Pipe gallery foundation pit supporting structure

Abstract

The utility model relates to the technical field of foundation pit supporting, in particular to a pipe gallery foundation pit supporting structure which comprises a combined pile supporting structure, a supporting structure and a foundation structure. The combined pile supporting structures are located on the side walls of the two sides of the pipe gallery foundation pit, and the lower ends of the combined pile supporting structures penetrate through a soft soil layer and extend into a stable soil layer below a foundation pit soil body. The supporting and protecting structures are connected with the combined pile supporting and protecting structures on the two sides of the pipe gallery foundation pit. The foundation structure is located at the bottom of the foundation pit soil body, penetrates through the soft soil layer and extends into a stable soil layer below the foundation pit soil body. According to the pipe gallery foundation pit supporting structure, a combined supporting system of the combined pile supporting structure, the supporting structure and the foundation structure is adopted, the combined pile supporting structure and the foundation structure both penetrate through the soft soil layer and extend into the stable soil layer below the foundation pit soil body, supporting is stable, sedimentation is prevented, and the safety of a pipe gallery mechanism is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of foundation pit support, in particular to a pipe gallery foundation pit support structure, in particular to a pipe gallery foundation pit support structure in a thick soft soil area. Background Art

[0002] The underground integrated pipe gallery concentrates various public pipes such as water, electricity, gas, heating and communication in a limited underground space, greatly reducing the amount of municipal pipeline excavation. It also has the advantages of convenient operation and maintenance, saving underground space, etc., and has been widely used in new city construction and old city reconstruction. However, in naturally formed deep soft soil areas, due to the low foundation bearing capacity of soft soil, small compression modulus and shear resistance parameter values, the foundation of the integrated pipe gallery may produce large settlement or settlement difference under the action of its own weight and external load, making the safety of the pipe gallery structure not guaranteed. Summary of the invention

[0003] The present application provides a pipe gallery foundation pit support structure, which is mainly used to solve the problem of poor safety of pipe gallery structures in the prior art.

[0004] The present application provides a pipe gallery foundation pit support structure, comprising:

[0005] A combined pile support structure, wherein the combined pile support structure is located at the side walls of the tunnel foundation pit, and the lower end of the combined pile support structure penetrates the soft soil layer and extends into the stable soil layer below the foundation pit soil body;

[0006] A supporting structure connecting the combined pile supporting structures on both sides of the tunnel foundation pit;

[0007] The foundation structure is located at the bottom of the foundation pit soil body, and the foundation structure penetrates the soft soil layer and extends into the stable soil layer below the foundation pit soil body.

[0008] The above-mentioned tunnel foundation pit support structure adopts a combined support system of combined pile support structure + supporting support structure + foundation structure. Both the combined pile support structure and the foundation structure penetrate the soft soil layer and extend into the stable soil layer below the foundation pit soil body 1, providing stable support and preventing settlement, thereby improving the safety of the tunnel structure.

[0009] In the technical solution of one embodiment, the combined pile support structure includes a plurality of steel pipe piles and a plurality of Larsen steel sheet piles, and the steel pipe piles and the Larsen steel sheet piles are arranged alternately and tightly connected to form a closed closed system; the lower ends of the steel pipe piles and the Larsen steel sheet piles penetrate the soft soil layer and extend into the stable soil layer below the foundation pit soil.

[0010] In the technical solution of one embodiment, the combined pile support structure further includes a crown beam, and the tops of the steel pipe piles and the Larsen steel sheet piles are connected into a whole by the crown beam.

[0011] In a technical solution of an embodiment, the crown beam includes a skeleton and a crown beam body, the skeleton is arranged at the upper end of the crown beam body, and the skeleton and the crown beam body are formed as a whole by concrete pouring.

[0012] In the technical solution of one embodiment, a fertilizer trough is arranged between the combined pile support structure and the pipe gallery structure, the bottom of the fertilizer trough is backfilled with C40 plain concrete with a thickness equal to that of the bottom plate of the pipe gallery structure, and the upper part of the C40 plain concrete is backfilled with medium-coarse sand; and tarpaulin is arranged between the Larsen steel sheet piles and the steel pipe piles and the C40 plain concrete respectively.

