Composite supporting system for deep foundation pit

Abstract

The utility model provides a deep foundation pit composite supporting system and belongs to the technical field of deep foundation pit supporting, the supporting system comprises a vertical supporting structure and a horizontal supporting structure, the vertical supporting structure comprises a supporting pile, the supporting pile comprises a main pile and an auxiliary pile, and the main pile is connected with the horizontal supporting structure. The horizontal supporting structure comprises a composite beam assembled between the two main piles; the multiple composite beams are arranged, each composite beam comprises two prefabricated concrete beams and an inner supporting truss assembled between the two prefabricated concrete beams, and the ends, away from the inner supporting trusses, of the prefabricated concrete beams are fixedly connected with the corresponding main piles. An inner supporting wall is poured on the side, away from the side wall of the foundation pit, of the supporting pile. The length of the inner supporting truss can be fixed in a telescopic mode. The utility model has the effects that the construction efficiency of the deep foundation pit is improved, and the applicability to the deep foundation pit with medium and small spans is improved.

Description

Technical Field

[0001] This utility model relates to the field of deep foundation pit support technology, and in particular to a deep foundation pit composite support system. Background Technology

[0002] Deep foundation pits refer to excavations with significant depths, typically used in the construction of deep building structures such as basements, subway stations, and tunnels. The support and stability of deep foundation pits are critical issues during construction, often requiring a comprehensive support structure to ensure their safety. Generally, retaining piles provide the vertical support structure to prevent soil collapse, while concrete support beams provide lateral support, resisting lateral earth pressure and ensuring the stability of the foundation pit during excavation.

[0003] However, existing concrete support beams are usually reinforced and poured on-site after excavation to the specified depth. They also need to be cut in sections and in stages, resulting in many cutting points. This construction method is slow and time-consuming. Moreover, a large number of cut concrete support beams can usually only be used for backfilling, which wastes resources. However, there are also existing methods that use servo steel supports to replace concrete. However, this method is usually more expensive and has low applicability to deep foundation pits with small to medium spans. Utility Model Content

[0004] The purpose of this invention is to provide a composite support system for deep foundation pits, so as to improve the construction efficiency of deep foundation pits and enhance the applicability to deep foundation pits with small and medium spans.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0006] A deep foundation pit composite support system includes a vertical support structure and a horizontal support structure. The vertical support structure includes support piles, which include a plurality of main piles and a plurality of auxiliary piles. The horizontal support structure includes a composite beam assembled between two main piles. The system is characterized by having multiple composite beams, each including two precast concrete beams and an internal bracing truss assembled between the two precast concrete beams. The ends of the precast concrete beams away from the internal bracing truss are fixedly connected to the corresponding main piles. An internal bracing wall is cast on the side of each support pile away from the foundation pit sidewall. The internal bracing truss is a fixed-length, extendable internal bracing truss.

[0007] During construction of the aforementioned deep foundation pit composite support system, after each deep foundation pit is excavated to the specified depth, a precast concrete beam is hoisted to the corresponding position for installation, and then an inner support wall is poured to connect the precast concrete beam with the inner support wall.

[0008] Then, an internal bracing truss is installed between two corresponding precast concrete beams, thereby fixing the internal bracing truss between the two precast concrete beams and cooperating with the precast concrete beams for internal bracing.

[0009] This design is suitable for deep foundation pits with small to medium spans. These pits do not require high-precision equipment or servo control; the combination of internal bracing trusses and precast concrete provides sufficient strength and stability. Compared to the complex control mechanism of servo steel support systems, using adjusting nuts and supporting steel pipes allows for faster internal bracing construction while meeting strength requirements.

[0010] Moreover, using precast concrete beams and connecting them to the internal support walls ensures a secure connection between the precast concrete beams and eliminates the need for on-site formwork erection, rebar tying, and concrete pouring. Furthermore, when dismantling the internal support beams later, it is only necessary to retract the supporting steel pipes into the internal support truss and remove them, then cut off the precast concrete beams. This reduces the amount of cutting and significantly decreases the amount of waste concrete, improving construction efficiency and meeting the requirements of low-carbon construction.

