Method and system for detecting connection and seam sealing of underground diaphragm wall and main body structure

Abstract

The invention discloses a method and a system for detecting connection and seam sealing of an underground diaphragm wall and a main body structure, and belongs to the technical field of underground construction engineering. The method comprises the steps that a first subsystem and a second subsystem are constructed, specifically, the first subsystem is provided with a degradable first embedded pipe in advance in an underground diaphragm wall, a cavity is formed after degradation, a main body structure horizontal rib is inserted, and sealant is poured, so that tolerance connection and anchoring connection are achieved, alignment errors are effectively solved, and seam cracking is restrained; the second subsystem is provided with a degradable second embedded pipe at the joint of the foundation slab and the bracket, an annular cavity with a detection port is formed after degradation, and a permanent channel for air tightness detection and pressure grouting repair is formed. The two subsystems work cooperatively, whole-process guarantee from structure connection to long-term maintenance is achieved, and the hidden danger problem of hidden leakage of a two-in-one joint is solved fundamentally.

Description

Technical Field

[0001] This invention belongs to the field of underground construction engineering technology, specifically relating to a connection method between an underground continuous wall and the main structure in a "two-wall integration" design, and a joint sealing performance testing system. Background Technology

[0002] In the "two walls in one" design, the diaphragm wall serves as both a support structure during the foundation pit excavation stage and an exterior wall for the basement during the permanent use stage. Its connection points with the main structure (such as the foundation slab and floor slabs) are crucial for ensuring structural integrity and waterproofing reliability.

[0003] Currently, diaphragm walls and main structural steel reinforcement are generally connected using pre-embedded steel connectors or direct lap joints. However, this connection method has two inherent drawbacks: First, due to verticality errors during diaphragm wall construction, it is difficult to precisely align the pre-embedded connectors with the main structural steel reinforcement, making misaligned connection points inherently weak links; second, during long-term building use, when subjected to complex loads and uneven settlement, stress will concentrate at poorly aligned connection points, easily leading to hard-to-detect hidden cracks, forming seepage channels, and posing a serious permanent waterproofing hazard.

[0004] Current technologies for waterproofing joints often involve applying multiple waterproofing lines to the joint surface, supplemented by subsequent grouting. This method is passive waterproofing, unable to effectively monitor or intervene early in the connection quality and sealing condition hidden within the structure. It only becomes apparent when water seeps to the surface, often causing significant damage by then. Furthermore, traditional grouting repair is a "one-time" operation, making it difficult to verify its effectiveness, and lacks effective means for re-inspection and re-repair throughout the building's lifespan.

[0005] Therefore, there is an urgent need in this field for a systematic solution that can fundamentally solve alignment errors, improve the stress performance of connections, and enable long-term, repeatable testing and maintenance of the joint sealing condition. Summary of the Invention

[0006] The present invention aims to overcome the above-mentioned defects of the prior art and provide a method and system for detecting the connection and joint sealing of diaphragm wall and main structure. The core problems to be solved by the method and system include: (1) eliminating the adverse effects of construction errors on the structural connection quality, providing tolerance connection capability, and structurally suppressing the generation of hidden cracks at the joint; (2) establishing an active guarantee mechanism that can conduct long-term, quantitative detection and non-destructive repair of the sealing performance of hidden joints.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for detecting the connection and joint sealing between a diaphragm wall and the main structure, comprising constructing a first subsystem and a second subsystem.

[0008] The construction method of the first subsystem is as follows: S1. During the construction of the steel cage for the diaphragm wall, several first embedded pipes made of biodegradable materials are pre-installed vertically to the wall surface inside the steel cage. One end of each first embedded pipe extends to the inner wall surface of the foundation pit, and the other end is fitted with a biodegradable sealing component. S2. After the concrete of the diaphragm wall is poured and cured, the first embedded pipe and sealing component degrade, thereby forming a first reserved cavity with an opening in the wall. S3. Insert the horizontal steel bars of the main structure into the bottom of the corresponding first reserved cavity through the opening; S4. Inject sealant into the first reserved cavity to seal and anchor the horizontal steel bars of the main structure; Subsequently, the construction of the remaining parts of the main structure was completed.

