Large deep foundation pit supporting structure and supporting system and construction method thereof

Abstract

The invention provides a large-scale deep foundation pit supporting structure and system and a construction method thereof.The large-scale deep foundation pit supporting structure and system comprises a main pressure-bearing rod installed in a foundation pit, and the main pressure-bearing rod is provided with a first triangular supporting frame and a second triangular supporting frame; the supporting column is arranged on the lower portion of the main pressure-bearing rod, one end of the supporting column is connected with the main pressure-bearing rod, and the other end of the supporting column is connected with the bottom of a foundation pit. The first triangular supporting frames and the second triangular supporting frames are arranged on the main pressure-bearing rods, the bending strength of the main pressure-bearing rods on the vertical plane is enhanced, the bending strength of the main pressure-bearing rods on the horizontal plane is enhanced through mutual connection of the multiple main pressure-bearing rods, and therefore the requirement of a large foundation pit for the large span is met, and the construction cost is reduced. The number of the supporting columns is greatly reduced, operation at the bottom of a foundation pit is facilitated, the main pressure bearing rod, the first triangular supporting frame and the second triangular supporting frame are composed of a plurality of blocks, transportation is convenient after disassembly, the main pressure bearing rod, the first triangular supporting frame and the second triangular supporting frame are connected through flanges and can be disassembled and reused, and the use cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of engineering infrastructure construction, and in particular to a large-scale deep foundation pit support structure and support system and a construction method thereof. Background Art

[0002] At present, with the rapid development of urban infrastructure construction in my country, the scale of high-rise buildings, underground shopping malls and other buildings in large cities is gradually expanding. When carrying out this type of construction, it is necessary to excavate foundation pits. In order to prevent the collapse of the foundation pit from affecting the safety of adjacent buildings, it is necessary to use foundation pit support structures and support systems. For example, Chinese patent application number 202211303689.6 discloses a prefabricated assembled concrete support structure for a foundation pit, which supports the surrounding areas of the foundation pit through a number of supporting piles, crown beams, a number of supporting beams and a number of adapters. However, in this support system, there are many supporting columns at the bottom of the foundation pit, and the actual construction is to ensure the stability of the support. The spacing between the supporting columns is about 10 meters, resulting in a small construction space at the bottom of the foundation pit. The construction affects the construction equipment. For this reason, people have designed some new support structures to reduce the number of support columns in the foundation pit. For example, Chinese patent application number 202122967239.4 discloses an assembled suspended support device for foundation pit support. This scheme forms a support system through columns and lattice beam structures, which can ensure the support effect while reducing the number of columns and increasing the column spacing. However, in this scheme, two pillars are required to support the lattice beams, which still restricts the space in the foundation pit. Therefore, it is necessary to design a large-scale deep foundation pit support structure and support system and construction method thereof. For supporting large deep foundation pits, each main pressure beam only needs one column, which can further reduce the number of pillars while ensuring the support effect and increase the space for operation in the foundation pit. Summary of the invention

[0003] In order to solve the above problems, the present application proposes a large deep foundation pit support structure and support system and its construction method, by using a triangular support frame to reinforce the main pressure-bearing rod, and supporting the middle part of the main pressure-bearing beam through pillars, thereby reducing the number of pillars and increasing the space for operations in the foundation pit.

[0004] This application is implemented through the following technical solutions:

[0005] This application proposes a large deep foundation pit support structure, including:

[0006] A main pressure-bearing rod is installed in the foundation pit, and a first triangular support frame and a second triangular support frame are provided on the main pressure-bearing rod;

[0007] A support column is arranged at the lower part of the main pressure-bearing rod, one end of the support column is connected to the main pressure-bearing rod, and the other end of the support column is connected to the bottom of the foundation pit;

[0008] The first triangular support frame is detachably connected to both ends of the main pressure-bearing rod, and the second triangular support frame is detachably connected to the middle portion of the main pressure-bearing rod.

[0009] Furthermore, the first triangular support frame and the second triangular support frame are vertically installed on the main pressure-bearing rod, and the first triangular support frame and the second triangular support frame are in the same vertical plane.