[0011] Furthermore, the internal bracing truss is lightweight and high-strength, which reduces the overall weight of the internal bracing beams, thereby reducing the additional burden on the internal bracing walls.

[0012] Furthermore, each of the four chords of the inner support truss is slidably connected to a supporting steel pipe, and an adjusting nut is rotatably connected to the end of the chord of the inner support truss. The supporting steel pipe is threadedly connected to the adjusting nut, and the supporting steel pipe is pressed against the end of the precast concrete beam away from the inner support wall.

[0013] Furthermore, the main pile is embedded with a plurality of first connecting bars, which are used to assemble and connect with the corresponding precast concrete beam; the precast concrete beam is provided with a second connecting bar at the end away from the inner support truss, and the second connecting bar is fixedly connected to the corresponding first connecting bar.

[0014] Furthermore, each layer of the deep foundation pit is equipped with a temporary support frame, which supports the corresponding composite beam.

[0015] Furthermore, a third connecting bar is embedded in the support pile, the inner support wall is a reinforced waterproof concrete wall, the third connecting bar is connected to the steel mesh of the inner support wall, and the end of the precast concrete beam, the first connecting bar, the second connecting bar and the third connecting bar are all located inside the inner support wall.

[0016] Therefore, the third connecting bar is connected to the steel mesh of the inner support wall, which further enhances the solidity of the inner support wall, making it a complete integrated structure with the precast concrete beam and support piles, while ensuring good waterproof performance, making it suitable for environments with high groundwater levels.

[0017] Furthermore, several connecting sleeves are pre-embedded in the end of the precast concrete beam away from the inner support wall, and an abutment steel plate is provided on the end face of the precast concrete beam. The abutment steel plate is provided with a fixing bolt, and the fixing bolt is threadedly connected to the corresponding connecting sleeve. The abutment steel plate is provided with an insertion groove corresponding to the supporting steel pipe, and the supporting steel pipe is inserted into the corresponding insertion groove and abuts against the abutment steel plate.

[0018] Therefore, the design of the embedded sleeve and the abutment steel plate ensures a tight connection between the supporting steel pipe and the precast concrete beam, which can effectively prevent the structure from loosening and improve the overall structure's compressive and deformation resistance.

[0019] Furthermore, the diameters at both ends of the chord of the inner support truss are larger than the diameter at the middle of the chord of the inner support truss, and the diameter of the supporting steel pipe is not smaller than the diameter at the middle of the chord of the inner support truss.

[0020] Therefore, this design allows for an increase in the diameter of the supporting steel pipe, strengthens the contact surface between the supporting steel pipe and the precast concrete, improves the reliability of the lateral support, and reduces structural deformation or instability caused by uneven stress.

[0021] Furthermore, both the main piles and the auxiliary piles are rotary drilling piles, and the main piles and the auxiliary piles are staggered, with the main piles and the adjacent auxiliary piles interlocking with each other.

[0022] Furthermore, the main pile is a reinforced concrete pile, and the auxiliary pile is a plain concrete pile.

[0023] Therefore, by staggering and interlocking the main piles and auxiliary piles, the overall shear resistance and stability of the foundation pit support can be greatly improved. Especially when the bearing pressure of the sidewall of the deep foundation pit is large, this structure can effectively enhance the resistance to lateral pressure and the seepage prevention effect.

[0024] Furthermore, the cross-sectional width of the inner support truss is 300mm to 1000mm.

[0025] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0026] (I) The support system of this utility model is suitable for deep foundation pits with small to medium spans. Deep foundation pits with small to medium spans do not require high-precision equipment and servo control. The structure combining internal support trusses and precast concrete can provide sufficient strength and stability in deep foundation pits with small to medium spans. Compared with the complex control mechanism of servo steel support systems, the method of using adjusting nuts and supporting steel pipes can carry out internal support construction more quickly while meeting strength requirements.

