A construction method for staggered water flow in underground earthwork structures in reverse construction engineering

Abstract

This application relates to a construction method for a staggered underground earthwork structure for reverse construction engineering, comprising: step S1, constructing a diaphragm wall and pile foundations within the construction pit; step S2, dividing the construction area within the pit into zone A and zone B, with earthwork workers excavating the first underground level of zone A; step S3, after constructing a retaining wall structure on the first underground level of zone A to support the soil in zone B, structural workers construct the first-floor structural beams and slabs of zone A; simultaneously, earthwork workers excavate the first underground level of zone B; step S4, structural workers construct the first-floor structural beams and slabs of zone B; simultaneously, earthwork workers excavate the second underground level of zone A; step S5, after constructing a retaining wall structure on the second underground level of zone A to support the soil in zone B, structural workers construct the first underground level structural beams and slabs of zone A; simultaneously, earthwork workers excavate the second underground level of zone B.

Description

Technical Field

[0001] This application relates to the field of building construction technology, and in particular to a construction method for a staggered water flow structure in underground earthwork in a reverse construction project. Background Technology

[0002] The reverse construction method is an unconventional construction approach, typically used in special circumstances such as deep foundations, complex geology, and high groundwater levels. It involves first constructing diaphragm walls or other supporting structures along the basement axis or surrounding area. Simultaneously, intermediate support piles and columns are poured or driven into relevant locations within the building to provide support for the self-weight of the superstructure and construction loads before the bottom slab is sealed. Then, excavation is carried out to the bottom elevation of the first basement level, and the beam-slab floor structure of that level is completed, providing strong support for the diaphragm walls. Subsequently, excavation and pouring of each subsequent basement level are carried out layer by layer downwards until the bottom slab is sealed.

[0003] The traditional reverse-construction underground construction process involves excavating one layer of earthwork, constructing one layer of beam and slab structure, and only proceeding with the next layer of earthwork excavation after the entire layer of concrete in the beam and slab structure has reached its design strength. This process continues in this manner. The inventor believes that this technique has the following drawbacks: it creates significant technical gaps between structural and earthwork operations, leading to stagnation in different trades and failing to achieve the goal of continuous flow operations. Therefore, further improvements are needed. Summary of the Invention

[0004] To reduce the possibility of work stoppages between structural and earthwork operations, this application provides a construction method for staggered water flow in underground earthwork structures in reverse construction projects.

[0005] The construction method for staggered-level water flow in underground earthwork structures in reverse construction engineering provided in this application adopts the following technical solution:

[0006] A construction method for a staggered-level water flow structure in an underground earthwork project involving reverse construction includes the following steps:

[0007] Step S1: Construction of foundation pit support and foundation reinforcement, construction of underground continuous wall and pile foundation in the construction pit;

[0008] Step S2: Divide the construction area in the foundation pit into area A and area B. The earthwork workers will first excavate area A and excavate to the ground level of the first basement level.

[0009] Step S3: After the structural work team erects a retaining wall structure on the first basement level of Area A to support the soil in Area B, the first-floor structural beams and slabs of Area A are constructed; at the same time, the earthwork work team excavates Area B and excavates to the ground level of the first basement level.

[0010] Step S4: The structural work crew constructs the first-floor structural beams and slabs of Area B; simultaneously, after the first-floor structural beams and slabs of Area A reach the structural design strength, the earthwork work crew excavates Area A and excavates to the ground level of the second basement level.

[0011] Step S5: After the structural work team erects a retaining wall structure on the second basement level of Area A to support the soil in Area B, the structural work team constructs the structural beams and slabs on the first basement level of Area A; at the same time, after the earthwork work team has reached the structural design strength of the first-floor structural beams and slabs in Area B, the earthwork work team excavates Area B and excavates to the ground level of the second basement level.

[0012] Step S6: The structural work crew constructs the structural beams and slabs of the first basement level in Area B; simultaneously, after the structural beams and slabs of the first basement level in Area A reach the structural design strength, the earthwork work crew excavates Area A and excavates to the ground level of the third basement level.

