Wall repairing treatment method for ultra-deep diaphragm wall of high-pressure-bearing water-rich soft soil stratum

Abstract

The invention provides a wall repairing treatment method for an ultra-deep diaphragm wall in a high-pressure-bearing water-rich soft soil layer, relates to the field of foundation pit engineering, and aims to solve the problems that water burst and sand burst are easily caused, the anti-floating capacity of a structure is insufficient and the durability is poor during defect treatment of the ultra-deep diaphragm wall in the high-pressure-bearing water-rich soft soil layer. According to the method, the range of a defective wall body is determined through ultrasonic detection, reinforcement is carried out in the mode that a linear reinforcement wall and a Z-shaped reinforcement wall are combined, meanwhile, ultrahigh-pressure jet grouting piles are arranged between the reinforcement walls and the defective wall for water stop, and the integrity of a waterproof curtain of a foundation pit is ensured. In addition, the method is combined with an expanded crown beam structure to optimize the anti-floating design, and the anti-floating safety of the main body structure is improved. By the adoption of the method, the bearing capacity and durability of the ultra-deep diaphragm wall can be effectively improved, the water and sand burst risk in the foundation pit excavation process is reduced, and a safe and efficient wall repairing treatment scheme is provided for deep foundation pit engineering under the high-pressure-bearing water-rich soft soil stratum.

Description

Technical Field

[0001] The invention relates to a method for treating an ultra-deep ground-connected wall in a high-pressure, water-rich soft soil stratum and relates to the field of foundation pit engineering. Background Art

[0002] In recent years, with the acceleration of urbanization, more and more engineering projects are located in floodplain areas near rivers and lakes. These projects usually involve deep and large foundation pit construction. The groundwater level at the construction site is high and pressure-bearing, and the strata are mostly soft soil strata. To ensure the safety of foundation pit construction, the retaining structure generally adopts underground continuous walls with high bearing capacity and good water-stopping performance. The insertion ratio of the retaining structure in the high-pressure water-rich soft soil stratum is about 1:1, so the depth of the retaining structure of the deep and large foundation pit in the floodplain area near rivers and lakes is generally more than 60m, which is an ultra-deep underground continuous wall.

[0003] When constructing ultra-deep underground continuous walls in water-rich and highly pressurized water strata, the effects of groundwater and improper construction control may lead to local instability of the trench wall of the ground-connected wall. If this instability occurs during the wall pouring process, it is very easy to cause quality defects in the ground-connected wall, which will have a huge impact on the later bearing capacity of the wall, and may even fail to meet the bearing capacity requirements. There is currently no relevant treatment method for underground continuous wall defects in highly pressurized water-rich soft soil strata. The most common methods currently used are direct reinforcement methods for general underground continuous wall defects, that is, excavating to the defective part and then reinforcing it; or methods of repairing the wall outside the pit under general stratum conditions, without considering the anti-floating effect of the reinforced wall.

[0004] In addition, the retaining structure is subject to stress throughout the entire process from excavation construction to operation of deep and large foundation pits. During the excavation of the foundation pit, the underground continuous wall needs to have a high bearing capacity and good water-stopping performance. During the structural operation stage, the underground continuous wall participates in the structural anti-floating and needs to have high durability.

[0005] In summary, with the increasing number of deep and large foundation pit projects in riverside and floodplain areas, the frequency of engineering accidents caused by serious defects in underground continuous walls is also increasing. For the serious defects of underground continuous walls under high-pressure water-rich soft soil strata, the existing treatment methods have great safety hazards and do not meet the requirements of engineering durability. In view of this, the application of this patent is specially proposed. Summary of the invention

[0006] The present invention relates to a method for repairing and disposing an ultra-deep ground-connected wall in a high-pressure, water-rich, soft soil layer, and relates to the technical field of shield tunnel engineering. The invention aims to solve the problem that the ultra-deep ground-connected wall in a high-pressure, water-rich, soft soil layer is prone to water and sand gushing, insufficient anti-floating ability of the structure, and poor durability when the defects are treated. The present invention reduces the occurrence of water and sand gushing accidents during foundation pit excavation through the design of the ground-connected wall construction process and the design of construction parameters, comprehensively improves the construction quality of the ground-connected wall, improves the water-stopping effect and enhances the anti-floating ability, reduces the risk of sudden water and sand gushing during foundation pit excavation, and provides a safe and efficient wall repair and disposal solution for deep foundation pit projects under high-pressure, water-rich, soft soil layers.

