arranged between the two rows of piles far from the diaphragm wall of the connected foundation pit. The second connecting beam 10 of the first double-row pile group of the currently excavated foundation pit is arranged between the capping beam 7 of the first double-row pile of the currently excavated foundation pit and the diaphragm wall of the separated foundation pit. The two rows of piles in the second double-row pile group 4 of the currently excavated foundation pit are both vertically arranged with the diaphragm wall of the connected foundation pit and have a spacing from the diaphragm wall of the connected foundation pit. The tops of the two rows of piles in the second double-row pile group 4 of the currently excavated foundation pit are provided with the capping beam of the second double-row pile group and are connected to the capping beam 2 of the diaphragm wall of the separated foundation pit through the connecting beam 11 of the second double-row pile group of the currently excavated foundation pit. The capping beam 8 of the second double-row pile group of the currently excavated foundation pit is also arranged between the two rows of piles far from the diaphragm wall of the connected foundation pit. Diaphragm walls 5 of the currently excavated foundation pit are respectively arranged in the middle of one end of the first double-row pile group 3 and the second double-row pile group 4 of the currently excavated foundation pit far from the diaphragm wall of the connected foundation pit. Row piles 6 of the currently excavated foundation pit are respectively arranged at one end of the diaphragm walls 5 of the currently excavated foundation pit far from the diaphragm wall of the connected foundation pit. Double-row deep-hole grouting water-stop curtains 14 are arranged on one side of the first double-row pile group 3 of the currently excavated foundation pit close to the diaphragm wall of the separated foundation pit. Double-row deep-hole grouting water-stop curtains 14 are arranged on one side of the second double-row pile group 4 of the currently excavated foundation pit close to the diaphragm wall of the separated foundation pit. Grouting reinforcements 15 are arranged between the first double-row pile group 3 of the currently excavated foundation pit and the diaphragm wall of the separated foundation pit. Grouting reinforcements 15 are arranged on one side of the second double-row pile group 4 of the currently excavated foundation pit far from the diaphragm wall of the separated foundation pit; The construction process includes the following steps Step 1: Construction of the force-converting piles for the first double-row pile group 3 and the second double-row pile group 4 of the currently excavated foundation pit, including drilling and pouring; Step 2: Construction of the double-row deep-hole grouting water-stop curtain 14 and the grouting reinforcement 15, including drilling and grouting. The grouting adopts the backward deep-hole grouting process. According to the soil layers exposed by the excavation and backfilling of the adjacent foundation pit that has been constructed, two grouting devices are used for the drilling and grouting equipment to drill and grout in a skip-hole manner every 2 m. The grouting pressure is strictly controlled. The drilling and grouting sequence is carried out in the long-side direction, from the middle to both sides in a skip-hole manner; Step 3: Construct the first capping beam 7 of the double-row piles in the freshly excavated foundation pit and the second capping beam 8 of the double-row pile group in the freshly excavated foundation pit, and construct the first connecting beam 9 of the double-row pile group in the freshly excavated foundation pit, the second connecting beam 10 of the double-row pile group in the freshly excavated foundation pit, and the connecting beam 11 of the double-row pile group in the freshly excavated foundation pit; Step 4: Cut off the anchor cables on the connected foundation pit diaphragm wall; Step 5: Construct the diaphragm wall 5 of the freshly excavated foundation pit; Step 6: Construct the row piles 6 of the freshly excavated foundation pit.

[0019] As a preferred solution of this embodiment, a shaft shotcrete section 16 is further provided between the first double-row pile group 3 in the freshly excavated foundation pit and the second double-row pile group 4 in the freshly excavated foundation pit and the connected foundation pit diaphragm wall, and the shaft shotcrete section 16 is arranged on a row of piles of the first double-row pile group 3 or the second double-row pile group 4 in the freshly excavated foundation pit close to the connected foundation pit diaphragm wall. One end of the shaft shotcrete section 16 is connected to the connected foundation pit diaphragm wall, and the other end of the shaft shotcrete section 16 is connected to the first double-row pile group 3 or the second double-row pile group 4 in the freshly excavated foundation pit.

[0020] As a preferred solution of this embodiment, the distance between the two rows of piles of the second double-row pile group 4 in the freshly excavated foundation pit is greater than the distance of the first double-row pile group 3 in the freshly excavated foundation pit, and an intermediate connecting pile is arranged in the middle of the second double-row pile group 4 in the freshly excavated foundation pit away from the connected foundation pit diaphragm wall.