[0013] Step S7: After the structural work team erects a retaining wall structure on the third basement level of Area A to support the soil in Area B, the structural work team constructs the structural beams and slabs on the second basement level of Area A; at the same time, after the earthwork work team has reached the structural design strength of the structural beams and slabs on the first basement level of Area B, the earthwork work team excavates Area B and excavates to the ground level of the third basement level.

[0014] Step S8: The structural work type constructs the structural base slab of Area A and the structural beams and slabs of the second basement level of Area B. After the structural beams and slabs of the second basement level of Area B reach the structural design strength, the structural base slab of Area B is constructed.

[0015] By adopting the above-mentioned technical solution, the excavation and staggered construction of Zones A and B are carried out alternately until the bottom structural beams and slabs and the bottom slab are completed. After the concrete in Zone A is poured, the time is used to wait for the concrete to reach the required strength before the excavation of the underground soil in Zone B is carried out. The entire construction is divided into left and right sequential construction, which allows labor and large machinery to work in parallel. This reduces the possibility of work stoppages between different types of workers, such as structural workers and earthmoving workers. Moreover, in the staggered excavation construction, retaining wall structures are added to the areas excavated first, which effectively reduces the possibility of soil collapse in the later excavated areas of the same layer and improves construction safety.

[0016] Preferably, the process also includes step S9, where the structural work type simultaneously performs post-cast strip construction between the first-floor structural beams and slabs of areas A and B, between the first basement structural beams and slabs of areas A and B, between the second basement structural beams and slabs of areas A and B, and between the structural base slabs of areas A and B.

[0017] By adopting the above technical solution, the structural beams and slabs and the structural base slabs located on the same floor in areas A and B are connected into a whole through post-cast strip construction, reducing the possibility of cracks in the structural beams / slabs / base slabs due to uneven shrinkage or settlement.

[0018] Preferably, the retaining wall structure includes several detachable supporting base plates connected to the ground, retaining wall plates abutting against the soil in area B, and diagonal bracing arms set between the supporting base plates and the retaining wall plates. Back ribs are fixedly connected between the multiple retaining wall plates, and a reinforcement structure is added between the back ribs and the pile foundation.

[0019] By adopting the above technical solution, the retaining wall panels are equipped with back ribs, which connect multiple retaining wall panels into a whole, thereby improving the structural strength of the retaining wall. A reinforcement structure is added between the back ribs and the pile foundation, which fixes the retaining wall structure and the pile foundation, further improving the support strength of the retaining wall structure.

[0020] Preferably, the reinforcement structure includes a connecting arm disposed on the back rib and a pair of clamping members movably disposed on the end of the connecting arm away from the back rib to clamp and fix the pile foundation.

[0021] By adopting the above technical solution, the pile foundation can be clamped and fixed using clamping components, which is simple and convenient.

[0022] Preferably, the back rib is slidably connected to a sliding seat, and the connecting arm is disposed on the sliding seat.

[0023] By adopting the above technical solution, the relative position of the reinforcing structure and the pile foundation can be adjusted by sliding the sliding seat, which facilitates the clamping component to clamp and fix the pile foundation.

[0024] Preferably, the connecting arm includes a connecting sleeve disposed on the back rib and a connecting rod that slides toward or away from the back rib and is connected to the connecting sleeve. The clamping member is disposed at the end of the connecting rod away from the back rib, and the connecting sleeve is provided with a driving member for driving the connecting rod to slide.

[0025] By adopting the above technical solution, the sliding position of the connecting rod is adjusted by driving the driving component, thereby adjusting the length of the connecting arm, which facilitates the clamping component to clamp and fix the pile foundation.

[0026] Preferably, the retaining wall plate is provided with an air injection pipe inserted into the soil of area B. The outer peripheral wall of the air injection pipe has an air outlet hole that communicates with the inner cavity. Before excavating the soil of area B, the air injection pipe is injected with air by an air pump, so that the soil above the air injection pipe becomes soft.

