A diaphragm wall joint anti-leakage structure and construction method

Abstract

The application relates to a diaphragm wall joint anti-leakage structure and a construction method, and relates to the technical field of foundation pit engineering. The diaphragm wall joint anti-leakage structure comprises a plurality of reinforcing piles which are arranged outside the soil-facing surface of a diaphragm wall, the reinforcing piles are arranged at intervals along the wall body trend of the diaphragm wall and are arranged in the vertical direction; a grouting assembly which is embedded in the diaphragm wall at the joint position and extends in the vertical direction of the joint of the diaphragm wall; and a plugging assembly which is arranged inside a foundation pit and covers the joint of the diaphragm wall, the reinforcing piles, the grouting assembly and the plugging assembly are sequentially arranged in the thickness direction of the diaphragm wall at the joint of the diaphragm wall and cooperatively form an anti-seepage system. The diaphragm wall joint anti-leakage structure solves the problem that, in the prior art, there is a lack of a multiple-barrier cooperative linkage mechanism and it is difficult to realize dynamic control and self-adaptive sealing in the whole process.

Description

Technical Field

[0001] This invention relates to the field of foundation pit engineering technology, specifically to a seepage-proof structure and construction method for diaphragm wall joints. Background Technology

[0002] Diaphragm walls, as a support structure that combines soil retention and water prevention, are widely used in urban deep foundation pit projects, especially in ultra-deep foundation pit projects near rivers, lakes, and seas with high water levels. However, diaphragm walls are constructed by pouring concrete in batches from multiple unit sections, and the joints between these unit sections are often the weakest link in the entire support system. During the excavation process, with the unloading of soil and changes in the groundwater level, water leakage is highly likely to occur at the joints. In severe cases, this can lead to water inrush, sand inrush, and even major safety accidents such as ground subsidence and wall collapse.

[0003] In existing technologies, the following methods are commonly used for seepage prevention treatment of diaphragm wall joints: The first is pre-embedded water-stopping measures, that is, water-stopping steel plates, rubber water-stopping strips, or I-beam joints are pre-embedded at the joints during the construction of the diaphragm wall; the second is external reinforcement curtain, that is, a water-stopping curtain is formed on the outside of the diaphragm wall using high-pressure jet grouting piles (such as the MJS method) or mixing piles; the third is grouting and sealing within the pit, that is, when seepage is found at the joints during or after the excavation of the foundation pit, grouting is performed to seal the leaks through pre-embedded pipes or boreholes; the fourth is rigid sealing within the pit, that is, water-stopping steel plates are directly installed at the joints on the inside of the foundation pit.

[0004] However, existing diaphragm wall joint seepage prevention technologies mostly focus on single-stage defense, making it difficult to adapt to the dynamic changes during the excavation and unloading process of ultra-deep foundation pits in high-water-pressure, highly permeable strata. Pre-embedded water-stopping measures are passive defenses, prone to displacement during construction, and defects are difficult to remedy later. External reinforcement curtains are difficult to control in terms of quality and are prone to failure. Grouting and sealing inside the pit has a lag effect, and the grout is easily diluted and washed away under high water pressure. Traditional rigid sealing inside the pit lacks flexible transitions and is difficult to adapt to uneven wall surfaces and dynamic deformation of the wall, making it prone to failure. There is also a lack of a multi-barrier collaborative linkage mechanism, making it difficult to achieve dynamic control and adaptive sealing throughout the entire process. Summary of the Invention

[0005] This application provides a seepage prevention structure and construction method for diaphragm wall joints, which can solve the problems of existing diaphragm wall joint seepage prevention technologies, which mostly focus on the defense of a single link and are difficult to adapt to the dynamic changes during the excavation and unloading process of ultra-deep foundation pits in high water pressure and highly permeable strata. The pre-embedded water-stopping measures are passive defenses, which are prone to displacement during construction and are difficult to remedy later. The quality control of external reinforcement curtains is difficult and they are prone to failure. Grouting and sealing in the pit has a lag, and the grout is easily diluted and washed away under high water pressure. Traditional rigid sealing in the pit is prone to failure due to the lack of flexible transition and difficulty in adapting to uneven wall surfaces and dynamic deformation of the wall. There is also the problem of lacking a multi-barrier collaborative linkage mechanism, making it difficult to achieve dynamic control and adaptive sealing throughout the entire process.

