A self-balanced foundation pit assembly support structure and construction method

Abstract

A self-balanced foundation pit assembly support structure and construction method, the structure comprises a foundation pit, a dumbbell type pile and a sheet pile are arranged in the foundation pit to form a support structure in the foundation pit; the dumbbell type pile comprises a tie beam and end beams fixed at both ends of the tie beam, a through hole is penetrated in the end beam, an anchoring pipe extending into the deep soil is installed in the through hole, and the side wall of the end beam has a vertical groove; the side wall of the sheet pile is provided with a groove matching convex that matches the vertical groove, and an upper support is installed on the dumbbell type pile and the sheet pile, the upper support is connected with the dumbbell type pile, one end of the upper support abuts against a diagonal bracing mechanism, and the bottom end of the diagonal bracing mechanism abuts against the bottom of the foundation pit, the end beam of the dumbbell type pile provides a larger bending section, and the anchoring of the anchoring pipe in the deep soil provides reliable bottom restraint. This makes the dumbbell type pile itself effectively resist and balance the lateral earth pressure transmitted from the sheet pile, reduces the complete dependence on the internal support system, and improves the overall stability and safety redundancy of the support system.

Description

Technical Field

[0001] This invention relates to the fields of geotechnical engineering and underground construction technology, and in particular to a self-balancing prefabricated support structure for foundation pits and its construction method. Background Technology

[0002] In urban construction, deep foundation pit projects are becoming increasingly common, making the safety and economy of their support structures crucial. Currently, common foundation pit support structures include pile walls combined with internal bracing, diaphragm walls, and steel-cement-soil mixing walls. These traditional methods have some shortcomings: for example, pile structures have relatively poor overall integrity, and water leakage easily occurs between piles; while diaphragm walls offer good water-stopping effects, they are expensive, have long construction periods, and pose significant environmental risks due to mud treatment; and conventional sheet pile or combined support structures have limited lateral stiffness and self-stabilizing capacity, requiring a robust internal bracing system, which restricts the working space inside the foundation pit, and makes the installation and dismantling of the support system complex and difficult.

[0003] Furthermore, the existing seepage prevention systems of support structures are mostly pre-embedded in one go. Once local leakage occurs during the use of the foundation pit, it is difficult to quickly and effectively remedy the situation, posing a safety hazard. At the same time, the internal supports in the foundation pit affect the working space within the pit. The installation of internal supports or diagonal braces requires high precision. Traditional methods often require complex on-site measurements and cutting matching, resulting in low construction efficiency and difficulty in adjustment. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of existing technology, such as easy water leakage between piles, complex installation and difficult dismantling of foundation pit support, and to provide a self-balancing foundation pit assembly support structure and construction method.

[0005] The technical solution adopted by the present invention to solve its technical problem is a self-balancing foundation pit assembly support structure and construction method, including a foundation pit, wherein dumbbell-shaped piles and sheet piles are set in the foundation pit to form a retaining structure in the foundation pit. The dumbbell-shaped pile includes a tie beam and end beams fixed at both ends of the tie beam. The end beams have through holes extending along the length direction. An anchor pipe is installed in the through holes, and the bottom of the anchor pipe extends into the deep soil. The side wall of the end beam closer to the pit has a vertical groove. The sidewall of the sheet pile is provided with a groove protrusion that matches the vertical groove. One end of the sheet pile along the length direction is provided with a receiving protrusion and the other end has a receiving groove. Two symmetrically installed oblique plates are provided on the sidewall of the sheet pile. The receiving protrusion and the receiving groove of the sheet pile match each other to realize the installation of multiple sheet piles. When adjacent sheet piles are installed, the adjacent oblique plates on the two sheet piles abut against each other. The dumbbell-shaped piles and sheet piles are equipped with upper supports, which are connected to the dumbbell-shaped piles. One end of the upper support located in the foundation pit abuts against a diagonal bracing mechanism, and the bottom end of the diagonal bracing mechanism abuts against the bottom of the foundation pit.

[0006] Furthermore, the lower part of the anchor pipe has grouting holes. Grout is injected into the anchor pipe through the grouting holes to form a solidified body that wraps around the lower part of the anchor pipe and consolidates it with the deep soil.

