A foundation pit support structure and a construction method thereof

Abstract

This invention discloses a foundation pit support structure and its construction method, belonging to the field of foundation pit support technology. It includes several precast beam components made of UHPC material and embedded steel plates set on the retaining structure. The embedded steel plates have protrusions fixed on them. Each precast beam component has a connecting structure at both ends, and each connecting structure has an installation end plate. Each installation end plate has a servo cylinder parallel to the precast beam component fixed on it. Each servo cylinder's output end has a connecting end plate fixed on it. Each connecting end plate has a coaxially arranged annular extrusion block. Several telescopic guide rods are fixedly connected between the extrusion block and the connecting end plate. Each connecting end plate has several circularly arrayed grooves facing its axis. Each groove has a slidably connected support, and an elastic reset element is provided between the support and the groove. The purpose is to solve the problems of high cost and difficulty in underwater docking of precast steel structures in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of foundation pit support technology, specifically relating to a foundation pit support structure and its construction method. Background Technology

[0002] As the depth of urban underground space development continues to increase, the requirements for deformation control in deep foundation pit engineering are becoming increasingly stringent. Traditional foundation pit construction generally adopts a passive support mode of "excavation first, then support". In soft, water-rich soil strata, the retaining structure has already undergone a certain degree of initial deformation before the support system is installed. Traditional support is in a passive stress state, and concrete support is subject to relaxation effects caused by shrinkage and creep, which will produce irreversible compressive deformation, which is extremely detrimental to the surrounding environment of the foundation pit and the safety of the retaining structure.

[0003] Existing technologies include a "support before excavation" pre-support technique, which involves erecting supports and applying pre-jacking forces before earthwork excavation, transforming the traditional "resistance after displacement" into "defense before displacement," significantly improving the ability to control foundation pit deformation. However, existing pre-support structures mostly adopt composite steel frame systems, which have problems such as high cost of steel structural components, large overall weight, and the need for large lifting equipment for on-site hoisting. In addition, the underwater corrosion resistance and durability of steel components are poor, resulting in high maintenance costs. At the same time, under underwater installation conditions, the docking and positioning of prefabricated supports and embedded retaining structures is difficult. Due to construction deviations, there is often a radial positional deviation between the embedded protrusions and the axis of the servo cylinder, making underwater manual adjustment and alignment construction risky and inefficient. Summary of the Invention

[0004] In view of this, the present invention discloses a foundation pit support structure and its construction method, the purpose of which is to solve the problems of high cost of pre-support of steel structures and difficulty of underwater docking in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A foundation pit support structure includes several precast beam components made of UHPC material and embedded steel plates set on the retaining structure. Protrusions are fixed on the embedded steel plates. Each precast beam component has a connecting structure at both ends, and each connecting structure has an mounting end plate. A servo cylinder parallel to the precast beam component is fixed on each mounting end plate. A connecting end plate is fixed on the output end of each servo cylinder. An annular pressing block is coaxially arranged beside each connecting end plate. Several guide rods with telescopic structures are fixedly connected between the pressing block and the connecting end plate. Several circularly arrayed grooves facing their axis are opened on the connecting end plates. Supports are slidably connected within each groove, and elastic reset elements are provided between the supports and the grooves. Clamping blocks for holding the protrusions are fixed on each support. The opposing end faces of the pressing block and the clamping block are mutually abutting wedge-shaped surfaces.

[0006] This solution uses the axial feed stroke of the servo cylinder itself as the clamping power, eliminating the need for an additional independent hydraulic clamping mechanism. The power source is the same, the structure is simplified, and there are fewer potential failure points in underwater conditions. Simultaneously, multiple sets of clamping blocks are distributed in a circular array and synchronously converge, resulting in uniform circumferential clamping force and balanced force distribution, eliminating eccentricity and uneven load issues. Furthermore, the wedge-shaped surface of the extrusion block and clamping block has a force amplification effect, allowing a small axial thrust to generate a large radial clamping force, ensuring reliable locking. The entire solution relies on the linkage control of the cylinder's extension and retraction, which can be completed remotely from the surface, eliminating the need for underwater operations by divers and ensuring high construction safety.