[0021] As a preferred solution of this embodiment, the first double-row pile group 3 in the freshly excavated foundation pit has four piles, with two piles in each row, the second double-row pile group 4 in the freshly excavated foundation pit has five piles, with two piles in each row, and there is an intermediate connecting pile in the middle.

[0022] As a preferred solution of this embodiment, the pile diameter of the first double-row pile group 3 and the second double-row pile group 4 in the freshly excavated foundation pit is 800 mm, the pile depth is 32 m, the steel cage is provided with 18 main bars of 28 mm, the cross-sectional dimensions of the first connecting beam 9 of the double-row pile group in the freshly excavated foundation pit, the second connecting beam 10 of the double-row pile group in the freshly excavated foundation pit, and the connecting beam 11 of the double-row pile group in the freshly excavated foundation pit are 600*600 mm, the main steel bars of the reinforcement are 18 bars with a diameter of B25, the stirrups are A8@200 mm, the protective layer is 70 mm, and the concrete pouring is C30.

[0023] 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.

[0024] As a preferred solution of this embodiment, dowels are set at the outer ends of the capping beam 1 of the connected foundation pit diaphragm wall and the capping beam 2 of the separated foundation pit diaphragm wall.

[0025] As a preferred solution of this embodiment, an internal support is provided between the first double-row pile group 3 of the existing excavation foundation pit and the second double-row pile group 4 of the existing excavation foundation pit. The steel collar beam + steel support is adopted. An internal support is provided between the diaphragm walls 5 of the existing excavation foundation pits on both sides. The two internal supports close to the diaphragm wall of the connected foundation pit are concrete supports, and the rest are steel supports. An internal support 17 is provided between the row piles 6 of the existing excavation foundation pits on both sides, and the steel support is adopted.

[0026] The beneficial effects of the present invention are reflected in: aiming at the construction project A at a position adjacent to the project B, and the project B has an L-shaped internal corner shape, while the project A is to be connected to one side of the project B, but there is a spacing from the other side. In the construction condition where the diaphragm wall at the connection position has no construction conditions due to the excavation constraints of the foundation pits of the two projects. Compared with the conventional method of waiting for the construction of the foundation pit structure of project B to be completed and then excavating the foundation pit of project A, first, the present application creates a unique support form of double-row piles at two places to convert the force on the existing connected diaphragm wall plus anchor cable, ensuring the structural stability of project B and the support of project A. The top parts of the double-row piles at the two places are respectively provided with U-shaped capping beams, and the capping beams at the two places of project B are respectively connected by connecting beams to form a spatial grid structure, so as to cut off the anchor cables of project B to achieve force conversion, ensuring the safety and stability of all supports, and being able to be carried out under the condition of space limitation and realizing it in the case where the two projects need to be constructed synchronously, shortening the construction period and improving the efficiency. Second, in addition, the first double-row pile group 3 of the existing excavation foundation pit close to the separated foundation pit adopts a form of four rows arranged, and the second double-row pile group 4 of the existing excavation foundation pit far from the separated foundation pit adopts a form of five rows arranged, further ensuring the overall safety and stability. Third, a double-row deep-hole grouting water-stop curtain 14 is provided on the side of the first double-row pile group 3 of the existing excavation foundation pit close to the diaphragm wall of the separated foundation pit, and a double-row deep-hole grouting water-stop curtain 14 is provided on the side of the second double-row pile group 4 of the existing excavation foundation pit close to the diaphragm wall of the separated foundation pit. A grouting reinforcement 15 is provided between the first double-row pile group 3 of the existing excavation foundation pit and the diaphragm wall of the separated foundation pit, and a grouting reinforcement 15 is provided on the side of the second double-row pile group 4 of the existing excavation foundation pit far from the diaphragm wall of the separated foundation pit. Fourth, a shaft shotcrete section 16 is also provided between the first double-row pile group 3 of the existing excavation foundation pit and the second double-row pile group 4 of the existing excavation foundation pit. One end of the shaft shotcrete section 16 is connected to the diaphragm wall of the connected foundation pit, and the other end of the shaft shotcrete section 16 is connected to the first double-row pile group 3 of the existing excavation foundation pit or the second double-row pile group 4 of the existing excavation foundation pit. Through the mutual cooperation of the above four points and the mutual support and connection of the structures, the safe and stable synchronous construction of foundation pits A and B is realized, saving at least two months of construction period and having good progress.

