Reinforcement Structure and Construction Method of Large Deep Shaft with High-pressure Rotary Jet Grouting Piles in Complex Geological Conditions

Abstract

The present invention relates to a structure of a large and deep well reinforced by high-pressure jet grouting piles in complex geology and its construction method, including the steps of: measuring and setting out, and carrying out construction of circumferential tracks and replacement reinforcement; carrying out construction of high-pressure jet grouting piles, high-pressure jet grouting piles for hole reinforcement, and high-pressure jet grouting piles for bottom reinforcement; constructing dewatering wells between the high-pressure jet grouting piles and the caisson; the caisson structure sinks by its own weight, and the large and deep well excavation technology is used to assist in sinking; constructing a plain concrete bottom seal and pouring the caisson bottom slab; constructing vertical drainage grouting pipes into the high-pressure jet grouting piles for hole reinforcement from the ground; constructing inclined drainage grouting pipes into the high-pressure jet grouting piles for hole reinforcement from the jacking pipe hole. The beneficial effects of the present invention are: ensuring the reinforcement and anti-seepage effect around the large and deep well under complex geological conditions, reducing construction risks, and ensuring project safety; a prefabricated capping beam with embedded parts is arranged at the top of the high-pressure jet grouting pile to realize rapid connection with the superstructure of the high-pressure jet grouting pile.

Description

Technical Field

[0001] The present invention belongs to the technical field of caisson engineering, and particularly relates to a large and deep caisson structure reinforced by high-pressure jet grouting piles in complex geology and a construction method thereof. Background Art

[0002] With the continuous progress of national key hydraulic projects, the water diversion project has solved the drinking water problems of the masses and alleviated the pressure of urban and rural domestic and production water use. The working wells and receiving wells of the water diversion project mostly adopt caisson structures. How to ensure the safe construction of large and deep caissons in complex hydrogeological environments is crucial for the successful completion and long-term reliable operation of the water diversion project, and it is a key engineering problem that needs to be solved urgently.

[0003] Caissons in water diversion projects are usually in the form of reinforced concrete caisson structures, which have the characteristics of large cross-sectional dimensions, large self-weight, large burial depth, strong durability, good stability, and strong environmental adaptability. However, in complex water-rich soft soil strata, when such large and deep caissons are sunk for construction, problems such as overall inclination of the caisson structure, collapse or settlement of the surface soil, and leakage inside the caisson may occur. These problems will not only pose a threat to the safety of surrounding pipelines or buildings, but also may affect the construction progress of the entire water diversion project. To solve the above engineering problems, high-pressure jet grouting piles are often used to reinforce the strata around the caisson. Due to the complexity of the soil layer and the limitation of the construction technology, leakage problems still cannot be completely avoided in the surrounding soil layer during the caisson construction process. At the same time, the high-pressure jet grouting pile construction machinery is heavy and tall. When constructing high-pressure jet grouting piles with a circular layout on the construction plane outside the caisson structure, there are problems such as difficult handling and high safety risks.

[0004] Therefore, to prevent and control leakage accidents in caisson engineering, for caisson engineering in complex geology, it is urgent to develop a high-pressure jet grouting pile reinforced large and deep caisson structure and construction method that are convenient in construction, economical and safe, and comprehensive and effective. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a large and deep caisson structure reinforced by high-pressure jet grouting piles in complex geology and a construction method thereof.

[0006] This complex geological high-pressure jet grouting pile for strengthening large and deep caisson structures includes a caisson structure, a brick retaining wall, a drainage grouting pipe, a high-pressure jet grouting pile, a prefabricated capping beam, embedded parts, and a circumferential track; the large and deep caisson structure is successively provided with a caisson structure, a drainage grouting pipe, a high-pressure jet grouting pile, and a circumferential track from the inside to the outside; the well wall and the caisson cutting edge of the caisson structure are embedded with grouting pipes, the bottom of the caisson structure is provided with a caisson pipe jacking opening and a caisson cutting edge from top to bottom, and a brick retaining wall is provided at the top; the bottom of the caisson structure is filled with plain concrete for bottom sealing; the pipe jacking openings are horizontally distributed on both sides of the well wall of the caisson structure; the caisson cutting edge is integrally and obliquely arranged at the lower port of the caisson structure; the elevation of the caisson bottom slab and the plain concrete bottom sealing is higher than the bottom end of the caisson cutting edge;

