A foundation pit support structure and construction method

Abstract

This application relates to the field of foundation pit support equipment technology, and more particularly to a foundation pit support structure, which includes a corner retaining wall, a waler assembly, and a jacking assembly. The corner retaining wall has a construction joint extending along its height to the top and bottom of the corner retaining wall, and also penetrating along its thickness. The corner retaining wall includes an L-shaped wall and a support wall, with the L-shaped wall positioned on one side of the support wall and the support wall on the other side of the construction joint. The waler assembly includes an inner waler and an outer waler, with the inner waler installed on the side of the L-shaped wall away from the soil, and the outer waler installed on top of the inner waler. The jacking assembly includes several jacks; when the piston rods of the jacks extend or retract, the inner waler moves away from or towards the outer waler. This application effectively ensures the safety factor of the corner while guaranteeing sufficient construction space.

Description

Technical Field

[0001] This application relates to the field of foundation pit support equipment technology, and in particular to a foundation pit support structure and construction method. Background Technology

[0002] During construction, it is usually necessary to excavate a foundation pit and install a support structure to maintain its stability and reduce the risk of collapse. The shape of the foundation pit varies depending on the type of building being constructed. In some foundation pits, there are often external corners, i.e., protruding edges within the pit. Because the corner retaining wall is L-shaped, the soil pressure at the corner is concentrated, construction is more difficult, and the quality is often lower. Therefore, the safety factor of the external corner is generally lower than that of other parts of the foundation pit, posing a significant safety hazard. Thus, the external corner, as a weak point in the foundation pit support structure, often requires additional reinforcement to ensure its safety.

[0003] In existing technologies, to ensure the safety factor of external corners, the density of internal supports is usually increased to enhance their structural strength, thus ensuring the safety factor of the external corner. In addition, a corner tie plate is typically poured on the outer side of the external corner, closer to the soil. This tie plate increases the connection area between the two retaining walls at the external corner, thereby increasing the structural integrity of the corner and further ensuring its safety factor.

[0004] Regarding the aforementioned technologies, corner bracing requires a significant amount of construction land. When the outer side of the corner is close to the land boundary line, corner bracing becomes difficult to install. In this case, to ensure the safety factor of the corner, it is generally necessary to further increase the density of the internal supports. However, further increasing the density of the internal supports will reduce the construction work space, making it difficult to carry out normal construction. Summary of the Invention

[0005] In order to ensure the safety factor of the external corner while ensuring sufficient construction space, this application provides a foundation pit support structure and construction method.

[0006] Firstly, the technical solution for the foundation pit support structure and construction method provided in this application is as follows:

[0007] A foundation pit support structure includes a corner retaining wall, a water-stopping mechanism, a support mechanism, and an adjustment mechanism. The corner retaining wall has a construction joint that extends along the height of the corner retaining wall to its top and bottom, and also extends through the corner retaining wall along its thickness. The corner retaining wall includes an L-shaped wall and a support wall. The L-shaped wall is located within the support wall, and the L-shaped wall and the support wall are respectively located on both sides of the construction joint. The water-stopping mechanism is used to reduce groundwater entering the foundation pit through the construction joint.

[0008] The support mechanism includes a waler assembly and an inner support assembly. The waler assembly includes an inner waler and an outer waler. The inner waler is installed on the side of the L-shaped wall away from the soil, and the outer waler is installed on the inner waler. The inner support assembly is used to fix the outer waler.

[0009] The adjustment mechanism includes an ejector assembly and a support connection assembly. The ejector assembly includes several jacks, all of which are disposed between the inner waler and the outer waler. When the piston rods of the several jacks extend or retract, the inner waler moves away from or closer to the outer waler. The support connection assembly is used to ensure that the outer waler is disposed within the inner waler.

[0010] By adopting the above technical solution, the L-shaped wall is set independently from the supporting wall, while the outer waler is fixed relative to both the L-shaped wall and the supporting wall. By controlling the extension and retraction of the piston rod of the jack, the inner waler moves the L-shaped wall towards or away from the soil, thereby actively adjusting the deflection of the L-shaped wall and ensuring that its deflection remains within a safe range. Actively controlling the deflection of the L-shaped wall with jacks reduces the need for extensive support structures, which helps to reduce the construction space occupied by the foundation pit support structure. This ensures sufficient construction space while guaranteeing the safety factor of the external corner, effectively reducing the possibility of corner collapse.

[0011] Optionally, several supporting connection components are provided, each disposed between the inner waler and the outer waler. Each supporting connection component includes a connecting seat and a connecting pipe. Each connecting seat is fixedly installed on the outer waler and has an insertion cavity. One end of each connecting pipe is inserted into the insertion cavity, with a gap between the outer circumferential surface of the connecting pipe and the inner wall of the insertion cavity. The other end of each connecting pipe is fixedly installed on the outer waler. Each connecting seat has an insertion hole, which communicates with each insertion cavity.

[0012] By adopting the above technical solution, when the piston rod of the jack extends or retracts, the connecting pipe slides along the insertion cavity, limiting the movement of the inner waler. This increases the stability of the L-shaped wall when the inner waler moves, reducing the occurrence of misalignment between the inner and outer walers. Simultaneously, after the connecting pipe slides along the insertion cavity to the designated position, the cavity is filled with a steel plate or other filler material through the insertion hole. This allows the earth pressure to be transmitted to the outer waler through the connecting seat and connecting pipe, thus facilitating a more even distribution of earth pressure and reducing the risk of instability and failure due to excessive local adhesion of the outer waler. This ensures the safety factor of the external corner.

[0013] Optionally, both the L-shaped wall and the supporting wall are TRD method cement-soil mixing walls.