[0027] (II) The support system of this utility model adopts a precast concrete beam and connects it to the internal support wall. This ensures a firm connection of the precast concrete beam and eliminates the need for on-site formwork erection, rebar tying, and concrete pouring. Furthermore, when dismantling the internal support beam later, it is only necessary to retract the support steel pipe into the internal support truss and remove it, then cut off the precast concrete beam. This reduces the amount of cutting and significantly decreases the amount of waste concrete, thus improving construction efficiency and meeting the requirements of low-carbon construction.

[0028] (III) The internal support truss of this utility model is lightweight and high-strength, which reduces the overall weight of the internal support beam, thereby reducing the additional burden on the internal support wall.

[0029] (iv) The support system of this utility model can greatly improve the overall shear resistance and stability of the foundation pit support by the staggered distribution and interlocking of the main piles and auxiliary piles. Especially when the bearing pressure of the sidewall of the deep foundation pit is large, this structure can effectively enhance the resistance to lateral pressure and the seepage prevention effect. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of one embodiment of the present utility model.

[0031] Figure 2 This is a schematic diagram of the structure of the first connecting rib, the second connecting rib, and the supporting steel pipe in one embodiment of the present invention.

[0032] Figure 3 yes Figure 2 An enlarged schematic diagram of part A in the middle.

[0033] Figure 4 yes Figure 2 Enlarged schematic diagram of part B.

[0034] Explanation of reference numerals in the attached drawings: 1. Support pile; 11. Main pile; 12. Secondary pile; 13. First connecting bar; 14. Third connecting bar; 2. Precast concrete beam; 21. Second connecting bar; 22. Connecting sleeve; 23. Abutting steel plate; 231. Insertion groove; 24. Fixing bolt; 3. Internal support truss; 31. Supporting steel pipe; 32. Adjusting nut; 4. Internal support wall; 5. Temporary support frame. Detailed Implementation

[0035] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other. For ease of description, the terms "upper," "lower," "left," and "right" appearing below only indicate that they correspond to the upper, lower, left, and right directions in the accompanying drawings and do not limit the structure.

[0036] The following is in conjunction with the appendix Figure 1 -Appendix Figure 4 This embodiment will be described in further detail.

[0037] like Figure 1 , Figure 2 and Figure 3 As shown, this embodiment of a deep foundation pit composite support system includes a vertical support structure and a horizontal support structure. The vertical support structure includes support piles 1, which include several main piles 11 and several secondary piles 12. The horizontal support structure includes a composite beam assembled between two main piles 11. The composite beam has multiple beams, each including two precast concrete beams 2 and an internal support truss 3 assembled between the two precast concrete beams 2. The end of each precast concrete beam 2 away from the internal support truss 3 is fixedly connected to a corresponding main pile 11. An internal support wall 4 is cast on the side of the support pile 1 away from the foundation pit sidewall. The internal support truss 3 is a fixed-length, extendable internal support truss.

[0038] The four chords of the inner support truss 3 are all slidably connected with supporting steel pipes 31. The ends of the chords of the inner support truss 3 are rotatably connected with adjusting nuts 32. The supporting steel pipes 31 are threadedly connected to the adjusting nuts 32. The supporting steel pipes 31 are pressed against the end of the precast concrete beam 2 away from the inner support wall 4.

[0039] The support pile 1 includes a main pile 11 and an auxiliary pile 12. Both the main pile 11 and the auxiliary pile 12 are rotary drilling piles. The main pile 11 is a reinforced concrete pile (the steel cage of the main pile 11 is not shown in the drawing), and the auxiliary pile 12 is a plain concrete pile. The main pile 11 and the auxiliary pile 12 are staggered and driven into the side wall of the deep foundation pit along the outline of the deep foundation pit. The main pile 11 and the adjacent auxiliary pile 12 interlock with each other.