[0027] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope 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 in that: 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, the side of the connecting foundation pit close to the existing foundation pit is provided with a connecting foundation pit ground connection wall and an anchor cable, the top of the connecting foundation pit ground connection wall is provided with a connecting foundation pit ground connection wall crown beam (1), the side of the separated foundation pit close to the existing foundation pit is provided with a separated foundation pit ground connection wall, and the top of the separated foundation pit ground connection wall is provided with a separated foundation pit ground connection wall crown beam (2); The supporting structure comprises a first double-row pile group (3) for an existing excavated foundation pit, a second double-row pile group (4) for an existing excavated foundation pit, a ground-connected wall (5) for an existing excavated foundation pit, a row of piles (6) for an existing excavated foundation pit, a first crown beam (7) for an existing excavated foundation pit, a second crown beam (8) for an existing excavated foundation pit, a first connecting beam (9) for an existing excavated foundation pit, a second connecting beam (10) for an existing excavated foundation pit, a second connecting beam (11) for an 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 first double-row pile group (3) for an existing excavated foundation pit is arranged at one end of the existing excavated foundation pit close to the connecting 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 spacing with 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 1 (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) A connecting beam (10) of the existing excavated foundation pit double row pile group one is arranged between the foundation pit ground connection wall, the two rows of piles in the existing excavated foundation pit double row pile group two (4) are arranged vertically to the connected foundation pit ground connection wall and have a spacing with the connected foundation pit ground connection wall, a crown beam (8) of the existing excavated foundation pit double row pile group two (4) is arranged on the top of the two rows of piles of the existing excavated foundation pit double row pile group two (4) and is connected to the crown beam (2) of the separated foundation pit ground connection wall through the connecting beam (11) of the existing excavated foundation pit double row pile group two, a crown beam (8) of the existing excavated foundation pit double row pile group two (4) 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 group one (3) and the existing excavated foundation pit double row pile group two (4) are far away from the connected foundation pit ground connection wall. A newly excavated foundation pit diaphragm wall (5) is respectively arranged at the middle of one end of the connected foundation pit diaphragm wall, and a newly excavated foundation pit row pile (6) is respectively arranged 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 arranged 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 arranged 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 arranged between the newly excavated foundation pit double row pile group (3) and the separated foundation pit diaphragm wall, and a grouting reinforcement (15) is arranged 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) of 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 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. Step 3: constructing the first crown beam (7) of the double-row piles in the existing foundation pit, the second crown beam (8) of the double-row pile group in the existing foundation pit, the first connecting beam (9) of the double-row pile group in the existing foundation pit, the second connecting beam (10) of the double-row pile group in the existing foundation pit, and the second connecting beam (11) of the double-row pile group in the existing foundation pit; Step 4: Cut off the anchor cable connected to the foundation pit ground wall; Step 5: construct the ground-connected wall in the excavated foundation pit (5); Step 6: Excavate the foundation pit and arrange the piles (6).

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

3. The support coupling construction method for the existing foundation pit at the inner corner of the foundation pit according to claim 2 is characterized by: The spacing between the two rows of piles of the existing excavated foundation pit double-row pile group 2 (4) is greater than the spacing between the existing excavated foundation pit double-row pile group 1 (3), and the existing excavated foundation pit double-row pile group 2 (4) 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 the existing foundation pit at the inner corner of the foundation pit according to claim 3 is characterized by: The double-row pile group 1 (3) of the existing excavated foundation pit has four piles, each row has two piles, and the double-row pile group 2 (4) of the existing excavated foundation pit has five piles, each row has two piles, and there is an intermediate connecting pile in the middle.

5. The support coupling construction method for the existing foundation pit at the inner corner of the 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) is 800 mm, the pile depth is 32 m, 18 main bars of 28 mm are arranged 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*600 mm, 18 main bars of B25 are adopted, the stirrups are A8@200 mm, the protective layer is 70 mm, and C30 is adopted for concrete pouring.

6. The support coupling construction method for the existing foundation pit at the inner corner of the 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 the existing foundation pit at the inner corner of the foundation pit according to claim 6, characterized in that: Embedded reinforcement is arranged at the outer ends of the crown beam (1) of the foundation pit ground connection wall and the crown beam (2) of the foundation pit ground connection wall separated from each other.

8. The support coupling construction method for the existing foundation pit at the inner corner of the foundation pit according to claim 7, characterized in that: Internal supports are arranged between the first double-row pile group (3) and the second double-row pile group (4) of the existing foundation pit, and adopt steel purlin + steel support. Internal supports are arranged between the existing foundation pit ground-connecting walls (5) on both sides, and two internal supports close to the connecting foundation pit ground-connecting walls are concrete supports, and the rest are steel supports. Internal supports (17) are arranged between the existing foundation pit rows (6) on both sides, and adopt steel supports.

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