[0007] Furthermore, the connection structure includes an adjustment groove coaxially formed at the end of the precast beam component. Each adjustment groove has a through groove coaxially formed at the end facing the mounting end plate, the diameter of which is smaller than the diameter of the adjustment groove. A connecting plate is provided inside each adjustment groove. The connecting plate slides radially relative to the adjustment groove along the central axis of the precast beam component, and a sliding gap is reserved between the side wall of the connecting plate and the inner wall of the adjustment groove. A locking structure for restricting the sliding of the connecting plate is provided between the periphery of the connecting plate and the through groove. A connecting rod is coaxially formed on each connecting plate, extending through the through groove, and the diameter of the connecting rod is smaller than the diameter of the through groove. The ends of the connecting rods are fixedly connected to the corresponding mounting end plates.

[0008] In this design, the connecting plate slides by relying on the contact reaction force of the protrusion during the docking process of the clamping block and the protrusion, without the need for electrical control or hydraulic assistance, resulting in high underwater reliability. The stepped structure of the adjustment groove and the through groove provides radial sliding movement margin and forms axial limit, ensuring a clear and reliable force transmission path. At the same time, the connecting plate fits the inner wall of the adjustment groove over a large area, dispersing the force, resulting in low local stress in the precast beam components and strong overall load-bearing capacity.

[0009] Furthermore, the locking structure includes several support shafts parallel to the precast beam components. The support shafts are rotatably connected to the end face of the through groove. Each support shaft has a connecting rod of a telescopic structure fixed to its side wall, and the ends of the connecting rods are hinged to the side wall of the connecting plate. Each support shaft has a limit gear fixed coaxially. An annular groove is coaxially formed on the side wall of the through groove away from the mounting end plate. An annular block is slidably connected coaxially in the annular groove. Both ends of the inner wall of the annular block are fixed with a limit gear ring that can mesh with the limit gear, and a gap is reserved between the two limit gear rings. A drive ring is coaxially provided on the periphery of the connecting end plate. An annular receiving groove is coaxially formed on the inner wall of the drive ring. The periphery of the connecting end plate extends into the receiving groove and is slidably connected to it. Several pull rods are fixed between the drive ring and the corresponding limit gear ring. A sliding groove is provided at the end of the adjusting groove for the pull rods to pass through. The diameter of the sliding groove is larger than the diameter of the pull rod.

[0010] In this solution, two sets of limiting gear rings are engaged and locked with limiting gears, resulting in strong locking rigidity, uniform force distribution, and the ability to withstand large lateral loads. Furthermore, locking and unlocking are driven by the axial stroke linkage of a servo cylinder, eliminating the need for underwater manual operation and sharing the same drive source with the main clamping mechanism. Simultaneously, the above structure allows the connecting plate to slide radially only during docking, effectively enhancing the overall structural strength after docking.

[0011] Furthermore, the connecting end plate has several circularly arrayed mounting slots inside, and each mounting slot corresponds to a sliding groove. The side wall of the sliding groove has several connecting grooves that communicate with the corresponding mounting slots. A positioning block is slidably connected in each connecting groove. The end face of the positioning block in the sliding groove is arc-shaped, and both the positioning block and the connecting groove are provided with elastic reset components. An adjusting shaft is coaxially rotatably connected in each mounting groove. Each adjusting shaft has several receiving grooves on one side for accommodating the positioning blocks. The support has positioning holes that cooperate with the positioning blocks.

[0012] Furthermore, the protrusion includes a fixed section fixed to the pre-embedded steel plate and a spherical section fixed to the end of the fixed section, and the end face of the clamping block that contacts the spherical section is adapted to the shape of the spherical section.

[0013] Furthermore, each of the pull rods is slidably fitted with a sealing sleeve, and the sealing sleeve has an annular limiting groove on its periphery for engaging the sliding groove.

[0014] Furthermore, it also includes several guide rods, and several vertically arranged guide grooves are provided on the precast beam component. The upper and lower ends of the guide grooves are fixed with guide seats for the guide rods to pass through, and the guide seats and guide rods are detachably connected.