[0013] In the technical solution of one embodiment, the supporting and retaining structure includes a reinforced concrete support, and the reinforced concrete support is cast-connected to the cap beam.

[0014] In the technical solution of one embodiment, the supporting structure also includes a steel support and a frame-shaped steel waist beam, the steel waist beam is arranged on the inner side of the combined pile supporting structure composed of the Larsen steel sheet piles and the steel pipe piles, the end of the steel support is connected to the steel waist beam on the corresponding side, and the gap between the steel waist beam and the Larsen steel sheet piles and the steel pipe piles is back-filled with C20 fine stone concrete; steel corbels are arranged on the inner sides of the Larsen steel sheet piles and the steel pipe piles, and the steel corbels abut against and support the steel supports.

[0015] In the technical solution of one embodiment, the foundation treatment structure includes a plurality of cement-soil bidirectional mixing piles and a crushed stone cushion layer, wherein the plurality of cement-soil bidirectional mixing piles are arranged in a rectangular array at the bottom of the foundation pit soil, and the plurality of cement-soil bidirectional mixing piles penetrate the thick soft soil and extend into the stable soil layer below the foundation pit soil; the crushed stone cushion layer is arranged at the bottom of the tunnel foundation pit and above the cement-soil bidirectional mixing piles.

[0016] In the technical solution of one embodiment, the foundation treatment structure further includes a C20 plain concrete cushion layer, which is laid on the crushed stone cushion layer and is located below the pipe gallery structure.

[0017] In the technical solution of one embodiment, the pipe gallery foundation pit support structure also includes a drainage ditch, and the drainage ditch is arranged on the surface of the top of the pipe gallery foundation pit.

[0018] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings in this application are used to illustrate preferred embodiments, so as to facilitate a person skilled in the art to clearly understand various other advantages and benefits, and should not be considered as limiting this application. In addition, the same reference numerals are used to represent the same components in all the drawings.

[0020] Figure 1 It is a schematic plan view of a pipe gallery foundation pit supporting structure according to one embodiment of the utility model.

[0021] Figure 2 for Figure 1 AA cross-sectional structure schematic diagram.

[0022] Figure 3 This is a backfill large-scale drawing of a combined pile support structure according to one embodiment of the utility model.

[0023] Figure 4 This is a schematic diagram of the crown beam reinforcement in the inserted steel pipe pile area of ​​one embodiment of the utility model.

[0024] Figure 5 This is a schematic diagram of the crown beam reinforcement in the area without inserted steel pipe piles in one embodiment of the utility model.

[0025] Figure 6 This is a schematic diagram of reinforced concrete support reinforcement according to an embodiment of the utility model.

[0026] Figure 7 This is a schematic diagram of the large-scale connection between the combined pile support structure and the steel support according to one embodiment of the utility model.

[0027] Explanation of the figures: 1. Foundation pit soil, 2. Steel pipe piles, 3. Larsen steel sheet piles, 4. Crown beam, 5. Reinforced concrete support, 6. Pipe gallery structure, 7. Cement-soil bidirectional mixing piles, 8. Foundation pit top, 9. Intercepting ditch, 10. Steel support, 11. Medium-coarse sand, 12. Roofing felt, 13. C40 plain concrete, 14. C20 plain concrete cushion, 15. Gravel cushion, 16. C20 fine stone concrete, 17. Steel waist beam, 18. Crown beam longitudinal reinforcement, 19. Crown beam stirrups, 20. Reinforced concrete support top longitudinal reinforcement, 21. Reinforced concrete support side longitudinal reinforcement, 22. Reinforced concrete support stirrups, 23. Reinforced concrete support tension reinforcement, 24. Steel plate, 25. Steel corbel, 26. Weld foot. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0029] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0030] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0031] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0032] The underground integrated pipe gallery has greatly reduced the amount of municipal pipeline excavation by concentrating various public pipelines such as water, electricity, gas, heating and communications in a limited underground space. It also has the advantages of convenient operation and maintenance, saving underground space, etc., and has been widely used in new city construction and old city renovation. However, in naturally formed deep soft soil areas, due to the low foundation bearing capacity of soft soil, small values ​​of compression modulus and shear resistance parameters, the foundation of the integrated pipe gallery may produce large settlement or settlement difference under the action of its own weight and external load, which poses great challenges to the safety and waterproofness of the pipe gallery structure and the safe operation of the internal pipelines of the pipe gallery. In addition, excavating foundation pits in deep soft soil areas is also very likely to cause foundation pit instability. Engineering practice shows that when the foundation treatment method of the pipe gallery uses cement soil one-way mixing piles, the quality of the mixing piles is often unreliable due to the deep soft soil, which makes the normal operation of the pipe gallery a safety hazard. At present, the foundation of the pipeline corridor is mostly reinforced by bored piles, high-pressure rotary jet piles, pipe piles, etc., while the excavation of foundation pits in deep soft soil areas mostly adopts bored piles or SMW cement soil mixing wall support structures. The above methods have high costs, large carbon emissions, low material recyclability, and long construction period, which greatly affects the construction efficiency of the comprehensive pipeline corridor.

