A method for controlling the active outward expansion construction of a double-wall-in-one diaphragm wall

Abstract

The present application relates to a kind of double-wall underground continuous wall active expansion construction control method, belong to foundation construction technical field.The present application proposes systematic active pre-control scheme: the center line of ground continuous wall is actively deviated to the outside of foundation pit, triaxial mixing pile and guide wall are progressively expanded outside simultaneously, form 80mm-120mm, 60mm-100mm, 20mm-30mm three-level expansion control system;With two sides first, middle after taking order slotting, based on the calculation of bending moment balance principle, double-machine lifting and time-magnitude control pipe pulling process, realize whole process deviation pre-control.The present application effectively avoids the occupation of subsequent lining wall structure by underground continuous wall construction deviation, has the remarkable effect of convenient construction, reliable quality, reduce rework, and is suitable for deep foundation pit double-wall underground engineering.

Description

Technical Field

[0001] This invention relates to the field of foundation construction technology, specifically to an active outward expansion construction control method for a double-wall integrated underground continuous wall. Background Technology

[0002] Diaphragm wall construction technology has matured over many years. With its excellent support and seepage prevention performance, low disturbance to the surrounding environment, and strong geological adaptability, it has irreplaceable advantages in large-scale projects such as deep foundation pits and underground complexes. Among these, the two-wall-in-one (also known as double-wall-in-one) design mode has become the preferred structural form for underground engineering in soft soil areas due to its short construction period, low cost, and high space utilization. This design concept uses the diaphragm wall as a retaining structure for foundation pit support, ensuring the safety of the foundation pit and isolating groundwater during excavation. Simultaneously, it works in conjunction with the inner reinforced concrete wall (lining wall) to form a composite structural wall that jointly bears the load during the permanent service phase.

[0003] However, unlike ordinary diaphragm walls used solely as retaining structures for deep foundation pits, the combined double-wall technology places higher demands on the precision of construction processes. Existing construction methods suffer from the following technical shortcomings: First, there is the problem of construction deviations encroaching on the structural space of the inner lining wall. Under current construction methods, diaphragm wall construction typically involves direct measurement and layout based on the design axis dimensions, followed by the construction of water-stop piles, guide walls, and the diaphragm wall itself. Limited by equipment accuracy and the uncertainties of underground operations, verticality deviations are unavoidable during diaphragm wall construction. Taking the standard of ≤1 / 300 for verticality deviation control in conventional diaphragm walls as an example, the reasonable limit deviation at the bottom of a 50m deep diaphragm wall can reach 166mm. This deviation directly encroaches on the original design structural dimensions of the inner lining wall. Since the net internal dimensions of the underground space are a rigid design constraint, the inner lining wall cannot be moved or adjusted inwards, resulting in insufficient structural thickness and weakened load-bearing capacity in this area, leading to serious potential engineering quality problems.

[0004] Second, the adverse effects of water-stop mixing piles on trenching quality. Existing methods do not fully consider the impact of triaxial mixing pile construction deviations on subsequent diaphragm wall trenching. Triaxial mixing piles also have reasonable verticality deviations; if they tilt inward, they will encroach on the space of the diaphragm wall structure. Because the strength of the solidified mixing piles is significantly higher than that of the original soil in the trenching area, the grab bucket of the trenching machine is prone to deflection in uneven strata, leading to loss of verticality control of the trench wall and a decline in trenching quality.

[0005] Third, insufficient precision in guide wall construction leads to difficulties in lowering the reinforcing cage. Current guide wall construction often follows the theoretical width of a diaphragm wall, without considering construction deviations and equipment operating space requirements. In actual construction, the reinforcing cage frequently gets stuck against the guide wall during lowering, affecting construction efficiency.

[0006] Fourth, trenching operations are hampered at special nodes. At special locations such as corners and bends in the diaphragm wall, the fixed size of the trenching machine's grab bucket and the lack of adaptive expansion in the existing guide wall design prevent the trenching machine from being lowered smoothly, thus restricting construction efficiency.