[0007] Furthermore, the inclined plate on the sheet pile is divided into an inclined left plate and an inclined right plate. The inclined left plate is provided with a snap-fit ​​block, and the inclined right half has a snap-fit ​​groove, and the snap-fit ​​block matches the snap-fit ​​groove. When two sheet piles are installed together, the snap-fit ​​groove of the inclined right plate on one sheet pile and the snap-fit ​​block of the inclined left plate on the other sheet pile are interlocked, and the sheet pile, the inclined left plate and the inclined right plate form a triangular cavity.

[0008] Furthermore, the upper support includes an embedded tube, a crossbeam, and corner braces. One end of the crossbeam is provided with an embedded tube, and the other end of the crossbeam has a support groove. The embedded tube is inserted into the anchor tube for fixation. The crossbeam is installed facing the direction into the foundation pit. The corner braces are installed at the bottom of the crossbeam, and the sides of the corner braces are fixedly installed on the sheet piles.

[0009] Furthermore, the diagonal bracing mechanism includes a diagonal brace, a connecting end, and an anchoring column. The top end of the diagonal brace is installed in the support groove, and the anchoring column is set and abuts against the bottom of the foundation pit. One end of the connecting end is connected to the bottom of the diagonal brace, and the other end is connected to the top of the anchoring column.

[0010] Furthermore, the connecting end includes a movable hinge, a movable hinge, and a mounting frame. The movable hinge is movably connected to the top of the anchor column and the bottom of the mounting frame via the movable hinge, and the bottom end of the diagonal brace is fitted into the mounting frame.

[0011] Furthermore, the top of the anchor pile is equipped with a telescopic rod that can extend and retract. The extension and retraction of the telescopic rod fixes the top of the diagonal brace in the support groove, and the bottom of the diagonal brace can be installed in the mounting frame. After the diagonal brace mechanism is installed stably, a connecting rod is welded to the movable hinge, so that the movable hinge changes from a rotating connection to a fixed connection.

[0012] A further solution to the technical problem of this invention is a construction method for a self-balancing foundation pit assembly support structure, comprising the following steps: S1. Excavation trenches are excavated in the soil of the foundation pit to be excavated using the trenching method. The dumbbell-shaped pile is driven into the excavation trench, and the anchor pipe is driven into the through hole of the dumbbell-shaped pile end beam so that the bottom end of the anchor pipe enters the deep soil. Grout is injected into the deep soil through the grouting hole at the bottom of the anchor pipe to form a solid body that wraps the bottom of the anchor pipe, thereby achieving deep anchoring of the dumbbell-shaped pile. S2. Construction of sheet pile driving and joint seepage prevention structure: Based on dumbbell-shaped piles, sheet piles are driven into the soil in sequence, so that the joint protrusion of each sheet pile is inserted into the vertical groove of the end beam of the adjacent dumbbell-shaped pile; adjacent sheet piles form the first interface by inserting the receiving protrusion and the receiving groove, and form the second interface by the engagement of the snap-fit ​​groove and the snap-fit ​​block on the inclined plate; a triangular cavity is formed between the inclined plate of two adjacent sheet piles and the sheet pile body. S3. Initial excavation of the foundation pit and installation of the upper support: Excavate the foundation pit to the initial excavation surface, the elevation of which is lower than the bottom elevation of the upper support to be installed; install the upper support by first inserting the embedded pipe into the anchor pipe and fixing it, then installing the crossbeam so that one end is connected to the end beam and the embedded pipe, and then installing the corner brace at the bottom of the crossbeam and supporting the side of the corner brace on the inner side of the sheet pile. S4. Excavation of the foundation pit to the bottom and installation of the inclined bracing mechanism: Continue excavating the foundation pit to the designed bottom elevation; An anchoring column is installed at a predetermined position at the bottom of the pit. The top of the anchoring column is provided with a connecting end, which includes a movable hinge and a mounting frame connected by a movable hinge shaft. Install the diagonal bracing mechanism: Adjust the movable hinge and the telescopic rod on the anchor column to lower the top of the connection end, making room for the bottom of the diagonal bracing mechanism. After initially fixing the bottom of the diagonal bracing mechanism, adjust the extended movable hinge and the telescopic rod so that the telescopic rod presses against the bottom surface of the diagonal bracing mechanism and fixes the bottom of the diagonal bracing mechanism in the installation frame. At the same time, install the top of the diagonal bracing mechanism in the support groove of the crossbeam. S5. Main Structure Construction and Support Removal: The base slab and subsequent structures of the main construction structure are constructed; after the main construction is completed, the diagonal bracing mechanism, upper support and foundation pit support structure are dismantled in sequence.