[0006] In a first aspect, embodiments of this application provide a waterproofing structure for diaphragm wall joints, comprising: Multiple reinforcing piles are used to be installed on the outer side of the soil-facing surface of the diaphragm wall. The multiple reinforcing piles are spaced apart along the wall direction of the diaphragm wall and are installed in a vertical direction. Grouting components are used to be pre-embedded in the corresponding joint of the diaphragm wall and extend vertically along the joint of the diaphragm wall. A sealing component is used to be installed inside the foundation pit. The sealing component is used to cover the joint of the diaphragm wall. The reinforcing pile, the grouting component and the sealing component are sequentially and correspondingly installed at the joint of the diaphragm wall along the thickness direction of the diaphragm wall, and cooperate with each other to form a seepage prevention system.

[0007] In one embodiment, the sealing assembly includes a rigid sealing plate and a flexible impermeable layer. The rigid sealing plate is used to cover the joint of the diaphragm wall, and the flexible impermeable layer is used to sandwich between the rigid sealing plate and the diaphragm wall surface.

[0008] In one embodiment, a sealing material is filled between the edge of the rigid sealing plate and the diaphragm wall surface.

[0009] In one embodiment, the sealing assembly includes a plurality of sealing units arranged in layers along the vertical direction. Each sealing unit includes the rigid sealing plate and the flexible seepage-proof layer, and adjacent rigid sealing plates are overlapped or welded together.

[0010] In one embodiment, the rigid sealing plate is used to be fixed to the diaphragm wall surface by expansion bolts, which pass through the flexible waterproof layer.

[0011] In one embodiment, a base sealing layer is further included, which is disposed at the bottom of the pit and connected to the bottom edge of the sealing assembly to seal the bottom of the joint of the diaphragm wall.

[0012] Secondly, this application also provides a construction method for a diaphragm wall joint waterproofing structure, which is used to construct the above-mentioned diaphragm wall joint waterproofing structure, including the following steps: Multiple reinforcing piles are installed at intervals along the wall direction of the diaphragm wall on the outer side of the soil-facing surface of the diaphragm wall. During the construction of the diaphragm wall, grouting components are pre-embedded at the joints of the diaphragm wall. During the excavation of the foundation pit, a sealing component is installed to cover the joint of the diaphragm wall.

[0013] In one implementation, when installing the sealing assembly: A flexible waterproof layer is laid on the surface of the diaphragm wall; A rigid sealing plate is installed on the outside of the flexible impermeable layer so that the rigid sealing plate covers the joint of the diaphragm wall; A sealant is filled between the edge of the rigid sealing plate and the diaphragm wall surface.

[0014] In one embodiment, the installation of a sealing assembly during the excavation of the foundation pit, such that the sealing assembly covers the joint of the diaphragm wall, includes: After excavating a layer of soil to expose the joint at the corresponding height, a sealing unit is installed. Continue excavating the next layer of earthwork and installing the next layer of sealing units; The two adjacent rigid sealing plates are overlapped or welded together.

[0015] In one embodiment, when installing the sealing assembly, the lowest rigid sealing plate is extended into the construction area of ​​the base sealing layer, and when pouring the base sealing layer, the lower part of the lowest rigid sealing plate is poured into the base sealing layer.

[0016] The beneficial effects of the technical solutions provided in this application include: By constructing a three-in-one collaborative seepage prevention system consisting of external reinforcing piles, internal grouting components, and pit sealing components, with the three components sequentially arranged along the thickness direction of the diaphragm wall, seepage blind spots are eliminated, significantly improving the reliability of seepage prevention. This structure combines passive defense and active management capabilities. The pre-embedded grouting components can be used to achieve emergency plugging after leakage, avoiding the risk of failure of a single measure. At the same time, the redundant design of multiple barriers can effectively adapt to the dynamic deformation and high water head pressure during the excavation of ultra-deep foundation pits, greatly reducing the risk of water and sand inrush accidents and ensuring the safety of the foundation pit and the surrounding environment. This technology addresses several issues: existing diaphragm wall joint seepage prevention techniques primarily focus on single-stage defense, making them ill-suited to the dynamic changes during the excavation and unloading process of ultra-deep foundation pits in high-water-pressure, highly permeable strata; pre-embedded water-stopping measures are passive defenses, prone to displacement during construction, and defects are difficult to remedy later; external reinforcement curtains are difficult to control in terms of quality and are prone to failure; grouting and sealing within the pit has a lag effect, and the grout is easily diluted and washed away under high water pressure; traditional rigid sealing within the pit lacks flexible transitions and is prone to failure due to uneven wall surfaces and dynamic deformation; and there is a lack of a multi-barrier collaborative linkage mechanism, making it difficult to achieve dynamic control and adaptive sealing throughout the entire process. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a cross-sectional structural diagram of an embodiment of a diaphragm wall joint anti-leakage structure according to the present invention.