[0007] The pipe jacking opening is provided with a high-pressure jet grouting pile for hole reinforcement, and a drainage grouting pipe is arranged in the high-pressure jet grouting pile area. The drainage grouting pipe includes a vertical drainage grouting pipe and an inclined drainage grouting pipe;

[0008] The upper end of the high-pressure jet grouting pile is provided with a prefabricated capping beam and embedded parts; a high-pressure jet grouting pile for hole reinforcement is arranged in the soil outside the pipe jacking opening; a high-pressure jet grouting pile for bottom reinforcement is arranged below the caisson structure; a high-pressure jet grouting construction machine is arranged on the circumferential track, and replacement reinforcement is arranged below the circumferential track.

[0009] Preferably: a water stop casing is arranged at the pipe jacking opening; the water stop casing is hermetically connected to the caisson structure, and the water stop casing is inserted into the high-pressure jet grouting pile for hole reinforcement; the brick retaining wall is rigidly connected to the caisson structure.

[0010] Preferably: the drainage grouting pipe passes through the ground or the pipe jacking opening; the inclined drainage grouting pipe extends from the pipe jacking opening into the high-pressure jet grouting pile for hole reinforcement; the connection between the inclined drainage grouting pipe and the pipe jacking opening is sealed; the vertical drainage grouting pipe extends from the ground into the high-pressure jet grouting pile outside the pipe jacking opening for hole reinforcement.

[0011] Preferably: the reinforcement range of the high-pressure jet grouting pile for hole reinforcement is larger than the size of the caisson pipe jacking opening, and the high-pressure jet grouting pile is connected to the caisson pipe jacking opening; the reinforcement radius of the high-pressure jet grouting pile for bottom reinforcement is larger than the outer diameter of the caisson structure; the high-pressure jet grouting piles for hole reinforcement and bottom reinforcement are both connected to the high-pressure jet grouting pile; the bottom end of the caisson cutting edge is inserted into the high-pressure jet grouting pile for bottom reinforcement, and a sealed connection is made between the caisson cutting edge and the plain concrete bottom sealing.

[0012] Preferably: the prefabricated capping beam wraps the pile body of the high-pressure jet grouting pile through a sleeve, and the prefabricated capping beam and the high-pressure jet grouting pile are also connected through a steel reinforcement cage; according to the installation structure requirements of the upper part of the high-pressure jet grouting pile, embedded parts are provided at the top of the prefabricated capping beam;

[0013] The positioning and dimensions of the circumferential track are determined by the type of high-pressure jet grouting construction machinery and the design parameters of the high-pressure jet grouting piles.

[0014] This construction method for strengthening large deep caissons with high-pressure jet grouting piles in complex geology includes the following steps:

[0015] S1. Measuring and setting out, and carrying out circumferential track and replacement reinforcement construction;

[0016] S2. Determining the water-cement ratio of the slurry for the high-pressure jet grouting piles for hole reinforcement and the high-pressure jet grouting piles for bottom reinforcement through tests and adding sodium silicate; installing the high-pressure jet grouting construction machinery; carrying out the construction of the high-pressure jet grouting piles, the high-pressure jet grouting piles for hole reinforcement and the high-pressure jet grouting piles for bottom reinforcement;

[0017] S3. Installing the precast capping beam with embedded parts; constructing dewatering wells between the high-pressure jet grouting piles and the caisson according to the design requirements, and observing the change of the groundwater level in the dewatering wells to judge whether there is a risk of seepage and leakage;

[0018] S4. Carrying out the construction of the caisson cutting edge, the pipe jacking hole at the caisson wall and the caisson structure, and embedding grouting pipes in the caisson wall and the caisson cutting edge; the caisson structure sinks by its own weight, and the large deep caisson excavation technology is used to assist the sinking;

[0019] S5. After the caisson structure sinks to the design elevation, constructing a plain concrete bottom seal and pouring the caisson bottom slab;

[0020] S6. Constructing vertical drainage grouting pipes into the high-pressure jet grouting piles for hole reinforcement from the ground; constructing inclined drainage grouting pipes into the high-pressure jet grouting piles for hole reinforcement from the pipe jacking hole, and sealing the connection between the inclined drainage grouting pipe and the pipe jacking hole; completing the construction of the large deep caisson.