[0013] Furthermore, in step S2, if leakage is found at a specific connection interface during the use or maintenance of the foundation pit, anti-seepage material is pressure-injected into the triangular cavity corresponding to the interface to form a local rigid anti-seepage body.

[0014] Furthermore, in step S4, after the diagonal bracing mechanism is installed and stabilized under force, a connecting rod is welded between adjacent movable hinges at the connection end, so that the movable hinges are changed to a fixed connection.

[0015] In summary, the present invention has the following beneficial technical effects: 1. Strong self-balancing ability and high support safety: This invention combines dumbbell-shaped piles with anchor pipes and deep consolidation bodies to form a unique self-balancing system. The end beams of the dumbbell-shaped piles provide a large bending cross-section, and the anchoring of the anchor pipes in the deep soil provides reliable bottom restraint. This allows the dumbbell-shaped piles themselves to effectively resist and balance the lateral earth pressure transmitted from the sheet piles, reducing complete reliance on the internal support system and improving the overall stability and safety redundancy of the support system.

[0016] 2. Dynamic seepage prevention and reliable water stopping: This invention designs a triangular cavity between the inclined joints of adjacent sheet piles. This cavity not only serves as a construction observation channel, but more importantly, it provides a "dynamic seepage prevention" mechanism. When a seepage point is found at any connection interface (first interface or second interface) during the use or maintenance phase of the foundation pit, quick-setting concrete or other materials can be immediately injected into the corresponding triangular cavity to quickly form a locally thickened rigid seepage barrier, achieving "immediate sealing upon leakage." This overcomes the shortcomings of traditional pre-embedded waterstops, which are difficult to remedy once they fail, and significantly improves the long-term water stopping reliability of the foundation pit.

[0017] 3. Standardized components, precise connections, and convenient and efficient construction: Both dumbbell-shaped piles and sheet piles are prefabricated in the factory, ensuring controllable quality. Through precisely matched vertical grooves and connecting protrusions, receiving protrusions and receiving grooves, and snap-fit ​​blocks and snap-fit ​​grooves, rapid and precise assembly connections between retaining wall components are achieved, ensuring the integrity and verticality of the retaining wall and significantly improving on-site construction efficiency.

[0018] 4. The support system is easy to install and adjust, and has strong applicability: The bottom connection end of the diagonal brace in this invention is ingeniously designed, integrating a movable hinge, a movable pivot, a mounting frame, and a telescopic rod. This design allows for simple mechanical operations during installation, first lowering the installation position to provide operating space, and then precisely lifting and locking the diagonal brace. This adjustable design greatly reduces the stringent requirements on the pit bottom elevation and anchor column installation accuracy, simplifies the diagonal brace installation process, and improves construction efficiency and adaptability to complex working conditions. After installation, it can be transformed into a rigid node by welding connecting rods to ensure reliable stress distribution.

[0019] 5. Clear force transmission path and reasonable structural system: The present invention resists lateral earth pressure by combining the retaining structure, upper support and diagonal bracing mechanism. The earth pressure is borne by the sheet piles, transmitted to the crossbeam through the corner braces and diagonal bracing rods, and then transmitted to the dumbbell-shaped piles and their anchoring system through the embedded pipes. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of an embodiment of a self-balancing foundation pit assembly support structure of the present invention; Figure 2This is a schematic diagram of the enclosure and superstructure construction of an embodiment of a self-balancing foundation pit assembly support structure according to the present invention; Figure 3 for Figure 2 Enlarged view of node A in the middle; Figure 4 This is a schematic diagram of a dumbbell-shaped pile structure according to an embodiment of a self-balancing foundation pit assembly support structure of the present invention; Figure 5 This is a schematic diagram of the dumbbell-shaped pile excavation trench installation according to an embodiment of the self-balancing foundation pit assembly support structure of the present invention; Figure 6 This is a schematic diagram of a sheet pile structure according to an embodiment of a self-balancing foundation pit assembly support structure of the present invention; Figure 7 for Figure 6 Enlarged view of node B in the middle; Figure 8 for Figure 7 Enlarged view of node B1; Figure 9 for Figure 7 Enlarged view of node B2; Figure 10 This is a schematic diagram showing the installation and connection of sheet piles and dumbbell-shaped piles. Figure 11 for Figure 10 Enlarged view of node C in the middle; Figure 12 This is a schematic diagram of the anchor pipe structure of an embodiment of the self-balancing foundation pit assembly support structure of the present invention; Figure 13 This is a schematic diagram of the anchor column and its connection end structure according to an embodiment of the self-balancing foundation pit assembly support structure of the present invention.