[0014] By adopting the above technical solutions, compared with traditional cement-soil mixing piles and SMW method piles, the TRD method cement-soil mixing wall has strong integrity, small surface undulations, and uniform wall thickness. When subjected to concentrated earth pressure at the external corner, it is less likely to crack, thus ensuring the safety factor of the external corner. Secondly, the strong integrity of the TRD method cement-soil mixing wall also makes it easier for several jacks to drive the inner waler to move the entire L-shaped wall. This reduces the occurrence of local misalignment and cracking of the L-shaped wall relative to the rest of the L-shaped wall when the piston rod of several jacks extends or retracts.

[0015] Furthermore, the TRD method for cement-soil mixing walls has a smaller soil displacement effect, which helps to reduce the increase in soil density outside the foundation pit due to the setting of L-shaped walls and support walls, and the occurrence of situations where several jacks cannot extend their piston rods. Finally, the TRD method generates less construction waste and the height of related construction equipment is lower, which helps to reduce the interference with existing buildings outside the land boundary during foundation pit construction.

[0016] Optionally, the L-shaped wall is provided with a first core material assembly, which includes a plurality of first H-beams. The plurality of first H-beams are distributed along the length direction of the L-shaped wall, and the first H-beams are all inserted into the L-shaped wall along the height direction of the L-shaped wall.

[0017] By adopting the above technical solution, several first H-beams, as the core material of the L-shaped wall, together with the concrete used to pour the L-shaped wall, resist the earth pressure, which helps to increase the rigidity of the L-shaped wall, thereby reducing the deflection of the L-shaped wall and ensuring the safety factor of the external corner.

[0018] Optionally, the retaining wall is provided with a second core material assembly, which includes a plurality of second H-beams. The plurality of second H-beams are distributed along the length direction of the retaining wall and inserted into the retaining wall along the height direction of the retaining wall. The distance between the plurality of first H-beams is smaller than the distance between each second H-beam.

[0019] By adopting the above technical solution, the distance between several first H-beams is smaller than the distance between each second H-beam. That is, the several first H-beams are arranged in a denser manner, which helps to further ensure the rigidity of the L-shaped wall, thereby further ensuring the safety factor of the external corner.

[0020] Optionally, one of the first H-beams near the corner of the L-shaped wall is designated as a corner H-beam. The corner H-beam is inclined, meaning that there is an angle between the web of the corner H-beam and the webs of the other first H-beams, and the corner H-beam is positioned close to the soil.

[0021] By adopting the above technical solution, when the soil pressure at both ends of the L-shaped wall is uneven or misalignment occurs due to other reasons, the setting of the corner H-beam will help ensure the connection stability between the two ends of the L-shaped wall, i.e., at the corner, thereby reducing the occurrence of cracks at the corner of the L-shaped wall and ensuring the safety factor of the external corner.

[0022] Optionally, the water-stopping mechanism includes a connecting H-beam and a water-stopping component, wherein the connecting H-beam is disposed within the construction joint, and the two flanges of the connecting H-beam are respectively inserted into the L-shaped wall and the supporting wall;

[0023] The water-stopping component includes a polyurethane coating, a water-swellable rubber sheet, and a fixing steel plate. The polyurethane coating fills the construction joint and is applied to the side of the support wall away from the soil and the side of the L-shaped wall away from the soil. The water-swellable rubber sheet is covered by the polyurethane coating, and the fixing steel plate is covered by the water-swellable rubber sheet. Both sides of the fixing steel plate are fixed to the support wall and the L-shaped wall, respectively.

[0024] By adopting the above technical solution, the two flanges of the connecting H-beam are respectively inserted into the L-shaped wall and the support wall, so that the connection relationship between the L-shaped wall and the support wall is transformed into an elastic connection. This is beneficial to ensure the stability of the connection between the L-shaped wall and the support wall while ensuring that the L-shaped wall is set independently from the support wall. In addition, the web of the connecting H-beam also helps to reduce the groundwater entering the foundation pit from the construction joint.

[0025] Meanwhile, the polyurethane coating fills the construction joint, further reducing the amount of groundwater entering the foundation pit from the construction joint; in addition, the groundwater that is not blocked by the web of the connected H-beam and the polyurethane coating is absorbed by the water-swellable rubber sheet. The water-swellable rubber sheet expands after absorbing water, reducing the gap between the fixed steel plate and the polyurethane coating, further reducing the amount of groundwater entering the foundation pit from the construction joint.

[0026] By connecting H-beams, using polyurethane coatings, water-swellable rubber sheets, and fixing steel plates, groundwater entering the foundation pit through construction joints is reduced. This avoids the conventional practice of installing concrete mixing water-stop piles in the soil outside the foundation pit. It also helps reduce the occurrence of soil compaction increases due to the soil squeezing effect during the construction of the concrete mixing water-stop piles, making it difficult for several jacks to extend their piston rods. Furthermore, avoiding the conventional practice of installing concrete mixing water-stop piles in the soil outside the foundation pit also helps reduce the possibility of excessive deflection of the L-shaped wall before the soil inside the foundation pit is excavated due to the volume expansion of the concrete mixing water-stop piles during initial setting.

[0027] Optionally, the internal support assembly includes several main beams, several auxiliary beams, and several stiffening plates. The main beams and auxiliary beams are all fixedly installed on the outer waler. The main beams and auxiliary beams are arranged in a mesh pattern. The stiffening plates are all cast between each main beam and each auxiliary beam, and the stiffening plates are all arranged close to the outer waler.

[0028] By adopting the above technical solution, the stiffening plate increases the stability of the connection between each main beam and each auxiliary beam, thereby increasing the stiffness of the internal support component, thus ensuring the fixing effect of the internal support component on the outer waler.