[0027] By adopting the above technical solution, after the retaining wall structure is erected, the air injection pipe is inserted into the soil of area B. The air injection pipe is then injected with air using an air pump, which softens the soil above the air injection pipe, thereby reducing the excavation difficulty of area B.

[0028] Preferably, the air injection pipe is detachably connected to several unit jacking pipes. The inner cavity of the unit jacking pipe is connected to the inner cavity of the air injection pipe. Adjacent unit jacking pipes are detachably connected and their inner cavities are interconnected. In area A, the air injection pipe is gradually jacked into the soil of area B using the jacking method with a jacking device. Air is injected into the unit jacking pipe by an air pump, and the gas overflows from the air outlet of the air injection pipe. During the excavation of the soil in area B, the excavation is carried out gradually from the side closer to the retaining wall to the side farther away from the retaining wall.

[0029] By adopting the above technical solution, in area A, the jacking device is used to gradually insert the venting pipe into the soil of area B in a horizontal direction using the pipe jacking method. After each unit pipe is jacked in, air is injected into the unit pipe using an air pump. The gas overflows from the air outlet of the venting pipe, thereby performing venting operations at different locations in the soil of area B. At the same time, the earthmoving work is carried out in the same direction as the excavation of the soil in area B and the jacking direction of the venting pipe, so as to achieve synchronous construction of the venting pipe jacking operation and the excavation operation. Furthermore, if the unit pipe / venting pipe is exposed during the excavation process, it indicates that the excavation elevation has been reached, and the excavation is moved to another location.

[0030] Preferably, one end of the air injection pipe has an insertion ring groove on its inner wall, and one end of the unit top pipe is coaxially fixedly connected to an insertion ring sleeve inserted into the insertion ring groove. The inner wall of the insertion ring groove has a limit groove, and the insertion ring sleeve has a sliding hole in the radial direction. The insertion ring sleeve is provided with a limit block that is slidably connected to the sliding hole and inserted into the limit groove. The unit top pipe is provided with a control component for controlling the sliding of the limit block.

[0031] By adopting the above technical solution, when installing the unit jacking pipe and the gas injection pipe, the limiting block is first controlled by the control component to slide towards the axis of the insertion ring sleeve, so that the limiting block retracts into the sliding hole, and then the insertion ring sleeve is inserted into the insertion ring groove. The limiting block is then controlled by the control component to slide away from the axis of the insertion ring sleeve, so that the limiting block is inserted into the limiting groove, thereby effectively preventing the insertion ring sleeve from sliding backward and coming out of the insertion ring groove.

[0032] Preferably, the control component includes a transmission rod built into the unit top tube and sliding axially, a hinge rod with one end hinged to the transmission rod and the other end hinged to the limiting block, and a control component for driving the transmission rod to slide.

[0033] By adopting the above technical solution, the transmission rod is driven to slide back and forth along the axial direction of the unit jacking pipe through the control component, thereby driving the limiting block to slide radially along the unit jacking pipe through the hinge rod.

[0034] In summary, this application includes at least one of the following beneficial technical effects:

[0035] 1. The excavation and construction of Zones A and B are carried out alternately and in staggered layers until the bottom structural beams and slabs are completed. After the concrete in Zone A is poured, the underground earthwork in Zone B is excavated while waiting for the concrete to reach the required strength. The construction of the whole layer is divided into left and right sequential construction, which allows labor and large machinery to work in a cross-operation manner. This reduces the possibility of work stoppages between different types of workers, such as structural workers and earthwork workers. In addition, in the staggered excavation construction, retaining wall structures are added to the areas excavated first, which effectively reduces the possibility of collapse of the soil excavated later in the same layer and improves construction safety.

[0036] 2. The structural beams and slabs and the structural floor slabs located on the same floor in areas A and B are connected into a whole by post-cast strip construction, which reduces the possibility of cracks in the structural beams / slabs / floor slabs due to uneven shrinkage or settlement.

[0037] 3. After the retaining wall structure is erected, the air injection pipe is inserted into the soil in area B. The air injection pipe is then injected with air using an air pump, which softens the soil above the pipe and reduces the excavation difficulty of area B. Attached Figure Description

[0038] Figure 1 This is a schematic diagram after excavation of a construction method for a reverse-engineering underground earthwork structure with staggered water flow.