[0021] Preferably, in step S2, the slurry for the high-pressure jet grouting piles for hole reinforcement and the high-pressure jet grouting piles for bottom reinforcement is pure cement slurry or Portland cement, and the slurry density is greater than or equal to 1.8 g / cm 3 ; the water-cement ratio is 1.0, and the slurry also includes a quick-setting agent and an early-strength agent; the water-binder ratio is 1.0, the admixture amount is greater than or equal to 25%, and sodium silicate is also added;

[0022] When carrying out the construction, the spraying pressure is greater than or equal to 20 MPa at the nozzle, the flow rate is greater than 30 L / min; the lifting speed of the grouting pipe is 25 - 28 cm / min; the rotation speed is 20 - 28 r / min; the lifting speed is 20 - 23 cm / min and the rotation speed is 20 r / min in the range of the top 1 m; the diffusion radius is greater than or equal to 0.4 m;

[0023] Triple-tube grouting is adopted, and the hole diameter is determined according to the engineering design. The slurry pressure is 0.2 - 0.8 MPa, the slurry specific gravity is 1.60 - 1.80, the compressed air pressure is 0.5 - 0.8 MPa, and the high-pressure water pressure is 30 - 50 MPa; the unconfined compressive strength of the soil around the working well and the receiving well after reinforcement is greater than or equal to 1 MPa, and the unconfined compressive strength of the soil around the entrance and exit of the well wall and at the bottom of the cutting edge of the open caisson after reinforcement is greater than or equal to 1.2 MPa, and the permeability coefficient is less than or equal to 1×10 -7 cm / s.

[0024] Preferably, steps S3 and S4 are carried out step by step in sequence or simultaneously;

[0025] In step S4, the construction of the pipe jacking hole at the open caisson wall includes reserving a pipe jacking through-wall casing, a steel ring plate, a ring sealing plate, an inner sealing plate, and a ring-shaped flange at the entrance and exit of the open caisson;

[0026] The open caisson structure is constructed by segmental formwork pouring; for the large and deep open caisson excavation technology, the earthwork excavation inside the large and deep open caisson is carried out by combining various excavation machines. In the early stage, a crane is used in cooperation with a small excavator for excavation, in the middle and late stages, a long-arm excavator is used for excavation, and for the underwater part, a cutter suction dredger is used for excavation to realize the excavation operation of the open caisson.

[0027] Preferably, in step S5, underwater bottom sealing technology is adopted for the plain concrete bottom sealing; in case of leakage accidents at the bottom slab of the open caisson and the plain concrete bottom sealing, grouting is carried out under pressure through the grouting pipe for treatment.

[0028] Preferably, in step S6, the positions of the vertical drainage grouting pipes and the inclined drainage grouting pipes are determined according to the design; in case of leakage at the pipe jacking hole, grouting reinforcement is first carried out through the inclined drainage grouting pipes; then, according to the severity, the vertical drainage grouting pipes are used to expand the grouting reinforcement.

[0029] The beneficial effects of the present invention are as follows:

[0030] 1) In the present invention, the outside of the open caisson is reinforced by the bottom-reaching high-pressure jet grouting piles. Further, a high-pressure jet grouting pile reinforcement and anti-seepage technology formed by combining high-pressure jet grouting piles, high-pressure jet grouting piles for hole reinforcement, and high-pressure jet grouting piles for bottom reinforcement is adopted, supplemented by monitoring the anti-seepage effect with dewatering wells, ensuring the anti-seepage effect of the reinforcement around the large and deep open caisson under complex geological conditions, reducing construction risks, and guaranteeing the project safety.

[0031] 2) The present invention develops a large and deep open caisson water stop treatment technology by combining pre-buried grouting pipes and drainage grouting pipes on the open caisson wall, reducing the risk of water and mud gushing at the bottom of the open caisson, being able to locate and grout for water stop in the leakage area near the pipe jacking entrance and exit, ensuring the water stop effect at the hole, reducing the adverse effects of the project, and having significant social benefits.