[0009] The construction method of the second subsystem is as follows: P1. When constructing the foundation slab and corbel, at the joint between the two, several biodegradable second embedded pipes are horizontally buried along the length of the diaphragm wall. Each second embedded pipe is parallel to each other and surrounds the joint. After their two ends meet, they are led to the upper surface of the foundation slab. P2. After the concrete of the foundation slab and corbel is poured and cured, the second embedded pipe degrades, forming several independent annular second reserved cavities. Each second reserved cavity has a detection port on the upper surface of the foundation slab.

[0010] After the reliable connection between the diaphragm wall and the main structure is completed through the first subsystem, the airtightness of the second reserved cavity can be tested and pressure grouting repaired through the detection port of the second subsystem throughout the entire life cycle of the building.

[0011] Preferably, in step S1, a positioning steel plate parallel to the wall is also provided inside the reinforcing cage, and a through hole is provided on the positioning steel plate for the first pre-embedded pipe to pass through; the sealing component is located on the side of the positioning steel plate facing away from the foundation pit, and its outer diameter is larger than the diameter of the through hole.

[0012] Preferably, in step S2, the diameter of the first reserved cavity on the side facing away from the pit is larger than the diameter of the cavity on the side facing the pit, with the positioning steel plate as the boundary; the sealant injected in step S4 forms an enlarged anchor head in the cavity with a larger diameter, and forms a mechanical locking key effect through the positioning steel plate, which greatly enhances the anchoring strength.

[0013] Preferably, in step S1, the first embedded pipe includes a reference embedded pipe and a spare embedded pipe; the axis of the reference embedded pipe is aligned with the design position of the horizontal reinforcement of the main structure; the spare embedded pipes are arranged vertically at intervals on the upper and lower sides of the reference embedded pipe, and their number is an even multiple of the number of reference embedded pipes, providing redundant connection points for possible alignment deviations.

[0014] Preferably, the sealant is epoxy resin anchoring adhesive or high-strength non-shrink cement-based grout.

[0015] Preferably, the first embedded pipe, the sealing component, and the second embedded pipe are made of biodegradable polymer materials, such as polylactic acid-based composite materials, which can be controlled to degrade within a set time through biodegradation, photodegradation, or water degradation.

[0016] Preferably, the number of the second pre-embedded pipes is no less than three, to ensure the representativeness and reliability of the test.

[0017] Preferably, the positioning steel plate is located at the middle position in the thickness direction of the diaphragm wall.

[0018] Preferably, the method for airtightness testing and repair is as follows: the testing port is equipped with an openable sealing device; after the diaphragm wall and main structure are constructed, the sealing device is opened, and the airtightness of the second reserved cavity on the water-facing side is tested first. The sealing device is opened, and compressed air is injected into it or a negative pressure is formed, and the pressure change rate is monitored within a predetermined time to perform the airtightness test; when the pressure change rate is lower than a preset threshold, it is judged as qualified; when it exceeds the preset threshold, it is judged as unqualified. In the case of unqualified, pressure grouting is performed through the testing port for repair. After repair, the airtightness of the adjacent second reserved cavity is tested, and those with unqualified airtightness are repaired until qualified. Finally, all ports are sealed; during the building's service life, the remaining cavities are periodically re-inspected and maintained through the testing port.

[0019] This invention also provides a detection system for the connection and joint sealing of diaphragm walls and main structures constructed by the above method, characterized in that it includes: The first subsystem consists of several first reserved cavities formed in the diaphragm wall, horizontal steel bars of the main structure inserted into the bottom of the cavities, and a sealant that fills and anchors the horizontal steel bars. The second subsystem consists of several independent annular second reserved cavities surrounding the joint between the foundation plate and the corbel, and detection ports located on the upper surface of the foundation plate and communicating with each second reserved cavity.

[0020] Beneficial effects of the present invention Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Solved the alignment problem: The pre-reserved cavity formed by the biodegradable embedded pipe provides sufficient tolerance space for the insertion of steel bars, fundamentally eliminating the impact of construction errors on connection quality and improving the reliability of the project; 2. Significantly improves structural performance: By changing the traditional joint connection to an anchored connection, stress is effectively buffered and dispersed, significantly reducing the risk of hidden cracks caused by stress concentration at the joint and improving structural durability; 3. Achieve proactive intelligent maintenance: The innovative construction of a built-in annular detection cavity network makes it possible to directly and quantitatively detect the sealing performance of the deepest joints, realizing the transformation from "passive waterproofing" to "proactive monitoring, early warning and repair"; 4. Full life cycle maintainable: The design of the inspection port allows for multiple re-inspections and non-destructive repairs during the building's service life, providing a permanent technical guarantee for the long-term safety of underground structures; 5. Significant system synergy: The first subsystem ensures the "inherent health" of the connection, while the second subsystem provides "lifetime protection." Based on the common technical means of "degradable pre-formed cavity," the two together constitute a complete and efficient solution, producing a synergistic effect of "1+1>2." Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a structural schematic diagram of steps S1 and S2 of the present invention, showing the state of the first embedded pipe in the diaphragm wall steel cage and the cavity formed after the wall is completed.