[0019] Figure 2 This is a longitudinal cross-sectional schematic diagram of an embodiment of a diaphragm wall joint anti-leakage structure according to the present invention.

[0020] Figure 3 This is a schematic diagram of the sealing component in an embodiment of a diaphragm wall joint anti-leakage structure of the present invention.

[0021] In the diagram: 1. Reinforcing pile; 2. Diaphragm wall; 3. Grouting assembly; 4. Sealing assembly; 41. Rigid sealing plate; 42. Flexible seepage prevention layer; 43. Sealing material; 5. Expansion bolt; 6. Base sealing layer. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0023] This application provides a seepage prevention structure and construction method for diaphragm wall joints, which can solve the problems of existing diaphragm wall joint seepage prevention technologies, which mostly focus on the defense of a single link and are difficult to adapt to the dynamic changes during the excavation and unloading process of ultra-deep foundation pits in high water pressure and highly permeable strata. The pre-embedded water-stopping measures are passive defenses, which are prone to displacement during construction and are difficult to remedy later. The quality control of external reinforcement curtains is difficult and they are prone to failure. Grouting and plugging in the pit has a lag, and the grout is easily diluted and washed away under high water pressure. Traditional rigid sealing in the pit lacks flexible transition and is difficult to adapt to uneven wall surfaces and dynamic deformation of the wall, and is prone to failure. There is a lack of a multi-barrier collaborative linkage mechanism, which makes it difficult to achieve dynamic control and adaptive sealing throughout the process.

[0024] like Figure 1 and Figure 2 As shown, this application provides a waterproofing structure for diaphragm wall joints, comprising: Multiple reinforcing piles 1 are used to be installed on the outer side of the soil-facing surface of the diaphragm wall 2. The multiple reinforcing piles 1 are spaced apart along the wall direction of the diaphragm wall 2, and the reinforcing piles 1 are installed in the vertical direction. Grouting component 3 is used to be pre-embedded in the corresponding joint of the diaphragm wall 2 and extends vertically along the joint of the diaphragm wall 2. The sealing component 4 is used to be installed inside the foundation pit and to cover the joint of the diaphragm wall 2. The reinforcing pile 1, the grouting component 3 and the sealing component 4 are sequentially installed at the joint of the diaphragm wall 2 along the thickness direction of the diaphragm wall 2, and they cooperate to form a seepage prevention system.

[0025] By constructing a three-in-one collaborative seepage prevention system consisting of external reinforcing piles 1, internal grouting components 3, and pit sealing components 4, with the three components sequentially arranged along the thickness direction of the diaphragm wall 2, seepage blind spots are eliminated, significantly improving the reliability of seepage prevention. This structure combines passive defense and active treatment capabilities. The pre-embedded grouting components 3 can be used to achieve emergency plugging after leakage, avoiding the risk of failure of a single measure. At the same time, the redundant design of multiple barriers can effectively adapt to the dynamic deformation and high water head pressure during the excavation of ultra-deep foundation pits, greatly reducing the hidden dangers of water and sand inrush accidents and ensuring the safety of the foundation pit and the surrounding environment. This technology addresses several issues: existing diaphragm wall joint seepage prevention techniques primarily focus on single-stage defense, making them ill-suited to the dynamic changes during the excavation and unloading process of ultra-deep foundation pits in high-water-pressure, highly permeable strata; pre-embedded water-stopping measures are passive defenses, prone to displacement during construction, and defects are difficult to remedy later; external reinforcement curtains are difficult to control in terms of quality and are prone to failure; grouting and sealing within the pit has a lag effect, and the grout is easily diluted and washed away under high water pressure; traditional rigid sealing within the pit lacks flexible transitions and is prone to failure due to uneven wall surfaces and dynamic deformation; and there is a lack of a multi-barrier collaborative linkage mechanism, making it difficult to achieve dynamic control and adaptive sealing throughout the entire process.