[0007] To address the aforementioned issues, existing technologies have proposed several improvement solutions. For example, Chinese invention patent application CN118621768A discloses a construction method for a combined diaphragm wall system, which shortens the operation time by optimizing formwork connections and construction processes; Chinese invention patent application CN120819090A discloses a construction method for ultra-wide diaphragm walls in subway stations, which improves trenching efficiency through trench width adjustment and equipment combination. However, none of these existing technologies effectively solve the problem of encroachment on subsequent inner lining structure walls by early diaphragm wall construction deviations under the combined diaphragm wall design, nor do they systematically consider the impact of water-stop mixing piles and guide wall positioning on the trenching quality of the diaphragm wall. Their technical improvement directions are fundamentally different from those of this invention. Summary of the Invention

[0008] The present invention aims to overcome the defects of the prior art and provide an active outward expansion construction control method for a double-wall integrated underground continuous wall, fundamentally avoiding the adverse effects of underground continuous wall construction on the subsequent inner lining wall structure.

[0009] To solve the above-mentioned technical problems, the present invention is implemented as follows: A method for active outward expansion construction control of a double-wall integrated underground diaphragm wall, characterized by comprising the following steps: Step 1: Preliminary Preparation Stage Based on the design depth of the diaphragm wall and the accuracy parameters of the trenching equipment, the active offset of the diaphragm wall centerline to the outside of the foundation pit is determined, the design technical verification is obtained, a special construction plan is prepared, and measurement and setting out are carried out. Step Two: Construction Stage of Water-Stop Curtain Using the offset diaphragm wall centerline as a reference, the three-axis mixing piles are offset to the outside of the foundation pit, and the water-stop curtain is constructed using a single-hole splicing process. Step 3: Guide Wall Construction Stage Using the offset centerline of the diaphragm wall as a reference, the guide wall is offset to the outside of the foundation pit, and the outer contour of the guide wall is extended at the corners and bends. Step 4: Trenching Construction Stage The excavation of underground continuous wall sections was carried out using a sequential trenching process of "first excavation on both sides and then removal in the middle". Step 5: Reinforcing Cage Hoisting Stage Based on the principle of bending moment balance, the transverse and longitudinal lifting points were calculated and set, and the steel cage was lifted and placed using a dual-machine lifting method. Step Six: Connector Setup Stage Install the junction box according to the design requirements; Step 7: Concrete Pouring Stage Underwater concrete was poured using the tremie pipe method. Step 8: Connector box removal stage After the concrete pouring is completed, the joint box is pulled out according to the time-amplitude control process. The active offset, the three-axis mixing pile offset, and the guide wall offset form a progressive outward expansion control system, which reserves space for the construction deviation of the underground continuous wall and prevents it from encroaching on the structural dimensions of the inner lining wall.

[0010] The active offset of the diaphragm wall centerline to the outside of the foundation pit in step one is 80mm-120mm, and this offset is dynamically adjusted according to the actual depth of the diaphragm wall.

[0011] In step two, the offset of the triaxial mixing pile to the outside of the foundation pit is 60mm-100mm, and the cement content is controlled at 20%-22%.

[0012] In step three, the offset of the guide wall to the outside of the pit is 20mm-30mm; the expansion of the guide wall at the corner and bend is determined according to the size of the grab bucket of the trenching machine.

[0013] The sequential trenching process described in step four, which involves excavating the soil on both sides first and then excavating the soil in the middle, is as follows: For a single diaphragm wall trench section that is 4m-6m wide, the soil on both sides is excavated first, and then the soil in the middle is excavated.

[0014] Step five, which calculates the lifting point location based on the principle of moment equilibrium, satisfies the condition: +M = -M, that is, the positive and negative bending moments are equal, where: +M= -M= In the formula, q is the uniformly distributed load, L1 is the distance from the end lifting point to the end of the steel cage, L2 is the spacing between adjacent lifting points, and the total length L = 2L1 + 3L2.

[0015] The parameters for the dual-crane lifting operation mentioned in step five are as follows: the lifting weight of a single crane shall not exceed 0.8 times its rated lifting capacity, the total lifting weight of the two cranes shall not exceed 75% of the rated total lifting capacity, and the lifting weight when traveling with a load shall not exceed 70%.

[0016] The connector box mentioned in step six includes one of the following: a lock-type tube, a rubber strip connector, or a cross-shaped steel plate connector.

[0017] The conduit method described in step seven uses D260 circular spiral quick-connect conduit. When the width of the trench section is 4.0m-6m, two conduits are arranged for each trench section.

[0018] The time-amplitude control process described in step eight is as follows: After the first section of the guide pipe is removed at the start of concrete pouring, the pull is started 4 hours later. Thereafter, it is lifted once every 15 minutes, and the single lifting amplitude is no more than 50mm-100mm.