[0015] A construction method for a foundation pit support structure includes the following steps: S1. Equipment prefabrication and pre-installation: Prefabricate UHPC precast beam components in the factory, and pre-install guide seats on the precast beam components; construct the retaining structure, embed steel plates at the design elevation of the retaining structure, and weld and fix protrusions on the embedded steel plates, including fixed sections and spherical sections; ensure that the protrusions face the inside of the foundation pit; S2. First support hoisting and positioning: Fix the guide rod to the guide seat on the bottom precast beam component with bolts; use hoisting tools to lower the bottom precast beam component; when the precast beam component is lowered to the corresponding position, the ground remote control servo cylinder extends forward, driving the connecting end plate and clamping block to move closer to the protrusion of the embedded steel plate. When there is a radial positional deviation between the spherical segment and the central axis of the servo cylinder, the clamping block generates a lateral reaction force after contacting the spherical segment. The reaction force is transmitted to the connecting plate through the connecting end plate, the servo cylinder, the mounting end plate, and the connecting rod, pushing the connecting plate to slide radially in the adjustment groove. This automatically adjusts the overall position of the servo cylinder, making the central axis of the servo cylinder coincide with the center of the spherical segment, thus eliminating the radial positional deviation. During this process, the axial movement of the connecting end plate drives the drive ring to move synchronously. The drive ring pulls the annular block to slide axially in the annular groove via the pull rod, causing the initially meshed limit gear ring near the connecting end to disengage from the limit gear. The support shaft is unlocked, and the connecting plate can slide radially for alignment. As the servo cylinder continues to feed, the front end of the extrusion block abuts against the pre-embedded steel plate and moves toward the connecting end plate under pressure, causing the guide rod to retract. The inner wedge-shaped surface of the extrusion block gradually presses against the outer wedge-shaped surface of each clamping block, generating a radial force that pushes each support to slide synchronously toward the axis along the slide groove, causing the clamping blocks to retract toward the center. Finally, multiple sets of clamping blocks synchronously cover and clamp the spherical section, completing the rigid connection between the servo cylinder and the pre-embedded steel plate of the enclosure. At this time, the pull rod drives the limit gear ring on the other side to mesh synchronously with the limit gears on each support shaft, restricting the rotation of the support shaft, thereby constraining the radial sliding freedom of the connecting plate and achieving rigid locking of the connecting plate position. S3. Enhanced locking of clamping mechanism: Rotate the adjusting shaft so that the receiving groove on the adjusting shaft is no longer aligned with each positioning block. Under the action of the elastic reset element, the positioning block remains in the state of being inserted into the positioning hole of the support, locking the support and preventing the clamping block from loosening outward after being loaded, further enhancing the connection stability between the clamping block and the protrusion. S4. Layer-by-layer hoisting and docking: After installing the bottom precast beam components, insert the upper end of the guide rod on the next precast beam component into the guide seat of the previous precast beam component, and hoist and dock it; hoist all precast beam components to the design position layer by layer.

[0016] Other advantages, objectives, and features of the invention will be set forth in the following description and will be apparent to those skilled in the art in some respects, or may be learned by practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0017] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration: Figure 1 This is a structural schematic diagram of a precast beam component in an embodiment of the present invention; Figure 2 for Figure 1 Enlarged view of point A in the middle; Figure 3 This is a longitudinal sectional view of an embodiment of the present invention; Figure 4 for Figure 3 Enlarged view of point B in the middle; Figure 5 for Figure 3 Enlarged diagram of point C in the middle.

[0018] The following components are labeled in the attached diagram: 1. Precast beam component; 2. Enclosure structure; 3. Embedded steel plate; 4. Servo cylinder; 5. Connecting end plate; 6. Extrusion block; 7. Guide rod; 8. Support; 9. Clamping block; 10. Connecting plate; 11. Connecting rod; 12. Support shaft; 13. Connecting rod; 14. Limiting gear; 15. Ring block; 16. Limiting gear ring; 17. Drive ring; 18. Tie rod; 19. Positioning block; 20. Adjusting shaft; 21. Receiving groove; 22. Fixed section; 23. Spherical section; 24. Sealing sleeve; 25. Guide rod; 26. Guide seat; 27. Elastic reset component. Detailed Implementation

[0019] like Figures 1-5 As shown: A foundation pit support structure includes several precast beam components 1 made of UHPC material and embedded steel plates 3 set on the retaining structure 2. The embedded steel plates 3 are fixed with protrusions. Each precast beam component 1 has a connecting structure at both ends. Each connecting structure is equipped with an installation end plate. Each installation end plate is fixed with a servo cylinder 4 parallel to the precast beam component 1. Each output end of the servo cylinder 4 is fixed with a connecting end plate 5. Each connecting end plate 5 is coaxially provided with an annular pressing block 6. Several telescopic guide rods 7 are fixedly connected between the pressing block 6 and the connecting end plate 5. Each connecting end plate 5 has several circularly arrayed grooves facing its axis. Each groove is slidably connected with a support 8. Each support 8 and the groove is provided with an elastic reset member 27. Each support 8 is fixed with a clamping block 9 for clamping the protrusion. The opposing end faces of the pressing block 6 and the clamping block 9 are wedge-shaped surfaces that fit together.