[0039] Figure 2 This is a structural diagram of the retaining wall structure.

[0040] Figure 3 This is a structural diagram of the reinforced structure.

[0041] Figure 4 This is a schematic diagram of the connecting arm.

[0042] Figure 5 This is a schematic diagram of the jacking device.

[0043] Figure 6 This is a schematic diagram of the connection structure between the unit jacking pipe and the gas injection pipe.

[0044] Figure 7 yes Figure 6 A magnified view of a portion at point C.

[0045] Figure 8 This is a schematic diagram of the connection structure between the pull-back gripper and the second cylinder.

[0046] Explanation of reference numerals in the attached drawings: 10. Diaphragm wall; 20. Pile foundation; 201. Cast-in-place pile; 202. Lattice column; 30. First floor structural beams and slabs; 40. First basement floor structural beams and slabs; 50. Second basement floor structural beams and slabs; 60. Structural base slab; 70. Post-cast strip structure; 1. Retaining wall structure; 11. Support base slab; 12. Retaining wall plate; 13. Diagonal brace arm; 14. Back rib; 15. Sliding seat; 2. Reinforcement structure; 21. Connecting arm; 211. Connecting sleeve; 212. Connecting rod; 213. First cylinder; 214. Installation. 1. Strip; 22. Clamping component; 23. Two-way lead screw; 24. Handwheel; 3. Air injection pipe; 31. Air outlet; 32. Insertion ring groove; 33. Limiting groove; 34. Airbag; 35. Sealing groove; 36. Sealing bladder body; 37. Vent pipe; 38. Slot; 4. Unit jacking pipe; 41. Insertion ring sleeve; 42. Sliding hole; 43. Limiting block; 5. Control component; 51. Transmission rod; 52. Hinge rod; 53. Electric push rod; 6. Jacking device; 61. Bracket; 62. Second cylinder; 63. Push plate; 64. Pull-back gripper. Detailed Implementation

[0047] The following is in conjunction with the appendix Figure 1-8 This application will be described in further detail.

[0048] This application discloses a construction method for staggered-level water flow in underground earthwork structures during reverse construction, referring to... Figure 1 , Figure 2 This includes the following steps:

[0049] Step S1: Construction of foundation pit support and foundation reinforcement, including the construction of underground continuous wall 10 and pile foundation 20 in the foundation pit. The pile foundation 20 includes cast-in-place piles 201 driven into the ground and lattice columns 202 fixedly connected to the upper part of the cast-in-place piles 201. The lattice columns 202 and the cast-in-place piles 201 are constructed in a one-column-one-pile manner.

[0050] Step S2: Divide the construction area in the foundation pit into Zone A and Zone B. The earthwork workers will first excavate Zone A and excavate to the ground level of the first basement level.

[0051] Step S3: After the structural work crew erects retaining wall structure 1 on the first basement floor of area A to support the soil in area B, they construct the first-floor structural beams and slabs 30 of area A; at the same time, the earthwork work crew excavates area B and excavates to the ground level of the first basement floor.

[0052] Step S4: The structural work crew constructs the first-floor structural beams and slabs 30 in Area B; simultaneously, the earthwork work crew excavates Area A after the first-floor structural beams and slabs 30 in Area A reach the structural design strength, and excavates to the ground level of the second basement level.

[0053] Step S5: After the structural work crew erects the retaining wall structure 1 on the second basement level of Area A to support the soil in Area B, they construct the structural beams and slabs 40 on the first basement level of Area A. At the same time, after the earthwork work crew has reached the structural design strength of the first-floor structural beams and slabs 30 in Area B, they excavate Area B and excavate to the ground level of the second basement level.

[0054] Step S6: The structural work crew constructs the structural beams and slabs 40 of the first basement level in Area B; simultaneously, the earthwork work crew excavates Area A after the structural beams and slabs 40 of the first basement level in Area A reach the structural design strength, and excavates to the ground level of the third basement level.