[0019] The beneficial effects of this invention are as follows: As can be seen from the above technical solution, this application provides an active outward expansion construction control method for a double-wall integrated underground diaphragm wall. Traditional construction methods passively accept verticality deviations caused by equipment precision limitations and uncertainties in underground operations. This invention innovatively adopts an active pre-control strategy, offsetting the diaphragm wall centerline outward by 80mm-120mm, simultaneously offsetting the three-axis mixing piles outward by 60mm-100mm, and offsetting the guide wall outward by 20mm-30mm, forming a three-level progressive outward expansion control. This system provides sufficient space for a reasonable limit deviation of 166mm at the bottom of a 50m deep diaphragm wall, ensuring that the inner lining wall can be constructed according to the original design thickness after the foundation pit is excavated, without weakening the structural bearing capacity, and completely avoiding engineering quality hazards and rework costs caused by insufficient thickness.

[0020] This invention effectively eliminates the adverse effects of water-stop mixing piles on the trenching quality of diaphragm walls. Existing technologies do not fully consider the deflection effect of triaxial mixing piles tilting inwards on the trenching machine's grab bucket. This invention, by offsetting the mixing piles outwards from the foundation pit, ensures that even with reasonable verticality deviations, the solidified mixing pile body will not encroach on the trenching space of the diaphragm wall. The trenching machine's grab bucket operates in homogeneous strata, making it easier to control the verticality of the trench walls, significantly improving trenching quality, and solving the technical bottleneck of grab bucket deflection in uneven strata.

[0021] This invention significantly improves the working conditions for lowering the reinforcing cage and increases construction efficiency. When the guide wall is constructed according to its theoretical width, frequent jamming occurs during the lowering of the reinforcing cage, severely impacting construction progress. This invention offsets the guide wall 20mm-30mm outward from the foundation pit and extends its outer contour at special locations such as corners and bends, providing ample operating space for hoisting the reinforcing cage. Combined with optimized hoisting point settings based on the bending moment balance principle and controlled dual-machine hoisting process parameters, reinforcing cage deformation is minimized, ensuring a smooth and stable hoisting process and eliminating construction failures such as jamming and collisions.

[0022] This invention achieves systematic quality control throughout the entire construction process of a double-wall integrated underground continuous wall. From the initial determination of the active offset to each step—including the water-stop curtain, guide wall, trenching, hoisting, jointing, pouring, and pipe removal—a complete technical chain is formed. In particular, the sequential trenching process—with the two sides working first and the middle removed later—and the time-amplitude controlled joint box removal process ensure the stability of the trench walls, continuous concrete pouring, and joint quality. This method is convenient to construct, requires less rework, and has a high first-time acceptance rate, providing a replicable technical paradigm for similar projects and promoting the development of underground space construction technology in urban renewal. Attached Figure Description

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of active outward offset control; Figure 2 This is a construction diagram of the socket hole; Figure 3 This is a schematic diagram of the guide wall outline at the corner. Figure 4 This is a schematic diagram of the guide wall outline at the corner. Figure 5 This is a schematic diagram of the sequential troughing process; Figure 6 This is a schematic diagram of a double-machine lifting system for a steel cage. Figure 7 This is a schematic diagram for calculating the bending moment balance at the lifting point; Figure 8 This is a schematic diagram of a junction box. Figure 9 This is a schematic diagram of concrete pouring using the tremie pipe method. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection claimed in this application. Example 1

[0025] A method for active expansion construction control of a double-wall integrated underground diaphragm wall, the specific steps of which are as follows: Step 1: Preliminary Preparation. Based on the depth of the diaphragm wall in the design drawings and the accuracy of the selected trenching equipment, confirm the relevant construction dimensions (active expansion or offset), and obtain a technical verification form from the design institute; at the same time, prepare a special construction plan and conduct approval and demonstration; on-site measurement and layout are carried out according to the construction dimensions determined by the plan.

[0026] As attached Figure 1 As shown, the centerline of the diaphragm wall is shifted 100mm outward from the pit (the shift dimension can be adjusted according to the actual depth of the diaphragm wall). Sufficient space is reserved to prevent encroachment on the inner lining wall.