[0029] Secondly, this application provides a construction method for a foundation pit support structure, including the following specific steps:

[0030] S1. Construct L-shaped walls and retaining walls using the TRD method, and set construction joints between the L-shaped walls and retaining walls;

[0031] S2. Insert several first H-beams and several second H-beams into the L-shaped wall and the supporting wall respectively; place the connecting H-beams in the construction joint and insert the two flanges of the connecting H-beams into the L-shaped wall and the supporting wall respectively;

[0032] S3. Excavate the soil of the foundation pit to the design elevation and install inner walers, outer walers, several main beams, several auxiliary beams and several stiffening plates;

[0033] S4. Place several jacks, several connecting seats, and several connecting pipes between the inner waler and the outer waler;

[0034] S5. Extend the piston rods of several jacks to move the inner waler away from the outer waler;

[0035] S6. Continue excavating the soil at the bottom of the inner waler, outer waler, several main beams, several auxiliary beams, and several stiffening plates, and install polyurethane coating, water-swellable rubber sheets, and fixing steel plates.

[0036] By adopting the above technical solution, before excavating the foundation pit, the piston rod of the jack is extended, causing the inner waler to move away from the outer waler and push the soil outside the foundation pit. This causes the L-shaped wall to deflect in the opposite direction, which helps to offset some of the displacement that occurs after excavating the foundation pit, thereby reducing the deflection of the L-shaped wall and ensuring the safety factor of the external corner. Simultaneously, during the excavation of the foundation pit, the deflection of the L-shaped wall can be further controlled by adjusting the extension or retraction of the piston rod of the jack, thus further ensuring the safety factor of the external corner.

[0037] Optionally, in step S2, the method for setting up the connecting H-beams specifically includes:

[0038] S21. Insert two temporary steel plates with friction-reducing agent on their outer surfaces between the L-shaped wall and the supporting wall along the extension direction of the construction joint, and leave a gap between the two temporary steel plates.

[0039] S22. Insert the connecting H-beam into the gap between the two temporary steel plates, and insert the two flanges of the connecting H-beam into the L-shaped wall and the supporting wall respectively;

[0040] S23. After the L-shaped wall and the supporting wall are formed and the two flanges connecting the H-shaped steel are respectively embedded in the L-shaped wall and the supporting wall, pull out the two temporary steel plates.

[0041] By adopting the above technical solution, the connecting H-beam is inserted through the gap between the two temporary steel plates, which facilitates the positioning of the connecting H-beam and ensures the installation accuracy of the connecting H-beam. At the same time, after the two temporary steel plates are pulled out, a construction joint with a relatively flat inner wall is formed, which is conducive to the subsequent filling of the construction joint with polyurethane coating, reducing the gap between the polyurethane coating and the inner wall of the construction joint, thereby ensuring the water-stopping effect of the polyurethane coating;

[0042] In addition, by forming a construction joint with two temporary steel plates, the L-shaped wall and the support wall can be constructed simultaneously. This effectively reduces the need to wait until the L-shaped wall or support wall is formed before continuing to construct the support wall or L-shaped wall to form a construction joint, thus ensuring construction efficiency.

[0043] In summary, this application includes at least one of the following beneficial technical effects:

[0044] 1. The L-shaped wall is independently installed relative to the retaining wall, while the outer waler is fixed relative to both the L-shaped wall and the retaining wall. By controlling the extension and retraction of the piston rod of the jack, the inner waler moves the L-shaped wall towards or away from the soil, thus actively adjusting the deflection of the L-shaped wall to ensure it remains within a safe range. Actively controlling the deflection of the L-shaped wall with jacks reduces the need for extensive support structures, which helps reduce the construction space occupied by the foundation pit support structure. This ensures sufficient construction space while maintaining a safe corner, effectively reducing the possibility of corner collapse.

[0045] 2. When the piston rod of the jack extends or retracts, the connecting pipe slides along the insertion cavity, limiting the movement of the inner waler. This increases the stability of the L-shaped wall when the inner waler moves, reducing the possibility of misalignment between the inner and outer walers. Simultaneously, after the connecting pipe slides along the insertion cavity to the designated position, the cavity is filled with a steel plate or other filler material through the insertion hole. This allows the earth pressure to be transmitted to the outer waler through the connecting seat and connecting pipe, ensuring a more even distribution of earth pressure and reducing the risk of instability and failure due to excessive local adhesion of the outer waler. This, in turn, ensures the safety factor of the external corner.

[0046] 3. Compared with traditional cement-soil mixing piles and SMW method piles, TRD method cement-soil mixing walls have strong integrity, small surface undulations, and uniform wall thickness. When subjected to concentrated earth pressure at the external corner, they are less likely to crack, thus ensuring the safety factor of the external corner. Secondly, the strong integrity of TRD method cement-soil mixing walls also makes it easier for several jacks to move the inner waler and drive the entire L-shaped wall. This reduces the occurrence of local misalignment and cracking of the L-shaped wall relative to the rest of the L-shaped wall when the piston rod of several jacks extends or retracts.

[0047] Furthermore, the TRD method for cement-soil mixing walls has a smaller soil displacement effect, which helps to reduce the increase in soil density outside the foundation pit due to the setting of L-shaped walls and support walls, and the occurrence of situations where several jacks cannot extend their piston rods. Finally, the TRD method generates less construction waste and the height of related construction equipment is lower, which helps to reduce the interference with existing buildings outside the land boundary during foundation pit construction.

[0048] 4. Before excavating the foundation pit, extend the piston rod of the jack to move the inner waler away from the outer waler and push the soil outside the foundation pit. This causes the L-shaped wall to deflect in the opposite direction, which helps to offset some of the displacement that occurs after excavating the foundation pit, thereby reducing the deflection of the L-shaped wall and ensuring the safety factor of the external corner. Simultaneously, during the excavation of the foundation pit, the deflection of the L-shaped wall can be further controlled by adjusting the extension or retraction of the piston rod of the jack, further ensuring the safety factor of the external corner. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the overall structure of an embodiment of this application.

[0050] Figure 2 This is a schematic diagram of the overall structure of the water-stopping mechanism in the embodiment of this application.

[0051] Figure 3 This is a cross-sectional schematic diagram of the L-shaped wall in an embodiment of this application.