[0055] Step S7: After the structural work crew erects the retaining wall structure 1 on the third underground level of area A to support the soil in area B, the structural work crew constructs the structural beams and slabs 50 on the second underground level of area A. At the same time, after the structural beams and slabs 40 on the first underground level of area B reach the structural design strength, the earthwork work crew excavates area B and excavates to the ground level of the third underground level.

[0056] Step S8: The structural work involves constructing the structural base slab 60 of Area A and the structural beams and slabs 50 of the second basement level of Area B. After the structural beams and slabs 50 of the second basement level of Area B reach the structural design strength, the structural base slab 60 of Area B is constructed. In this embodiment, the basement structure has three levels. In other embodiments, Area A and Area B can be excavated alternately and constructed in a staggered manner according to the number of basement levels until the bottom structural base slab 60 is completed.

[0057] Step S9: Simultaneously, the structural work involves constructing post-cast strip structures 70 between the first-floor structural beams and slabs 30 of areas A and B, between the first basement structural beams and slabs 40 of areas A and B, between the second basement structural beams and slabs 50 of areas A and B, and between the structural floor slabs 60 of areas A and B. This connects the structural beams and slabs and the structural floor slabs 60 on the same floor of areas A and B into a unified whole through the construction of the post-cast strip structures 70, reducing the possibility of cracks arising from uneven shrinkage or settlement of the structural beams / slabs / floor slabs 60.

[0058] Reference Figure 2 , Figure 3 In steps S3, S5, and S7, the retaining wall structure 1 includes several detachably connected supporting base plates 11 to the ground in area A, retaining wall plates 12 abutting against the soil in area B, and diagonal bracing arms 13 disposed between the supporting base plates 11 and the retaining wall plates 12. The diagonal bracing arms 13 are telescopic arms, with one end of the diagonal bracing arm 13 hinged to the supporting base plate 11 and the other end of the diagonal bracing arm 13 hinged to the retaining wall plate 12. Multiple retaining wall plates 12 are assembled sequentially, and back ribs 14 are fixedly connected between the back sides of the multiple retaining wall plates 12. A reinforcing structure 2 is added between the back ribs 14 and the lattice column 202. The reinforcing structure 2 includes connecting arms 21 disposed on the back ribs 14 and a pair of clamping members 22 movably disposed on the end of the connecting arms 21 away from the back ribs 14 to clamp and fix the pile foundation 20.

[0059] Reference Figure 3 , Figure 4 The back rib 14 is slidably connected to a sliding seat 15 along its own length direction. The connecting arm 21 includes a connecting sleeve 211 fixedly connected to the sliding seat 15 and a connecting rod 212 slidably inserted into the connecting sleeve 211 in a direction closer to or farther from the back rib 14. The connecting sleeve 211 is provided with a driving component for driving the connecting rod 212 to slide. Specifically, the driving component is a first cylinder 213, and the piston rod of the first cylinder 213 is fixedly connected to the connecting rod 212. An installation strip 214 is fixedly connected to the end of the connecting rod 212 away from the back rib 14. The length direction of the installation strip 214 is parallel to the back rib 14. Each clamping member 22 is a clamping plate arranged in a U-shape, so that the two clamping plates are adapted to clamp the lattice column 202. The clamping plate is fixedly connected to a slider that is slidably connected to the mounting strip 214. In this embodiment, the mounting strip 214 adjusts the slider's sliding by means of a screw drive. Specifically, the mounting strip 214 is rotatably connected to a bidirectional screw 23. The two sliders are respectively threaded onto the two threaded sections of the bidirectional screw 23 with opposite thread directions. The end of the bidirectional screw 23 is coaxially fixedly connected to a handwheel 24. By rotating the handwheel 24, the bidirectional screw 23 is driven to rotate, thereby synchronously driving the two clamping plates to slide towards each other or away from each other.