[0027] Step 2: Construction of the three-axis mixing pile water-stop curtain. The cement content should be 20%-22%. (See attached...) Figure 1As shown, the three-axis mixing piles on both sides of the diaphragm wall are also 80mm outward from the centerline. The three-axis mixing piles also have a reasonable verticality deviation. If they tilt inward, they will encroach on the diaphragm wall structure. Since the strength of the mixing piles is greater than that of the original soil in the trenching area, the grab bucket is prone to tilting during trenching, which will affect the quality of trenching.

[0028] The three-axis mixing pile adopts the method shown in the attached figure. Figure 2 As shown, this is a construction method involving connecting one hole.

[0029] Step 3: Guide wall construction. (See attached image) Figure 1 As shown, the guide wall is offset outward by 25mm from the centerline. If the guide wall is constructed according to the theoretical width of the diaphragm wall, problems such as jamming may occur when the steel cage is lowered.

[0030] As attached Figure 3 Appendix Figure 4 As shown, at special locations such as corners and bends, the guide wall needs to have an appropriate outer profile because the size of the grab bucket of the trenching machine is fixed, so that the trenching machine can be lowered smoothly.

[0031] Step 4: Trenching with a trenching machine. (See attached image) Figure 5 As shown, a single-span diaphragm wall is formed by trenching (generally 4-6m wide). First, soil from the two sides is taken, and then soil from the middle is taken, i.e., 1→2→3.

[0032] Step 5: Lowering the Reinforcing Cage. Fabricate the reinforcing cage according to the design drawings and set up the lifting points. The reinforcing cage for the diaphragm wall is heavy and long, as shown in the attached... Figure 6 As shown, lifting is generally carried out using a dual-crane lifting method. When using a dual-crane lifting operation, the lifting weight shall not exceed 0.8 times the rated lifting capacity of each crane, and shall not exceed 75% of the rated total lifting capacity. When traveling with a load, the lifting weight shall be controlled at 70%.

[0033] Selection of lifting points: Generally, four horizontal lifting points are set for diaphragm walls. According to the law of moment equilibrium, the deformation of the reinforcing cage is minimized when the positive and negative bending moments are equal. (See attached...) Figure 7 As shown, +M = -M.

[0034] Where +M= -M= q is the uniformly distributed load, and M is the bending moment.

[0035] Therefore: The total length L = 2L1 + 3L2. The location of the lifting point can be determined based on the total length.

[0036] The longitudinal suspension point settings are similar.

[0037] Step 6: Install the junction box; install the junction box according to the design requirements. (See attached document.) Figure 8 As shown, common types of connector boxes include lock-joint tubes, rubber strip connectors, and cross-shaped steel plate connectors.

[0038] Step 7: Install the concrete tremie pipe and pour the diaphragm wall concrete. Underwater concrete pouring is carried out using the tremie pipe method, as shown in the attached diagram. Figure 9 As shown, the concrete conduit uses a D260 circular spiral quick-connect type. The conduit joint should be well-sealed and easy to disassemble. The trench section width is 4.0m to 6m, and two conduits are arranged in each trench section.

[0039] Step 8: Pull out the joint box. The joint box lifting is combined with concrete pouring. Based on the law of underwater concrete solidification speed and construction practice, the lifting begins 4 hours after the first section of the guide pipe is removed at the start of concrete pouring. Thereafter, it is lifted once every 15 minutes, and the amplitude should not exceed 50-100mm. Example 2

[0040] A subway station is located in the soft soil area of ​​the Yangtze River Delta. The excavation depth of the foundation pit is approximately 18 meters, and a double-wall integrated structure is adopted. The diaphragm wall is designed to a depth of 50 meters, a wall thickness of 800 mm, a trench width of 6 meters, a concrete strength grade of C35, and a permeability grade of P8. The inner lining wall is designed to be 400 mm thick, forming a combined load-bearing system with the diaphragm wall.

[0041] Step 1: Preliminary Preparations Based on the diaphragm wall design depth of 50m and the accuracy parameters of the selected hydraulic grab trenching machine (verticality control 1 / 300), the bottom limit deviation is calculated to be approximately 166mm. Taking into account safety margins, the centerline of the diaphragm wall is determined to be actively offset 100mm outwards from the pit, and a technical verification sheet from the design institute is obtained. A specific construction plan is prepared and approved by experts. On-site measurement and layout are carried out according to the offset centerline to establish a construction control network.