[0007] The present invention provides a method for treating an ultra-deep ground-connected wall in a high-pressure, water-rich soft soil stratum, comprising the following steps:

[0008] Step 1: Perform ultrasonic testing on the defective wall to obtain the location and size of the defective part;

[0009] Step 2: Build a reinforcement wall on the outside of the defective wall;

[0010] Step 3: Set up jet grouting piles to stop water between the defective wall and the reinforcement wall;

[0011] Step 4: Chisel off the top wall of the defective wall and recast it. The new ground-connected wall is connected to the reinforced wall through shear steel bars, and the new ground-connected wall is connected to the expanded crown beam through reinforced steel bars;

[0012] Step 5: construct the first ring frame beam and the first support at a vertical position from the top of the foundation pit to the bottom of the foundation pit;

[0013] Step 6: Continue to excavate the foundation pit. When the excavation reaches the second ring frame beam and the third ring frame beam in sequence, determine whether the defective part of the defective wall is within the range of the ring frame beam according to the detection in step 1. When there is a defect within the range of the second ring frame beam or the third ring frame beam, perform grouting at the defective position;

[0014] Step 7: Construct waterproofing and main structure.

[0015] Furthermore, the reinforcement wall includes a straight reinforcement wall and a Z-shaped reinforcement wall arranged outside the defective wall, the length of the straight reinforcement wall is shorter than the length of the defective wall, and the Z-shaped reinforcement walls are arranged on both sides of the straight reinforcement wall.

[0016] Furthermore, the reinforcement layer of the reinforced wall groove wall has the same construction process as the existing groove wall reinforcement layer, and the reinforcement needs to penetrate the soft soil layer, that is, meet the following requirements:

[0017] Z 1 ≤Z≤Z 2

[0018] Among them, Z is the depth of the reinforcement layer of the wall, Z 1is the burial depth of the bottom plate in soft soil layer, Z 2 is the instability depth of the groove wall.

[0019] Furthermore, the crown beam is expanded into a cantilever structure, and the cantilever length of the expanded crown beam is equal to the width of the defective wall.

[0020] Furthermore, jet grouting water-stopping is arranged between the bottom of the defective wall and the reinforced wall: an N-jet conduit is pre-buried on the reinforcement cage of the reinforced wall, the inner diameter of the N-jet conduit is larger than the diameter of the N-jet drill bit, and after the reinforcement wall construction is completed, the N-jet drill bit drills from the N-jet conduit into the bottom of the ground-connected wall to perform jet grouting water-stopping.

[0021] Furthermore, the bottom of the defective wall and the reinforced wall forms a wall bottom N-jet reinforcement body, and the wall bottom N-jet reinforcement body satisfies:

[0022]

[0023] Among them, a 1 is the distance of the N-jet reinforcement at the bottom of the wall beyond the edge of the defective wall or reinforced wall, h1 is the thickness of the ground-connected wall, c 1 is the thickness of the N-jet reinforcement at the bottom of the wall, c 2 It is the N-jet bottom cover thickness of the existing foundation pit.

[0024] Preferably, step 4 satisfies:

[0025]

[0026] Among them, F 浮 is the design value of buoyancy per linear meter of reinforcement wall, f yv is the design value of shear reinforcement strength, A sv1 is the area of ​​a single shear reinforcement, H is the height of the defective wall, x is the horizontal spacing of the shear reinforcement, y is the vertical spacing of the shear reinforcement, and f y is the design value of the reinforcement strength, A s1 is the area of ​​a single reinforcing steel bar, s is the spacing between reinforcing steel bars, H1 is the buried depth of the bottom of the first ring frame beam, and H2 is the depth of the defective wall removed below the bottom of the first ring frame beam.

[0027] Furthermore, the N-jet catheter meets the following requirements:

[0028]

[0029] Among them, l is the length of N-jet pipe, L is the depth of the groove of the reinforcement wall, d is the inner diameter of N-jet pipe, D is the diameter of N-jet drill pipe, and α is the aperture coefficient.