[0010] Furthermore, the main pressure-bearing rod includes a straight pipe, a K-shaped joint, a Y-shaped joint, and a cross joint. The K-shaped joint and the Y-shaped joint are connected through the straight pipe and the flange and are symmetrically installed on both sides of the cross joint.

[0011] Furthermore, the first triangular support frame is in the shape of a right triangle, and includes a first splicing block, a second splicing block, and a third splicing block. The first splicing block, the second splicing block, and the third splicing block are connected by a flange, and one end of the first splicing block is connected to the main pressure rod by a flange.

[0012] Furthermore, the second triangular support frame is an isosceles triangle, and the second triangular support frame includes a straight pipe, a K-shaped joint, a Y-shaped joint, a Rice-shaped joint, and a special-shaped joint. The K-shaped joint, Y-shaped joint, Rice-shaped joint, and special-shaped joint are connected through a straight pipe and a flange. The straight pipe, K-shaped joint, Y-shaped joint, Rice-shaped joint, and special-shaped joint are used to connect between the second triangular support frame and the main pressure-bearing rod to form multiple triangular frames.

[0013] A large deep foundation pit support system comprises a plurality of main pressure-bearing rods and a plurality of supporting piles. The plurality of supporting piles are arranged at intervals inside the foundation pit. The upper ends of the supporting piles are connected to each other via a crown beam. Both ends of the main pressure-bearing rods are connected to the crown beam via a first triangular support frame. The main pressure-bearing rods are connected to each other via a connecting beam.

[0014] A construction method for a large deep foundation pit support system comprises the following steps:

[0015] Construct support piles, cap beams and column pile foundations, and implant columns on the column pile foundations;

[0016] The foundation pit is excavated to 0.5m below the bottom elevation of the main pressure rod, the main pressure rod is spliced ​​in sections, and after the first triangular support frame and the second triangular support frame are installed on the main pressure rod, the main pressure rod is connected to the crown beam;

[0017] The first triangular support frames and the second triangular support frames on the plurality of main pressure-bearing rods are respectively connected to each other through connecting beams;

[0018] The foundation pit is excavated to the designed pit bottom elevation.

[0019] Furthermore, the main pressure-bearing rod, the first triangular support frame, and the second triangular support frame are connected via flanges.

[0020] Furthermore, when there are two layers of main pressure-bearing rods, after installing the main pressure-bearing rods of the first layer, excavate to 0.5m below the bottom elevation of the second layer of main pressure-bearing rods, and after constructing two waist beams on the supporting piles, install the main pressure-bearing rods of the second layer. The main pressure-bearing rods of the second layer are connected to the waist beams through the first triangular support frames, and the middle parts between the upper and lower adjacent main pressure-bearing rods are connected to each other through the second triangular support frames.

[0021] Furthermore, the second triangular support frames are in the same vertical plane when stacked up and down.

[0022] The beneficial effects of the present application are as follows: by arranging the first triangular support frame and the second triangular support frame on the main pressure-bearing rod, the bending strength of the main pressure-bearing rod is enhanced in the vertical plane, and by interconnecting multiple main pressure-bearing rods, the bending strength of the main pressure-bearing rod in the horizontal plane is enhanced, thereby meeting the demand for large spans of large foundation pits, greatly reducing the number of pillars, and facilitating operations at the bottom of the foundation pit. The main pressure-bearing rod, the first triangular support frame, and the second triangular support frame are composed of multiple blocks, which are convenient for transportation after disassembly, and are connected by flanges, so they can be disassembled and reused, reducing the cost of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the structure of the main pressure rod assembly when it is a single-layer structure;

[0024] Figure 2 The connection diagram of the main pressure rod assembly in the case of a double-layer structure;

[0025] Figure 3 An exploded schematic diagram of the main bearing rod assembly and the second triangular support frame;

[0026] Figure 4 is an exploded schematic diagram of the first triangular support frame;

[0027] Figure 5 It is a schematic diagram of a single-layer support system;