[0021] Explanation of reference numerals in the attached figures: 1. Excavation pit; 2. Soil; 3. Excavation trench; 4. Dumbbell pile; 5. Tie beam; 6. End beam; 7. Through hole; 8. Vertical trench; 9. Anchor pipe; 10. Grouting hole; 11. Consolidated body; 12. Sheet pile; 13. Joint protrusion; 14. Receiving protrusion; 15. Receiving groove; 16. Diagonal joint plate; 17. Snap-fit ​​groove; 18. Snap-fit ​​block; 19. First interface; 20. Second interface; 21. Triangular cavity; 22. Initial excavation face; 23. Pit bottom; 24. Upper support; 25. Embedded pipe; 26. Horizontal beam; 27. Angle brace; 28. Support groove; 29. ​​Diagonal bracing mechanism; 30. Connecting end; 31. Anchor column; 32. Movable hinge shaft; 33. Movable hinge; 34. Mounting frame; 35. Telescopic rod; 36. Base plate. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0023] Reference Figure 1 and Figure 2 This embodiment of a self-balancing foundation pit 1 assembly support structure includes dumbbell-shaped piles 4, sheet piles 12, an upper support 24, and a diagonal bracing mechanism 29 disposed inside the foundation pit 1. Multiple dumbbell-shaped piles 4 and multiple sheet piles 12 form the retaining structure of the foundation pit 1. The upper support 24 is connected to the dumbbell-shaped piles 4. One end of the diagonal bracing mechanism 29 abuts against the bottom of the foundation pit 1, and the other end abuts against the upper support 24.

[0024] Reference Figure 4 , Figure 5 and Figure 12 The dumbbell-shaped pile 4 includes a tie beam 5 located in the middle and end beams 6 connected to both ends of the tie beam 5. The tie beam 5 is a long strip, and the end beams 6 are polygons with parallel upper and lower bottom edges, with one bottom edge being longer and the other bottom edge being shorter. The length of the shorter side is the same as the width of the tie beam 5 and they are connected to each other. The dumbbell shape is formed by the axes of the tie beam 5 and the two end beams 6 coinciding with each other.

[0025] Specifically, a through hole 7 extending along the length direction is passed through the end beam 6, and one of the end beams 6 contacts the sheet pile 12. The side wall of the end beam 6 in contact with the sheet pile 12 has a vertical groove 8. An anchoring pipe 9 is installed in the through hole 7 on the dumbbell-shaped pile 4. The outer diameter of the anchoring pipe 9 is slightly smaller than the diameter of the through hole 7. The upper part of the anchoring pipe 9 is inserted into the through hole 7, and the lower part of the anchoring pipe 9 extends into the deep soil 2. At the same time, the lower part of the anchoring pipe 9 has a grouting hole 10. The presence of the grouting hole 10 allows for the formation of a solidified body 11 through grouting to achieve deep anchoring.

[0026] Reference Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 and Figure 11 Multiple sheet piles 12 are installed in the foundation pit 1, arranged in two groups side by side, with the sheet piles 12 connected end to end in each group. A groove protrusion 13 is integrally formed on the side wall of the sheet pile 12 away from the interior of the foundation pit 1, and the groove protrusion 13 matches the shape of the vertical groove 8 on the end beam 6 of the dumbbell-shaped pile 4. The groove protrusion 13 fits into the vertical groove 8 of the dumbbell-shaped pile 4, allowing the dumbbell-shaped pile 4 to be secured to the sheet pile 12. Two symmetrical groove protrusions 13 are provided on the sheet pile 12, enabling the simultaneous installation of two dumbbell-shaped piles 4 on one sheet pile 12.

[0027] The right end of the sheet pile 12 is provided with a receiving protrusion 14, and the left end of the sheet pile 12 is provided with a receiving groove 15. The shapes of the receiving protrusion 14 and the receiving groove 15 match, so that the receiving protrusion 14 of the previous sheet pile 12 and the receiving groove 15 of the next sheet pile 12 match and fit together, realizing the mutual connection between the sheet piles 12 and the sheet pile 12. The receiving protrusion 14 and the receiving groove 15 form a plug-in type first interface 19.