[0030] Furthermore, the casting hole is set at the center line of the new ground-connected wall, and the hole diameter meets the following requirements:

[0031] d 1 =max(αD 1 , d 0 )

[0032] Among them, d 1 is the diameter of the pouring hole 18, D 1 is the diameter of the vibrating rod, d 0 is the minimum diameter required for construction vibration of the new ground-connected wall 22, and α is the aperture coefficient.

[0033] Preferably, d 0 ≥200mm.

[0034] The beneficial effects of the present invention are:

[0035] The present invention provides a systematic, efficient and safe solution for the repair and reinforcement of broken walls of ultra-deep underground continuous walls by comprehensively improving the construction quality of the ground-connected wall, improving the water-stopping effect and enhancing the anti-floating ability.

[0036] 1. The present invention determines the scope of the defective wall through ultrasonic detection, and adopts a combination of a straight-line reinforcement wall and a Z-shaped reinforcement wall for reinforcement. At the same time, an ultra-high pressure rotary jet pile water-stopping device is arranged between the reinforcement wall and the defective wall to ensure the integrity of the foundation pit water-stopping curtain.

[0037] 2. The present invention improves the stability of the groove wall of the reinforced wall by controlling the depth of the reinforcement of the ground-connected wall groove wall, further ensures the construction quality of the reinforced wall, and improves the durability of the reinforced wall.

[0038] 3. The present invention sets a pre-buried N-jet conduit between the reinforcement wall and the defective wall. The ultra-high pressure jet grouting piles can enter the bottom of the wall through the N-jet conduit to perform jet grouting to stop water, thereby ensuring the sealing of the foundation pit water-stopping curtain and improving the safety of the foundation pit against sudden surges.

[0039] 4. The present invention improves the anti-floating safety of the main structure by setting up an anti-floating structure and optimizing the anti-floating design in combination with expanding the crown beam structure, so that the crown beam and the reinforcement wall can better participate in the anti-floating of the structure, thereby improving the safety reserve of the anti-floating of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0041] Figure 1 It is a construction flow chart of the wall connection and wall repair treatment method of the present invention;

[0042] Figure 2 It is the floor and wall plan layout of the present invention;

[0043] Figure 3 It is a plan view of the groove wall reinforcement of the present invention;

[0044] Figure 4 It is the plan layout of the guide wall of the present invention;

[0045] Figure 5 It is a plan view of the water-stop reinforcement of the present invention;

[0046] Figure 6 It is a cross-sectional view of the present invention:

[0047] Figure 7 This is a partial enlarged view of node A.

[0048] Figure numbers: 1-adjacent wall, 2-defective wall, 3-I-shaped reinforcement wall, 4-Z-shaped reinforcement wall, 5-defective wall groove edge, 6-steel joint, 7-existing groove wall reinforcement layer, 8-reinforcement wall groove wall reinforcement layer, 9-existing guide wall, 10-reinforcement wall guide wall, 11-N-jet water-stop reinforcement point, 12-N-jet guide tube, 13-1-first ring frame beam, 13-2-second ring frame beam, 13-3-third ring frame beam, 14-1-first support, 14-2-second support, 14-3-third support, 15-N-jet reinforcement body at the bottom of the wall, 16-N-jet bottom cover, 17-expanded crown beam, 18-casting hole, 19-micro-expansive concrete, 20-reinforcement steel bars, 21-shear steel bars, 22-newly made ground-connected wall. DETAILED DESCRIPTION

[0049] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] The present invention proposes a method for repairing ultra-deep diaphragm walls in highly pressurized water-rich soft soil strata, relates to the field of deep foundation pit engineering under highly pressurized water-rich soft soil strata conditions, and is used for treating serious defects of ultra-deep diaphragm walls in foundation pit engineering where the pressurized water head pressure is greater than the weight of the covering soil in the range from the bottom of the base plate to the top plate of the pressurized water layer.

[0051] According to the Technical Specifications for Testing of Building Foundation Pile Foundations, pile integrity is divided into four categories, as shown in Table 1. Among them, Class I and Class II piles do not affect the structural bearing capacity, while Class III and Class IV piles have an impact on the structural bearing capacity, especially Class IV piles that require rework.