[0032] 3) The present invention determines through tests the water-cement ratio of the jet grouting piles for hole reinforcement and the jet grouting piles for bottom reinforcement, and appropriately incorporates sodium silicate to reduce the volume of jet grouting pile reinforcement, reducing the leakage risk of the pipe jacking hole at the top of the caisson wall and the caisson cutting edge area, which conforms to the construction concept of low-carbon, green, and environmental protection.

[0033] 4) The present invention sets an assembled capping beam with embedded parts at the top of the jet grouting pile. The embedded parts can meet different connection requirements, realizing rapid connection with the superstructure of the jet grouting pile, effectively accelerating the construction progress; the assembled capping beam with embedded parts can be reused after disassembly, which is economical and reasonable.

[0034] 5) The present invention places a sleeve under the assembled capping beam to wrap the pile body of the jet grouting pile, supplemented by the connection of the steel reinforcement cage, improving the connection stiffness between the assembled capping beam and the jet grouting pile, which is safe and efficient.

[0035] 6) In the present invention, a precise construction technology for jet grouting piles based on a circumferential track is developed. Through the construction technology of the jet grouting pile construction machinery walking on the circumferential track, it effectively solves the problems of difficult handling, high engineering safety risks, low construction positioning accuracy, and slow construction speed caused by the large weight and high height of the jet grouting pile construction machinery. Especially when constructing the jet grouting piles with a circular plane layout on the outside of the caisson structure, it greatly improves the construction speed and construction accuracy of the jet grouting piles, with significant engineering benefits.

[0036] 7) The present invention uses a combination of various excavation machinery for earth excavation in large and deep caissons. In the early stage, a crane is used in cooperation with a small excavator for excavation, and in the middle and late stages, a long-arm excavator is used for excavation. For the underwater part, an advanced cutter suction dredger is used for excavation, realizing the efficient and safe excavation operation of the caisson, reducing working hours, and making the construction faster. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a sectional view of a large and deep caisson structure reinforced by jet grouting piles in complex geology;

[0038] In the figure: Caisson structure 1, Grouting pipe 1-1, Pipe jacking hole 1-2, Caisson cutting edge 1-3, Caisson bottom slab 1-4, Plain concrete seal 1-5; Brick retaining wall 2; Drainage grouting pipe 3, Vertical drainage grouting pipe 3-1, Inclined drainage grouting pipe 3-2; Jet grouting pile 4, Jet grouting pile for hole reinforcement 4-1, Jet grouting pile for bottom reinforcement 4-2, Assembled capping beam 5, Steel reinforcement cage 5-1, Embedded part 6, Circumferential track 7, Replacement and reinforcement 8. DETAILED DESCRIPTION OF THE INVENTION

[0039] The present invention will be further described below in conjunction with embodiments. The description of the following embodiments is only for helping to understand the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0040] Embodiment 1

[0041] As an embodiment, as Figure 1 shown, the structure of a large deep well reinforced by a high-pressure jet grouting pile in complex geology includes a caisson structure 1, a brick retaining wall 2, a drainage grouting pipe 3, a high-pressure jet grouting pile 4, a prefabricated capping beam 5, a buried part 6, and a circumferential track 7; the caisson structure 1, the drainage grouting pipe 3, the high-pressure jet grouting pile 4, and the circumferential track 7 are arranged from the inside to the outside; the well wall and the caisson cutting edge 1-3 of the caisson structure 1 are embedded with grouting pipes 1-1, and the caisson pipe jacking hole 1-2 and the caisson cutting edge 1-3 are arranged from top to bottom at the bottom, and a brick retaining wall 2 is arranged at the top; the bottom of the caisson floor 1-4 at the bottom of the caisson structure 1 is filled with a plain concrete seal 1-5; the pipe jacking holes 1-2 are horizontally distributed on both sides of the well wall of the caisson structure 1; the caisson cutting edge 1-3 is arranged at the lower port of the caisson structure 1 and is integrally inclined on both sides; the caisson floor 1-4 and the plain concrete seal 1-5 are arranged above the caisson cutting edge 1-3;

[0042] A drainage grouting pipe 3 is arranged in the area of the high-pressure jet grouting pile 4-1 for hole reinforcement outside the pipe jacking hole 1-2, including a vertical drainage grouting pipe 3-1 and an inclined drainage grouting pipe 3-2; a water stop sleeve is arranged at the pipe jacking hole 1-2; the water stop sleeve should be hermetically connected to the caisson structure 1 by welding with a straight-seam submerged arc steel pipe and inserted into the high-pressure jet grouting pile 4-1 for hole reinforcement; the brick retaining wall 2 is rigidly connected to the caisson structure 1.