[0052] Figure 4 This is a cross-sectional schematic diagram of the support wall in an embodiment of this application.

[0053] Figure 5 This is a schematic diagram showing the connection relationship between the inner waler and the support waler in an embodiment of this application.

[0054] Figure 6 yes Figure 1 Enlarged schematic diagram of part A.

[0055] Figure 7 This is a construction diagram of inserting and connecting H-beams according to an embodiment of this application.

[0056] Explanation of reference numerals in the attached drawings: 1. External corner retaining wall; 101. Construction joint; 102. First EPE foam film; 103. Second EPE foam film; 104. Water-stop groove; 11. L-shaped wall; 111. First H-beam; 1111. First insertion part; 1112. First fixing part; 12. Support wall; 121. Second H-beam; 1211. Second insertion part; 1212. Second fixing part; 2. Water-stopping mechanism; 21. Connecting H-beam; 22. Polyurethane coating; 23. Water-swellable rubber sheet; 24. Fixing steel. 3. Supporting mechanism; 31. Inner waler; 311. Connecting plate; 312. Connecting reinforcement; 32. Support waler; 33. Outer waler; 34. Main beam; 35. Auxiliary beam; 36. Stiffening plate; 4. Adjusting mechanism; 41. Jack; 42. I-beam; 43. Connecting seat; 4301. Insertion cavity; 4302. Insertion hole; 431. First positioning ring; 432. Second positioning ring; 433. Positioning block; 44. Adjusting steel plate; 45. Connecting pipe; 5. First cap beam; 6. Second cap beam; 7. Temporary steel plate. Detailed Implementation

[0057] The following is in conjunction with the appendix Figure 1-7 This application will be described in further detail.

[0058] This application discloses a foundation pit support structure and construction method. (Refer to...) Figure 1 and Figure 2 The foundation pit support structure includes a corner retaining wall 1, a water-stopping mechanism 2, a support mechanism 3, and an adjustment mechanism 4.

[0059] Reference Figure 1 and Figure 2 The external corner retaining wall 1 has an "L"-shaped cross-section and is installed vertically. Construction joints 101 are provided in the external corner retaining wall 1. In this embodiment, two construction joints 101 are provided, located near both ends of the external corner retaining wall 1. The construction joints 101 extend along the height direction of the external corner retaining wall 1 to its top and bottom, and also penetrate along the thickness direction of the external corner retaining wall 1.

[0060] Continue to refer to Figure 1 and Figure 2 The external corner retaining wall 1 includes an L-shaped wall 11 and a supporting wall 12, both of which are TRD method cement-soil mixing walls. In this embodiment, the supporting wall 12 is provided on two sides. The two supporting walls 12 are respectively located at both ends of the L-shaped wall 11, and the L-shaped wall 11 and the two supporting walls 12 are distributed in an "L" shape; two construction joints 101 are respectively set between the L-shaped wall 11 and the two supporting walls 12, so that the L-shaped wall 11 is independently set relative to the two supporting walls 12, thereby reducing the occurrence of the L-shaped wall 11 tilting under soil pressure or other external forces, causing the supporting walls 12 to tilt as well.

[0061] Continue to refer to Figure 1 and Figure 2 The L-shaped wall 11 is provided with a first core material assembly, which includes a plurality of first H-beams 111, which are distributed along the length of the L-shaped wall 11. The first H-beams 111 are inserted into the interior of the L-shaped wall 11 along the height of the L-shaped wall 11, and the flanges of the first H-beams 111 face the soil outside the pit, so as to fully utilize the compressive and bending strength of the first H-beams 111.

[0062] One of the first H-beams 111 near the corner of the L-shaped wall 11 is set as a corner H-beam. The corner H-beam is inclined, that is, there is an angle between the web of the corner H-beam and the web of the other first H-beams 111. The web of the corner H-beam is set close to the soil outside the foundation pit, so as to ensure the connection stability between the two ends of the L-shaped wall 11, thereby reducing the occurrence of cracks at the corner of the L-shaped wall 11 and ensuring the safety factor of the external corner.

[0063] In this embodiment of the application, the two ends of the first H-beam 111 are respectively provided as a first insertion part 1111 and a first fixing part 1112. The first insertion part 1111 is inserted into the interior of the L-shaped wall 11 along the height direction of the L-shaped wall 11, and the first fixing part 1112 is provided at the top of the first insertion part 1111 and extends out from the top of the L-shaped wall 11.

[0064] Reference Figure 3 The L-shaped wall 11 is topped with a first capping beam 5, which is a cast-in-place reinforced concrete beam. The bottoms of several first fixing parts 1112 are embedded within the first capping beam 5, and the tops of several first fixing parts 1112 extend beyond the top of the first capping beam 5. The first capping beam 5 facilitates the connection of several first H-beams 111 into a whole, thereby increasing the structural integrity of the L-shaped wall 11 and ensuring the safety factor of the external corners.

[0065] The bottom outer surface of the first fixing part 1112 is covered with a first EPE foam film 102. The first EPE foam film 102 and the bottom of the first fixing part 1112 are embedded in the first capping beam 5 together to reduce the friction between the bottom of the first fixing part 1112 and the concrete used to pour the first capping beam 5. This facilitates the removal of the first H-beam 111 from the L-shaped wall 11 and the first capping beam 5 after the foundation pit is backfilled, thus enabling the first H-beam 111 to be reused. Reusing the first H-beam 111 reduces construction costs and also helps reduce construction waste, thus promoting civilized construction.

[0066] Looking back Figure 1 and Figure 2The retaining wall 12 is equipped with a second core material assembly, which includes several second H-beams 121 distributed along the length of the retaining wall 12. The distance between several first H-beams 111 is smaller than the distance between each second H-beam 121, meaning the first H-beams 111 are arranged in a denser configuration to ensure the rigidity of the L-shaped wall 11, thereby reducing the deflection of the L-shaped wall 11 under the action of the soil outside the foundation pit, and further ensuring the safety factor of the external corner. The second H-beams 121 are inserted into the interior of the retaining wall 12 along its height, with the flanges of the second H-beams 121 facing the soil outside the foundation pit, so as to fully utilize the compressive and bending strength of the second H-beams 121.