[0026] In this example, reinforcement pile 1 was constructed using the MJS method. Reinforcement pile 1 has a diameter of 2000mm and a permeability coefficient of no more than 1×10⁻⁶. -6 The grouting unit 3 includes multiple spaced grouting sleeve valves, which are made of rigid PVC material with an outer diameter of 50mm. The grouting unit 3 has a 28-day unconfined compressive strength of not less than 1.0MPa. The grouting unit 3 includes multiple spaced grouting sleeve valves, which are made of rigid PVC material with an outer diameter of 50mm.

[0027] like Figure 1 , Figure 2 and Figure 3 As shown, in some optional embodiments, the sealing component 4 includes a rigid sealing plate 41 and a flexible seepage-proof layer 42. The rigid sealing plate 41 is used to cover the joint of the diaphragm wall 2, and the flexible seepage-proof layer 42 is used to be sandwiched between the rigid sealing plate 41 and the wall surface of the diaphragm wall 2.

[0028] In this embodiment, a composite structure combining a rigid sealing plate 41 and a flexible seepage-proof layer 42 is adopted in the sealing component 4, achieving a seepage-proof effect that combines rigidity and flexibility. The flexible seepage-proof layer 42 is sandwiched between the rigid sealing plate 41 and the wall surface of the diaphragm wall 2, and can adaptively fill the micro-unevenness of the wall surface, effectively eliminating the gaps caused by direct contact between the rigid plate and the wall surface, and significantly improving the tightness of the seal. At the same time, the rigid sealing plate 41, as the main pressure-bearing component, can resist the pressure of groundwater and prevent the flexible layer from being damaged or squeezed out due to direct pressure. The synergistic effect of the two ensures the overall strength and stability of the sealing structure, and ensures reliable sealing under uneven wall surface conditions, effectively solving the technical problem of easy leakage due to poor fit of traditional single rigid sealing.

[0029] In this example, the rigid sealing plate 41 is a water-stop steel plate made of Q235B material with a thickness of not less than 6mm. The flexible seepage-proof layer 42 is a seepage-proof geotextile made of polypropylene filament needle-punched nonwoven fabric composite PE geomembrane with a permeability coefficient of not more than 1×10⁻⁶. -10 cm / s; The leak-stopping compound is a fast-hardening sulfoaluminate type cement-based leak-stopping material with an initial setting time of no more than 5 minutes and a 1-day compressive strength of no less than 25 MPa.

[0030] like Figure 1 and Figure 2 As shown, in some optional embodiments, the edge of the rigid sealing plate 41 is filled with a sealant 43 between itself and the wall surface of the diaphragm wall 2.

[0031] In this embodiment, by filling the gap between the edge of the rigid sealing plate 41 and the wall surface of the diaphragm wall 2 with sealing material 43, a critical secondary sealing barrier is formed at the edge, which effectively seals the gaps at the edge of the plate caused by unevenness of the wall surface or installation errors, preventing groundwater from flowing around and seeping in along the edge of the rigid sealing plate 41. This measure, in conjunction with the surface sealing of the flexible seepage-proof layer 42, achieves all-round sealing, makes up for the possible insufficient sealing of a single flexible layer at the edge, further eliminates the risk of leakage, and significantly improves the sealing tightness and overall seepage-proof reliability at the connection between the sealing component 4 and the wall.

[0032] In this example, the sealing material 43 is a leak-stopping agent, and the application width of the leak-stopping agent is not less than 30mm and the thickness is not less than 10mm.

[0033] like Figure 1 and Figure 3 As shown, in some optional embodiments, the sealing assembly 4 includes a plurality of sealing units arranged in layers along the vertical direction. Each sealing unit includes a rigid sealing plate 41 and a flexible impermeable layer 42, and adjacent rigid sealing plates 41 are overlapped or welded together.

[0034] In this embodiment, by setting the sealing component 4 as a sealing unit arranged in layers along the vertical direction, it can match the construction procedure of layered excavation of the foundation pit, realize sealing as excavation, and effectively reduce the exposure time of joints and the risk of soil and water loss. The overlapping or welding connection between adjacent rigid sealing plates 41 ensures the continuity of the vertical seepage barrier and eliminates the potential leakage channel of interlayer gaps. At the same time, the layered structure can better adapt to the dynamic deformation of the wall joints with the depth during the excavation of ultra-deep foundation pits, avoid the problem of the integral sealing plate tearing or failing due to excessive deformation, and significantly improve the convenience of construction and the overall reliability of the seepage prevention system.

[0035] In this example, bevel welding is used between adjacent rigid sealing plates 41.