[0060] Reference Figure 2 , Figure 5 , Figure 6 A venting pipe 3 is inserted into the soil of area B through the lower part of the retaining wall plate 12. Several vent holes 31, connected to the inner cavity, are opened on the outer peripheral wall of the venting pipe 3. A fine mesh is installed inside the vent holes 31 to reduce the possibility of soil entering the inner cavity of the venting pipe 3 through the vent holes 31. One end of the venting pipe 3 has an insertion ring groove 32 connected to the inner cavity, making one end of the venting pipe 3 open. The closed end of the venting pipe 3 is tapered. Several unit jacking pipes 4 are detachably connected to the venting pipe 3. The inner cavity of each unit jacking pipe 4 is connected to the inner cavity of the venting pipe 3. Adjacent unit jacking pipes 4 are detachably connected, and their inner cavities are interconnected.

[0061] Reference Figure 6 , Figure 7Specifically, the inner peripheral wall of the insertion ring groove 32 is radially provided with limiting grooves 33, and multiple limiting grooves 33 are provided and distributed around the axis of the insertion ring groove 32. One end of the unit top pipe 4 is coaxially fixedly connected to an insertion ring sleeve 41 inserted into the insertion ring groove 32, and the inner cavity of the insertion ring sleeve 41 is connected to the inner cavity of the air injection pipe 3. The outer peripheral wall of the insertion ring sleeve 41 is radially provided with a sliding hole 42 connected to the inner cavity, and the insertion ring sleeve 41 is provided with a limiting block 43 that is slidably connected to the sliding hole 42 and used for insertion into the limiting groove 33. The unit jacking pipe 4 is provided with a control component 5 for controlling the sliding of the limiting block 43. The control component 5 includes a transmission rod 51 built into the unit jacking pipe 4 and sliding axially, a hinge rod 52 with one end hinged to the transmission rod 51 and the other end hinged to the limiting block 43, and a control component for driving the transmission rod 51 to slide. In this embodiment, the control component is an electric push rod 53 built into the unit jacking pipe 4. The piston rod of the electric push rod 53 is coaxially fixedly connected to the transmission rod 51. In other embodiments, the control component can also use a screw drive to realize the sliding movement of the transmission rod 51.

[0062] A sealing groove 35 is formed around the inner peripheral wall of the insertion ring groove 32, and a sealing bladder 36 is embedded in the sealing groove 35. The sealing bladder 36 is elastically set. A sliding plate is slidably connected in the limiting groove 33. An air bladder 34 is fixedly connected to one end of the sliding plate away from the limiting block 43. The other end of the air bladder 34 is fixedly connected to the inner wall of the limiting groove 33. The inner cavity of the air bladder 34 and the inner cavity of the sealing bladder 36 are connected by a vent pipe 37. The splicing method between unit jacking pipes 4 is the same as that between unit jacking pipes 4 and air injection pipes 3, and will not be described in detail here.

[0063] Taking the splicing process of unit jacking pipe 4 and air injection pipe 3 as an example, under normal conditions, the limiting block 43 is retracted into the sliding hole 42, and the insertion ring sleeve 41 located at one end of unit jacking pipe 4 is inserted into the insertion ring groove 32 of air injection pipe 3. At this time, the limiting block 43 and the limiting groove 33 are in corresponding positions. The transmission rod 51 is driven to slide by the electric push rod 53, thereby driving the limiting block 43 to slide away from the axis of the insertion ring sleeve 41 through the hinge rod 52, so that the limiting block 43 is inserted into the limiting groove. 33, thereby effectively preventing the insertion ring sleeve 41 from sliding out of the insertion ring groove 32 in the opposite direction. During the process of the limiting block 43 sliding into the limiting groove 33, it pushes the slide plate to slide towards the airbag 34, thereby squeezing the airbag 34. This forces the gas in the airbag 34 to be driven to the sealing bladder 36 through the vent pipe 37, causing the sealing bladder 36 to expand and press against the outer peripheral wall of the insertion ring sleeve 41, thereby improving the airtightness between the insertion ring sleeve 41 and the insertion ring groove 32.