[0040] Several sets of first connecting bars 13 are inserted into the main pile 11 along its height direction, and several first connecting bars 13 are provided in each set. Several third connecting bars 14 are also inserted into the main pile 11 along its height direction.

[0041] like Figure 3 and Figure 4Each precast concrete beam 2 has a second connecting bar 21 extending from one end and several connecting sleeves 22 embedded at the other end. The second connecting bar 21 corresponds to the first connecting bar 13 and overlaps with each other. An abutting steel plate 23 is provided on the end face of the precast concrete beam 2 away from the second connecting bar 21. The abutting steel plate 23 fits against the end face of the precast concrete beam. A fixing bolt 24 passes through the abutting steel plate 23. The fixing bolt 24 is threaded with the connecting sleeve 22, so that the abutting steel plate 23 abuts against the end face of the precast concrete beam. Several insertion grooves 231 are opened on the end face of the abutting steel plate 23 away from the precast concrete beam 2.

[0042] An inner support wall 4 is poured between the precast concrete beam 2 and the main pile 11 and the auxiliary pile 12. The inner support wall 4 is a reinforced waterproof concrete wall. The third connecting bar 14 is connected to the steel mesh of the inner support wall 4 (not shown in the steel mesh diagram). The ends of the precast concrete beam 2, the first connecting bar 13, the second connecting bar 21 and the third connecting bar 14 are all located inside the inner support wall 4.

[0043] The internal support truss 3 is located between two opposing precast concrete beams 2. Each of the four chords of the internal support truss 3 is slidably connected to a supporting steel pipe 31. Adjusting nuts 32 are rotatably connected to the ends of the chords of the internal support truss 3. The supporting steel pipes 31 are threadedly connected to the adjusting nuts 32, and the supporting steel pipes 31 are pressed against the end of the precast concrete beam 2 away from the internal support wall 4. Each supporting steel pipe 31 corresponds to a slot 231, and the supporting steel pipe 31 is inserted into the corresponding slot 231 and pressed against the abutment steel plate 23.

[0044] The diameters at both ends of the chord members of the inner supporting truss 3 are larger than the diameter at the middle of the chord members. The diameter of the supporting steel pipe 31 is not smaller than the diameter at the middle of the chord members of the inner supporting truss 3. In this embodiment, the diameters at both ends of the chord members of the inner supporting truss 3 are 1.5 times the diameter at the middle of the chord members, and the diameter of the supporting steel pipe 31 is the same as the diameter at the middle of the chord members of the inner supporting truss 3. The supporting steel pipe 31 is located inside the end of the chord members of the inner supporting truss 3.

[0045] The materials for the internal support truss 3 are Q345B steel / Q235 steel / S355 steel / weathering steel.

[0046] Q345B steel is suitable for medium to large span truss structures, can withstand large loads, and performs well in complex construction environments.

[0047] Q235 steel is suitable for relatively small truss structures and light load applications, such as shallow foundation pits or support beam systems with low support requirements.

[0048] S355 steel is suitable for large-scale projects and deep foundation pit projects with heavy loads.

[0049] Weathering steel is suitable for humid or corrosive environments, such as deep foundation pits with high groundwater levels.

[0050] The specific materials to be selected can be determined based on the specific circumstances of the construction project.

[0051] The cross-sectional dimensions of the internal support truss 3 range from 300mm x 300mm to 1000mm x 1000mm.

[0052] For deep foundation pits with small spans, internal bracing trusses with smaller cross-sectional areas can be used, with cross-sectional dimensions of approximately 300mm×300mm or 400mm×400mm.

[0053] For deep foundation pits with medium spans, internal bracing trusses with larger cross sections are used, typically ranging from 500mm×500mm to 800mm×800mm.