[0028] Figure 6 It is a schematic diagram of the double-layer support system;

[0029] The descriptions of the reference numerals in the figures are as follows:

[0030] 1-main pressure rod, 2-first triangular support frame, 3-second triangular support frame, 4-pillar, 5-first splicing block, 6-second splicing block, 7-third splicing block, 8-K-shaped joint, 9-Y-shaped joint, 10-meter-shaped joint, 11-special-shaped joint, 12-cross joint, 13-support pile, 14-crown beam, 15-connecting beam, 16-waist beam. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0033] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0034] like Figures 1 to 6 As shown, an embodiment of the present invention provides a large-scale deep foundation pit support structure, including: a main pressure-bearing rod 1, a pillar 4, the main pressure-bearing rod 1 is installed in the foundation pit, a first triangular support frame 2 and a second triangular support frame 3 are provided on the main pressure-bearing rod 1, the pillar 4 is arranged at the lower part of the main pressure-bearing rod 1, one end of the pillar 4 is connected to the main pressure-bearing rod 1, and the other end of the pillar 4 is connected to the bottom of the foundation pit, the first triangular support frame 2 is detachably connected to both ends of the main pressure-bearing rod 1, and the second triangular support frame 3 is detachably connected to the middle part of the main pressure-bearing rod 1.

[0035] The crown beam 14 is connected to multiple supporting piles 13, and then the crown beam 14 is supported by the main pressure-bearing rod 1, so as to prevent the supporting piles 13 from tilting inward and avoid the foundation pit collapse. The main pressure-bearing rods 3 are connected by connecting beams 15, so that all the main pressure-bearing rods 1 form a whole, thereby improving the stability of the support system. The pillars 4 support the main pressure-bearing rods 1 in the middle part of the main pressure-bearing rods 1 to avoid the main pressure-bearing rods 1 from bending downward in the case of a large span, thereby ensuring the support effect and achieving the purpose of reducing the number of pillars 4 and facilitating operations at the bottom of the foundation pit.

[0036] In a preferred embodiment, the first triangular support frame 2 and the second triangular support frame 3 are vertically installed on the main pressure-bearing rod 1, and the first triangular support frame 2 and the second triangular support frame 3 are in the same vertical plane. The high stability of the triangle is utilized to improve the bending strength of the first triangular support frame 2 and the second triangular support frame 3, and the bending strength of the main pressure-bearing rod 1 is improved by connecting the first triangular support frame 2 and the second triangular support frame 3 to the main pressure-bearing rod 1. When supporting a large foundation pit, each main pressure-bearing rod 1 only needs to be provided with one pillar 4 in the middle, thereby reducing the number of pillars 4 and facilitating operations at the bottom of the foundation pit.

[0037] In a preferred embodiment, Figure 3 As shown, the main pressure-bearing rod 1 includes a straight tube, a K-shaped joint 8, a Y-shaped joint 9, and a cross joint 12. The K-shaped joint 8 and the Y-shaped joint 9 are connected through a straight tube and a flange and symmetrically installed on both sides of the cross joint 12. The various joints on the main pressure-bearing rod 1 are used to provide an installation position for connection with the second triangular support frame 3. After connection, a plurality of small triangular frames can be formed. The high stability of the triangle is utilized to enhance the bending resistance of the main pressure-bearing rod 1 and avoid bending and deformation of the main pressure-bearing rod 1 during the support process.

[0038] In a preferred embodiment, Figure 4 As shown, the first triangular support frame 2 is a right triangle, and the first triangular support frame 2 includes a first splicing block 5, a second splicing block 6, and a third splicing block 7. The first splicing block 5, the second splicing block 6, and the third splicing block 7 are connected by a flange, and one end of the first splicing block 5 is connected to the main pressure rod 1 by a flange. The multi-piece splicing design allows the first triangular support frame 2 to be reused and easy to transport after disassembly. The third splicing block 7 is connected to the crown beam 14. During support, the supporting force can be transmitted to each supporting pile 13 through the first triangular support frame 2, so as to maintain stability in the foundation pit.