[0036] like Figure 1 , Figure 2 and Figure 3 As shown, in some optional embodiments, the rigid sealing plate 41 is used to fix the diaphragm wall 2 to the wall surface by expansion bolts 5, which pass through the flexible waterproof layer 42.

[0037] In this embodiment, the rigid sealing plate 41 is fixed to the wall surface of the diaphragm wall 2 by expansion bolts 5. The connection strength is high and the construction is convenient, which can ensure that the sealing component 4 does not loosen or fall off under high water pressure. The expansion bolts 5 pass through the flexible seepage-proof layer 42, which applies axial pressure to the flexible seepage-proof layer 42 while fixing the rigid plate, so that it fits more tightly to the wall surface, which enhances the sealing effect between the flexible layer and the wall surface, prevents the flexible layer from shifting or wrinkling, and realizes the organic combination of the fixed structure and the sealing structure. This ensures both the overall structural stability of the sealing component 4 and the continuous sealing performance of the flexible seepage-proof layer 42.

[0038] like Figure 1 and Figure 3 As shown, in some optional embodiments, a base sealing layer 6 is also included. The base sealing layer 6 is used to be disposed at the bottom of the pit. The base sealing layer 6 is connected to the bottom edge of the sealing component 4 and is used to seal the bottom of the joint of the diaphragm wall 2.

[0039] In this embodiment, by adding a base sealing layer 6 and connecting it to the bottom edge of the sealing component 4, the bottom of the foundation pit joint is effectively sealed, eliminating the potential for bottom leakage. This structure integrates the vertical sealing component 4 with the bottom of the foundation pit, forming a complete closed seepage prevention system from top to bottom. This effectively prevents groundwater from flowing around the bottom of the diaphragm wall 2 or seeping into the foundation pit through the bottom joint, solving the problem that the bottom of the foundation pit is a weak point in seepage prevention and is prone to water inrush. This significantly improves the integrity and safety of the overall seepage prevention system.

[0040] On the other hand, this application also provides a construction method for a diaphragm wall joint waterproofing structure, which is used to construct the above-mentioned diaphragm wall joint waterproofing structure, including the following steps: Multiple reinforcing piles 1 are installed at intervals along the wall direction of the diaphragm wall 2 on the outer side of the soil-facing surface of the diaphragm wall 2. During the construction of the diaphragm wall 2, grouting components 3 are pre-embedded at the joints of the diaphragm wall 2; During the excavation of the foundation pit, the sealing component 4 is installed so that it covers the joint of the diaphragm wall 2.

[0041] By constructing a three-in-one collaborative seepage prevention system consisting of external reinforcing piles 1, internal grouting components 3, and pit sealing components 4, with the three components sequentially arranged along the thickness direction of the diaphragm wall 2, seepage blind spots are eliminated, significantly improving the reliability of seepage prevention. This structure combines passive defense and active treatment capabilities. The pre-embedded grouting components 3 can be used to achieve emergency plugging after leakage, avoiding the risk of failure of a single measure. At the same time, the redundant design of multiple barriers can effectively adapt to the dynamic deformation and high water head pressure during the excavation of ultra-deep foundation pits, greatly reducing the hidden dangers of water and sand inrush accidents and ensuring the safety of the foundation pit and the surrounding environment. This technology addresses several issues: existing diaphragm wall joint seepage prevention techniques primarily focus on single-stage defense, making them ill-suited to the dynamic changes during the excavation and unloading process of ultra-deep foundation pits in high-water-pressure, highly permeable strata; pre-embedded water-stopping measures are passive defenses, prone to displacement during construction, and defects are difficult to remedy later; external reinforcement curtains are difficult to control in terms of quality and are prone to failure; grouting and sealing within the pit has a lag effect, and the grout is easily diluted and washed away under high water pressure; traditional rigid sealing within the pit lacks flexible transitions and is prone to failure due to uneven wall surfaces and dynamic deformation; and there is a lack of a multi-barrier collaborative linkage mechanism, making it difficult to achieve dynamic control and adaptive sealing throughout the entire process.

[0042] In some optional embodiments, when installing the sealing component 4: A flexible waterproof layer 42 is laid on the wall surface of the diaphragm wall 2; A rigid sealing plate 41 is installed on the outside of the flexible impermeable layer 42 so that the rigid sealing plate 41 covers the joint of the diaphragm wall 2. Sealant 43 is filled between the edge of the rigid sealing plate 41 and the wall surface of the diaphragm wall 2.