[0054] For deep foundation pits with large spans, internal bracing trusses 3 with large cross-sectional heights are used. The cross-sectional area of ​​internal bracing trusses 3 needs to reach 1000mm×1000mm, and stiffening ribs or double-row trusses are required to ensure sufficient rigidity and strength.

[0055] Temporary support frames 5 are installed on each floor slab of the deep foundation pit. The temporary support frames 5 are steel pipe scaffolding, which support the corresponding precast concrete beams 2 and internal bracing trusses 3.

[0056] The deep foundation pit composite support system of this embodiment typically requires construction using the reverse construction method. The specific construction method is as follows:

[0057] Excavate the foundation pit to the bottom elevation of the first-floor precast concrete beam 2, exposing the main piles 11 and auxiliary piles 12 to the soil. Insert the first connecting bar 13 and the third connecting bar 14 into the main piles 11. Overlap the second connecting bar 21 of the precast concrete beam 2 with the corresponding first connecting bar 13. Overlap the steel mesh of the inner support wall 4 with the third connecting bar 14. Then, pour waterproof concrete to form the inner support wall 4, integrating the ends of the precast concrete beam 2 with the inner support wall 4. Next, hoist the inner support truss 3 between the two precast concrete beams 2. Rotate the adjusting nut 32 to insert the supporting steel pipe 31 into the corresponding insertion slot 231 and tighten it against the abutment steel plate 23, completing the construction of the inner support beam.

[0058] After completing the construction of the first-floor internal support, excavation continues downwards to the bottom elevation of the first-floor slab, exposing the main piles 11 and auxiliary piles 12 in this section to the soil. Then, the construction of the internal support wall 4 begins. Next, the construction of the first-floor slab commences, with working openings reserved to facilitate further downward construction. Once the first-floor slab is completed and reaches its design strength, temporary support frames 5 are erected to support the precast concrete beams 2 and the internal support truss 3.

[0059] Then continue excavating the foundation pit to the bottom elevation of the second layer of precast concrete beam 2, repeating the above construction steps until the deep foundation pit excavation is completed and all the bottom slab construction is finished. Finally, in order from bottom to top, cut and dismantle the precast concrete beam 2, dismantle the internal support truss 3 and the temporary support frame 5.

[0060] The implementation principle of this embodiment is as follows: during construction, after each deep foundation pit is excavated to the specified depth, the precast concrete beam 2 is hoisted to the corresponding position, the first connecting bar 13 is overlapped with the second connecting bar 21, and then the inner support wall 4 is poured to connect the precast concrete beam 2 with the inner support wall 4.

[0061] Then, an inner support truss 3 is placed between two corresponding precast concrete beams 2, and the adjusting nut 32 is rotated so that the supporting steel pipe 31 is pressed against the end of the precast concrete beam 2, thereby fixing the inner support truss 3 between the two precast concrete beams 2 and cooperating with the precast concrete beams 2 for internal support.

[0062] This design is suitable for deep foundation pits with small to medium spans. These pits do not require high-precision equipment or servo control; the combination of the internal support truss 3 and the precast concrete beam 2 provides sufficient strength and stability. Compared to the complex control mechanism of servo steel support systems, the use of adjusting nuts 32 and supporting steel pipes 31 allows for faster internal support construction while meeting strength requirements.

[0063] Furthermore, the use of precast concrete beams 2 and their connection to the internal support wall 4 ensures a secure connection for the precast concrete beams 2 without requiring on-site formwork erection, rebar tying, or concrete pouring. Additionally, when dismantling the internal support beams later, it is only necessary to retract the supporting steel pipes 31 into the internal support truss 3 and remove them, then cut off the precast concrete beams 2. This reduces the amount of cutting and significantly decreases the amount of waste concrete, improving construction efficiency and meeting the requirements of low-carbon construction.

[0064] The above embodiments should be understood as being used only to illustrate the present invention more clearly, and not to limit the scope of the present invention. After reading the present invention, any modifications of the embodiments by those skilled in the art in various equivalent forms fall within the scope defined by the appended claims.