[0039] Specifically, Figure 3 As shown, the second triangular support frame 3 is an isosceles triangle, and the second triangular support frame 3 includes a straight pipe, a K-shaped joint 8, a Y-shaped joint 9, a rice-shaped joint 10, and a special-shaped joint 11. The K-shaped joint 8, the Y-shaped joint 9, the rice-shaped joint 10, and the special-shaped joint 11 are connected through a straight pipe and a flange. The straight pipe, the K-shaped joint 8, the Y-shaped joint 9, the rice-shaped joint 10, and the special-shaped joint 11 are used to connect between the second triangular support frame 3 and the main pressure-bearing rod 1 to form a plurality of triangular frames. A variety of joints and straight pipes are spliced ​​together to form the second triangular support frame 3. The joints provide connection positions for easy docking. A small triangular frame can be formed within the main frame of the second triangular support frame 3 to enhance the structural strength of the second triangular support frame 3. After the second triangular support frame 3 is connected to the main pressure-bearing rod 1, the bending resistance of the main pressure-bearing rod 1 can be enhanced, thereby keeping the main pressure-bearing rod 1 straight during support.

[0040] like Figure 5 As shown, a large-scale deep foundation pit support system includes multiple main pressure-bearing rods 1 and multiple supporting piles 13. The multiple supporting piles 13 are arranged at intervals inside the foundation pit. The upper ends of the supporting piles 13 are connected to each other through a crown beam 14. The two ends of the main pressure-bearing rods 1 are connected to the crown beam 14 through a first triangular support frame 2. The main pressure-bearing rods 1 are connected to each other through a connecting beam 15. During support, the first triangular support frame 2 and the second triangular support frame 3 are used to enhance the bending resistance of the main pressure-bearing rods 1 in the vertical plane. At the same time, the multiple main pressure-bearing rods 1 are connected through the connecting beam 15 to enhance the bending resistance of the main pressure-bearing rods 1 in the horizontal plane, thereby forming a support system to ensure the safety in the foundation pit and reduce the use of the anti-internal support 4 to ensure convenient operation.

[0041] A construction method for a large deep foundation pit support system comprises the following steps:

[0042] 1. Construct support piles, crown beams and column pile foundations, and implant columns on the column pile foundations to prepare for support for foundation pit excavation;

[0043] 2. Excavate the foundation pit to 0.5m below the bottom elevation of the main pressure rod, splice the main pressure rod in sections, and after installing the first triangular support frame and the second triangular support frame on the main pressure rod, connect the main pressure rod with the crown beam. After excavation, it is convenient for the installation operation of the main pressure rod assembly;

[0044] 3. The first triangular support frame and the second triangular support frame on the plurality of main pressure-bearing rods are connected to each other through connecting beams, so that the main pressure-bearing rods are connected to each other to form a frame structure, thereby improving the overall strength;

[0045] 4. Excavate the foundation pit to the designed pit bottom elevation to complete the excavation of the foundation pit and facilitate construction within the pit.

[0046] Specifically, the main pressure rod, the first triangular support frame, and the second triangular support frame are connected by flanges. The flange connection is firm and can be reused, which is convenient for reducing the project cost.

[0047] Specifically, Figure 6 As shown, when there are two layers of main pressure-bearing rods, after installing the main pressure-bearing rods of the first layer, excavate to 0.5m below the bottom elevation of the second layer of main pressure-bearing rods, and after constructing two waist beams on the supporting piles, install the second layer of main pressure-bearing rods. The second layer of main pressure-bearing rods are connected to the waist beams through the first triangular support frame, and the middle parts between the upper and lower adjacent main pressure-bearing rods are connected to each other through the second triangular support frame. For deep foundation pits, it is not enough to support only the upper part of the supporting piles, so it is also necessary to support the supporting piles in the middle. After constructing the waist beam on the supporting piles, connect it to the waist beam through the first triangular support frame, and distribute the supporting force provided by the main pressure-bearing rods to the middle part of the supporting piles, thereby improving the stability of the middle part of the supporting piles in the deep foundation pit.