[0043] The drainage grouting pipe 3 is used for positioning grouting and water stopping in the leakage area near the pipe jacking hole 1-2 through the ground or the pipe jacking hole 1-2, ensuring the water stopping effect of the hole and reducing the construction risk; the inclined drainage grouting pipe 3-2 is arranged in the high-pressure jet grouting pile 4-1 for hole reinforcement through the pipe jacking hole 1-2; the connection between the inclined drainage grouting pipe 3-2 and the pipe jacking hole 1-2 is sealed; the vertical drainage grouting pipe 3-1 is arranged outside the pipe jacking hole 1-2 through the ground and is used for reinforcing the high-pressure jet grouting pile 4-1 outside the grouting range of the drainage grouting pipe 3-2.

[0044] The reinforcement range of the high-pressure jet grouting pile 4-1 for hole reinforcement should be larger than the size of the open caisson pipe jacking hole 1-2 and be connected to the open caisson pipe jacking hole 1-2; the reinforcement radius of the high-pressure jet grouting pile 4-2 for bottom reinforcement should be larger than the outer diameter of the caisson structure 1; the high-pressure jet grouting pile 4-1 for hole reinforcement and the high-pressure jet grouting pile 4-2 for bottom reinforcement are both connected to the high-pressure jet grouting pile 4; the caisson cutting edge 1-3 is inserted into the high-pressure jet grouting pile 4-2 for bottom reinforcement and is hermetically connected to the plain concrete bottom seal 1-5.

[0045] The high-pressure jet grouting pile 4 performs bottom reinforcement on the soil outside the caisson structure 1, and is provided with an assembled capping beam 5 and embedded parts 6 at its upper end for rapid connection of the upper structure; the high-pressure jet grouting pile 4-1 for hole reinforcement is arranged in the soil outside the pipe jacking hole 1-2; the high-pressure jet grouting pile 4-2 for bottom reinforcement is arranged below the caisson structure 1; the circumferential track 7 is used for the high-pressure jet grouting pile 4 construction machinery to walk, and the lower part is provided with replacement and reinforcement 8;

[0046] The assembled capping beam 5 is provided with a sleeve at the lower part to wrap the pile body of the high-pressure jet grouting pile 4 and is connected by a steel reinforcement cage 5-1; according to the installation structure requirements of the upper part of the high-pressure jet grouting pile 4, the assembled capping beam 5 with embedded parts 6 meeting different connection requirements can be selected; the assembled capping beam 5 with embedded parts 6 can be disassembled and reused after the project is completed.

[0047] The positioning and dimensions of the circumferential track 7 are determined by the high-pressure jet grouting pile 4 construction machinery model and the high-pressure jet grouting pile 4 design parameters; the strength of the circumferential track 7 and the replacement and reinforcement 8 provided below it should meet the safety operation requirements of the high-pressure jet grouting pile 4 construction machinery.

[0048] Embodiment 2

[0049] As another embodiment, the construction method of the high-pressure jet grouting pile for complex geological conditions to reinforce large and deep caissons in Embodiment 1 includes the following steps:

[0050] S1. Measuring and setting out, and constructing the circumferential track 7 and the replacement and reinforcement 8 below it;

[0051] S2. After the strength of the circumferential track 7 and the replacement and reinforcement 8 below it meets the requirements, install the high-pressure jet grouting pile 4 construction machinery; after precise setting out, construct the high-pressure jet grouting pile 4, the high-pressure jet grouting pile 4-1 for hole reinforcement, and the high-pressure jet grouting pile 4-2 for bottom reinforcement;

[0052] S3. After the construction of the high-pressure jet grouting pile 4, the high-pressure jet grouting pile 4-1 for hole reinforcement, and the high-pressure jet grouting pile 4-2 for bottom reinforcement is completed, install the assembled capping beam 5 with embedded parts 6;

[0053] Construct dewatering wells between the high-pressure jet grouting piles 4 and the caisson according to the design requirements, and observe the change of the groundwater level in the dewatering wells to judge whether there is a risk of seepage water.