[0052] Table 1 Pile body integrity classification table

[0053] Pile integrity classification Classification principles Class I pile Pile body complete Class II pile The pile body has slight defects, which will not affect the normal performance of the pile body structure bearing capacity Class III pile The pile body has obvious defects, which affects the bearing capacity of the pile body structure Class IV pile There are serious defects in the pile

[0054] The present invention is a method for repairing ultra-deep ground-connected walls in high-pressure water-rich soft soil strata, which is mainly aimed at Class IV piles, i.e., piles with serious defects. The method specifically includes the following steps: Figure 1-Figure 7 As shown:

[0055] Step 1: Perform ultrasonic testing on the defective wall 2 to make a preliminary judgment on the defect location and size, and provide a basis for grouting and wall filling at the later support position;

[0056] Step 2: Adjust the width of the adjacent wall 1 to meet the layout of the Z-shaped reinforcement wall 4, and build a reinforcement wall on the outside of the defective wall 2 (relative to the foundation pit). The reinforcement wall includes a straight reinforcement wall 3 and a Z-shaped reinforcement wall 4, and then build a groove wall reinforcement layer 8 and a reinforcement wall guide wall 10 of the straight reinforcement wall 3 and the Z-shaped reinforcement wall 4. Because the geology of the water-rich soft soil layer is poor, the groove wall is not easy to stabilize, and the reinforcement of the reinforcement wall groove wall needs to penetrate the soft soil layer. During the construction of the reinforcement wall, the defective wall groove edge 5 should be brushed several times to remove the backfill materials such as gravel at this location. The backfill materials when the defective wall is grooved at this location need to be brushed several times to remove them. The steel joint 6 is consistent with the prototype steel joint, and the reinforcement wall guide wall 10 has the same construction process as the existing guide wall 9.

[0057] Step 3: Since the I-shaped reinforcement wall 3 and the Z-shaped reinforcement wall 4 are in a high pressure water environment, the pressure water head is high and greater than the weight of the covering soil in the range from the bottom plate to the top plate of the pressure water layer, the pressure water can easily flow into the foundation pit through the gap between the I-shaped reinforcement wall 3, the Z-shaped reinforcement wall 4 and the defective wall 2. To prevent this accident, a jet grouting pile is set between the defective wall 2 and the reinforcement wall. Since the effective construction depth of ordinary jet grouting piles is much smaller than the ground wall depth, N-jet ultra-high pressure jet grouting piles are required for the jet grouting water stop at the bottom of the wall. The specific method is to pre-embed N-jet conduit 12 on the reinforcement wall steel cage. The inner diameter of N-jet conduit 12 is larger than the diameter of N-jet drill bit. After the construction of I-shaped reinforcement wall 3 and Z-shaped reinforcement wall 4 is completed, N-jet drill bit drills into the bottom of ground-connected wall from N-jet conduit 12 to perform rotary spraying water stopping. N-jet water stopping reinforcement point 11 is directly applied to the side of ground wall. High-pressure rotary spraying is performed through newly made and pre-embedded N-jet reinforcement casing. The arrangement points of newly made N-jet water stopping reinforcement point 11 and pre-embedded N-jet conduit are shown in Fig. Figure 5 .

[0058] Step 4: The groundwater level in the water-rich soft soil layer is relatively high. The main structure in this type of layer is often subject to a large buoyancy. The structure itself cannot meet the anti-buoyancy requirements of the structure, and the surrounding structure is often required to participate in the anti-buoyancy. The main structure includes a top plate, a bottom plate, a side wall and an internal structure. The main structure transfers the buoyancy to the I-shaped reinforcement wall 3 and the Z-shaped reinforcement wall 4 by expanding the crown beam 17. Because there is a defective wall 2 between the main structure and the I-shaped reinforcement wall 3 and the Z-shaped reinforcement wall 4, the crown beam 17 is expanded to connect the I-shaped reinforcement wall 3 and the Z-shaped reinforcement wall 4 with other complete ground-connected walls into a whole, that is, the distance between the buoyancy action point of the main structure and the I-shaped reinforcement wall 3 and the Z-shaped reinforcement wall 4 is the width of the defective wall 2. Within this range, the crown beam 17 is expanded to press the top beam, which is a cantilever structure. The cantilever length is the length of the defective wall 2 to meet the force of the expanded crown beam 17. Under the action of vertical buoyancy, the expanded crown beam 17 is subjected to bending moment, torque and shear force, and the force is relatively complex. The expanded crown beam 17 is mainly subjected to horizontal bending moment, and the vertical bending and torsion bearing capacity is relatively weak. In order to improve the force of the expanded crown beam 17, the top wall of the defective wall 2 is chiseled out and re-cast. The new ground-connected wall 22 is connected to the I-shaped reinforcement wall 3 and the Z-shaped reinforcement wall 4 through the shear steel bar 21, and the new ground-connected wall 22 is connected to the expanded crown beam 17 through the reinforcement steel bar 20. The buoyancy of the main structure can be transmitted to the I-shaped reinforcement wall 3 and the Z-shaped reinforcement wall 4 through the expanded crown beam 17 and the new ground-connected wall 22. In this way, it can be ensured that the expanded crown beam 17 is only subjected to shear, which is consistent with the original force.