[0020] In this scheme, after the precast beam component 1 is hoisted into place, the servo cylinder 4 extends forward, driving the connecting end plate 5 and clamping block 9 to move closer to the protrusion of the embedded steel plate 3. The clamping block 9 first contacts the outer periphery of the protrusion. At this time, the wedge-shaped surfaces of the pressing block 6 and the clamping block 9 are not yet fully fitted, and the clamping block 9 is in an open state under the action of the elastic reset component 27. As the servo cylinder 4 continues to feed, the pressing block 6 is pressed by the embedded steel plate 3 and moves towards the connecting end plate 5. The inner wedge-shaped surface of the pressing block 6 gradually presses the outer wedge-shaped surfaces of each clamping block 9. The wedge-shaped surfaces generate radial force, pushing each support 8 to slide synchronously along the slide groove towards the axis, driving the clamping block 9 to retract towards the center. Finally, multiple sets of clamping blocks 9 synchronously cover and clamp the protrusion, completing the rigid connection between the servo cylinder 4 and the embedded steel plate 3.

[0021] During disassembly, the servo cylinder 4 retracts, the pressing block 6 retracts, the wedge-shaped surface pressing force disappears, the elastic reset component 27 pushes the support 8 and the clamping block 9 to slide outward along the slide groove to reset, and the clamping block 9 opens and disengages from the protrusion.

[0022] In this solution, the axial feed stroke of the servo cylinder 4 itself is used as the clamping power, eliminating the need for an additional independent hydraulic clamping mechanism. The power source is the same, the structure is simplified, and there are fewer potential failure points in underwater conditions. At the same time, multiple sets of clamping blocks 9 are distributed in a circular array and synchronously converge towards the center, resulting in uniform circumferential clamping force and balanced force distribution, without any eccentricity or uneven load issues. The wedge-shaped surface of the extrusion block 6 and the clamping block 9 have a force amplification effect, so a small axial thrust can generate a large radial clamping force, ensuring reliable locking. In the entire solution, clamping and unlocking are entirely controlled by the extension and retraction linkage of the cylinder, which can be completed remotely from the water surface without the need for underwater operations by divers, thus ensuring high construction safety.

[0023] Furthermore, the connection structure includes an adjustment groove coaxially formed at the end of the precast beam member 1. Each adjustment groove has a through groove coaxially formed at the end facing the mounting end plate, and the diameter of the through groove is smaller than the diameter of the adjustment groove. A connecting plate 10 is provided inside each adjustment groove. The connecting plate 10 slides radially relative to the adjustment groove along the central axis of the precast beam member 1, and a sliding gap is reserved between the side wall of the connecting plate 10 and the inner wall of the adjustment groove. A locking structure for restricting the sliding of the connecting plate 10 is provided between the periphery of the connecting plate 10 and the through groove. A connecting rod 11 coaxially formed on each connecting plate 10, extending through the through groove, and the diameter of the connecting rod 11 is smaller than the diameter of the through groove. The ends of the connecting rods 11 are fixedly connected to the corresponding mounting end plates.

[0024] In this scheme, during the docking process between the precast beam component 1 and the embedded steel plate 3, when there is a radial positional deviation between the protrusion of the embedded steel plate 3 and the central axis of the servo cylinder 4, after the clamping block 9 contacts the protrusion, the protrusion generates a lateral reaction force on the clamping block 9. This force is transmitted to the connecting plate 10 through the connecting end plate 5, the servo cylinder 4, the mounting end plate, and the connecting rod 11, pushing the connecting plate 10 to slide radially within the adjusting groove, automatically adjusting the overall position of the servo cylinder 4 so that the central axis of the servo cylinder 4 coincides with the center of the protrusion, eliminating the radial positional deviation. After alignment is completed, the locking structure is activated to constrain the radial sliding freedom of the connecting plate 10 and fix its position.