[0054] S4. Construct the caisson blade feet 1-3, the pipe jacking openings 1-2 at the caisson wall and the caisson structure 1. Embedded grouting pipes 1-1 are pre-buried in the caisson wall and the caisson blade feet 1-3.

[0055] The caisson structure 1 sinks by its own weight, and the large-deep caisson excavation technology is adopted to assist the sinking.

[0056] The steps S3 and S4 can be carried out step by step in sequence or synchronously.

[0057] In the step S4, the construction of the pipe jacking openings 1-2 at the caisson wall includes reserving the pipe jacking through-wall sleeves, steel ring plates, ring seal plates, inner seal plates, and annular flange plates at the caisson inlet and outlet openings. When reserving, it is necessary to ensure that the embedded steel bars and rubber strip embedded parts for the rigid joint between the portal structure and the caisson are installed in the accurate positions.

[0058] The caisson structure 1 is cast by sectional formwork. For the large-deep caisson excavation technology, the earthwork in the large-deep caisson is excavated orderly and quickly by combining various excavation machines. In the early stage, the crane is used to cooperate with the small excavator for excavation, and in the middle and later stages, the long-arm excavator is used for excavation. For the underwater part, the advanced cutter suction dredger is used for excavation to achieve the efficient excavation operation of the caisson.

[0059] S5. After the caisson sinks to the design elevation, carry out the construction of the plain concrete bottom seal 1-5 and pour the caisson bottom slab 1-4. The plain concrete bottom seal 1-5 adopts the underwater bottom seal technology. In case of leakage accidents at the caisson bottom slab 1-4 and the plain concrete bottom seal 1-5, grouting is carried out under pressure through the grouting pipe 1-1 for treatment.

[0060] S6. Vertically construct the drainage grouting pipe 3-1 into the high-pressure jet grouting pile 4-1 for hole reinforcement from the ground. Inclined drainage grouting pipe 3-2 is constructed into the high-pressure jet grouting pile 4-1 for hole reinforcement from the pipe jacking opening 1-2, and the connection between the inclined drainage grouting pipe 3-2 and the pipe jacking opening 1-2 is sealed. The positions of the vertical drainage grouting pipe 3-1 and the inclined drainage grouting pipe 3-2 are determined according to the design. In case of leakage at the pipe jacking opening 1-2, it is preferred to grout and reinforce with the inclined drainage grouting pipe 3-2. When the leakage area is too large and the grouting effect of the inclined drainage grouting pipe 3-2 is not good, the vertical drainage grouting pipe 3-1 is used to expand the grouting and reinforcement.

[0061] S7. Complete the construction of the large-deep caisson.

[0062] The grouting process parameters of the high-pressure jet grouting pile are as follows:

[0063] Slurry type: pure cement slurry or Portland cement 425#.

[0064] Slurry density: not less than 1.8 g / cm 3 ; Determine the water-slurry ratio of the high-pressure jet grouting piles 4-1 for portal reinforcement and the high-pressure jet grouting piles 4-2 for bottom reinforcement through tests;

[0065] Water-cement ratio: 1.0, and appropriate amounts of accelerating agent and early strength agent can be added.

[0066] Water-binder ratio: 1.0, with an admixture amount not less than 25%. To improve the anti-seepage effect, appropriate water glass can be incorporated.

[0067] Jet grouting pressure: not less than 20 MPa at the nozzle; the flow rate should be greater than 30 L / min.

[0068] Grouting pipe: lifting speed 25 - 28 cm / min; rotation speed 20 - 28 r / min; at the top 1 m, the lifting speed is 20 - 23 cm / min; rotation speed 20 r / min.

[0069] Diffusion radius: not less than 0.4 m.