[0067] In this embodiment of the application, the two ends of the second H-beam 121 are respectively provided as a second insertion part 1211 and a second fixing part 1212. The second insertion part 1211 is inserted into the interior of the L-shaped wall 11 along the height direction of the support wall 12, and the second fixing part 1212 is provided at the top of the second insertion part 1211 and extends out from the top of the support wall 12.

[0068] Reference Figure 4 A second capping beam 6 is provided at the top of the retaining wall 12. The second capping beam 6 is also a cast-in-place reinforced concrete beam. The second capping beam 6 is intermittently arranged with the first capping beam 5 to reduce the possibility of the second capping beam 6 interfering with the movement of the first capping beam 5. The bottom of several second fixing parts 1212 are embedded in the second capping beam 6, and the top of several second fixing parts 1212 extends out of the top of the second capping beam 6. The arrangement of the second capping beam 6 facilitates the connection of several second H-beams 121 into a whole, thereby increasing the structural integrity of the retaining wall 12 and further ensuring the safety factor of the external corner.

[0069] The bottom outer surface of the second fixing part 1212 is covered with a second EPE foam film 103. The second EPE foam film 103 and the bottom of the second fixing part 1212 are embedded in the second capping beam 6 to reduce the friction between the bottom of the second fixing part 1212 and the concrete used to pour the second capping beam 6. This facilitates the removal of the second H-beam 121 from the retaining wall 12 and the second capping beam 6 after the foundation pit is backfilled, thus enabling the second H-beam 121 to be reused. Reusing the second H-beam 121 further reduces construction costs and also helps to reduce construction waste, thereby promoting civilized construction.

[0070] Looking back Figure 2The water-stopping mechanism 2 includes connecting H-beams 21 and water-stopping components. In this embodiment, two connecting H-beams 21 are provided, each located within one of the two construction joints 101. The connecting H-beams 21 are positioned along the extension direction of the construction joints 101, with their two flanges inserted into the L-shaped wall 11 and the retaining wall 12, respectively. The height direction of the web of the connecting H-beams 21 is perpendicular to the penetration direction of the construction joint 101, thereby reducing groundwater entering the foundation pit from the construction joint 101 through the web of the connecting H-beams 21. Furthermore, the connection of the H-beams 21 transforms the connection between the L-shaped wall 11 and the retaining wall 12 into an elastic connection, which helps ensure the stability of the connection between the L-shaped wall 11 and the retaining wall 12 while maintaining relative independence between the L-shaped wall 11 and the retaining wall 12.

[0071] Continue to refer to Figure 2 A water-stop groove 104 is provided on the side of the external corner retaining wall 1 away from the soil. There are two water-stop grooves 104. The two water-stop grooves 104 are respectively located near the two construction joints 101 and are respectively connected to the two construction joints 101. The two water-stop components are respectively installed in the two water-stop grooves 104.

[0072] The water-stopping assembly includes a polyurethane coating 22, a water-swellable rubber sheet 23, and a fixing steel plate 24. The polyurethane coating 22 fills the construction joint 101 and is applied to the side of the retaining wall 12 away from the soil and the side of the L-shaped wall 11 away from the soil, to effectively block groundwater not effectively blocked by the web of the connected H-beam 21. The water-swellable rubber sheet 23 covers the polyurethane coating 22, and the fixing steel plate 24 covers the water-swellable rubber sheet 23, pressing the water-swellable rubber sheet 23 against the polyurethane coating 22. Two sides of the fixing steel plate 24 are respectively bolted to the L-shaped wall 11 and the retaining wall 12. This facilitates the absorption of groundwater not effectively blocked by the polyurethane coating 22 by the water-swellable rubber sheet 23, and fills the gap between the fixing steel plate 24 and the polyurethane coating 22 through the water-swellable property of the rubber sheet 23, thereby further reducing groundwater entering the foundation pit from the construction joint 101.

[0073] Looking back Figure 1 The support mechanism 3 includes a waler assembly and an inner support assembly. The waler assembly includes an inner waler 31, a supporting waler 32, and an outer waler 33. In this embodiment, there are two inner walers 31, which are respectively installed at both ends of the L-shaped wall 11, and both inner walers 31 are steel walers. The inner walers 31 are arranged horizontally and are fixedly installed to the L-shaped wall 11 by bolts.

[0074] Two walers 32 are provided, and the two walers 32 are installed on the two retaining walls 12 respectively. The walers 32 are cast-in-place reinforced concrete walers, and the walers 32 are fixedly connected to the retaining walls 12 by steel bars and concrete, and the walers 32 are set in the horizontal direction.

[0075] Reference Figure 5 The inner waler 31 is connected to the support waler 32 via a waler connecting assembly, which includes a connecting plate 311 and connecting reinforcing bars 312. One side of the connecting plate 311 is vertically welded and fixedly connected to one end of the inner waler 31. Two connecting reinforcing bars 312 are provided, with one end of each bar vertically welded and fixedly connected to the other side of the connecting plate 311. Both connecting reinforcing bars 312 are embedded within the support waler 32, and the ends of each bar 312 away from the connecting plate 311 are provided with hooks to ensure the stability of the connection between the two connecting reinforcing bars 312 and the concrete used for pouring the support waler 32, thereby increasing the stability of the connection between the inner waler 31 and the support waler 32.