[0023] Figure 2 This is a schematic diagram of steps S3 and S4 of the present invention, showing the process of inserting the horizontal reinforcing bars of the corbel and the horizontal reinforcing bars of the base plate into the cavity and injecting sealant.

[0024] Figure 3 This is a structural diagram of steps P1 and P2 of the present invention, showing the pre-embedding process of the second pre-embedded pipe and the subsequent construction process of the main structure.

[0025] Figure 4 yes Figure 3 The enlarged view of part A in the middle shows in detail the final structure of the first subsystem, including the anchor head, sealant, etc.

[0026] Figure 5This is a schematic diagram of the connection between the diaphragm wall and the floor slab in this invention.

[0027] Figure 6 This is a schematic diagram of the horizontal arrangement of the second pre-embedded pipe at the joint position in this invention.

[0028] Figure 7 This is a schematic diagram showing the position of the detection port of the second cavity on the upper surface of the base plate in this invention.

[0029] Figure 8 This is a flowchart of the airtightness test and repair process for the second cavity at the joint.

[0030] In the diagram: 1. Diaphragm wall, 11. Longitudinal reinforcement of diaphragm wall, 12. Horizontal reinforcement of diaphragm wall, 13. Positioning steel plate, 14. First embedded pipe, 141. First reserved cavity, 142. Sealant, 143. Anchor head, 2. Foundation slab, 21. Horizontal reinforcement of foundation slab, 3. Corbel, 31. Horizontal reinforcement of corbel, 32. Second embedded pipe, 321. Second reserved cavity, 322. Detection port, 33. Joint, 4. Floor slab, 5. Subbase. Detailed Implementation

[0031] Example 1: Taking an ultra-deep foundation pit project in a confined aquifer as an example 1. Construction of the first subsystem (tolerance connection between diaphragm wall and main structure) Step S1: Prefabrication of the diaphragm wall reinforcement cage and the first embedded pipe (e.g.) Figure 1 (As shown) Diaphragm wall design: The thickness of diaphragm wall 1 in this project is 1000mm, the depth is 50m, and the concrete design strength grade is C35.

[0032] Positioning steel plate 13 installation: 10mm thick Q235B steel plate, with length and width dimensions adapted to the docking area. The diaphragm wall reinforcement cage consists of several longitudinal diaphragm wall bars 11 and several horizontal diaphragm wall bars 12. The two ends of the horizontal diaphragm wall bars 12 are welded to the two ends of the longitudinal diaphragm wall bars 11. During the binding process of the diaphragm wall reinforcement cage, a positioning steel plate 13 is set vertically at design depths according to the depth of the diaphragm wall. Its upper and lower edges are fully welded to the horizontal diaphragm wall bars 12 using E50 series welding rods to ensure that its plate surface is parallel to the diaphragm wall surface.

[0033] As one of the preferred methods, the positioning steel plate 13 is located at the middle position in the thickness direction of the diaphragm wall 1.

[0034] First pre-embedded pipe 14: Materials and Specifications: The first embedded pipe 14 is made of polylactic acid (PLA) based composite material through extrusion molding, with an outer diameter of 40 mm and a wall thickness of 2 mm. Its degradation time is controlled by molecular weight and additives to 28 ± 3 days after concrete pouring, to ensure that the concrete reaches the design strength before degradation.

[0035] Reference pipe arrangement: According to the design elevation of the horizontal reinforcement 21 of the main structure base plate, a 35mm diameter through hole is made at the corresponding position on the positioning steel plate 13. The first embedded pipe 14 is passed through the through hole, with one end tightly against the inner side template of the ground connecting wall, and the other end is fitted with a biodegradable sealing component of the same material with an outer diameter of 50mm.