[0070] Construction technical parameters: triple-tube grouting is adopted, the hole diameter is determined according to the engineering design, the normal slurry pressure is 0.2 - 0.8 MPa, the slurry specific gravity is 1.60 - 1.80, the compressed air pressure is 0.5 - 0.8 MPa, and the high-pressure water pressure is 30 - 50 MPa. The unconfined compressive strength of the soil after reinforcement around the working shaft and the receiving shaft is greater than or equal to 1 MPa, and the unconfined compressive strength of the soil after reinforcement at the shaft wall entrance / exit and the bottom of the cutting edge is greater than or equal to 1.2 MPa, and the permeability coefficient is not greater than 1×10 -7 cm / s.

Claims

1. A complex geological high-pressure jet grouting pile for reinforcing a large deep well structure, characterized in that; It includes a caisson structure (1), a brick retaining wall (2), a drainage grouting pipe (3), a high-pressure jet grouting pile (4), a precast girder (5), a embedded part (6) and a circumferential track (7); The large and deep caisson structure is successively provided with a caisson structure (1), a drainage grouting pipe (3), a high-pressure jet grouting pile (4) and a circumferential track (7) from inside to outside; Grouting pipes (1-1) are embedded in the well wall and the caisson cutting edge (1-3) of the caisson structure (1). A caisson pipe jacking hole (1-2) and a caisson cutting edge (1-3) are arranged at the bottom of the caisson structure (1) from top to bottom, and a brick retaining wall (2) is arranged at the top; Under the caisson floor slab (1-4) at the bottom of the caisson structure (1), a plain concrete seal (1-5) is filled; The pipe jacking holes (1-2) are horizontally distributed on both sides of the well wall of the caisson structure (1); The caisson cutting edge (1-3) is integrally and obliquely arranged at the lower port of the caisson structure (1); The elevation of the caisson floor slab (1-4) and the plain concrete seal (1-5) is higher than the bottom end of the caisson cutting edge (1-3). The pipe jacking hole (1-2) is provided with a high-pressure jet grouting pile (4-1) for hole reinforcement. A drainage grouting pipe (3) is arranged in the area of the high-pressure jet grouting pile (4-1) for hole reinforcement. The drainage grouting pipe (3) includes a vertical drainage grouting pipe (3-1) and an inclined drainage grouting pipe (3-2). The upper end of the high-pressure jet grouting pile (4) is provided with a precast girder (5) and an embedded part (6); A high-pressure jet grouting pile (4-1) for hole reinforcement is arranged in the soil outside the pipe jacking hole (1-2); A high-pressure jet grouting pile (4-2) for bottom reinforcement is arranged below the caisson structure (1); A high-pressure jet grouting construction machine is arranged on the circumferential track (7), and a replacement reinforcement (8) is arranged below the circumferential track (7). The inclined drainage grouting pipe (3-2) extends from the pipe jacking hole (1-2) into the high-pressure jet grouting pile (4-1) for hole reinforcement; The connection between the inclined drainage grouting pipe (3-2) and the pipe jacking hole (1-2) is sealed; The vertical drainage grouting pipe (3-1) extends from the ground into the high-pressure jet grouting pile (4-1) outside the pipe jacking hole (1-2).

2. The reinforced large deep well structure with high-pressure jet grouting piles in complex geology according to claim 1, characterized in that, The pipe jacking hole (1-2) is provided with a water stop sleeve; The water stop sleeve is sealed and connected with the caisson structure (1), and the water stop sleeve is inserted into the high-pressure jet grouting pile (4-1) for hole reinforcement; The brick retaining wall (2) is rigidly connected with the caisson structure (1).

3. The deep well structure reinforced by the complex geological high-pressure jet grouting pile according to claim 1, characterized in that, The reinforcement range of the high-pressure jet grouting pile (4-1) for hole reinforcement is larger than the size of the caisson pipe jacking hole (1-2), and the high-pressure jet grouting pile (4-1) is connected with the caisson pipe jacking hole (1-2); The reinforcement radius of the high-pressure jet grouting pile (4-2) for bottom reinforcement is larger than the outer diameter of the caisson structure (1); The high-pressure jet grouting pile (4-1) for hole reinforcement and the high-pressure jet grouting pile (4-2) for bottom reinforcement are both connected with the high-pressure jet grouting pile (4); The bottom end of the caisson cutting edge (1-3) is inserted into the high-pressure jet grouting pile (4-2) for bottom reinforcement, and a sealed connection is made between the caisson cutting edge (1-3) and the plain concrete seal (1-5).

