Octagonal working pit support component and installation construction method thereof

Abstract

The present invention discloses an octagonal working pit support component and an installation construction method thereof, including an octagonal working pit retaining wall support component formed by docking, wherein a frame plate and a straight plate are connected by symmetrically distributed H-shaped steel cross braces; the working pit retaining wall includes inner and outer two layers of steel plates provided with steel plate stiffening ribs, and the bottom of the working pit retaining wall is provided with an interlayer connector connected to the adjacent interlayer working pit retaining wall; the working pit retaining wall is connected by H-shaped steel cross braces, and adjacent octagonal support components are connected by interlayer connectors, and the working pit is excavated layer by layer by jacking pipe or directional drilling, and the octagonal support components after excavation are reversely disassembled and recovered. The support structure of the working pit can be excavated layer by layer from the ground, and the support components can be recovered in reverse layers, thereby reducing waste and avoiding the risk of accidents such as difficult sinking, sudden sinking, and partial sinking during construction, and has the advantages of reuse, space saving, cost reduction, energy consumption reduction, and green environmental protection.

Description

Technical Field

[0001] The invention relates to the technical field of urban construction engineering, and in particular to an octagonal working pit support component and an installation construction process thereof when urban municipal pipelines are constructed by pipe jacking and directional drilling. Background Art

[0002] With the development and construction of cities, the construction scale and types of various municipal infrastructure supporting pipelines, other underground structures and facilities in cities have increased to varying degrees, and the number of above-ground buildings has also increased, leading to a shortage of urban underground space. At the same time, considering the reasons such as urban traffic diversion caused by the construction site encroaching on the existing traffic space, and the protection of existing underground and above-ground pipelines and structures, the construction space is often restricted to varying degrees during the construction of other newly built municipal infrastructure supporting pipelines in the later stage. Therefore, non-grooving construction has become the preferred method for various pipeline construction when the construction space is limited, especially pipe jacking construction, directional drilling construction, etc.

[0003] When constructing urban underground pipelines by pipe jacking or directional drilling, it is necessary to set up working pits according to the needs of the construction, including pushing working pits and receiving working pits. Due to the limitations of the construction site and other existing pipelines, underground and above-ground structures, the working pits must adopt safe and reliable support forms to ensure the smooth progress of pipe jacking construction.

[0004] According to the current construction situation of urban underground pipeline laying, the common pit support methods for pipe jacking construction (or directional drilling construction) include reinforced concrete retaining wall (reverse construction), reinforced concrete caisson, etc. These support methods have the following shortcomings:

[0005] 1. The reinforced concrete retaining wall is constructed in reverse, excavating one layer from the ground downwards (depth not exceeding 2m) and supporting one layer at a time. The process is complicated (supporting formwork, pouring, maintenance, dismantling formwork, etc.) and the construction period is long.

[0006] 2. The reinforced concrete caisson is cast on site (tube body), and soil is excavated and transported layer by layer from the shaft, so that the caisson gradually sinks under its own weight. After reaching the predetermined design elevation, the bottom is sealed. This has relatively high construction technology requirements and a long construction period. It is easy for the caisson to be difficult to sink, suddenly sink, or sink unevenly during construction, and the risk of accidents is relatively high.

[0007] 3. The reinforced concrete structure of the working pit support can only be used once, which invisibly increases the investment cost of the project and causes waste of resources.

[0008] 4. After the construction of the working pit support structure is completed, only the reinforced concrete structure within 3.5m from the ground is removed, and the rest remains permanently underground, causing unnecessary waste of the city's underground space, which not only affects the natural environment, but also encroaches on the construction space of subsequent underground pipelines.

[0009] In view of the above situation, it is urgent to develop a new type of working pit support form and construction technology, which is the only way for the current development and construction of urban infrastructure pipeline construction. Summary of the invention

[0010] In order to solve the above-mentioned defects existing in the prior art, the purpose of the present invention is to provide an octagonal working pit support prefabricated assembly component and its installation construction process. The support structure of the working pit can be excavated from the ground layer by layer downward, and the support components can be recovered layer by layer in reverse order, thereby reducing waste and avoiding the risk of accidents such as difficult sinking, sudden sinking, and partial sinking during construction. It has the advantages of reuse, space saving, cost reduction, energy consumption reduction, and green environmental protection.

[0011] The present invention is achieved through the following technical solutions.

[0012] An octagonal working pit supporting component comprises a frame-shaped working pit retaining wall, wherein the frame-shaped working pit retaining wall is formed by connecting a frame plate and a straight plate to form an octagonal supporting component, wherein the frame plate and the straight plate are connected by symmetrically distributed H-shaped steel cross braces; the working pit retaining wall comprises an inner layer and an outer layer of steel plates, steel plate stiffening ribs are arranged between the inner layer and the outer layer of steel plates, and a connecting piece connected to the working pit retaining wall between adjacent layers is arranged at the bottom of the working pit retaining wall.