[0036] Spare pipe arrangement: A spare embedded pipe is arranged 150mm above and below each benchmark embedded pipe. One end of the spare pipe is pressed tightly against the template, and the other end is fitted with a biodegradable sealing component. All embedded pipes are temporarily tied and fixed with wire inside the reinforcing cage to prevent displacement during concrete pouring.

[0037] Step S2: Constructing the diaphragm wall and forming the cavity (e.g.) Figure 1 (As shown) The underwater concrete pouring of the diaphragm wall was carried out using the tremie pipe method. After 28 days of curing, the concrete strength reached the design requirements. At this time, the first pre-embedded pipe 14 and its sealing components had basically degraded, forming a first reserved cavity 141 with an inner diameter of about 40mm inside the diaphragm wall 1. The cavity left a regular circular opening on the inner wall of the foundation pit.

[0038] Step S3: Insertion of horizontal reinforcement bars in the main structure (e.g.) Figure 2 , Figure 3 (As shown) Under normal circumstances: After the foundation pit is excavated to the design elevation and the foundation slab 5 is completed, the foundation slab 2 and corbel 3 are constructed on top of it. When tying the corbel and slab reinforcement, one end of the 25mm diameter HRB400 grade corbel horizontal reinforcement 31 and the slab horizontal reinforcement 21 is aligned with the corresponding first reserved cavity 141 opening on the diaphragm wall and inserted until it reaches the bottom of the cavity. Since the cavity diameter (40mm) is much larger than the reinforcement diameter (25mm), even if there is a 50mm vertical construction error in the diaphragm wall, the reinforcement can be easily inserted, perfectly solving the alignment problem.

[0039] Use of spare pipes: When a significant vertical construction error occurs in the local diaphragm wall, causing the cavity formed by the reference embedded pipe to deviate from the design position of the main structural reinforcement beyond the allowable value, the cavity formed by the spare embedded pipes above and below will be used. Construction personnel can select the closest spare cavity for connection based on the actual deviation on site. This ensures that a usable connection point can always be found under any construction error, achieving true tolerance-tolerant connection.

[0040] Step S4: Inject sealant to form an anchor (e.g.) Figure 2 (As shown) Sealant 142 Selection: Grade A epoxy resin anchoring adhesive is used, and its performance meets the requirements of GB / T 37127-2018 "Anchoring Adhesive for Concrete Structures".

[0041] Injection Process: Using a specialized injection-type rebar caulking gun, the mixed rebar caulking adhesive is injected into the cavity opening, with the amount of adhesive just enough to slightly overflow from the opening. During injection, the adhesive completely coats the rebar and fills the entire cavity. In the enlarged cavity inside the positioning steel plate 13, the adhesive forms an anchor head 143 with a diameter of approximately 50mm, which, together with the positioning steel plate 13, creates a strong mechanical locking effect. Cavities without inserted rebar are also sealed with grout.

[0042] Steps S5-S6: Main structure construction (e.g.) Figure 3 , Figure 5 (As shown) Subsequently, following standard procedures, the reinforcement binding, formwork erection, and concrete pouring of the remaining main structures, including the foundation slab 2, corbel 3, and floor slab 4, were completed. The diaphragm wall 1 is connected to the main structure as a whole through the first subsystem.

[0043] Through the above construction, the adverse effects of construction errors on the quality of structural connections were eliminated, providing tolerance-tolerant connection capabilities, resulting in tighter connections and superior shear resistance. It also solved the problem of cracking caused by stress and strain due to misalignment of steel bar joints, thus structurally suppressing the generation of hidden cracks at structural joints.

[0044] 2. Construction of the second subsystem and joint sealing inspection Step P1: Installation of the second pre-embedded pipe 32 (e.g.) Figure 3 , Figure 6 , Figure 7 (As shown) Location and Specifications: At the longitudinal center of the joint 33 between the foundation slab 2 (2.5m thick) and the corbel 3, three second embedded pipes 32 are horizontally installed along the length of the diaphragm wall. The embedded pipes are made of the same material as the first embedded pipes, with an outer diameter of 20mm. The three pipes are parallel to each other on the same horizontal plane, spaced 200mm apart, and tightly encircle the joint 33 to form a closed loop.