4. The large deep well structure reinforced by the complex geological high-pressure jet grouting pile according to claim 1, characterized in that, The prefabricated capping beam (5) wraps the pile body of the high-pressure jet grouting pile (4) through a sleeve, and the prefabricated capping beam (5) and the high-pressure jet grouting pile (4) are also connected through a steel reinforcement cage (5-1); according to the installation structure requirements of the upper part of the high-pressure jet grouting pile (4), embedded parts (6) are provided at the top of the prefabricated capping beam (5).

5. The construction method of the complex geological high-pressure jet grouting pile for reinforcing large and deep shafts according to any one of claims 1 to 4, characterized in that, The method includes the following steps: S1. Measuring and setting out, and constructing the circumferential track (7) and replacement and reinforcement (8). S2. Determining the slurry-water ratio of the high-pressure jet grouting pile (4-1) for hole reinforcement and the high-pressure jet grouting pile (4-2) for bottom reinforcement through tests and adding water glass; installing the high-pressure jet grouting pile construction machinery; constructing the high-pressure jet grouting pile (4), the high-pressure jet grouting pile (4-1) for hole reinforcement and the high-pressure jet grouting pile (4-2) for bottom reinforcement. S3. Installing the prefabricated capping beam (5) with embedded parts (6); constructing a dewatering well between the high-pressure jet grouting pile (4) and the caisson structure according to the design requirements, and observing the change of the groundwater level in the dewatering well to judge whether there is a risk of seepage and leakage. S4. Constructing the caisson cutting edge (1-3), the pipe jacking hole (1-2) at the caisson wall and the caisson structure (1), and embedding grouting pipes (1-1) in the caisson wall and the caisson cutting edge (1-3); the caisson structure (1) sinks by its own weight, and the large-deep caisson excavation technology is used to assist the sinking. S5. After the caisson structure (1) sinks to the design elevation, constructing a plain concrete bottom seal (1-5) and pouring the caisson bottom slab (1-4). S6. Constructing a vertical drainage grouting pipe (3-1) into the high-pressure jet grouting pile (4-1) for hole reinforcement from the ground; constructing an inclined drainage grouting pipe (3-2) into the high-pressure jet grouting pile (4-1) for hole reinforcement from the pipe jacking hole (1-2), and sealing the connection between the inclined drainage grouting pipe (3-2) and the pipe jacking hole (1-2); completing the construction of the large-deep caisson.

6. The construction method of the complex geological high-pressure jet grouting pile for reinforcing large and deep wells according to claim 5, characterized in that: The steps S3 and S4 are carried out step by step in sequence or simultaneously. In the step S4, the construction of the pipe jacking hole (1-2) at the caisson wall includes reserving a pipe jacking through-wall sleeve, a steel ring plate, a ring sealing plate, an inner sealing plate and a ring-shaped flange plate at the inlet and outlet of the caisson. The caisson structure (1) is cast by sectional formwork support; for the large-deep caisson excavation technology, the earthwork excavation in the large-deep caisson is carried out by combining various excavation machines. In the early stage, a crane is used to cooperate with a small excavator for excavation, and in the middle and later stages, a long-arm excavator is used for excavation. The underwater part is excavated by a cutter suction dredger to realize the excavation operation of the caisson.

7. The construction method of the complex geological high-pressure rotary jet grouting pile for reinforcing large deep wells according to claim 5, characterized in that: In the step S5, the plain concrete bottom seal (1-5) adopts underwater bottom sealing technology; in case of leakage accidents at the caisson bottom slab (1-4) and the plain concrete bottom seal (1-5), pressure grouting is carried out through the grouting pipe (1-1) for treatment.

8. The construction method of the complex geological high-pressure jet grouting pile for reinforcing large and deep wells according to claim 5, characterized in that: In the step S6, the positions of the vertical drainage grouting pipe (3-1) and the inclined drainage grouting pipe (3-2) are determined according to the design; in case of leakage at the pipe jacking hole (1-2), first grouting reinforcement is carried out through the inclined drainage grouting pipe (3-2); then, according to the severity, the vertical drainage grouting pipe (3-1) is used for enlarged grouting reinforcement.

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