[0059] Step 5: Construct the first ring frame beam 13-1 and the first support 14-1. The foundation pit support system adopts a layered combination structure consisting of a ring frame beam and a horizontal support component. In this embodiment, three support structures are preferably set, and the actual project can be expanded according to demand. The first ring frame beam 13-1 is used as the top bearing structure, which is arranged below the foundation pit crown beam to form an initial closed ring beam. The first support system 14-1 is arranged horizontally on the same layer, including horizontal bracing and diagonal support components; the second ring frame beam 13-2 is located at a set spacing below the first ring frame beam 13-1, and the second support system 14-2 is set on the same layer; the third ring frame beam 13-3 is located at a set spacing below the second ring frame beam 13-2, and the third support system 14-3 is set on the same layer. The ring frame beams of each layer form a spatial truss system through vertical support columns.

[0060] Step 6: Continue to excavate the foundation pit. When excavating to the second ring frame beam 13-2 and the third ring frame beam 13-3, it is necessary to determine whether the defective part of the defective wall 2 is within the range of the ring frame beam based on the detection in step 1. If there are defects within the range of the second ring frame beam 13-2 and the third ring frame beam 13-3, it is necessary to perform grouting at the defective position to ensure the compressive bearing capacity of the defective wall 2.

[0061] Step 7: Construction of waterproofing and main structure;

[0062] Step 8: Construction of micro-expansive concrete 19.

[0063] Step 9: Backfill the top plate with soil.

[0064] The geology of the water-rich soft soil layer is poor, and the wall of the ground-connected wall trench is not easy to stabilize. The reinforcement of the wall trench wall needs to penetrate the soft soil layer.

[0065] The construction process of the reinforced wall trench reinforcement layer 8 is the same as that of the existing trench wall reinforcement layer 7. The reinforcement needs to penetrate the soft soil layer, that is, it meets the following requirements:

[0066] Z 1 ≤Z≤Z 2

[0067] Wherein, Z is the depth of the wall reinforcement layer 8, Z 1 is the burial depth of the bottom plate in soft soil layer, Z 2 is the depth of trench wall instability. In water-rich soft soil layers, trench wall instability often occurs in the shallow overlying soil layer within 15 m, that is, Z 2 =15m, so it is recommended that the trench wall reinforcement should not only be greater than the bottom burial depth of the soft soil layer, but also meet the condition of not less than 15m.

[0068] For ultra-deep ground-connected walls, the ground wall depth is much greater than the effective pile depth of ordinary rotary jet piles. Therefore, the wall bottom rotary jet water stopping of the ultra-deep ground-connected wall adopts N-jet ultra-high pressure rotary jet piles. To ensure the ultra-high pressure pile effect, the construction parameters of ultra-high pressure rotary jet piles should not be lower than the following standards: the diameter of N-jet piles should be greater than 2.6m, and the verticality of piles should be ≤1 / 300; the water-cement ratio is recommended to be 1:1; the cement content is ≮45%; the cement slurry pressure is recommended to be 38-42MPa; the lifting speed is recommended to be 12-13min / m; the cement slurry flow rate is recommended to be 370-400L / min; the step stroke is 80-100mm; the main air pressure is ≥0.9MPa; the rotation speed is 3r / min; the main air flow rate is ≥3m 3 / min.

[0069] The distance between the N-jet reinforcement body 15 at the bottom of the wall and the edge of the defective wall 2 and the reinforcement wall is a 1 , the thickness of the wall bottom N-jet reinforcement 15 is c 1 , the existing foundation pit N-jet bottom cover 16 thickness is c 2 The above parameters should satisfy the following formula to ensure the reliability of water stopping at the bottom of the wall.