[0028] Two oblique connecting blocks are provided on the side wall of the sheet pile 12, which is the same as the groove protrusion 13. The two oblique connecting blocks are symmetrically positioned, but their structures are not exactly the same. The two oblique connecting blocks are divided into an oblique left block and an oblique right block according to their positions. The oblique left block is perpendicular to the sheet pile 12 and inclined towards the receiving groove 15, while the oblique right block is straight on the sheet pile 12 and inclined towards the receiving protrusion 14. At the same time, the two groove protrusions 13 are located between the two oblique blocks. A snap-fit ​​block 18 is provided on the oblique left block, and a snap-fit ​​block 18 is provided on the oblique right block. The snap-fit ​​groove 17 and the snap-fit ​​block 18 match the shape of the snap-fit ​​groove 17. When the two sheet piles 12 are installed together, the snap-fit ​​block 18 on the left side of the first sheet pile 12 matches and fits into the snap-fit ​​groove 17 on the right side of the second sheet pile 12. The snap-fit ​​block 18 and the snap-fit ​​groove 17 form a nested second interface 20. After the snap-fit ​​block 18 and the snap-fit ​​groove 17 fit together, the two inclined plates 16 and the sheet piles 12 enclose a closed triangular cavity 21, which serves as a seepage channel or monitoring space.

[0029] Reference Figure 1 and Figure 3 The upper support 24 includes an embedded tube 25, a crossbeam 26, and a corner brace 27. The crossbeam 26 is fixedly connected to the embedded tube 25, and the embedded tube 25 is inserted into the anchoring tube 9 and fixed by welding, so that the crossbeam 26 faces the pit 1. The corner brace 27 is triangular in shape. One right-angled side of the corner brace 27 is fixed to the bottom of the crossbeam 26, and the other right-angled side of the corner brace 27 is fixed to the side wall of the sheet pile 12 near the pit 1, so that the exposed suspended part of the crossbeam 26 is supported. The exposed part of the crossbeam 26 has a support groove 28 for installing the diagonal bracing mechanism 29.

[0030] Reference Figure 1 and Figure 13The diagonal bracing mechanism 29 includes a diagonal brace, a connecting end 30, and an anchor rod, which are connected sequentially. The top end of the diagonal brace is located in the support groove 28, and the bottom end is connected to the connecting end 30. The connecting end 30 is connected to the anchor rod. The connecting end 30 includes a movable hinge pin 32, a movable hinge 33, and a mounting frame 34. The movable hinge 33 is movably connected to the top of the anchor column 31 and the bottom of the mounting frame 34 through the movable hinge pin 32, so that the mounting frame 34 can be extended and retracted through the movable hinge 33. The mounting frame 34 is a hollow, through-hole square frame so that the bottom of the diagonal brace is fitted into the mounting frame 34.

[0031] An adjustable telescopic rod 35 is installed at the top of the anchor pile. When installing the diagonal brace, the movable hinge 33 and the telescopic rod 35 are first compressed to provide extra space for installation. After placing the diagonal brace in this space, the movable hinge 33 and the telescopic rod 35 extend, so that the telescopic rod 35 abuts against the bottom surface of the diagonal brace. The top of the diagonal brace is simultaneously installed into the support groove 28 on the crossbeam 26. At this time, the bottom of the diagonal brace fits into the mounting frame 34 as the movable hinge 33 extends. After the diagonal brace is stable, a connecting rod is welded between adjacent movable hinges 33, so that the movable hinge 33 changes from movable to fixed. The telescopic rod 35 provides a reinforcing force for the diagonal brace, allowing it to abut against the support groove 28. Simultaneously, before installing the diagonal brace, the anchor pile has already abutted against the bottom of the foundation pit 1, ensuring stability.

[0032] An embodiment of the present invention discloses a construction method for a self-balancing prefabricated support structure for a foundation pit, comprising the following steps: Sinking and deep anchoring of S1 and dumbbell-shaped pile 4 Within the soil 2 of the foundation pit 1 to be excavated, a trench 3 of a set size is excavated using a hydraulic grab bucket or a trenching machine; the pre-fabricated dumbbell-shaped piles 4 are hoisted and vertically sunk into the trench 3; the planar position of the dumbbell-shaped piles 4 is precisely arranged according to the connection requirements of the subsequent sheet piles 12, with two dumbbell-shaped piles 4 forming a group, and each group corresponding to a sheet pile 12 connection node.