[0045] Port Outlets: The two ends of the three pipes are joined together and led vertically upwards to 150mm above the upper surface of the foundation slab 2. The openings are temporarily sealed with tape to prevent concrete from entering. Before the foundation slab concrete is poured, steel sleeves are pre-embedded at the port locations as permanent test port 322 bases.

[0046] Step P2: The second reserved cavity 321 is formed (e.g.) Figure 3 , Figure 5 , Figure 6 (As shown) The foundation slab 2 and corbel 3 are poured with C40P10 impermeable concrete. After curing, the second embedded pipe 32 degrades according to the preset time, forming three independent annular second reserved cavities 321 in the concrete around the joint 33. Each cavity forms a detection port 322 on the upper surface of the foundation slab through a pre-embedded sleeve. The port is equipped with an openable stainless steel cap with an O-ring seal.

[0047] Air tightness testing and repair (see) Figure 8 flow chart) The airtightness of the joint 33 is tested by inspecting the airtightness of the second reserved cavity 321, and the watertightness of the joint 33 is indirectly tested. The joint 33 is repaired by injecting flexible sealing and waterproofing material into the second reserved cavity 321, thereby achieving the purpose of waterproofing.

[0048] Initial inspection (3 months after completion of main structure): Connect the equipment: Open the cap of the second reserved cavity 321 detection port 322 on the water-facing side and connect the dedicated air tightness tester (including pressure gauge, valve and air pump).

[0049] Pressure test: Slowly inject compressed air into the second reserved cavity 321 to stabilize the pressure at 0.15MPa, close the valve, and start the pressure holding process for 15 minutes.

[0050] Judgment criteria: Record the pressure values ​​at the beginning and end of the pressure holding period. If the pressure drop rate is ≤ 3% (i.e., the pressure drop does not exceed 0.0045 MPa within 15 minutes), the airtightness of the cavity is deemed acceptable. If it exceeds this threshold, it is deemed unacceptable.

[0051] Pressure grouting repair: If the test port 322 fails, immediately select one of the test ports 322 as the grouting port and connect it to the grouting machine. Inject flexible sealing and waterproofing material. After the other port overflows, seal the port. Continue to pressurize to 0.3MPa and stabilize the pressure for 3 minutes before stopping and sealing the grouting port.

[0052] Re-inspection: After grouting is completed and cured for 7 days, perform an airtightness test on the adjacent second reserved cavity 321 according to the above steps, check the airtightness of the joint 33, and repair any unqualified ones until they are qualified. Then seal all ports.

[0053] Long-term monitoring: During the building's operation period, it is recommended to conduct an airtightness re-inspection of the remaining second reserved cavity 321 every year or after abnormal displacement occurs at the diaphragm wall monitoring point, in accordance with the above method, to achieve lifelong inspectability and maintainability of the sealing status of the joint.

[0054] Example 2 (Alternative Solution) In another embodiment, the diaphragm wall 1 does not have a pre-installed positioning steel plate 13. The sealant 142 can be a C80 grade high-strength non-shrink cement-based grout. The first embedded pipe 14 and the second embedded pipe 32 can also be made of polyhydroxyalkanoate (PHA) composite material, and their hydrolytic degradation rate can be controlled by adjusting the proportion of comonomers. Air tightness testing can be performed using the negative pressure method, that is, by evacuating the cavity to reduce the pressure to -0.08 MPa, and monitoring whether the pressure recovery rate exceeds a set threshold. These modifications all achieve the purpose of the present invention.