[0042] Step Two: Construction of the Three-Axis Mixing Pile Water-Stop Curtain Using the offset centerline of the diaphragm wall as a reference, the three-axis mixing piles on both sides are offset 80mm outward from the foundation pit. The cement content is 21%, the water-cement ratio is 1.5, and a single-hole overlapping construction method is used to ensure the quality of the cut-off curtain overlap. This outward offset prevents the mixing piles from encroaching on the trench space of the diaphragm wall when tilted inward.

[0043] Step 3: Guide Wall Construction The guide wall is based on the offset centerline, with each side offset outwards by 25mm, and the net width of the guide wall is adjusted to 850mm (theoretical 800mm + 2×25mm). At the corner of the foundation pit (L-shaped node), the outer contour of the guide wall is extended by 300mm to accommodate the size of the trenching machine's grab bucket, ensuring smooth lowering of the trenching machine. The guide wall is made of C20 concrete with a thickness of 200mm and a embedment depth of 1.5m.

[0044] Step 4: Trenching with a trenching machine A hydraulic grab trenching machine was used to excavate 6m wide trench sections in a 1→2→3 sequence: first, the soil on both sides (approximately 1.8m wide on each side) was excavated, and then the soil in the middle (approximately 2.4m wide) was removed. The verticality of the trench walls was monitored in real time during trenching and controlled to within 1 / 300. The thickness of the sediment at the bottom of the trench was ≤100mm.

[0045] Step 5: Lowering the steel cage Lifting point calculation: The total length of the reinforcing cage is 50m, and the uniformly distributed load is q = 2.5kN / m. Based on moment equilibrium, +M = -M: Given that the distance from the end lifting point to the cage end is L1 = 3.5m and the distance between adjacent lifting points is L2 = 8.0m, verify: +M=qL1 2 / 2 = 2.5 × 3.5 2 / 2=15.31kN·m -M=qL2 2 / 8-qL1 2 / 2=2.5×8 2 / 8-15.31=20.00-15.31=4.69kN·m After iterative optimization, the final values ​​were L1=4.0m, L2=7.33m, and the total length L=2×4.0+3×7.33=29.99m (considering segmented fabrication of the steel cage). Four lifting points were set horizontally, and three sets of lifting points were set vertically.

[0046] Lifting Implementation: A 150t main crane and a 50t auxiliary crane were used for lifting. The total weight of the steel cage was approximately 45t, with the main crane handling 28t (≤0.8×35t=28t) and the auxiliary crane handling 17t (≤0.8×25t=20t), resulting in a total load factor of 70% (≤75%). The lifting process was smooth, without deformation or obstruction.

[0047] Step Six: Install the connector box Cross-shaped steel plate joints are used between the trench sections. The steel plates are 10mm thick and are inserted 300mm into the concrete of the previous trench section to ensure the joint's anti-seepage performance.

[0048] Step 7: Concrete Pouring Two D260 guide pipes are used, spaced 3.0m apart and 1.5m from the trench end. The bottom of the guide pipe is 300-500mm from the trench bottom, and the burial depth of the guide pipe is controlled at 2-6m during pouring. The concrete slump is 180-220mm, and the initial setting time is ≥20h. The pouring volume for a single trench section is approximately 240m³. 3 The continuous pouring was completed.

[0049] Step 8: Disconnect the connector box Four hours after the first section of the guide pipe was removed during concrete pouring, the cross plate was first pulled out. Thereafter, it was raised every 15 minutes, with a single lift of 80mm. The pipe pulling process was synchronized with the concrete setting speed, and there was no collapse or mud inclusion.

[0050] Testing revealed that the verticality deviation of the diaphragm wall in this embodiment was 1 / 350, and the wall itself was of good quality. Actual measurements after excavation showed that the maximum intrusion of the diaphragm wall was 65mm, which was completely absorbed by the pre-reserved 100mm active offset. The inner lining wall was constructed to the original design thickness of 400mm, and the structural bearing capacity met the design requirements. Compared to traditional construction methods, this embodiment reduced rework in 3 areas, saved 12 days of construction time, and achieved a 100% first-time quality acceptance rate.