[0025] In this scheme, during the docking process between the clamping block 9 and the protrusion, the connecting plate 10 is driven to slide by the contact reaction force of the protrusion, without the need for electrical control or hydraulic assistance, and has high underwater reliability. The stepped structure of the adjustment groove and the through groove provides radial sliding movement margin and forms axial limit, ensuring a clear and reliable force transmission path. At the same time, the connecting plate 10 fits the inner wall of the adjustment groove over a large area, dispersing the force, resulting in low local stress in the precast beam component 1 and strong overall load-bearing capacity.

[0026] Furthermore, the locking structure includes several support shafts 12 parallel to the precast beam member 1. Each support shaft 12 is rotatably connected to the end face of the through groove. A telescopic connecting rod 13 is fixed to the side wall of each support shaft 12, and the ends of the connecting rods 13 are hinged to the side wall of the connecting plate 10. Limit gears 14 are coaxially fixed to each support shaft 12. An annular groove is coaxially formed on the side wall of the through groove away from the mounting end plate. An annular block 15 is coaxially slidably connected within each annular groove, and both ends of the inner wall of the annular block 15 are fixed with energy-efficient... A limiting gear ring 16 is provided to mesh with the limiting gear 14, and a gap is reserved between the two limiting gear rings 16; a driving ring 17 is coaxially provided on the periphery of the connecting end plate 5, and an annular receiving groove 21 is coaxially opened on the inner wall of the driving ring 17. The periphery of the connecting end plate 5 extends into the receiving groove 21 and is slidably connected with it. Several pull rods 18 are fixed between the driving ring 17 and the corresponding limiting gear ring 16. A sliding groove for the pull rods 18 to pass through is provided at the end of the adjusting groove. The diameter of the sliding groove is larger than the diameter of the pull rod 18.

[0027] In this scheme, during the hoisting of the precast beam component 1, the limiting gear ring 16 near the connecting end meshes with the limiting gear 14, restricting the rotation of the support shaft 12, and thus restricting the radial sliding of the connecting plate 10. When the servo cylinder 4 drives the connecting end plate 5 to dock, the connecting end plate 5 pulls the annular block 15 axially within the annular groove via the tie rod 18, causing the limiting gear 14 to disengage from the limiting gear ring 16, allowing the support shaft 12 to rotate, and thus allowing the connecting plate 10 to slide radially for alignment. After the precast beam component 1 is docked with the embedded steel plate 3, the tie rod 18 drives the limiting gear ring 16 on the other side to mesh synchronously with the limiting gear 14 on each support shaft 12, restricting the rotation of the support shaft 12. The support shaft 12 is hinged to the connecting plate 10 via the connecting rod 13, and the inability of the support shaft 12 to rotate constrains the radial sliding freedom of the connecting plate 10, thus achieving rigid locking of the position of the connecting plate 10.

[0028] In this scheme, the two sets of limiting gear rings 16 are engaged and locked with the limiting gears 14 respectively, which has strong locking rigidity and uniform force distribution, and can withstand large lateral loads. Moreover, the locking and unlocking are driven by the axial stroke linkage of the servo cylinder 4, which does not require underwater manual operation and shares the same drive source with the main clamping mechanism. At the same time, through the above structure, the connecting plate 10 can only slide radially during docking, which can effectively strengthen the overall strength of the structure after docking.

[0029] Furthermore, the connecting end plate 5 has several circularly arrayed mounting slots inside, and each mounting slot corresponds to a sliding groove. The side wall of the sliding groove has several connecting grooves that communicate with the corresponding mounting slots. Each connecting groove has a slidably connected positioning block 19. The end face of the positioning block 19 in the sliding groove is arc-shaped, and both the positioning block 19 and the connecting groove are provided with elastic reset members 27. Each mounting groove has an adjusting shaft 20 that is rotatably connected to it on the same axis. Each side of the adjusting shaft 20 has several receiving grooves 21 for accommodating the positioning block 19. Each support 8 has a positioning hole that mates with the positioning block 19.