[0064] A jacking device 6 is installed on the ground in Area A. The jacking device 6 includes a support 61 and a second cylinder 62 fixedly connected to the support 61. The piston rod of the second cylinder 62 is detachably connected to a push plate 63 for pushing the jacking air injection pipe 3 / unit jacking rod. When jacking the air injection pipe 3, the unit jacking pipes 4 are spliced ​​together in sequence. The air injection pipe 3 is gradually jacked into the soil in Area B by extending and retracting the piston rod of the second cylinder 62. After each unit jacking pipe 4 is jacked, an air pump is used to inject air into the unit jacking pipe 4. The gas finally overflows from the air outlet 31 of the air injection pipe 3, thereby injecting air into different locations of the soil to be excavated, making the soil soft and reducing the excavation difficulty. Simultaneously, the earthmoving work involves excavating the soil in area B in the same direction as the jacking direction of the air injection pipe 3, ensuring synchronous construction of the air injection operation and excavation. Furthermore, if the unit jacking pipe 4 / air injection pipe 3 becomes exposed during excavation, it indicates that the excavation elevation has been reached, and the excavation proceeds to a different location. In this embodiment, the connecting pipe on the air pump and the unit jacking pipe 4 / air injection pipe 3 can be detachably connected using a threaded connection.

[0065] Reference Figure 8 After excavation is completed and the push plate 63 is disassembled, the pull-back gripper 64 is installed on the piston rod of the second cylinder 62. The pull-back gripper 64 is a pneumatic gripper, and the outer peripheral wall of the end of the unit jacking pipe 4 / air injection pipe 3 is provided with a slot 38 for the end of the pull-back gripper 64 to engage. After the pull-back gripper 64 engages in the slot 38 to clamp the unit jacking pipe 4, the piston rod of the second cylinder 62 retracts, pulling the unit jacking pipe 4 back and disassembling and retrieving it. The operation is repeated until the air injection pipe 3 is retrieved. For basement excavation with a high floor height, air injection operations are carried out in layers on the soil of area B of each layer by setting up multiple layers of air injection pipes 3 on the retaining wall plate 12.

[0066] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A construction method for staggered-layer water flow in underground earthwork structures in reverse-construction engineering, characterized in that: Includes the following steps: Step S1: Construction of foundation pit support and foundation reinforcement, construction of underground continuous wall (10) and construction of pile foundation (20) in the foundation pit. Step S2: Divide the construction area in the foundation pit into area A and area B. The earthwork workers will first excavate area A and excavate to the ground level of the first basement level. Step S3: After the structural work class erects the retaining wall structure (1) on the first basement floor of area A to support the soil in area B, the first floor structural beams and slabs (30) of area A are constructed; at the same time, the earthwork work class excavates area B and excavates to the ground elevation of the first basement floor. Step S4: The structural work crew constructs the first-floor structural beams and slabs (30) of Zone B; at the same time, the earthwork work crew excavates Zone A after the first-floor structural beams and slabs (30) of Zone A reach the structural design strength, and excavates to the ground level of the second basement level. Step S5: After the structural work class erects the retaining wall structure (1) on the second basement floor of area A to support the soil in area B, the structural beams and slabs (40) on the first basement floor of area A are constructed; at the same time, after the earthwork work class reaches the structural design strength of the first basement floor structural beams and slabs (30) in area B, area B is excavated and excavated to the ground elevation of the second basement floor. Step S6: The structural work type constructs the underground first floor structural beams and slabs (40) of area B; at the same time, the earthwork work type excavates area A after the underground first floor structural beams and slabs (40) of area A reaches the structural design strength, and excavates to the ground elevation of the third underground floor. Step S7: After the structural work class erects the retaining wall structure (1) on the third underground floor of area A to support the soil in area B, the structural beams and slabs (50) of the second underground floor of area A are constructed; at the same time, after the earthwork work class reaches the structural design strength of the structural beams and slabs (40) of the first underground floor of area B, area B is excavated and excavated to the ground elevation of the third underground floor. Step S8: The structural work type constructs the structural base slab (60) of area A and the structural beams and slabs (50) of the second basement level of area B. After the structural beams and slabs (50) of the second basement level of area B reach the structural design strength, the structural base slab (60) of area B is constructed. The retaining wall structure (1) includes several detachable support base plates (11) connected to the ground, retaining wall plates (12) abutting against the soil in area B, and inclined bracing arms (13) set between the support base plates (11) and the retaining wall plates (12). Back ribs (14) are fixedly connected between the multiple retaining wall plates (12). A reinforcement structure (2) is added between the back ribs (14) and the pile foundation (20). The retaining wall plates (12) are provided with air injection pipes (3) inserted into the soil in area B. The outer peripheral wall of the air injection pipe (3) is provided with an air outlet (31) connected to the inner cavity. Before excavating the soil in area B, the air injection pipe (3) is injected with air by an air pump, so that the soil above the air injection pipe (3) becomes soft.