[0033] like Figures 1 to 3 As shown, an embodiment of the present application provides a tunnel foundation pit support structure, including a combined pile support structure, a support support structure and a foundation treatment structure. The combined pile support structure is arranged at the position of each side wall of the tunnel foundation pit, and the lower end of the combined pile support structure penetrates the thick soft soil and extends into the stable soil layer below the foundation pit soil body 1. The support support structure is arranged in the tunnel foundation pit, and is adjacently arranged on the inner side of the combined pile support structure, and the support support structure is connected and fixed with the combined pile support structure, and the foundation treatment structure is arranged at the bottom of the tunnel foundation pit, and the foundation treatment structure penetrates the thick soft soil and extends into the stable soil layer below the foundation pit soil body 1. The tunnel foundation pit support structure adopts a combined support system of a combined pile support structure + a support support structure + a foundation structure, and the combined pile support structure and the foundation structure both penetrate the soft soil layer and extend into the stable soil layer below the foundation pit soil body 1, so that the support is stable, settlement is prevented, and the safety of the tunnel mechanism is improved.

[0034] In some embodiments, the combined pile support structure includes multiple steel pipe piles 2 and Larsen steel sheet piles 3, all of which are interlocked and staggered, and are buried in the foundation pit soil 1. The steel pipe piles 2 and Larsen steel sheet piles 3 penetrate the thick soft soil and extend into the stable soil layer below the foundation pit soil 1; the steel pipe piles 2 and Larsen steel sheet piles 3 are connected end to end along the front and rear side walls of the corridor foundation pit axis, and are tightly connected to the steel pipe piles 2 through the Larsen steel sheet piles 3 to form a closed closed system, thereby avoiding the risk of soil flow caused by the soft soil on the side wall of the foundation pit flowing into the foundation pit. The steel pipe piles 2 and Larsen steel sheet piles 3 can form a supporting structure, thereby providing a good support for the soft soil around the foundation pit.

[0035] In some specific embodiments, the Larsen steel sheet piles 3 and the steel pipe piles 2 are made of Q355B steel. The steel pipe piles 2 are made of round steel pipes with a diameter of 820 mm and a wall thickness of 14 mm. The spacing between the steel pipe piles 2 is 1.29 m, and the gaps between the steel pipe piles 2 are connected by Larsen steel sheet piles 3. The Larsen steel sheet piles 3 are FSP-IV type, with a wall thickness of 15.5 mm, a cross-sectional area of ​​96.99 cm2 per sheet, a secondary moment of 4670 cm4 per sheet, 38600 cm4 per meter, and a section modulus of 362 cm3 per sheet, 2270 cm3 per meter.

[0036] In a further embodiment, the combined pile support structure may further include a crown beam 4, and the tops of multiple steel pipe piles 2 and Larsen steel sheet piles 3 are connected by the crown beam 4. By setting the crown beam 4 and connecting the tops of the steel pipe piles 2 and Larsen steel sheet piles 3 into a whole, the soil pressure acting on the Larsen steel plate 24 can be transmitted to the steel pipe piles 2 and then to the deep soil. While saving construction materials of the Larsen steel sheet piles 3, the protection capability of the support system is comprehensively improved.