[0043] In this embodiment, a specific installation sequence is used: the flexible impermeable layer 42 is laid first, followed by the installation of the rigid sealing plate 41. This ensures a tight fit between the flexible layer and the wall, avoiding poor sealing or damage to the flexible layer caused by direct installation of the rigid plate. Subsequently, sealing material 43 is filled at the edges to form a secondary edge seal, preventing groundwater from seeping in along the edge of the plate. This construction process effectively eliminates installation gaps, improves the sealing tightness between the sealing component 4 and the wall, ensures the overall reliability of the seepage prevention system, and the construction steps are clear, facilitating on-site operation and quality control.

[0044] In some optional embodiments, the installation of the sealing component 4 during the excavation of the foundation pit, so that the sealing component 4 covers the joint of the diaphragm wall 2, includes: After excavating a layer of soil to expose the joint at the corresponding height, a sealing unit is installed. Continue excavating the next layer of earthwork and installing the next layer of sealing units; The two adjacent rigid sealing plates 41 are overlapped or welded together.

[0045] In this embodiment, by adopting a layered construction method of excavation and sealing simultaneously, the exposure time of joints is significantly shortened, effectively reducing the risk of sudden leakage caused by water pressure release during excavation. The overlapping or welding connection of adjacent rigid sealing plates 41 ensures the continuity of the vertical seepage barrier and eliminates the potential leakage channel of interlayer gaps. At the same time, compared with integral sealing, the layered structure is more adaptable to the dynamic deformation of the wall during deep foundation pit excavation, avoiding the tearing of sealing plates or sealing failure due to excessive deformation, and significantly improving construction safety and the overall reliability of the seepage prevention system.

[0046] In some alternative embodiments, when installing the sealing assembly 4, the lowest rigid sealing plate 41 is extended into the construction area of ​​the base sealing layer 6, and when pouring the base sealing layer 6, the lower part of the lowest rigid sealing plate 41 is poured into the base sealing layer 6.

[0047] In this embodiment, by casting the lower part of the lowest rigid sealing plate 41 into the base sealing layer 6, a rigid embedded connection between the vertical sealing component 4 and the bottom structure of the foundation pit is achieved, eliminating the gaps at the bottom junction and effectively preventing groundwater from flowing around or seeping in from the bottom of the joint; at the same time, the bonding force of the concrete in the base sealing layer 6 is used to anchor the bottom of the sealing plate, enhancing the sealing component 4's ability to resist the high pressure of the bottom water, ensuring the integrity and airtightness of the seepage prevention system at the bottom, and solving the technical problem of water inrush at the bottom of the foundation pit.