[0033] After the installation is completed, the anchor pipe 9 is driven into the through hole 7 of the end beam 6 of the dumbbell-shaped pile 4. The outer diameter of the anchor pipe 9 is slightly smaller than the diameter of the hole to ensure smooth insertion. The bottom end of the anchor pipe 9 penetrates the weak soil layer and enters the deep stable soil body 2. Cement grout is injected from the top of the anchor pipe 9. The grout seeps into the surrounding soil body 2 through the grouting hole 10 in the lower part of the anchor pipe 9. After solidification, it forms a solidified body 11 around the lower part of the anchor pipe 9. Since the upper part of the anchor pipe 9 is inserted into the hole of the dumbbell-shaped pile 4, the deep anchoring of the dumbbell-shaped pile 4 is achieved through the interlocking action of the solidified body 11 and the deep soil body 2.

[0034] S2, Sheet Pile 12 Sinking and Joint Seepage Prevention Construction After the dumbbell-shaped pile 4 is in place, the sheet piles 12 are driven in one after another close to its inner side; during the driving process, ensure that the joint protrusion 13 of each sheet pile 12 is accurately inserted into the vertical groove 8 of the corresponding dumbbell-shaped pile 4 end beam 6. Adjacent sheet piles 12 are connected by a receiving protrusion 14 and a receiving groove 15 to form a first interface 19; at the same time, they are fitted with a snap-fit ​​block 18 through a snap-fit ​​groove 17 on a wedge plate 16 to form a second interface 20; the two wedge plates 16 not on the same sheet pile 12 and the main body of the sheet pile 12 together form a triangular cavity 21; the triangular cavity 21 is kept empty in the initial stage and serves as a seepage channel or monitoring space. If leakage occurs later, concrete can be poured into the triangular cavity 21 to form a rigid seepage barrier.

[0035] S3, Initial excavation of foundation pit 1 and installation of upper support 24 After completing the retaining structure formed by the dumbbell-shaped piles 4 and sheet piles 12, the soil 2 of the foundation pit 1 is excavated to the initial excavation surface 22, and the elevation of this surface is slightly lower than the bottom of the upper support 24. Install the upper support 24, insert the embedded tube 25 into the anchoring tube 9 that has been installed in the through hole 7 of the dumbbell-shaped pile 4, and achieve a fixed connection between the embedded tube 25 and the anchoring tube 9 by full welding; install the crossbeam 26 so that one end of the end beam 6 and the embedded tube 25 are reliably connected, and the other end extends horizontally into the inside of the foundation pit 1; install the corner brace 27 at the bottom of the crossbeam 26, and the side of the corner brace 27 is close to and supported on the inner side of the sheet pile 12; thus, the lateral pressure of the soil 2 on the sheet pile 12 is transmitted in sequence through the corner brace 27, the crossbeam 26, the embedded tube 25, the anchoring tube 9, and the dumbbell-shaped pile 4, and is borne by the dumbbell-shaped pile 4 which has the ability to balance itself.

[0036] S4. Excavation of foundation pit 1 to the bottom and installation of diagonal bracing. Continue excavation to the designed pit bottom elevation 23; drive anchor columns 31 at the designated position at the pit bottom 23; the top of the anchor columns 31 is equipped with a connecting end 30; The connecting end 30 consists of a movable hinge 32, a movable hinge 33, and a mounting groove. The top of the movable hinge 33 is connected to the mounting frame 34 formed by the frame enclosure. The movable hinge 33 is movably connected to the top of the anchor column 31 and the bottom of the mounting frame 34 through the movable hinge 32. The top elevation of the mounting frame 34 can be adjusted by rotating the movable hinge 33 around the movable hinge 32. Anchor column 31 is equipped with telescopic rod 35 at the top; when installing diagonal brace, first press down to retract hinge 33 and telescopic rod 35, forming an installation space above connection end 30; temporarily fix the bottom end of diagonal brace in this space; then extend hinge 33 and telescopic rod 35, so that telescopic rod 35 rises and abuts against the bottom surface of diagonal brace, while the bottom end of diagonal brace is completely embedded in the groove of mounting frame 34; the top end of diagonal brace is simultaneously installed into support groove 28 on crossbeam 26; After the diagonal brace stabilizes under stress, a connecting rod is welded between adjacent movable hinges 33 to change the movable hinge 33 from movable to fixed, ensuring long-term stability.