[0013] The working pit retaining wall is connected by H-shaped steel cross braces, and the adjacent octagonal supporting components are connected by interlayer connectors, so that the working pit can be excavated layer by layer by jacking pipe or directional drilling, and the octagonal supporting components can be reversely disassembled and recovered after excavation.

[0014] As an improvement, the steel plate stiffening ribs are arranged at equal intervals between the inner and outer steel plates along the working pit retaining wall.

[0015] As an improvement, the steel plate stiffening rib includes a vertical plate and two horizontal stiffening rods connected therebetween. The vertical plate is welded at 90° along the inner and outer steel plate walls of the working pit guard wall; the two horizontal stiffening rods are respectively welded along the inner and outer steel plate walls of the working pit guard wall.

[0016] As an improvement, the steel plate stiffening ribs are vertical frame plates, and the flanges at both ends of the frame plates are welded to the inner and outer steel plate walls of the working pit guard wall.

[0017] As an improvement, the frame plate and the straight plate are butt-jointed to form an octagonal supporting member, the butt joint surfaces are inclined at 45°, and the inclination directions of the contact surfaces are the same; rubber waterstops or rubber wear pads are provided between the butt joint surfaces.

[0018] As an improvement, the outer surfaces of the inner and outer layers of steel plates of the working pit protective wall are both corrugated.

[0019] As an improvement, H-shaped steel cross braces are tied between the four sides of the octagonal supporting member and the corner cutting member, and at least four pairs of H-shaped steel cross braces are symmetrically distributed along the octagonal working pit retaining wall, and the H-shaped steel cross braces are hung or threaded.

[0020] As an improvement, at least one pair of H-shaped steel cross braces is tied between the long side and the corner cut member of the octagonal support member, and at least another pair of H-shaped steel cross braces is tied between the long side and the short side of the octagonal support member.

[0021] As an improvement, a stiffening brace is further connected to the H-shaped steel cross brace tied between the long side and the short side. The stiffening brace is a connecting ring welded along the middle of the H-shaped steel cross brace. A pair of stiffening braces are horizontally buckled on the connecting ring, and the other ends are respectively connected between the long side and the short side of the inner wall of the working pit guard wall to form a cross structure with the H-shaped steel cross brace.

[0022] The embodiment of the present invention provides an installation construction method using an octagonal working pit support component, comprising:

[0023] Dig vertically downward from the ground along the working pit position of the jacking pipe or directional drilling, dig a layer of working pit with the same height and area of ​​the working pit retaining wall, splice the working pit retaining wall, buckle the H-shaped steel cross brace, and form a layer of octagonal working pit support components; add rubber water stop strips or rubber wear pads between the component blocks, sections, and layers;

[0024] Then dig vertically downward to dig a layer of working pit, and assemble a layer of working pit support components by means of clamps, fasteners or pins; the maximum height of each layer shall not exceed 2m;

[0025] Support from top to bottom in sequence until the predetermined design elevation is reached, and then reinforced concrete bottom sealing is carried out;

[0026] After the excavation of the working pit and the assembly of the supports are completed, the laying direction of the two bottom layers of pipelines is replaced with the special section of the hole, and the single side is replaced in sequence;

[0027] After the installation and construction of the pipeline and ancillary facilities are completed, the working pit support components are backfilled and dismantled layer by layer starting from the bottom until the backfilling is completed and the working pit support components are recovered.

[0028] The present invention adopts the above technical solution, which has the following beneficial effects:

[0029] 1. The support structure adopts finished components, which is safe and reliable in construction, simple in operation process, relatively small in size and weight, and easy to transport and install.

[0030] 2. The support structure adopts an octagonal shape when viewed from above. Compared with a rectangle, it has better stress conditions, a stable structure and is easy to disassemble.

[0031] 3. The supporting structure adopts a box-type structural section with inner and outer double walls. Compared with the structure with only outer wall panels and stiffening ribs, it is beneficial to improve the structural rigidity, is not easy to deform, is safer and more durable, and has a flat and uniform appearance.

[0032] 4. The support components are easy to install, assemble on site, disassemble after construction, and reuse, which helps to achieve sustainable development; it helps to shorten the construction period, improve production efficiency, and reduce the adverse effects on urban traffic and residents' lives.

[0033] 5. The supporting structure adopts finished components, which are centrally managed and maintained, do not generate pollutants, save energy and reduce emissions, and protect the environment.

[0034] 6. The support structure will be completely dismantled after construction, which is conducive to energy conservation, emission reduction and environmental protection. There is no underground space left after the construction of the support components. Compared with the traditional reinforced concrete support structure, it is conducive to saving underground space and does not affect the laying space of subsequent municipal supporting pipelines.