[0037] In some specific embodiments, the crown beam 4 includes a skeleton and a crown beam body, and the skeleton and the crown beam body are cast by concrete to form the crown beam 4. The skeleton and the crown beam body are cast by concrete to form a whole, which can ensure the firmness and uniform force of the steel pipe piles 2 and the Larsen steel sheet piles 3, and ensure the structural stability of the steel pipe piles 2 and the Larsen steel sheet piles 3 support structure.

[0038] Specifically, Figure 4 , Figure 5 As shown, the skeleton is composed of a plurality of circular crown beam longitudinal bars 18 and a plurality of crown beam stirrups 19. The plurality of crown beam longitudinal bars 18 are arranged vertically at intervals, and then concrete is poured to form a crown beam 4 as a whole with a protective layer.

[0039] In some embodiments, a fertilizer trough is provided between the Larsen steel sheet pile 3 and the steel pipe pile 2 and the pipe gallery structure 6, the bottom of the fertilizer trough is backfilled with C40 plain concrete 13 having the same thickness as the bottom plate of the pipe gallery structure 6, the middle and upper parts of the fertilizer trough are backfilled with medium-coarse sand 11, and linoleum felt 12 is provided between the Larsen steel sheet pile 3 and the steel pipe pile 2 and the C40 plain concrete 13. By providing a fertilizer trough, backfilling with medium-coarse sand 11 and C40 plain concrete 13, and providing linoleum felt 12 to play an isolation role, not only the construction space for pouring the bottom plate, side wall and top plate of the pipe gallery structure 6 is guaranteed, which is convenient for personnel and equipment operation, but also the uniformity and compaction effect of the backfill material are ensured, so that the pipe gallery structure 6, the soil and the backfill material form a continuous force-bearing whole, and at the same time, when the Larsen steel sheet pile 3 and the steel pipe pile 2 are recovered, the disturbance and damage to the structure are avoided.

[0040] In some specific embodiments, the fertilizer tank is about 1 m wide.

[0041] In some embodiments, the supporting structure includes reinforced concrete supports 5, which are cast and connected to the crown beam 4. By casting the reinforced concrete supports 5 and the crown beam 4, the compressive strength, shear strength and bending stiffness of the reinforced concrete supports 5 can be fully utilized.

[0042] In some specific embodiments, Figure 5 As shown, the reinforced concrete support 5 includes a skeleton and a support body, the skeleton includes reinforced concrete support top surface longitudinal reinforcement 20, reinforced concrete support side longitudinal reinforcement 21, reinforced concrete support tension reinforcement 23 and reinforced concrete support stirrups 22, and the skeleton and the support body are cast by concrete to form the reinforced concrete support 5. The size (width x height) of the crown beam 4 is 1300mm×800mm, the size (width x height) of the reinforced concrete support 5 is 800mmx800mm, and the steel support 10 adopts a spiral steel pipe with a diameter of 609mm and a wall thickness of 16mm.

[0043] In a further embodiment, the support structure further comprises a steel support 10, a frame-shaped steel waist beam 17 and a steel corbel 25, the steel waist beam 17 is arranged on the inner side of the support structure of the Larsen steel sheet pile 3 and the steel pipe pile 2, and the two ends of the steel support 10 are respectively connected to the front and rear sides of the steel waist beam 17, and the gap between the steel waist beam 17 and the Larsen steel sheet pile 3 and the steel pipe pile 2 is backfilled with C20 fine stone concrete 16, and the steel corbel 25 is arranged at intervals along the length direction of the steel waist beam 17, and the steel corbel 25 abuts against the steel support 10 and supports the steel support 10. Specifically, see Figure 7 The steel plate 24 can be used to weld the steel support 10, the steel waist beam 17, the Larsen steel sheet pile 3 and the steel pipe pile 2, and the C20 fine stone concrete 16 can be used to fill the gaps between the steel waist beam 17 and the Larsen steel sheet pile 3 and the steel pipe pile 2 to make them an integral force-bearing system, which greatly improves the bending strength and force-bearing performance of the Larsen steel sheet pile 3 and the steel pipe pile 2. The protective structure is firm and the supporting structure is stable, which significantly reduces the deformation of the soil around the foundation pit. The steel corbel 25 can provide stable support for the steel support 10.