2. The construction method for staggered-level water flow in underground earthwork structures in a reverse-construction project according to claim 1, characterized in that: It also includes step S9, where the structural work type simultaneously performs post-cast strip structure (70) construction between the first-floor structural beams and slabs (30) of A and B, between the first-floor underground structural beams and slabs (40) of A and B, between the second-floor underground structural beams and slabs (50) of A and B, and between the structural base slabs (60) of A and B.

3. The construction method for staggered-layer water flow in underground earthwork structures in a reverse-construction project according to claim 1, characterized in that: The reinforcement structure (2) includes a connecting arm (21) disposed on the back rib (14) and a pair of clamping members (22) movably disposed on the end of the connecting arm (21) away from the back rib (14) to clamp and fix the pile foundation (20).

4. The construction method for staggered-level water flow in underground earthwork structures of a reverse-construction project according to claim 3, characterized in that: The back rib (14) is slidably connected to a sliding seat (15), and the connecting arm (21) is disposed on the sliding seat (15).

5. The construction method for staggered-layer water flow in underground earthwork structures of a reverse-construction project according to claim 3, characterized in that: The connecting arm (21) includes a connecting sleeve (211) disposed on the back rib (14) and a connecting rod (212) slidably connected to the connecting sleeve (211) in a direction toward or away from the back rib (14). The clamping member (22) is disposed at the end of the connecting rod (212) away from the back rib (14). The connecting sleeve (211) is provided with a driving member for driving the connecting rod (212) to slide.

6. The construction method for staggered-level water flow in underground earthwork structures in a reverse-construction project according to claim 1, characterized in that: The air injection pipe (3) is detachably connected to several unit jacking pipes (4). The inner cavity of the unit jacking pipe (4) is connected to the inner cavity of the air injection pipe (3). Two adjacent unit jacking pipes (4) are detachably connected and the inner cavities of the unit jacking pipes (4) are interconnected. In area A, the air injection pipe (3) is gradually jacked into the soil of area B by the jacking device (6) using the jacking method. The unit jacking pipe (4) is injected with air by the air pump. The gas overflows from the air outlet (31) of the air injection pipe (3). During the excavation of the soil in area B, the excavation is carried out gradually from the side close to the retaining wall (12) to the side away from the retaining wall (12).

7. The construction method for staggered-level water flow in underground earthwork structures of a reverse-construction project according to claim 6, characterized in that: One end of the air injection pipe (3) has an insertion ring groove (32) on its inner wall. One end of the unit top pipe (4) is coaxially fixedly connected to an insertion ring sleeve (41) inserted into the insertion ring groove (32). The inner wall of the insertion ring groove (32) has a limit groove (33). The insertion ring sleeve (41) has a sliding hole (42) in the radial direction. The insertion ring sleeve (41) is provided with a limit block (43) that is slidably connected to the sliding hole (42) and inserted into the limit groove (33). The unit top pipe (4) is provided with a control component (5) for controlling the sliding of the limit block (43).

8. The construction method for staggered-level water flow in underground earthwork structures in a reverse-construction project according to claim 7, characterized in that: The control component (5) includes a transmission rod (51) built into the unit top tube (4) and sliding along the axial direction, a hinge rod (52) with one end hinged to the transmission rod (51) and the other end hinged to the limit block (43), and a control component that drives the transmission rod (51) to slide.

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