[0037] S5. Main Structure Construction and Support Removal After the diagonal bracing is installed, the base slab 36 of the main structure is poured. After the main structure (including the base slab 36, side walls, and top slab) is fully constructed and reaches the design strength, the diagonal bracing, upper support 24, and other support components are removed in sequence. The removal process follows the principle of "install first, then remove" to ensure the safe transition of the structure to the permanent system.

[0038] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Identical components are represented by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, while the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component. Therefore, all equivalent changes made to the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A self-balancing foundation pit assembly support structure, characterized in that, Includes a foundation pit (1), in which dumbbell-shaped piles (4) and sheet piles (12) are installed to form a retaining structure within the foundation pit (1); The dumbbell-shaped pile (4) includes a tie beam (5) and end beams (6) fixed at both ends of the tie beam (5). The end beams (6) have through holes (7) extending along the length direction. An anchor pipe (9) is installed in the through hole (7), and the bottom of the anchor pipe (9) extends into the deep soil (2). The side wall of the end beam (6) closer to the pit (1) has a vertical groove (8). The side wall of the sheet pile (12) is provided with a groove protrusion (13) that matches the vertical groove (8). One end of the sheet pile (12) along the length direction is provided with a receiving protrusion (14) and the other end has a receiving groove (15). Two symmetrically installed oblique plates (16) are provided on the side wall of the sheet pile (12). The receiving protrusion (14) and the receiving groove (15) of the sheet pile (12) match each other to realize the mutual installation of multiple sheet piles (12). When adjacent sheet piles (12) are installed, the adjacent oblique plates (16) on the two sheet piles (12) abut against each other. The dumbbell-shaped pile (4) and sheet pile (12) are equipped with an upper support (24), which is connected to the dumbbell-shaped pile (4). The upper support (24) is located in the pit (1) and abuts against a diagonal bracing mechanism (29). The bottom end of the diagonal bracing mechanism (29) abuts against the bottom of the pit (1).

2. The self-balancing foundation pit assembly support structure according to claim 1, characterized in that, The lower part of the anchor pipe (9) has a grouting hole (10). The solidified body (11) formed by grouting into the anchor pipe (9) through the grouting hole (10) wraps the lower part of the anchor pipe (9) and is solidified with the deep soil (2).

3. The self-balancing foundation pit assembly support structure according to claim 1, characterized in that, The oblique plate (16) on the sheet pile (12) is divided into an oblique left plate and an oblique right plate. A snap-fit ​​block (18) is provided on the oblique left plate, and a snap-fit ​​groove (17) is provided on the oblique right half. The snap-fit ​​block (18) matches the snap-fit ​​groove (17). When two sheet piles (12) are installed together, the snap-fit ​​groove (17) of the oblique right plate on one sheet pile (12) and the snap-fit ​​block (18) of the oblique left plate on the other sheet pile (12) fit together. A triangular cavity (21) is formed between the sheet pile (12), the oblique left plate and the oblique right plate.

4. The self-balancing foundation pit assembly support structure according to claim 1, characterized in that, The upper support (24) includes an embedded tube (25), a crossbeam (26) and a corner brace (27). One end of the crossbeam (26) is provided with an embedded tube (25), and the other end of the crossbeam (26) has a support groove (28). The embedded tube (25) is inserted into the anchoring tube (9) for fixation. The crossbeam (26) is installed facing the direction of the foundation pit (1). The corner brace (27) is installed at the bottom of the crossbeam (26), and the side of the corner brace (27) is fixedly installed on the sheet pile (12).

5. The self-balancing foundation pit assembly support structure according to claim 4, characterized in that, The diagonal bracing mechanism (29) includes a diagonal bracing rod, a connecting end (30), and an anchoring column (31). The top end of the diagonal bracing rod is installed in the support groove (28). The anchoring column is set and abuts against the bottom of the foundation pit (1). One end of the connecting end (30) is connected to the bottom of the diagonal bracing rod, and the other end is connected to the top of the anchoring column.

6. The self-balancing foundation pit assembly support structure according to claim 5, characterized in that, The connecting end (30) includes a movable hinge (32), a movable hinge (33), and a mounting frame (34). The movable hinge (33) is movably connected to the top of the anchor column (31) and the bottom of the mounting frame (34) respectively through the movable hinge (32). The bottom end of the diagonal brace is fitted into the mounting frame (34).