[0044] In some specific implementations, the curing strength of the C20 fine stone concrete 16 is not less than 5 MPa.

[0045] In some specific embodiments, Figure 6As shown, the steel waist beam 17 is specifically a double-jointed steel waist beam composed of two groups of HN700x300x11x24 steel sections, wherein the end faces of the two groups of steel sections are respectively welded to the corresponding steel pipe piles 2 and Larsen steel sheet piles 3 through steel plates 24, and weld feet 26 are formed. The steel waist beam 17 is specifically a double-jointed steel waist beam, and the steel waist beam 17 is welded to the steel pipe piles 2 and Larsen steel sheet piles 3 through steel plates 24, so that they become an integral force-bearing system, and its protective structure is strong and convenient for the installation of the steel waist beam 17. Here, the welded steel plate between the steel waist beam 17 and the steel pipe piles 2 and Larsen steel sheet piles 3 is a 650mm×650mm×16mm steel plate. The material of the steel plate 24 is Q235 steel.

[0046] In some embodiments, the foundation treatment structure includes a plurality of cement-soil bidirectional mixing piles 7 and a crushed stone cushion layer 15. The plurality of cement-soil bidirectional mixing piles 7 are arranged at the bottom of the tunnel foundation pit, and the plurality of cement-soil bidirectional mixing piles 7 penetrate the deep soft soil and extend into the stable soil layer below the foundation pit soil body 1. The plurality of cement-soil bidirectional mixing piles 7 are evenly spaced in a rectangular array; the crushed stone cushion layer 15 is arranged at the bottom of the tunnel foundation pit and above the cement-soil bidirectional mixing piles 7. The crushed stone cushion layer 15 can adjust the load sharing of the piles and the soil, give full play to the joint effect of the piles and the soil between the piles, effectively reduce the pile-soil stress ratio, reduce the unevenness of the foundation, and achieve coordinated deformation of the foundation. At the same time, the two sets of mixing blades on the inner and outer concentric drill rods of the mixing equipment are used to rotate forward and reverse at the same time, so that the slurry and the soil are fully mixed to form the cement-soil bidirectional mixing piles 7, which greatly improves the compression modulus and bearing capacity of the foundation soil, thereby reducing the uneven settlement of the tunnel structure 6.

[0047] In a further embodiment, the foundation treatment structure further includes a C20 plain concrete cushion layer 14, which is laid on the crushed stone cushion layer 15, and the C20 plain concrete cushion layer 14 is located below the pipe gallery structure 6. The C20 plain concrete cushion layer 14 plays a role in protecting the foundation, and also has the effects of water isolation, antifreeze, and load diffusion, which significantly improves the deformation capacity of the foundation soil of the pipe gallery structure 6.

[0048] In some specific embodiments, the diameter of the cement-soil bidirectional mixing pile 7 is 500 mm, the longitudinal and lateral spacings of the cement-soil bidirectional mixing pile 7 are 1.5 m and 1.2 m respectively, the strength grade of the cement used is not less than 42.5 MPa, the reference cement content of the mixing pile is about 15%, the cement content in each cubic meter of mixed soil is about 260 kg, the depth of the cement-soil bidirectional mixing pile 7 entering the stable soil layer is not less than 1.0 m, the characteristic value of the single pile bearing capacity of the cement-soil bidirectional mixing pile 7 is 120 kN, and the characteristic value of the composite foundation bearing capacity is 110 kPa.

[0049] Optionally, the widths of the C20 plain concrete cushion layer 14 and the crushed stone cushion layer 15 are consistent with the overhanging dimensions of the foundation structure of the pipe gallery structure 6. The crushed stone cushion layer 15 uses graded crushed stone with a particle size not greater than 20 mm and a thickness of 30 cm. The crushed stone cushion layer 15 should preferably be compacted by static compaction, and the tamping degree of the crushed stone cushion layer 15 should not be greater than 0.9.