[0055] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for connecting and sealing the joints of a diaphragm wall and the main structure, used to solve the problem of hidden cracking at the joints caused by construction alignment errors and long-term stress and strain, characterized in that... The method includes constructing a first subsystem and a second subsystem; The construction method of the first subsystem is as follows: S1. In the steel cage of the diaphragm wall (1), a number of first embedded pipes (14) made of biodegradable material are pre-set perpendicular to the wall surface. One end of each first embedded pipe (14) extends to the inner wall surface of the foundation pit, and the other end is fitted with a biodegradable sealing component and left inside the steel cage. S2. After the concrete of the diaphragm wall is poured and cured, the first embedded pipe (14) and the sealing component degrade, thereby forming a number of first reserved cavities (141) in the wall. Each first reserved cavity (141) forms an opening on the wall surface inside the foundation pit. S3. Insert one end of the horizontal steel bar of the main structure into the bottom of the corresponding first reserved cavity (141) through the opening. The horizontal steel bar of the main structure is set perpendicular to the wall surface of the ground diaphragm wall. S4. Inject sealant (142) into the first reserved cavity (141) to seal and anchor the horizontal steel bars of the main structure; Subsequently, the construction of the remaining parts of the main structure was completed; The construction method of the second subsystem is as follows: P1. When constructing the steel mesh of the foundation slab (2) and corbel (3), several biodegradable second embedded pipes (32) are horizontally embedded along the length of the diaphragm wall at the joint (33); each second embedded pipe (32) surrounds the joint (33) and is arranged in parallel to each other, and its two ends converge and lead to the upper surface of the foundation slab (2); P2. After the foundation plate (2) and corbel (3) are poured and reach the predetermined strength, the second embedded pipe (32) is degraded, thereby forming several independent second reserved cavities (321) around the joint (33) in the concrete. Each second reserved cavity (321) has a detection port (322) on the upper surface of the foundation plate (2). After the connection between the diaphragm wall and the main structure is completed through the first subsystem, the airtightness of the second reserved cavity (321) is tested and pressure grouting is performed through the detection port (322) of the second subsystem throughout the entire life cycle of the building.

2. The method according to claim 1, characterized in that, In step S1, a positioning steel plate (13) parallel to the wall is also provided in the steel cage. The positioning steel plate (13) has a through hole for the first pre-embedded pipe (14) to pass through. The sealing component is located on the side of the positioning steel plate (13) facing away from the foundation pit, and its outer diameter is larger than the diameter of the through hole.

3. The method according to claim 2, characterized in that, The first reserved cavity (141) formed in step S2 has a cavity diameter on the side facing away from the pit that is larger than the cavity diameter on the side facing the pit, with the positioning steel plate (13) as the boundary; the sealant (142) injected in step S4 forms an enlarged anchor head (143) in the cavity with a larger diameter, and forms a mechanical locking effect through the positioning steel plate (13).

4. The method according to claim 1, characterized in that, In step S1, the first embedded pipe (14) includes a reference embedded pipe and a spare embedded pipe; the axis of the reference embedded pipe is aligned with the design position of the horizontal steel bar of the main structure; the spare embedded pipe is arranged vertically at intervals on the upper and lower sides of the reference embedded pipe, and its number is an even multiple of the number of reference embedded pipes.

5. The method according to claim 1, characterized in that, The sealant (142) is epoxy resin anchoring adhesive or high-strength non-shrink cement-based grout.

6. The method according to claim 1, characterized in that, The first embedded pipe (14), the sealing component and the second embedded pipe (32) are made of biodegradable polymer materials, such as polylactic acid-based composite materials, which can be controlled to degrade within a set time through biodegradation, photodegradation or water degradation.

7. The method according to claim 1, characterized in that, The number of the second pre-embedded pipe (32) shall not be less than three.

8. The method according to claim 2, characterized in that, The positioning steel plate (13) is located at the middle position in the thickness direction of the diaphragm wall (1).

9. The method according to claim 1, characterized in that, The method for airtightness testing and repair is as follows: the testing port (322) is equipped with an openable sealing device; after the diaphragm wall and the main structure are completed, the second reserved cavity (321) on the water-facing side is first tested for airtightness. The sealing device is opened, and compressed air is injected into it or a negative pressure is formed. The pressure change rate is monitored within a predetermined time to test for airtightness. When the pressure change rate is lower than the preset threshold, it is judged as qualified. When it exceeds the preset threshold, it is judged as unqualified. In the case of unqualified, pressure grouting is performed through the testing port (322) for repair. After repair, the airtightness of the adjacent second reserved cavity is tested. If the airtightness is unqualified, it is repaired until it is qualified. Finally, all ports are closed. During the building's service life, the remaining cavities are periodically re-inspected and maintained through the inspection port (322).

10. A system for detecting the connection and joint sealing between a diaphragm wall and the main structure, characterized in that, include: The first subsystem consists of a plurality of first reserved cavities (141) formed in the diaphragm wall (1), horizontal steel bars of the main structure inserted into the bottom of the cavities, and a sealant (142) that fills and anchors the horizontal steel bars; The second subsystem consists of several independent annular second reserved cavities (321) surrounding the joint (33) between the base plate (2) and the corbel (3), and a detection port (322) disposed on the upper surface of the base plate (2) and communicating with each second reserved cavity (321).

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