7. The self-balancing foundation pit assembly support structure according to claim 5, characterized in that, The top of the anchor pile is equipped with a telescopic rod (35) that can extend and retract. The extension and retraction of the telescopic rod (35) fixes the top of the diagonal brace in the support groove (28). The bottom of the diagonal brace can be installed in the mounting frame (34). After the diagonal brace mechanism (29) is installed and stabilized, a connecting rod is welded on the movable hinge (33) so that the movable hinge (33) changes from rotation to fixed connection.

8. A construction method for a self-balancing prefabricated support structure for a foundation pit according to claim 7, characterized in that, Includes the following steps: S1. Excavation trench (3) is excavated in the soil (2) of the foundation pit (1) to be excavated by trenching method; The dumbbell-shaped pile (4) is driven into the excavation trench (3), and the anchor pipe (9) is driven into the through hole (7) of the end beam (6) of the dumbbell-shaped pile (4), so that the bottom end of the anchor pipe (9) enters the deep soil (2); grout is injected into the deep soil (2) through the grouting hole (10) at the bottom of the anchor pipe (9) to form a solid body (11) that wraps the bottom of the anchor pipe (9), thereby achieving deep anchoring of the dumbbell-shaped pile (4); S2, Sinking of sheet piles (12) and construction of joint seepage prevention structure: Based on the dumbbell-shaped pile (4), the sheet piles (12) are successively driven into the soil (2), so that the joint protrusion (13) of each sheet pile (12) is inserted into the vertical groove (8) of the end beam (6) of the adjacent dumbbell-shaped pile (4); the adjacent sheet piles (12) form a first interface (19) by inserting the receiving protrusion (14) and the receiving groove (15), and form a second interface (20) by fitting the snap-fit ​​groove (17) on the inclined plate (16) and the snap-fit ​​block (18). A triangular cavity (21) is formed between the inclined plate (16) of the two adjacent sheet piles (12) and the main body of the sheet pile (12). S3, Excavation of foundation pit (1) and installation of upper support (24): Excavate the foundation pit (1) soil (2) to the initial excavation surface (22), the elevation of the initial excavation surface (22) is lower than the bottom elevation of the upper support (24) to be installed; install the upper support (24), first insert the embedded pipe (25) into the anchor pipe (9) and fix it, then install the crossbeam (26) so that one end is connected to the end beam (6) and the embedded pipe (25), then install the corner brace (27) at the bottom of the crossbeam (26) and make the side of the corner brace (27) support the inner side of the sheet pile (12); S4. Excavation of the foundation pit (1) to the bottom and installation of the inclined bracing mechanism (29): Continue excavating the foundation pit (1) to the designed pit bottom (23) elevation; An anchor post (31) is set at a predetermined position at the bottom of the pit (23). The top of the anchor post (31) is provided with a connecting end (30). The connecting end (30) includes a movable hinge (33) and a mounting frame (34) connected by a movable hinge shaft (32). Install the diagonal bracing mechanism (29): By adjusting the movable hinge (33) and the telescopic rod (35) on the anchor column (31), the top of the connecting end (30) is lowered to make room for the bottom of the diagonal bracing mechanism (29). After the bottom of the diagonal bracing mechanism (29) is initially fixed, the extended movable hinge (33) and the telescopic rod (35) are adjusted to make the telescopic rod (35) press against the bottom surface of the diagonal bracing mechanism (29) and fix the bottom of the diagonal bracing mechanism (29) in the mounting frame (34). At the same time, the top of the diagonal bracing mechanism (29) is installed in the support groove (28) of the crossbeam (26). S5. Main Structure Construction and Support Removal: The base plate (36) and subsequent structures of the main structure are constructed; after the main structure is completed, the diagonal bracing mechanism (29), the upper support (24) and the foundation pit (1) support structure are removed in sequence.

9. A construction method for a self-balancing prefabricated support structure for a foundation pit according to claim 8, characterized in that, In step S2, if leakage is found at a specific connection interface during the use or maintenance of the foundation pit (1), anti-seepage material is pressure-injected into the triangular cavity (21) corresponding to the interface to form a local rigid anti-seepage body.

10. A construction method for a self-balancing foundation pit assembly support structure according to claim 8, characterized in that, In step S4, after the diagonal bracing mechanism (29) is installed and stabilized under force, a connecting rod is welded between adjacent movable hinges (33) at the connecting end (30) to change the movable hinges (33) into a fixed connection.

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