[0050] In some embodiments, the tunnel foundation pit support structure further includes a drainage ditch 9, which is arranged on the surface of the tunnel foundation pit top 8. By setting the drainage ditch 9, surface water, rainwater and temporary water used for construction can be drained, reducing the scouring effect of the soil on the side wall of the foundation pit and significantly improving the stability of the support system.

[0051] In some specific implementations, the size of the intercepting ditch 9 is 300 mm×300 mm.

[0052] In summary, the specific implementation steps of the pipe gallery foundation pit support structure provided in this application are as follows:

[0053] Step 1: Site clearance, leveling, pipeline relocation and site enclosure. Before construction, necessary clearance work should be carried out, surface water should be drained, and the construction-affected area should be fenced to ensure safety.

[0054] Step 2: Construction of steel pipe piles 2 and Larsen steel sheet piles 3: Larsen steel sheet piles 3 are constructed with small stoppers. Before sinking the piles, butter, asphalt, sawdust or other sealing and water-stopping materials should be embedded in the lock mouth. The flatness and verticality of steel pipe piles 2 must be ensured, and distortion is not allowed. A special vibrating manipulator is used for pile insertion and drilling and driving. The lock mouth should be aligned when inserting the piles. The pores of steel pipe piles 2 are connected with Larsen steel sheet piles 3. The sinking speed of steel pipe piles 2 should be controlled during construction. The sinking speed of steel pipe piles 2 is generally 1m / min, the pile diameter deviation is not more than 10mm, and the elevation error is not more than 100mm.

[0055] Step 3: Use machinery to excavate the foundation pit soil 1. When the foundation pit is excavated to 0.5m below the design elevation of the reinforced concrete support 5, promptly set up the reinforced concrete support 5, and cast the reinforced concrete support 5 and the crown beam 4 as a whole. After the reinforced concrete support 5 reaches 80% of the design strength, continue to excavate the foundation pit to 0.5m below the design elevation of the steel support 10, and promptly set up the steel support 10. The steel support 10 is set on the steel waist beam 17. After the support is erected, the stability of the support should be checked and confirmed. Only after it is safe can the excavation construction continue to the bottom of the foundation pit.

[0056] Step 4: backfill the crushed stone cushion layer 15 and compact it, and then construct the cement-soil bidirectional mixing piles 7.

[0057] Step 5: After the cement-soil bidirectional mixing pile 7 is constructed and tested to be qualified, the C20 plain concrete cushion layer 14 is laid.

[0058] Step 6: When the C20 plain concrete cushion layer 14 reaches 100% of the design strength, the bottom plate, side wall and top plate structure of the pipe gallery structure 6 are constructed.

[0059] Step 7: After the construction of the pipe gallery structure 6 is completed and reaches 100% of the design strength, the foundation pit is backfilled. When the earth is backfilled to 50 cm below the bottom of the first support, the first support can be removed and backfilled to the ground as required.

[0060] Step 8: Recycling of steel pipe piles 2 and Larsen steel sheet piles 3: Use a special vibrating manipulator to pull out the piles. The gaps after the steel pipe piles 2 and Larsen steel sheet piles 3 are pulled out should be filled with sand in time. If the sand filling is not ideal, use 1:1 cement mortar to fill. The cement should be ordinary Portland cement with a strength grade of not less than 42.5MPa, and the grouting pressure should not exceed 0.1MPa. The grouting slurry should be added with an accelerated setting agent, and the grouting should be done while pulling out to complete the recycling of steel pipe piles 2 and Larsen steel sheet piles 3.

[0061] The above-mentioned tunnel foundation pit support structure adopts a combined support system of a combined pile support structure + a supporting support structure + a foundation structure. Both the combined pile support structure and the foundation structure penetrate the soft soil layer and extend into the stable soil layer below the foundation pit soil body 1, providing stable support and preventing settlement, thereby improving the safety of the tunnel structure. Moreover, the construction equipment is popular, the operation is simple, the construction technology is mature, and the steel can be recycled, which is economical and fully realizes the advantages of low-carbon energy saving and resource recycling.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some or all of the technical features therein can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no contradiction or conflict, the various technical features mentioned in the embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A pipe gallery foundation pit support structure, characterized in that include: A combined pile support structure, the combined pile support structure being located at the side walls of the tunnel foundation pit on both sides, the lower end of the combined pile support structure penetrating the soft soil layer and extending into the stable soil layer below the foundation pit soil body (1); A supporting structure connecting the combined pile supporting structures on both sides of the tunnel foundation pit; A foundation structure, wherein the foundation structure is located at the bottom of the foundation pit soil body (1), and the foundation structure penetrates the soft soil layer and extends into the stable soil layer below the foundation pit soil body (1).