[0070]

[0071] Among them, a 1 The distance from the wall bottom N-jet reinforcement body 15 beyond the edge of the defective wall 2 or the reinforced wall, and h1 is the thickness of the ground-connected wall. 1 The thickness of the N-jet reinforcement 15 at the bottom of the wall.2 It is the thickness of the existing foundation pit N-jet bottom cover 16.

[0072] Furthermore, the height of the top of the defective wall 2, the shear reinforcement 21, and the reinforcement 20 of the newly made ground-connected wall 22 should meet the following requirements, so that the buoyancy of the main structure can be transferred to the reinforcement wall through the shear reinforcement, reducing the load on the expanded crown beam:

[0073]

[0074] Among them, F 浮 It is the design value of buoyancy per linear meter of reinforcement wall, in kN. yv A is the design value of shear reinforcement 21 steel strength, in kPa. sv1 is the area of ​​a single steel bar of shear reinforcement 21, unit: m 2 H is the height of the defective wall 2, in m. x is the horizontal spacing of the shear reinforcement 21, in m. y is the vertical spacing of the shear reinforcement 21. y It is the design value of the strength of the reinforcement steel bar 20. s1 The area of ​​a single reinforcement steel bar 20, in m 2 s is the spacing of the reinforcing steel bars 20, in m. H1 is the buried depth of the bottom of the first ring frame beam 13-1. H2 is the depth of the defective wall 2 below the bottom of the first ring frame beam 13-1 that needs to be chiseled out, which is greater than or equal to 0.

[0075] Furthermore, the N-jet conduit 12 should meet the following requirements:

[0076]

[0077] Where, l is the length of the N-jet conduit 12, in meters, and L is the depth of the reinforced wall trench. When the length of the pre-buried N-jet conduit is greater than the trench depth, it will be difficult to dig the trench and there is a risk of bending. When it is less than the trench depth, the ground wall concrete will seal the conduit opening, and the N-jet spraying pipe cannot reach the bottom of the wall for spraying, so it is recommended that the two be equal. d is the inner diameter of the N-jet conduit 12. D is the diameter of the N-jet drill pipe. α is the aperture coefficient, which is recommended to be no less than 1.1.

[0078] Furthermore, the pouring holes 18 are arranged at the center line of the new ground connection wall 22, with a recommended spacing of 1m, and the hole diameters shall meet the following requirements:

[0079] d 1 =max(αD 1 , d 0 )

[0080] Among them, d 1 is the diameter of the casting hole 18. 1is the diameter of the vibrating rod in mm. α is the aperture coefficient, which is recommended to be no less than 1.1. 0 The minimum diameter required for the construction vibration of the new ground-connected wall 22 is recommended to be no less than 200mm to facilitate the observation of the concrete pouring liquid level of the new ground-connected wall 22.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for repairing ultra-deep ground-connected walls in high-pressure, water-rich soft soil strata, characterized in that: The steps include: Step 1: Perform ultrasonic testing on the defective wall (2) to obtain the location and size of the defective part; Step 2: construct a reinforcement wall on the outside of the defective wall (2); Step 3: Install jet grouting piles to stop water between the defective wall (2) and the reinforcement wall; Step 4: Chisel off the top wall of the defective wall (2) and recast it. The newly constructed ground-connected wall (22) is connected to the reinforced wall through the shear steel bars (21). The newly constructed ground-connected wall (22) is connected to the enlarged crown beam (17) through the reinforced steel bars (20); Step 5: constructing the first ring frame beam (13-1) and the first support (14-1) at a vertical position from the top of the foundation pit to the bottom of the foundation pit; Step 6: Continue to excavate the foundation pit, and when the second ring frame beam (13-2) and the third ring frame beam (13-3) are excavated in sequence, determine whether the defective part of the defective wall (2) is within the range of the ring frame beam according to the detection in step 1, and when there is a defect within the range of the second ring frame beam (13-2) or the third ring frame beam (13-3), perform hole grouting at the defective position; Step 7: Construct waterproofing and main structure.