[0051] The above are merely embodiments provided in this application and are not intended to limit this application. Although this application has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for active outward expansion construction control of a double-wall integrated underground diaphragm wall, characterized in that... It includes the following steps: Step 1: Preliminary Preparation Stage Based on the design depth of the diaphragm wall and the accuracy parameters of the trenching equipment, the active offset of the diaphragm wall centerline to the outside of the foundation pit is determined, the design technical verification is obtained, a special construction plan is prepared, and measurement and setting out are carried out. Step Two: Construction Stage of Water-Stop Curtain Using the offset diaphragm wall centerline as a reference, the three-axis mixing piles are offset to the outside of the foundation pit, and the water-stop curtain is constructed using a single-hole splicing process. Step 3: Guide Wall Construction Stage Using the offset centerline of the diaphragm wall as a reference, the guide wall is offset to the outside of the foundation pit, and the outer contour of the guide wall is extended at the corners and bends. Step 4: Trenching Construction Stage The excavation of underground continuous wall sections was carried out using a sequential trenching process of "first excavation on both sides and then removal in the middle". Step 5: Reinforcing Cage Hoisting Stage Based on the principle of bending moment balance, the transverse and longitudinal lifting points were calculated and set, and the steel cage was lifted and placed using a dual-machine lifting method. Step Six: Connector Setup Stage Install the junction box according to the design requirements; Step 7: Concrete Pouring Stage Underwater concrete was poured using the tremie pipe method. Step 8: Connector box removal stage After the concrete pouring is completed, the joint box is pulled out according to the time-amplitude control process. The active offset, the three-axis mixing pile offset, and the guide wall offset form a progressive outward expansion control system, which reserves space for the construction deviation of the underground continuous wall and prevents it from encroaching on the structural dimensions of the inner lining wall.

2. The active expansion construction control method for a double-wall integrated underground diaphragm wall according to claim 1, characterized in that: The active offset of the diaphragm wall centerline to the outside of the foundation pit in step one is 80mm-120mm, and this offset is dynamically adjusted according to the actual depth of the diaphragm wall.

3. The active expansion construction control method for a double-wall integrated underground diaphragm wall according to claim 1, characterized in that: In step two, the offset of the triaxial mixing pile to the outside of the foundation pit is 60mm-100mm, and the cement content is controlled at 20%-22%.

4. The active expansion construction control method for a double-wall integrated underground diaphragm wall according to claim 1, characterized in that: In step three, the offset of the guide wall to the outside of the pit is 20mm-30mm; the expansion of the guide wall at the corner and bend is determined according to the size of the grab bucket of the trenching machine.

5. The active expansion construction control method for a double-wall integrated underground diaphragm wall according to claim 1, characterized in that: The sequential trenching process described in step four, which involves excavating the soil on both sides first and then excavating the soil in the middle, is as follows: For a single diaphragm wall trench section that is 4m-6m wide, the soil on both sides is excavated first, and then the soil in the middle is excavated.

6. The active expansion construction control method for a double-wall integrated underground diaphragm wall according to claim 1, characterized in that: Step five, which calculates the lifting point location based on the principle of moment equilibrium, satisfies the condition: +M = -M, that is, the positive and negative bending moments are equal, where: +M= ,-M= In the formula, q is the uniformly distributed load, L1 is the distance from the end lifting point to the end of the steel cage, L2 is the spacing between adjacent lifting points, and the total length L = 2L1 + 3L2.

7. The active expansion construction control method for a double-wall integrated underground continuous wall according to claim 1, characterized in that: The parameters for the dual-crane lifting operation mentioned in step five are as follows: the lifting weight of a single crane shall not exceed 0.8 times its rated lifting capacity, the total lifting weight of the two cranes shall not exceed 75% of the rated total lifting capacity, and the lifting weight when traveling with a load shall not exceed 70%.

8. The active expansion construction control method for a double-wall integrated underground continuous wall according to claim 1, characterized in that: The connector box mentioned in step six includes one of the following: a lock-type tube, a rubber strip connector, or a cross-shaped steel plate connector.

9. The active expansion construction control method for a double-wall integrated underground diaphragm wall according to claim 1, characterized in that: The conduit method described in step seven uses D260 circular spiral quick-connect conduit. When the width of the trench section is 4.0m-6m, two conduits are arranged for each trench section.

10. The active expansion construction control method for a double-wall integrated underground diaphragm wall according to claim 1, characterized in that: The time-amplitude control process described in step eight is as follows: After the first section of the guide pipe is removed at the start of concrete pouring, the pull is started 4 hours later. Thereafter, it is lifted once every 15 minutes, and the single lifting amplitude is no more than 50mm-100mm.

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