2. The pipe gallery foundation pit support structure according to claim 1, characterized in that: The combined pile support structure comprises a plurality of steel pipe piles (2) and a plurality of Larsen steel sheet piles (3), wherein the steel pipe piles (2) and the Larsen steel sheet piles (3) are arranged in a staggered manner and are tightly connected to form a closed system; the lower ends of the steel pipe piles (2) and the Larsen steel sheet piles (3) penetrate the soft soil layer and extend into the stable soil layer below the foundation pit soil body (1).

3. The pipe gallery foundation pit support structure according to claim 2, characterized in that: The combined pile support structure also includes a crown beam (4), and the tops of the steel pipe piles (2) and the Larsen steel sheet piles (3) are connected into a whole by the crown beam (4).

4. The pipe gallery foundation pit support structure according to claim 3 is characterized in that: The crown beam (4) comprises a frame and a crown beam main body, the frame is arranged at the upper end of the crown beam main body, and the frame and the crown beam main body are formed as a whole by concrete pouring.

5. The pipe gallery foundation pit support structure according to claim 2, characterized in that: A fertilizer trough is arranged between the combined pile support structure and the pipe gallery structure (6), the bottom of the fertilizer trough is backfilled with C40 plain concrete (13) having a thickness equal to that of the bottom plate of the pipe gallery structure (6), and the upper part of the C40 plain concrete (13) is backfilled with medium-coarse sand (11); and tarpaulin (12) is arranged between the Larsen steel sheet pile (3) and the steel pipe pile (2) and the C40 plain concrete (13), respectively.

6. The pipe gallery foundation pit support structure according to claim 3, characterized in that: The supporting and retaining structure comprises a reinforced concrete support (5), and the reinforced concrete support (5) is connected to the crown beam (4) by casting.

7. The pipe gallery foundation pit support structure according to claim 6, characterized in that: The supporting structure also includes a steel support (10) and a frame-shaped steel waist beam (17), wherein the steel waist beam (17) is arranged on the inner side of the combined pile supporting structure formed by the Larsen steel sheet pile (3) and the steel pipe pile (2), and the end of the steel support (10) is connected to the steel waist beam (17) on the corresponding side, and the gap between the steel waist beam (17) and the Larsen steel sheet pile (3) and the steel pipe pile (2) is back-filled with C20 fine stone concrete (16); the inner sides of the Larsen steel sheet pile (3) and the steel pipe pile (2) are both provided with steel brackets (25), and the steel brackets (25) are in contact with the steel support (10) and support the steel support (10).

8. The pipe gallery foundation pit support structure according to claim 1, characterized in that: The foundation structure comprises a plurality of cement-soil bidirectional mixing piles (7) and a crushed stone cushion layer (15); the plurality of cement-soil bidirectional mixing piles (7) are arranged in a rectangular array at the bottom of the foundation pit soil body (1), and the plurality of cement-soil bidirectional mixing piles (7) penetrate the thick soft soil and extend into the stable soil layer below the foundation pit soil body (1); the crushed stone cushion layer (15) is arranged at the bottom of the tunnel foundation pit and is located above the cement-soil bidirectional mixing piles (7).

9. The pipe gallery foundation pit support structure according to claim 8, characterized in that: The foundation structure further comprises a C20 plain concrete cushion layer (14), wherein the C20 plain concrete cushion layer (14) is laid on the crushed stone cushion layer (15) and is located below the pipe gallery structure (6).

10. The pipe gallery foundation pit support structure according to claim 1, characterized in that: The pipe gallery foundation pit support structure further comprises a drainage ditch (9), wherein the drainage ditch (9) is arranged on the ground surface at the top (8) of the pipe gallery foundation pit.

Images