[0048] In a specific embodiment, the excavation depth of the foundation pit is 26m, and the width of the foundation pit is 22m. A diaphragm wall with internal bracing system is adopted. The diaphragm wall is 1200mm thick, with I-beam joints, and a wall depth of 46m, penetrating at least 3m into the moderately weathered silty mudstone. The strata, from top to bottom, are: miscellaneous fill (0-2m), silty clay (2-8m), interlayers of silty clay and silty sand (8-22m), fine sand layer (22-38m), strongly weathered silty mudstone (38-42m), and moderately weathered silty mudstone (below 42m). The groundwater level is approximately 0.8m deep, and the aquifer permeability coefficient is 5.2×10⁻⁶. -3 The water head difference at the bottom of the foundation pit is approximately 25m, with a flow rate of cm / s. The construction sequence for this project is as follows: first, high-pressure jet grouting reinforcement is carried out on the soil-facing side of the diaphragm wall along the axis of each joint using the MJS method equipment. Then, the first and second phases of diaphragm wall and joint I-beam construction are completed, followed by the implementation of other water-stopping measures. The MJS reinforcement piles are designed with a diameter of 2000mm, arranged along the joint axis, with a length extending from the ground surface to 10m below the foundation pit base (approximately 36m in depth), and are installed flush against the outer wall of the diaphragm wall. The MJS construction parameters are: jetting pressure 38–40MPa, air pressure 0.6–0.8MPa, lifting speed 5–8cm / min, grout water-cement ratio 1.5:1, 28-day unconfined compressive strength of the pile not less than 1.0MPa, and permeability coefficient not greater than 1×10⁻⁶.-6 cm / s. MJS piles form the first water-cutting barrier outside the joint, sealing the groundwater seepage channels in the soil layer surrounding the outer surface of the joint. During the fabrication of the diaphragm wall reinforcement cage, grouting sleeve valves are pre-embedded at each joint location. The sleeve valves are made of rigid PVC material with an outer diameter of 50mm, and two are arranged vertically side by side along the soil-facing side of the joint, extending 10m below the foundation pit base at the bottom and 0.8m above the ground at the top, with protective covers and grouting joints installed. After the diaphragm wall reaches the design strength, the gaps around the sleeve valves are first filled with grout, followed by the initial grouting of the joint, with the grouting pressure controlled between 0.5 and 1.5MPa. Before the foundation pit is excavated, preventative supplementary grouting is performed on each joint through the sleeve valves. If any abnormalities such as water seepage or sand inrush are found during the excavation process, emergency grouting is immediately performed through the pre-embedded sleeve valves of that joint. The grouting slurry and pressure are dynamically adjusted according to the leakage situation and monitoring feedback until the leakage is completely stopped. The foundation pit was excavated using the open-cut method, layer by layer from top to bottom, with each layer not exceeding 4 meters in depth. When the excavation reached the top surface of the soft soil layer below ground level (approximately 2 meters deep), the first layer of waterstop steel plates was laid. Subsequently, one layer was laid after each excavation layer (approximately 3-4 meters) until the foundation was reached. During the construction of the waterstop steel plates, at the completed elevation of each excavation layer, the concrete surface of the diaphragm wall on both sides of the joint was cleaned, removing surface inclusions of mud, laitance, loose materials, and oil stains to expose the dense concrete base surface. This surface was then washed clean with a high-pressure water gun. For areas in the joint where the depth of mud or slag inclusions exceeded 30mm, manual excavation combined with vacuuming was used to completely remove the mud until a clean interface was exposed at the joint between the first and second phase diaphragm wall sections. A layer of impermeable geotextile, with the same length and width as the waterstop steel plate, was then laid on the cleaned joint and the concrete walls on both sides. The geotextile is made of polypropylene filament needle-punched nonwoven fabric composite PE geomembrane, with a unit area mass of not less than 500 g / ㎡ and a permeability coefficient of not more than 1×10. -10The tensile strength should be no less than 18 kN / m longitudinally and no less than 15 kN / m transversely, and the CBR puncture strength should be no less than 3 kN. During installation, it should be laid naturally against the diaphragm wall surface, ensuring no wrinkles or gaps. Q235B material waterstop steel plate should be selected, with specifications of 750mm width × 10mm thickness × 1000mm length. The waterstop steel plate should be placed over the impermeable geotextile, with the joint centered. Expansion bolts (M16) should be used to fix both sides of the waterstop steel plate to the diaphragm walls on both sides, with a bolt spacing of 300mm, a distance of no less than 40mm from the edge of the steel plate, and an anchoring depth of no less than 100mm. Impermeable geotextile should be pressed against each edge of the waterstop steel plate for at least 150mm. A sealant should be applied to the perimeter (top and sides) of the waterstop steel plate for rigid sealing. The leak-stopping compound is a fast-hardening sulfoaluminate cement-based leak-stopping material with an initial setting time of no more than 5 minutes, a final setting time of no more than 10 minutes, a 1-day compressive strength of no less than 25 MPa, and a 1-day bond strength of no less than 1.5 MPa. The application width should be no less than 30 mm, and the thickness no less than 10 mm. It should cover the joint between the top edge of the uppermost steel plate and the diaphragm wall, as well as the joints between the two sides of the steel plate and the diaphragm wall. The application must be dense, without pores, and firmly bonded to the steel plate and concrete. The joints between adjacent upper and lower layers of waterstop steel plates are joined using bevel welding. After excavating to the design elevation of the foundation pit, the pit bottom is sealed. The bottom layer of waterstop steel plate is extended into the foundation cushion layer. The joint between the waterstop steel plate and the cushion layer is sealed with the leak-stopping compound. When pouring the cushion layer concrete, the lower part of the waterstop steel plate is poured into the cushion layer to form an embedded seal. Finally, all joint waterproof steel plates were reliably connected to the subgrade waterproof layer, achieving a leak-proof and water-stopping process from the ground to the foundation. Throughout the excavation process, joint leakage was monitored in real time. Monitoring included: joint seepage volume, grouting pressure and volume in the sleeve valve pipe, deformation of the water-stop steel plates, and changes in water levels inside and outside the foundation pit. When monitoring data exceeded warning values, reinforcement grouting was promptly performed through the pre-embedded sleeve valve pipe, or the water-stop steel plate seal was reinforced.