[0076] Looking back Figure 1 The outer waler 33 is L-shaped, and its two ends are respectively arranged parallel to the two inner walers 31. The adjustment mechanism 4 is located between the inner walers 31 and the outer walers 33;

[0077] The adjustment mechanism 4 includes an ejector assembly and a support connection assembly. The ejector assembly includes jacks 41 and I-beams 42. In this embodiment, the number of jacks 41 and I-beams 42 is set to four. The four jacks 41 and four I-beams 42 are divided into two groups, with each group having two jacks 41 and two I-beams 42. The two groups of jacks 41 and I-beams 42 are respectively arranged in each inner waler 31, and the two jacks 41 and two I-beams 42 in each group are evenly distributed along the length direction of each inner waler 31.

[0078] The cylinder of the jack 41 is fixedly connected to one side of the outer waler 33 by bolts. One of the flanges of the I-beam 42 is fixedly installed on the piston rod of the jack 41 in the horizontal direction. The other flange of the I-beam 42 is pressed against the inner waler 31 so that the inner waler 31 can move away from or towards the outer waler 33 by extending or retracting the piston rod of the jack 41. In turn, the inner waler 31 drives the L-shaped wall 11 to move, thereby actively adjusting the deflection of the L-shaped wall 11 and ensuring the safety factor of the external corner.

[0079] In this embodiment, the number of supporting connection components is set to six. The six supporting connection components are divided into two groups, with three supporting connection components in each group. The two groups of supporting connection components are respectively disposed in each inner waler 31, and the three supporting components in each group are evenly distributed along the length direction of each inner waler 31. The jack 41 is located between two supporting components to ensure that the inner waler 31 is evenly stressed.

[0080] Reference Figure 3 and Figure 6 The supporting connection assembly includes a connecting seat 43, an adjusting steel plate 44, and a connecting pipe 45. The connecting seat 43 is welded and fixedly connected to the inner waler 31, and the connecting seat 43 has an insertion cavity 4301 extending horizontally. Three adjusting steel plates 44 are provided, all of which are disposed within the insertion cavity 4301. The three adjusting steel plates 44 are stacked sequentially in the horizontal direction and abut against the inner wall of the insertion cavity 4301 in the horizontal direction. A positioning assembly is provided within the insertion cavity 4301. The positioning assembly includes a first positioning ring 431, a second positioning ring 432, and a positioning block 433. One side of the first positioning ring 431 and the second positioning ring 432 abuts against the same adjusting steel plate 44, and the sides of the first positioning ring 431 and the second positioning ring 432 away from the adjusting steel plate 44 are both inclined.

[0081] The positioning block 433 is frustum-shaped, and the side of the first positioning ring 431 and the second positioning ring 432 with the inclined surface is the end of the positioning block 433 with the smaller cross-sectional area. A gap is left between the end of the positioning block 433 with the smaller cross-sectional area and the adjusting steel plate 44. The end of the positioning block 433 away from the first positioning ring 431 and the second positioning ring 432 is welded and fixedly connected to one end of the connecting pipe 45. One end of the connecting pipe 45 and the positioning block 433 are inserted into the insertion cavity 4301 in the horizontal direction, and a gap is left between the outer peripheral surface of the connecting pipe 45 and the insertion cavity 4301.

[0082] When the L-shaped wall 11 moves the inner waler 31 and the connecting seat 43 together towards the outer waler 33 under the action of earth pressure, the connecting seat 43 abuts against three stacked adjusting steel plates 44. The adjusting steel plates 44 abut against the first positioning ring 431 and the second positioning ring 432. The first positioning ring 431 and the second positioning ring 432 clamp the positioning block 433 with inclined surfaces, limiting the positioning block 433 and the connecting pipe 45, thereby ensuring the stability of the connection between the connecting pipe 45 and the connecting seat 43 when the piston rod of the jack 41 is not extended or retracted. At the same time, when the piston rod of the jack 41 extends or retracts, the first positioning ring 431 and the second positioning ring 432 no longer abut against the positioning block 433, and thus no longer limit the positioning block 433 and the connecting pipe 45, making it easier to adjust the position of the connecting seat 43 by extending and retracting the piston rod of the jack 41. The position of the easily adjustable connecting seat 43 helps to reduce the interference of the connecting pipe 45 on the movement of the inner waler 31 and the L-shaped wall 11, thereby ensuring that the L-shaped wall 11 moves more stably under the action of the jack 41.

[0083] The other end of the connecting pipe 45 is fixedly connected to one side of the outer waler 33 so as to ensure the stability of the movement of the L-shaped wall 11 driven by the inner waler 31 when the inner waler 31 moves away from or close to the outer waler 33. The connecting seat 43 is also provided with a socket 4302. The socket 4302 is located near the inner waler 31 and is connected to the insertion cavity 4301. This allows the adjusting steel plate 44 to be inserted into or removed from the insertion cavity 4301 through the socket 4302, keeping the connecting pipe 45 pressed against the connecting seat 43. This allows the earth pressure to be transmitted to the outer waler 33 through the connecting seat 43 and the connecting pipe 45, which helps to distribute the earth pressure more evenly to the outer waler 33 and reduces the occurrence of instability and failure due to excessive local load on the outer waler 33.

[0084] Looking back Figure 1 The support assembly includes several main beams 34, several auxiliary beams 35, and several stiffening plates 36. The main beams 34 and auxiliary beams 35 are fixedly connected to one side of the outer waler 33 and also fixedly connected to the support waler 32. The main beams 34 and auxiliary beams 35 are fixedly connected to each other and are arranged in a mesh pattern to ensure the overall stability of the support assembly. Several stiffening plates 36 are cast between each main beam 34 and each auxiliary beam 35, and each stiffening plate 36 is set close to the outer waler 33 to ensure the fixing effect of the inner support assembly on the outer waler 33.