[0030] In this design, when the receiving groove 21 is aligned with the positioning block 19, the arc-shaped end face of the positioning block 19 can retract into the connecting groove as the support 8 slides within the groove, due to the pressure from the side wall of the support 8. When the support 8 slides until the positioning hole aligns with the positioning block 19, the elastic reset member 27 pushes the positioning block 19 into the positioning hole of the support 8, forming a temporary positioning position and restricting the free sliding of the support 8 in the absence of external force. When it is necessary to restrict the sliding of the support 8, the adjusting shaft 20 (the adjusting shaft 20 in this design is driven by a motor, which is a conventional technical means and is therefore not shown in the figure) is rotated so that the receiving groove 21 on the adjusting shaft 20 is no longer aligned with each positioning block 19, and the end of the positioning block 19 remains within the positioning hole, locking the support 8. During use, the connection stability between the clamping block 9 and the protrusion is further enhanced.

[0031] Furthermore, the protrusion includes a fixed section 22 fixed to the pre-embedded steel plate 3 and a spherical section 23 fixed to the end of the fixed section 22, and the end face of the clamping block 9 that contacts the spherical section 23 is adapted to the shape of the spherical section 23.

[0032] When clamped, multiple clamping blocks 9 converge towards the center, and the inner arc surface completely fits and covers the spherical surface of the spherical segment 23, forming a spherical clamping fit. Moreover, the spherical segment 23 is isotropic, so even if there is a slight angular deviation, the clamping block 9 and the spherical surface can still maintain surface contact, the force is uniform, and stress concentration is avoided.

[0033] Furthermore, each of the pull rods 18 is slidably fitted with a sealing sleeve 24, and the sealing sleeve 24 has an annular limiting groove on its periphery for engaging the sliding groove.

[0034] When the pull rod 18 moves axially with the drive ring 17, the sealing sleeve 24 slides synchronously with the pull rod 18, always sealing the annular gap between the sliding groove and the pull rod 18, preventing external water and sediment from entering the regulating tank.

[0035] Furthermore, it also includes several guide rods 25. Several vertically arranged guide grooves are provided on the precast beam component 1. Guide seats 26 for the guide rods 25 to pass through are fixed at the upper and lower ends of the guide grooves, and the guide seats 26 are detachably connected to the guide rods 25.

[0036] When hoisting the bottom precast beam component 1, the guide rod 25 is first fixed to the guide seat 26 on the precast beam component 1 with bolts. When installing the next support, the guide rod 25 on the next precast beam is inserted into the guide seat 26 of the previous precast beam to achieve vertical positioning of the upper and lower supports. After the precast beam component 1 is connected to the enclosure structure, the corresponding guide seat 26 is then fixed to the guide rod 25.

[0037] A construction method for a foundation pit support structure includes the following steps: S1. Equipment prefabrication and pre-installation: Prefabricate UHPC precast beam components 1 in the factory, and pre-install guide seats 26 on the precast beam components 1; construct the retaining structure 2, and pre-embed pre-embed steel plates 3 at the design elevation of the retaining structure 2, and weld and fix protrusions on the pre-embedded steel plates 3, the protrusions including fixed sections 22 and spherical sections 23; ensure that the protrusions face the inside of the foundation pit; S2. First support hoisting and positioning: The guide rod 25 is fixed to the guide seat 26 on the bottom precast beam component 1 with bolts; the bottom precast beam component 1 is lowered using hoisting tools; when the precast beam component 1 is lowered to the corresponding position, the ground remote control servo cylinder 4 extends forward, driving the connecting end plate 5 and clamping block 9 to move closer to the protrusion of the embedded steel plate 3. When there is a radial positional deviation between the spherical segment 23 and the central axis of the servo cylinder 4, the clamping block 9 generates a lateral reaction force after contacting the spherical segment 23. The reaction force is transmitted to the connecting plate 10 through the connecting end plate 5, the servo cylinder 4, the mounting end plate, and the connecting rod 11, pushing the connecting plate 10 to slide radially in the adjustment groove, automatically adjusting the overall position of the servo cylinder 4 so that the central axis of the servo cylinder 4 coincides with the center of the spherical segment 23, eliminating the radial positional deviation. During this process, the axial movement of the connecting end plate 5 drives the drive ring 17 to move synchronously. The drive ring 17 pulls the annular block 15 to slide axially in the annular groove via the pull rod 18, causing the initially meshed limiting gear ring 16 near the connecting end to disengage from the limiting gear 14, the support shaft 12 to unlock, and the connecting plate 10 to slide radially for alignment. As the servo cylinder 4 continues to feed, the front end of the extrusion block 6 is pressed against the pre-embedded steel plate 3 and moves toward the connecting end plate 5, causing the guide rod 7 to retract. The inner wedge-shaped surface of the extrusion block 6 gradually presses the outer wedge-shaped surface of each clamping block 9, generating a radial force that pushes each support 8 to slide synchronously toward the axis along the slide groove, causing the clamping blocks 9 to retract toward the center. Finally, multiple sets of clamping blocks 9 synchronously cover and clamp the spherical section 23, completing the rigid connection between the servo cylinder 4 and the pre-embedded steel plate 3. At this time, the pull rod 18 drives the limit gear ring 16 on the other side to mesh synchronously with the limit gear 14 on each support shaft 12, restricting the rotation of the support shaft 12, thereby constraining the radial sliding freedom of the connecting plate 10 and achieving rigid locking of the position of the connecting plate 10. S3. Clamping mechanism enhanced locking: Rotate the adjusting shaft 20 so that the receiving groove 21 on the adjusting shaft 20 is no longer aligned with each positioning block 19. Under the action of the elastic reset member 27, the positioning block 19 remains stuck in the positioning hole of the support 8, locking the support 8 and preventing the clamping block 9 from loosening outward after being loaded, further strengthening the connection stability between the clamping block 9 and the protrusion. S4. Layer-by-layer hoisting and docking: After installing the bottom precast beam component 1, insert the upper end of the guide rod 25 on the next precast beam component 1 into the guide seat 26 of the previous precast beam component 1, and hoist and dock it; hoist all precast beam components 1 to the design position layer by layer.