[0048] In a preferred embodiment, the second triangular support frame is in the same vertical plane when stacked up and down, and the double-layer main pressure-bearing rod 1 can use the same pillar 4. The supporting force provided by the pillar 4 is transmitted to the main pressure-bearing rod 1 of the upper layer through the second triangular support frame 3 of the lower layer, so that the middle part of the upper main pressure-bearing rod 1 is supported and maintained in a straight state.

[0049] Specifically, the main pressure rod 1 is parallel to the horizontal plane, and the upper hypotenuse of the first triangular support frame 2 and the second triangular support frame 3 has an angle of 20° with the main pressure rod 1, as shown in Tables 1 and 2 below. The foundation pit depth is 6m, the span of the first triangular support frame is 20m, the span of the second triangular support frame is 40m, the interval between the first triangular support frame and the second triangular support frame is 20m, the horizontal spacing of the main pressure rod is 6.0m, the cross section of the main pressure rod is 800mm×800mm×16mm, and the cross section of the oblique rod is 600mm×600mm×14mm. The modeling is simulated when the angles between the hypotenuse and the main pressure rod 1 are 10°, 20°, and 45°. The calculation results show:

[0050] As the angle of the hypotenuse increases, the height of the vertical side and the amount of steel on the triangular structure increase, indicating that increasing the angle of the hypotenuse will increase the amount of steel and the cost of the project. However, when the angle of the hypotenuse is greater than 20°, the increase in the amount of structural steel projects increases, and when the angle of the hypotenuse is 45°, the amount of steel even increases by nearly 40%.

[0051] As the angle of the bevel increases, the maximum compressive stress and the maximum tensile stress show a decreasing law, which means that increasing the angle of the bevel can reduce the stress in the structural system and increase the safety margin of the structure. However, when the angle of the bevel is greater than 20°, the reduction of the structural stress shows a decreasing trend.

[0052] As the angle of the oblique side increases, the buckling mode eigenvalue increases first and then decreases. When the angle of the oblique bar is 20°, the buckling mode eigenvalue reaches the maximum value.

[0053] In summary, considering stability and cost, the optimal angle of the diagonal rods in the new foundation pit support structure is 20°.

[0054]

[0055] Table 1

[0056]

[0057] Table 2

[0058] Preferably, the span of the first triangular support frame 2 is 20m, the span of the second triangular support frame 3 is 40m, and the interval between the first triangular support frame 2 and the second triangular support frame 3 is adjusted according to the size of the foundation pit. If the interval exceeds 20m, according to Article 4.9.11 of the Technical Code for Building Foundation Pit Support (JGJ120-2012), "When setting support columns, temporary columns should avoid beams, columns and load-bearing walls of the main structure; for vertical and horizontal bidirectional cross-support structures, columns should be set at the intersection of the supports; for columns used as main structure columns, columns should be set at the intersection of the supports. The load during the foundation pit support stage shall not exceed the design requirements of the main structure; the spacing between the columns and the support ends and between the columns shall be determined according to the stability requirements of the supporting components and the size of the vertical load, and should not be greater than 15m for concrete support and 20m for steel support". Therefore, the span of the first triangular support frame 2 and the second triangular support frame 3 is set to 20m, and the length of the straight pipe is adjusted according to the size of the foundation pit, so that this support system can meet the requirements of foundation pits of different sizes and reduce the amount of steel while meeting the "Technical Code for Building Foundation Pit Support".

[0059] Of course, the present application may have many other implementations. Based on the present implementation, other implementations obtained by ordinary technicians in this field without any creative work are all within the scope of protection of the present application.

Claims

1. A large deep foundation pit support structure, characterized in that: include: A main pressure-bearing rod (1) is installed in the foundation pit, and a first triangular support frame (2) and a second triangular support frame (3) are provided on the main pressure-bearing rod (1); A support column (4) is arranged at the lower part of the main pressure-bearing rod (1), one end of the support column (4) is connected to the main pressure-bearing rod (1), and the other end of the support column (4) is connected to the bottom of the foundation pit; The first triangular support frame (2) is detachably connected to both ends of the main pressure-bearing rod (1), and the second triangular support frame (3) is detachably connected to the middle portion of the main pressure-bearing rod (1).