2. The method for repairing ultra-deep ground-connected walls in high-pressure, water-rich soft soil strata according to claim 1 is characterized by: The reinforcing wall comprises a straight reinforcing wall (3) and a Z-shaped reinforcing wall (4) arranged outside the defective wall (2); the length of the straight reinforcing wall (3) is shorter than the length of the defective wall (2), and the Z-shaped reinforcing walls (4) are arranged on both sides of the straight reinforcing wall (3).

3. The method for repairing ultra-deep ground-connected walls in high-pressure, water-rich soft soil strata according to claim 1 is characterized by: The construction process of the reinforced wall trench wall reinforcement layer (8) is the same as that of the existing trench wall reinforcement layer (7). The reinforcement needs to penetrate the soft soil layer, that is, it meets the following requirements: Z1≤Z≤Z2 Wherein, Z is the depth of the trench wall reinforcement layer (8), Z1 is the burial depth of the bottom plate in the soft soil layer, and Z2 is the instability depth of the trench wall.

4. The method for repairing ultra-deep diaphragm walls in high-pressure water-rich soft soil strata according to claim 1 is characterized by: The expanded crown beam (17) is a cantilever structure, and the cantilever length of the expanded crown beam (17) is the width of the defective wall (2).

5. The method for repairing ultra-deep ground-connected walls in high-pressure, water-rich soft soil strata according to claim 1 is characterized by: A jet grouting pile water-stopping device is arranged between the defective wall (2) and the bottom of the reinforcement wall: an N-jet conduit (12) is pre-buried on the reinforcement cage of the reinforcement wall, the inner diameter of the N-jet conduit (12) is larger than the diameter of the N-jet drill bit, and after the reinforcement wall is constructed, the N-jet drill bit drills from the N-jet conduit (12) into the bottom of the ground-connected wall to perform jet grouting water-stopping.

6. The method for repairing ultra-deep ground-connected walls in high-pressure, water-rich soft soil strata according to claim 5 is characterized by: The bottom of the defective wall (2) and the reinforced wall forms a wall bottom N-jet reinforcement body (15), and the wall bottom N-jet reinforcement body (15) satisfies: Wherein, a1 is the distance of the N-jet reinforcement body (15) at the bottom of the wall beyond the edge of the defective wall (2) or the reinforced wall, h1 is the thickness of the ground-connected wall, c1 is the thickness of the N-jet reinforcement body (15) at the bottom of the wall, and c2 is the thickness of the N-jet bottom seal (16) of the existing foundation pit.

7. The method for repairing ultra-deep ground-connected walls in high-pressure, water-rich soft soil strata according to claim 1 is characterized by: Step 4 satisfies: Among them, F 浮 is the design value of buoyancy per linear meter of reinforcement wall, f yv is the design value of the shear reinforcement (21), A sv1 is the area of ​​a single steel bar of the shear reinforcement (21), H is the height of the defective wall (2) removed, x is the horizontal spacing of the shear reinforcement (21), y is the vertical spacing of the shear reinforcement (21), and f y is the design value of the strength of the reinforcing steel bar (20), A s1 is the area of ​​a single reinforcing steel bar (20), s is the spacing between reinforcing steel bars (20), H1 is the buried depth of the bottom of the first ring frame beam (13-1), and H2 is the depth of the defective wall (2) removed below the bottom of the first ring frame beam (13-1).

8. The method for repairing ultra-deep ground-connected walls in high-pressure, water-rich soft soil strata according to claim 5 is characterized by: The N-jet conduit (12) meets the following requirements: Wherein, l is the length of the N-jet conduit (12), L is the depth of the groove of the reinforcement wall, d is the inner diameter of the N-jet conduit (12), D is the diameter of the N-jet drill pipe, and α is the aperture coefficient.

9. The method for repairing ultra-deep ground-connected walls in high-pressure, water-rich soft soil strata according to claim 1, characterized in that: The casting hole (18) is arranged at the center line of the newly constructed ground connection wall (22), and the hole diameter satisfies the following requirements: d1=max(αD1,d0) Wherein, d1 is the diameter of the casting hole 18, D1 is the diameter of the vibrating rod, d0 is the minimum diameter required for the construction and vibration of the new ground-connected wall 22, and α is the aperture coefficient.

10. The method for repairing ultra-deep ground-connected walls in high-pressure, water-rich soft soil strata according to claim 9, characterized in that: d0≥200mm.

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