[0038] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A foundation pit support structure, characterized in that: The structure includes several precast beam components made of UHPC material and embedded steel plates set on the enclosure structure. Protrusions are fixed on the embedded steel plates. Each precast beam component has a connecting structure at both ends, and each connecting structure has an mounting end plate. A servo cylinder parallel to the precast beam component is fixed on each mounting end plate. A connecting end plate is fixed on the output end of each servo cylinder. An annular pressing block is coaxially arranged next to each connecting end plate. Several guide rods with telescopic structures are fixedly connected between the pressing block and the connecting end plate. Several circularly arrayed grooves facing the axis of the grooves are formed on the connecting end plates. Supports are slidably connected within each groove, and elastic reset components are provided between the supports and the grooves. Clamping blocks for holding the protrusions are fixed on each support. The opposing end faces of the pressing block and the clamping block are mutually abutting wedge-shaped surfaces.

2. The foundation pit support structure according to claim 1, characterized in that: The connecting structure includes an adjustment groove coaxially formed at the end of the precast beam component. Each adjustment groove has a through groove coaxially formed at the end facing the mounting end plate, the diameter of which is smaller than the diameter of the adjustment groove. A connecting plate is provided inside each adjustment groove. The connecting plate slides radially relative to the adjustment groove along the central axis of the precast beam component, and a sliding gap is reserved between the side wall of the connecting plate and the inner wall of the adjustment groove. A locking structure is provided between the periphery of the connecting plate and the through groove to restrict the sliding of the connecting plate. A connecting rod is coaxially formed on each connecting plate, extending through the through groove, and the diameter of the connecting rod is smaller than the diameter of the through groove. The ends of the connecting rods are fixedly connected to the corresponding mounting end plates.

3. The foundation pit support structure according to claim 2, characterized in that: The locking structure includes several support shafts parallel to the precast beam components. Each support shaft is rotatably connected to the end face of the through groove. A telescopic connecting rod is fixed to the side wall of each support shaft, and the ends of the connecting rods are hinged to the side wall of the connecting plate. Limiting gears are coaxially fixed to each support shaft. An annular groove is coaxially formed on the side wall of the through groove away from the mounting end plate. An annular block is coaxially slidably connected within each annular groove. Limiting gear rings that mesh with the limiting gears are fixed at both ends of the inner wall of each annular block, with a gap reserved between the two limiting gear rings. A driving ring is coaxially arranged on the periphery of the connecting end plate. An annular receiving groove is coaxially formed on the inner wall of the driving ring. The periphery of the connecting end plate extends into the receiving groove and is slidably connected to it. Several pull rods are fixed between the driving ring and the corresponding limiting gear rings. A sliding groove is provided at the end of the adjusting groove for the pull rods to pass through, and the diameter of the sliding groove is larger than the diameter of the pull rod.