Claims

1. A composite support system for deep foundation pit, comprising vertical support structures and horizontal support structures, the vertical support structures comprising support piles (1), the support piles (1) comprising a plurality of main piles (11) and a plurality of auxiliary piles (12), the horizontal support structures comprising composite beams assembled between two main piles (11); characterized in that, The combined beam is provided with a plurality of combined beams, which comprises two prefabricated concrete beams (2) and an inner support truss (3) assembled between the two prefabricated concrete beams (2), the prefabricated concrete beams (2) are fixedly connected with corresponding main piles (11) at one end away from the inner support truss (3); the support pile (1) is poured with an inner support wall (4) on the side away from the side wall of the foundation pit; the inner support truss (3) is an inner support truss with a telescopic fixed length.

2. The composite deep foundation pit support system according to claim 1, wherein, Four chord rods of the inner support truss (3) are slidably connected with support steel pipes (31), end portions of the chord rods of the inner support truss (3) are rotatably connected with adjusting nuts (32), the support steel pipes (31) are threadedly connected with the adjusting nuts (32), and the support steel pipes (31) are abuttingly connected with one end of the prefabricated concrete beam (2) away from the inner support wall (4).

3. The composite deep foundation pit support system according to claim 1, wherein, The main pile (11) is implanted with a plurality of first connecting ribs (13) for assembly connection with the corresponding prefabricated concrete beam (2); one end of the prefabricated concrete beam (2) away from the inner support truss (3) is provided with a second connecting rib (21), and the second connecting rib (21) is fixedly connected with the corresponding first connecting rib (13).

4. The composite deep foundation pit support system according to claim 1, wherein, A temporary support frame (5) is arranged on each floor slab of the deep foundation pit, and the temporary support frame (5) supports the combined beam.

5. The composite deep foundation pit support system according to claim 3, wherein, The support pile (1) is implanted with a third connecting rib (14), the inner support wall (4) is a reinforced waterproof concrete wall, the third connecting rib (14) is connected with a steel mesh of the inner support wall (4), and the end portion of the prefabricated concrete beam (2), the first connecting rib (13), the second connecting rib (21) and the third connecting rib (14) are located in the inner support wall (4).

6. The composite deep foundation pit support system according to claim 2, wherein, A plurality of connecting sleeves (22) are pre-buried in the end portion of the prefabricated concrete beam (2) away from the inner support wall (4), an abutting steel plate (23) is arranged on the end face of the prefabricated concrete beam (2), a fixing bolt (24) is arranged in the abutting steel plate (23), the fixing bolt (24) is threadedly connected with the corresponding connecting sleeve (22), an insertion slot (231) corresponding to the support steel pipe (31) is formed in the abutting steel plate (23), and the support steel pipe (31) is inserted into the corresponding insertion slot (231) and abuttingly connected with the abutting steel plate (23).

7. The composite deep foundation pit support system according to claim 2, wherein, The diameters of the two end portions of the chord rod of the inner support truss (3) are greater than the diameter of the middle portion of the chord rod of the inner support truss (3), and the diameter of the support steel pipe (31) is not less than the diameter of the middle portion of the chord rod of the inner support truss (3).

8. The composite deep foundation pit support system according to claim 1, wherein, The main pile (11) and the auxiliary pile (12) are rotary piles, the main piles (11) and the auxiliary piles (12) are staggered, and the main pile (11) and the adjacent auxiliary pile (12) are engaged with each other.

9. The composite deep foundation pit support system according to claim 8, wherein, The main pile (11) is a reinforced concrete pile, and the auxiliary pile (12) is a plain concrete pile.

10. The composite deep foundation pit support system according to any one of claims 1-9, wherein, The cross-sectional width of the inner support truss (3) is 300mm-1000mm. The cross-sectional width of the inner support truss (3) is 300mm-1000mm.

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