2. The large deep foundation pit support structure according to claim 1 is characterized in that: The first triangular support frame (2) and the second triangular support frame (3) are vertically mounted on the main pressure-bearing rod (1), and the first triangular support frame (2) and the second triangular support frame (3) are located on the same vertical plane.

3. The large deep foundation pit support structure according to claim 1 is characterized in that: The main pressure-bearing rod (1) comprises a straight pipe, a K-shaped joint (8), a Y-shaped joint (9), and a cross joint (12); the K-shaped joint (8) and the Y-shaped joint (9) are connected via the straight pipe and flanges and are symmetrically installed on both sides of the cross joint (12).

4. The large-scale deep foundation pit support structure according to claim 1 is characterized in that: The first triangular support frame (2) is in the shape of a right triangle. The first triangular support frame (2) comprises a first splicing block (5), a second splicing block (6), and a third splicing block (7). The first splicing block (5), the second splicing block (6), and the third splicing block (7) are connected via a flange. One end of the first splicing block (5) is connected to the main pressure-bearing rod (1) via a flange.

5. The large deep foundation pit support structure according to claim 1, characterized in that: The second triangular support frame (3) is in the shape of an isosceles triangle. The second triangular support frame (3) comprises a straight pipe, a K-shaped joint (8), a Y-shaped joint (9), a rice-shaped joint (10), and a special-shaped joint (11). The K-shaped joint (8), the Y-shaped joint (9), the rice-shaped joint (10), and the special-shaped joint (11) are connected via a straight pipe and a flange. The straight pipe, the K-shaped joint (8), the Y-shaped joint (9), the rice-shaped joint (10), and the special-shaped joint (11) are used to connect between the second triangular support frame (3) and the main pressure-bearing rod (1) to form a plurality of triangular frames.

6. A large deep foundation pit support system, using the foundation pit support structure according to any one of claims 1 to 5, characterized in that: The invention comprises a plurality of main pressure-bearing rods (1) and a plurality of supporting piles (13), wherein the plurality of supporting piles (13) are arranged at intervals inside a foundation pit, the upper ends of the supporting piles (13) are connected to each other via a crown beam (14), the two ends of the main pressure-bearing rods (1) are connected to the crown beam (14) via a first triangular support frame (2), and the main pressure-bearing rods (1) are connected to each other via a connecting beam (15).

7. The construction method of a large deep foundation pit support system according to claim 6, characterized in that: The following steps are involved: Construct support piles, cap beams and column pile foundations, and implant columns on the column pile foundations; The foundation pit is excavated to 0.5m below the bottom elevation of the main pressure rod, the main pressure rod is spliced ​​in sections, and after the first triangular support frame and the second triangular support frame are installed on the main pressure rod, the main pressure rod is connected to the crown beam; The first triangular support frames and the second triangular support frames on the plurality of main pressure-bearing rods are respectively connected to each other through connecting beams; The foundation pit is excavated to the designed pit bottom elevation.

8. The construction method of the large deep foundation pit support system according to claim 7, characterized in that: The main pressure-bearing rod, the first triangular support frame and the second triangular support frame are connected via flanges.

9. The construction method of the large deep foundation pit support system according to claim 7, characterized in that: When there are two layers of main pressure-bearing rods, after installing the main pressure-bearing rods of the first layer, excavate to 0.5m below the bottom elevation of the second layer of main pressure-bearing rods, and after constructing two waist beams on the supporting piles, install the main pressure-bearing rods of the second layer. The main pressure-bearing rods of the second layer are connected to the waist beams through the first triangular support frames, and the middle parts between the upper and lower adjacent main pressure-bearing rods are connected to each other through the second triangular support frames.

10. The construction method of the large deep foundation pit support system according to claim 9, characterized in that: The second triangular support frames are in the same vertical plane when stacked up and down.

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