[0085] The implementation principle of the foundation pit support structure in this application embodiment is as follows: by extending or retracting the piston rods of several jacks 41, the deflection of the L-shaped wall is actively controlled. Therefore, during the excavation of the soil in the foundation pit and the construction of the underground main structure, the deflection of the L-shaped wall 11 is controlled within a safe range based on monitoring results, ensuring the safety factor of the external corners and guaranteeing the safety inside and outside the foundation pit. Simultaneously, the jacks 41 occupy little construction space, facilitating construction and reducing the need for multiple internal supports or other reinforcement structures, thus ensuring the normal progress of construction.

[0086] This application also discloses a construction method for a pit support structure, including the following specific steps:

[0087] S1. Construct the external corner retaining wall 1 according to the TRD construction method;

[0088] S2. According to the specific design scheme, the external corner retaining wall 1 is divided into an L-shaped wall 11 and two supporting walls 12. Before the initial setting of the concrete used for pouring the external corner retaining wall 1, according to the specific construction scheme, several first H-beams 111 with the outer surface coated with friction reducing agent are sequentially inserted into the L-shaped wall 11, or several second H-beams 121 with the outer surface coated with friction reducing agent are sequentially inserted into the supporting walls 12, and finally several first H-beams 111 and several second H-beams 121 are respectively inserted into the L-shaped wall 11 and the supporting walls 12;

[0089] Reference Figure 7 When inserting the first H-beam 111 or the second H-beam 121, two temporary steel plates 7 with their outer surfaces coated with anti-friction agent are inserted at the location where the construction joint 101 needs to be set in the external corner retaining wall 1. Both temporary steel plates 7 are set along the extension direction of the construction joint 101, and a gap is left between the two temporary steel plates 7. The connecting H-beam 21 is inserted along the gap between the two temporary steel plates 7, so that the two flanges of the connecting H-beam 21 are respectively embedded in the L-shaped wall 11 and the supporting wall 12;

[0090] S3. After the L-shaped wall 11 and the supporting wall 12 are formed, all temporary steel plates 7 are pulled out from the external corner retaining wall 1 to form a construction joint 101.

[0091] S4. Cover the outer surfaces of the first fixing parts 1112 of a plurality of first H-beams 111 and the outer surfaces of the second fixing parts 1212 of a plurality of second H-beams 121 with a first EPE foam film 102 and a second EPE foam film 103 respectively, and fix the first EPE foam film 102 and the second EPE foam film 103 to the first fixing parts 1112 and the second fixing parts 1212 respectively with iron wire.

[0092] S5. Cast the first crown beam 5 and the second crown beam 6 on the top of the L-shaped wall 11 and the supporting wall 12 respectively;

[0093] S6. Excavate the soil of the foundation pit to the design elevation and install inner walers 31, outer walers 33, several main beams 34, several auxiliary beams 35 and several stiffening plates 36.

[0094] S6. Weld and fix several connecting seats 43 to the inner waler 31, then insert several connecting pipes 45 into the insertion cavity 4301 of each connecting seat 43, and make the positioning block 433 press against the first positioning ring 431 and the second positioning ring 432. Finally, fix the other end of several connecting pipes 45 to the outer waler 33 with bolts.

[0095] S7. The piston rods of several jacks 41 are pressed against the first crown beam 5 through the I-beam 42, and the cylinders of several jacks 41 are fixedly installed on the outer waler 33 by bolts.

[0096] S8. Extend the piston rods of several jacks 41 to make the inner waler 31 move away from the outer waler 33.

[0097] S9. Continue excavating the soil at the bottom of the inner waler 31, the supporting waler 32, the outer waler 33, several main beams 34, several auxiliary beams 35 and several stiffening plates 36; open a water-stop groove 104 on the side of the external corner retaining wall away from the soil, and open and install a polyurethane coating 22, a water-swellable rubber sheet 23 and a fixing steel plate 24 in the water-stop groove 104.

[0098] S10. After the construction of the underground building is completed and the foundation pit is backfilled, a number of first H-beams 111 and a number of second H-beams 121 will be pulled out from the L-shaped wall 11 and the support wall 12 respectively.