[0049] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0050] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0051] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A waterproof structure for diaphragm wall joints, characterized in that, include: Multiple reinforcing piles (1) are used to be installed on the outer side of the soil-facing surface of the diaphragm wall (2). The multiple reinforcing piles (1) are spaced apart along the wall direction of the diaphragm wall (2) and the reinforcing piles (1) are installed in the vertical direction. Grouting assembly (3) is used to be pre-embedded in the corresponding joint of the diaphragm wall (2) and extends vertically along the joint of the diaphragm wall (2); The sealing component (4) is used to be installed inside the foundation pit. The sealing component (4) is used to cover the joint of the diaphragm wall (2). The reinforcing pile (1), the grouting component (3) and the sealing component (4) are sequentially and correspondingly installed at the joint of the diaphragm wall (2) along the thickness direction of the diaphragm wall (2), and cooperate with each other to form a seepage prevention system.

2. The anti-leakage structure for diaphragm wall joints as described in claim 1, characterized in that, The sealing assembly (4) includes a rigid sealing plate (41) and a flexible seepage-proof layer (42). The rigid sealing plate (41) is used to cover the joint of the diaphragm wall (2), and the flexible seepage-proof layer (42) is used to be sandwiched between the rigid sealing plate (41) and the wall surface of the diaphragm wall (2).

3. The anti-leakage structure for diaphragm wall joints as described in claim 2, characterized in that, The edge of the rigid sealing plate (41) is filled with sealing material (43) between it and the wall surface of the diaphragm wall (2).

4. The anti-leakage structure for diaphragm wall joints as described in claim 2, characterized in that, The sealing assembly (4) includes multiple sealing units arranged in layers along the vertical direction. Each sealing unit includes a rigid sealing plate (41) and a flexible seepage-proof layer (42). Adjacent rigid sealing plates (41) are overlapped or welded together.

5. A waterproof structure for diaphragm wall joints as described in claim 2, characterized in that, The rigid sealing plate (41) is used to fix the diaphragm wall (2) wall surface by expansion bolts (5), which pass through the flexible waterproof layer (42).

6. The anti-leakage structure for diaphragm wall joints as described in claim 1, characterized in that, It also includes a base sealing layer (6), which is used to be installed at the bottom of the pit. The base sealing layer (6) is connected to the bottom edge of the sealing component (4) and is used to seal the bottom of the joint of the diaphragm wall (2).

7. A construction method for a seepage-proof structure for diaphragm wall joints, characterized in that, For constructing a diaphragm wall joint waterproofing structure as described in any one of claims 1-6, the following steps are included: Multiple reinforcing piles (1) are installed at intervals along the wall orientation of the diaphragm wall (2) on the outer side of the soil-facing surface of the diaphragm wall (2). During the construction of the diaphragm wall (2), grouting components (3) are pre-embedded at the joints of the diaphragm wall (2). During the excavation of the foundation pit, a sealing component (4) is installed so that the sealing component (4) covers the joint of the diaphragm wall (2).

8. A construction method for a diaphragm wall joint waterproofing structure as described in claim 7, characterized in that, When installing the sealing component (4): A flexible impermeable layer (42) is laid on the wall surface of the diaphragm wall (2); A rigid sealing plate (41) is installed on the outside of the flexible impermeable layer (42) so that the rigid sealing plate (41) covers the joint of the diaphragm wall (2); A sealant (43) is filled between the edge of the rigid sealing plate (41) and the wall surface of the diaphragm wall (2).

9. A construction method for a seepage-proof structure for diaphragm wall joints as described in claim 7, characterized in that, The installation of the sealing component (4) during the excavation of the foundation pit, so that the sealing component (4) covers the joint of the diaphragm wall (2), includes: After excavating a layer of soil to expose the joint at the corresponding height, a sealing unit is installed. Continue excavating the next layer of earthwork and installing the next layer of sealing units; The two adjacent rigid sealing plates (41) are overlapped or welded together.

10. A construction method for a seepage-proof structure for diaphragm wall joints as described in claim 7, characterized in that, When installing the sealing assembly (4), the lowest rigid sealing plate (41) is extended into the construction area of ​​the base sealing layer (6). When pouring the base sealing layer (6), the lower part of the lowest rigid sealing plate (41) is poured into the base sealing layer (6).

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