4. The foundation pit support structure according to claim 3, characterized in that: The connecting end plate has several circularly arrayed mounting slots inside, and each mounting slot corresponds to a sliding groove. The side wall of the sliding groove has several connecting grooves that communicate with the corresponding mounting slots. A positioning block is slidably connected in each connecting groove. The end face of the positioning block in the sliding groove is arc-shaped, and both the positioning block and the connecting groove are provided with elastic reset components. An adjusting shaft is coaxially rotatably connected in each mounting groove. Each adjusting shaft has several receiving grooves on one side for accommodating the positioning blocks. The support has positioning holes that cooperate with the positioning blocks.

5. The foundation pit support structure according to claim 4, characterized in that: The protrusion includes a fixed section fixed to the pre-embedded steel plate and a spherical section fixed to the end of the fixed section. The end face of the clamping block that contacts the spherical section is adapted to the shape of the spherical section.

6. The foundation pit support structure according to claim 5, characterized in that: Each pull rod is slidably fitted with a sealing sleeve, and the sealing sleeve has an annular limiting groove on its periphery for engaging the sliding groove.

7. A foundation pit support structure according to claim 6, characterized in that: It also includes several guide rods, and several vertically arranged guide grooves are provided on the precast beam component. The upper and lower ends of the guide grooves are fixed with guide seats for the guide rods to pass through, and the guide seats and guide rods are detachably connected.

8. The construction method of a foundation pit support structure according to claim 7, characterized in that: Includes the following steps: S1. Equipment prefabrication and pre-installation: Prefabricate UHPC precast beam components in the factory, and pre-install guide seats on the precast beam components; construct the retaining structure, embed steel plates at the design elevation of the retaining structure, and weld and fix protrusions on the embedded steel plates, including fixed sections and spherical sections; ensure that the protrusions face the inside of the foundation pit; S2. First support hoisting and positioning: Fix the guide rod to the guide seat on the bottom precast beam component with bolts; use hoisting tools to lower the bottom precast beam component; when the precast beam component is lowered to the corresponding position, the ground remote control servo cylinder extends forward, driving the connecting end plate and clamping block to move closer to the protrusion of the embedded steel plate. When there is a radial positional deviation between the spherical segment and the central axis of the servo cylinder, the clamping block generates a lateral reaction force after contacting the spherical segment. The reaction force is transmitted to the connecting plate through the connecting end plate, the servo cylinder, the mounting end plate, and the connecting rod, pushing the connecting plate to slide radially in the adjustment groove. This automatically adjusts the overall position of the servo cylinder, making the central axis of the servo cylinder coincide with the center of the spherical segment, thus eliminating the radial positional deviation. During this process, the axial movement of the connecting end plate drives the drive ring to move synchronously. The drive ring pulls the annular block to slide axially in the annular groove via the pull rod, causing the initially meshed limit gear ring near the connecting end to disengage from the limit gear. The support shaft is unlocked, and the connecting plate can slide radially for alignment. As the servo cylinder continues to feed, the front end of the extrusion block abuts against the pre-embedded steel plate and moves toward the connecting end plate under pressure, causing the guide rod to retract. The inner wedge-shaped surface of the extrusion block gradually presses against the outer wedge-shaped surface of each clamping block, generating a radial force that pushes each support to slide synchronously toward the axis along the slide groove, causing the clamping blocks to retract toward the center. Finally, multiple sets of clamping blocks synchronously cover and clamp the spherical section, completing the rigid connection between the servo cylinder and the pre-embedded steel plate of the enclosure. At this time, the pull rod drives the limit gear ring on the other side to mesh synchronously with the limit gears on each support shaft, restricting the rotation of the support shaft, thereby constraining the radial sliding freedom of the connecting plate and achieving rigid locking of the connecting plate position. S3. Enhanced locking of clamping mechanism: Rotate the adjusting shaft so that the receiving groove on the adjusting shaft is no longer aligned with each positioning block. Under the action of the elastic reset element, the positioning block remains in the state of being inserted into the positioning hole of the support, locking the support and preventing the clamping block from loosening outward after being loaded, further enhancing the connection stability between the clamping block and the protrusion. S4. Layer-by-layer hoisting and docking: After installing the bottom precast beam components, insert the upper end of the guide rod on the next precast beam component into the guide seat of the previous precast beam component, and then hoist and dock it. All precast beam components were hoisted to their designed positions, layer by layer.

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