[0099] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A foundation pit support structure, characterized in that: The structure includes a corner retaining wall (1), a water-stopping mechanism (2), a support mechanism (3), and an adjustment mechanism (4). The corner retaining wall (1) has a construction joint (101). The construction joint (101) extends along the height direction of the corner retaining wall (1) to the top and bottom of the corner retaining wall (1), and the construction joint (101) penetrates along the thickness direction of the corner retaining wall (1). The corner retaining wall (1) includes an L-shaped wall (11) and a support wall (12). The L-shaped wall (11) is located on the support wall (12). The L-shaped wall (11) and the support wall (12) are respectively located on both sides of the construction joint (101). The water-stopping mechanism (2) is used to reduce the groundwater entering the foundation pit from the construction joint (101). The water-stopping mechanism (2) includes a connecting H-beam (21) and a water-stopping component. The connecting H-beam (21) is installed in the construction joint (101). The two flanges of the connecting H-beam (21) are respectively inserted into the L-shaped wall (11) and the support wall (12). The water-stopping assembly includes a polyurethane coating (22), a water-swellable rubber sheet (23), and a fixing steel plate (24). The polyurethane coating (22) fills the construction joint (101) and is applied to the side of the retaining wall (12) away from the soil and the side of the L-shaped wall (11) away from the soil. The water-swellable rubber sheet (23) is covered by the polyurethane coating (22), and the fixing steel plate (24) is covered by the water-swellable rubber sheet (23). The fixed steel plate (24) is fixedly installed on both sides of the retaining wall (12) and the L-shaped wall (11); the support mechanism (3) includes a waler assembly and an inner support assembly. The waler assembly includes an inner waler (31) and an outer waler (33). The inner waler (31) is installed on the side of the L-shaped wall (11) away from the soil. The outer waler (33) is installed on the inner waler (31). The inner support assembly is used to fix the outer waler (33). The adjustment mechanism (4) includes an ejector assembly and a support connection assembly. The ejector assembly includes a plurality of jacks (41). The plurality of jacks (41) are all disposed between the inner waler (31) and the outer waler (33). When the piston rods of the plurality of jacks (41) extend or retract, the inner waler (31) moves away from or closer to the outer waler (33). The support connection assembly is used to ensure that the outer waler (33) is disposed on the inner waler (31). The support connection components are provided in a plurality of ways, and each plurality of the support connection components are provided between the inner waler (31) and the outer waler (33). Each plurality of the support connection components includes a connecting seat (43), an adjusting steel plate (44) and a connecting pipe (45). Each plurality of the connecting seats (43) are fixedly installed on the inner waler (31), and each plurality of the connecting seats (43) is provided with an insertion cavity (4301). The adjusting steel plate (44) is disposed in the insertion cavity (4301); One end of each of the connecting tubes (45) is inserted into each insertion cavity (4301), and a gap is left between the outer peripheral surface of the connecting tube (45) and the inner wall of the insertion cavity (4301). The other end of each of the connecting tubes (45) is fixedly installed on the outer waler (33). Each of the connecting seats (43) is provided with a socket (4302), and the socket (4302) is connected to each insertion cavity (4301). A positioning component is provided in the insertion cavity (4301). The positioning component includes a first positioning ring (431), a second positioning ring (432), and a positioning block (433). One side of the first positioning ring (431) and the second positioning ring (432) are both pressed against the same adjusting steel plate (44), and the side of the first positioning ring (431) and the second positioning ring (432) away from the adjusting steel plate (44) is set with an incline. The positioning block (433) is frustum-shaped, and the side of the first positioning ring (431) and the second positioning ring (432) with inclined surfaces are both pressed against the end of the positioning block (433) with the smaller cross-sectional area. A gap is left between the end of the positioning block (433) with the smaller cross-sectional area and the adjusting steel plate (44). The end of the positioning block (433) away from the first positioning ring (431) and the second positioning ring (432) is welded and fixedly connected to one end of the connecting pipe (45). One end of the connecting pipe (45) and the positioning block (433) are inserted into the insertion cavity (4301) in the horizontal direction. A gap is left between the outer circumferential surface of the connecting pipe (45) and the insertion cavity (4301).

2. The foundation pit support structure according to claim 1, characterized in that: The L-shaped wall (11) and the supporting wall (12) are both TRD method cement-soil mixing walls.

3. The foundation pit support structure according to claim 2, characterized in that: The L-shaped wall (11) is provided with a first core material assembly, which includes a plurality of first H-beams (111). The plurality of first H-beams (111) are distributed along the length direction of the L-shaped wall (11), and the first H-beams (111) are all inserted into the L-shaped wall (11) along the height direction of the L-shaped wall (11).

4. The foundation pit support structure according to claim 3, characterized in that: The retaining wall (12) is provided with a second core material assembly, which includes a plurality of second H-beams (121). The plurality of second H-beams (121) are distributed along the length direction of the retaining wall (12), and the plurality of second H-beams (121) are inserted into the retaining wall (12) along the height direction of the retaining wall (12). The distance between the plurality of first H-beams (111) is smaller than the distance between each second H-beam (121).

5. The foundation pit support structure according to claim 3, characterized in that: One of the first H-beams (111) near the corner of the L-shaped wall (11) is set as a corner H-beam. The corner H-beam is inclined, that is, there is an angle between the web of the corner H-beam and the web of each of the other first H-beams (111), and the corner H-beam is set close to the soil.

6. The foundation pit support structure according to claim 1, characterized in that: The internal support assembly includes several main beams (34), several auxiliary beams (35), and several stiffening plates (36). The main beams (34) and the auxiliary beams (35) are all fixedly installed on the outer waler (33). The main beams (34) and the auxiliary beams (35) are arranged in a mesh. The stiffening plates (36) are all cast between each main beam (34) and each auxiliary beam (35), and the stiffening plates (36) are all arranged close to the outer waler (33).

7. A construction method for a foundation pit support structure according to claim 6, comprising the following specific steps: S1. The L-shaped wall (11) and the retaining wall (12) are constructed using the TRD method, and a construction joint (101) is set between the L-shaped wall (11) and the retaining wall (12). S2. Insert a number of first H-beams (111) and a number of second H-beams (121) into the L-shaped wall (11) and the support wall (12) respectively; set the connecting H-beam (21) in the construction joint (101) and insert the two flanges of the connecting H-beam (21) into the L-shaped wall (11) and the support wall (12) respectively; S3. Excavate the soil of the foundation pit to the design elevation and set up an inner waler (31), an outer waler (33), several main beams (34), several auxiliary beams (35) and several stiffening plates (36); S4. Place several jacks (41), several connecting seats (43), and several connecting pipes (45) between the inner waler (31) and the outer waler (33); S5. Extend the piston rods of several jacks (41) to make the inner waler (31) move away from the outer waler (33); S6. Continue to excavate the soil of the foundation pit at the bottom of the inner waler (31), outer waler (33), several main beams (34), several auxiliary beams (35) and several stiffening plates (36), and install polyurethane coating (22), water-swellable rubber sheet (23) and fixing steel plate (24).

8. The construction method of a foundation pit support structure according to claim 7, characterized in that: In step S2, the method for setting up the connecting H-beam (21) specifically includes: S21. Insert two temporary steel plates (7) with friction-reducing agent on their outer surfaces between the L-shaped wall (11) and the supporting wall (12) along the extension direction of the construction joint (101), and leave a gap between the two temporary steel plates (7). S22. Insert the connecting H-beam (21) into the gap between the two temporary steel plates (7), and insert the two flanges of the connecting H-beam (21) into the L-shaped wall (11) and the supporting wall (12) respectively. S23. After the L-shaped wall (11) and the support wall (12) are formed and the two flanges of the connecting H-beam (21) are respectively embedded in the L-shaped wall (11) and the support wall (12), the two temporary steel plates (7) are pulled out.

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