[0035] 7. The supporting structure adopts steel (or composite material) components, which improves production efficiency, has advanced technology, saves resources and energy, and contributes to the development of the national economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of the present application, and do not constitute an improper limitation of the present invention. In the drawings:

[0037] Figure 1 (a) and (b) are schematic diagrams of the structure of the working pit support components;

[0038] Figure 2 It is a schematic diagram of the AA section of the working pit support component;

[0039] Figure 3 (a) and (b) are plan cross-sectional views of the wall of the working pit support component;

[0040] Figure 4 It is the wall protection section diagram of the working pit support components;

[0041] Figure 5 It is the elevation drawing of the special section of the working pit support component;

[0042] Figure 6 It is a cross-sectional view of the specially made section of the working pit support component;

[0043] Figure 7 It is the internal structure of the single-layer finite element calculation model of the working pit (top push);

[0044] Figure 8 It is a three-dimensional view of the single-layer finite element calculation model of the working pit (top push);

[0045] Fig. 9 It is the single layer stress cloud diagram when the burial depth is 16 to 18 m;

[0046] Fig.10 It is the deformation cloud map of a single-layer structure when the burial depth is 16 to 18 meters.

[0047] In the figure: 1—working pit protective wall, 2—steel plate stiffening ribs, 3—H-shaped steel cross braces, 4—interlayer connectors, 5—45° contact surface, 6—vertical interlayer contact surface, 7—lower inner arc frame, 8—upper inner arc frame, 9—jacking pipe inlet and outlet openings. DETAILED DESCRIPTION

[0048] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The exemplary embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0049] As shown in Figure 1(a) and (b), an octagonal working pit support component includes a frame-shaped working pit retaining wall 1, which is welded by inner and outer two layers of steel plates through steel plate stiffening ribs 2. A plurality of steel plate stiffening ribs 2 are arranged at equal intervals between the inner and outer layers of the working pit retaining wall 1.

[0050] In one embodiment, the steel plate stiffening rib 2 includes a vertical plate and two horizontal reinforcing rods connected therebetween, with uniform force and a firm structure. The vertical plate is welded at 90 degrees along the inner and outer steel plate walls of the working pit protective wall 1; and the two horizontal reinforcing rods are welded along the inner and outer steel plate walls of the working pit protective wall 1, respectively.

[0051] In another embodiment, the steel plate stiffening rib 2 is a vertical frame plate, and the flanges at both ends of the frame plate are respectively welded to the inner and outer steel plate walls of the working pit guard wall.

[0052] The frame-shaped working pit retaining wall 1 is a rectangle with four corners cut off to form an octagonal structure. The four sides of the octagon and the corner-cutting components are butt joint structures, and the butt joint surfaces are 45° contact surfaces 5. Rubber wear pads are added to the butt joint surfaces. The inclination directions of the 45° contact surfaces 5 are the same, which is convenient for assembly and dismantling. H-shaped steel cross braces 3 are tied between the four sides of the octagon and the corner-cutting components. The H-shaped steel cross braces 3 are symmetrically distributed along the octagonal working pit retaining wall 1, so that the overall force is uniform, safe and reliable.

[0053] like Figure 2 , Figure 4 As shown, the working pit wall 1 is multi-layered, and the vertical plates of the steel plate stiffening ribs 2 between the inner and outer walls of each layer of the working pit wall 1 are multiple upper and lower butt joint structures. Interlayer connectors 4 (clamps, fasteners or latches) are provided at the upper and lower ends of the inner wall of each layer of the working pit wall 1, and rubber wear pads are added to the vertical interlayer contact surfaces 6 between the layers of the working pit wall 1.

[0054] Among them, the octagonal working pit retaining wall 1 is divided into layers and blocks, and adopts cast or steel (or aluminum alloy, steel strip polyethylene, polypropylene and other composite materials) components, which are suitable for working pit width 4m~8m and length 4m~9.5m; each layer height is 1.5m and 2m (specially made for the entrance section, with height of 3m and 4m), with at least 4 layers (total depth not less than 6m); each layer is divided into at least 4 blocks (or 4 sections).

[0055] Among them, the wall thickness of the octagonal working pit protective wall 1 is 200-300mm, and the inner and outer walls of each component are welded with steel plate stiffening ribs; the horizontal inclination angle of the contact surfaces of two adjacent blocks in each layer is 45°, and the vertical spacing of the connection points of the H-shaped steel cross braces 3 between the two is not less than 1m; the upper and lower layers are connected by clamps and fasteners (or pins), and the clamps and fasteners (or pins) are evenly arranged on each component, and the upper and lower layers are matched with each other.

[0056] 10mm to 20mm thick rubber wear pads are added between the horizontal (45-degree contact surface) and vertical directions of the octagonal working pit support components to facilitate installation and disassembly, reduce collision and wear between components, and extend the service life of the components.

[0057] As shown in Figure 1(a), Figure 2 As shown in Figure 3(a), it is a small octagonal working pit supporting member of the present invention. H-shaped steel cross braces 3 are symmetrically tied between the long sides of the inner wall of the working pit protective wall 1 and the corner cutting member. Two pairs of H-shaped steel cross braces 3 are provided in each layer of the working pit protective wall 1. The H-shaped steel cross braces are hung or threadedly connected and distributed up and down on the inner wall of each layer of the working pit protective wall 1.

[0058] As shown in Figure 1(b), Figure 2 3(b) shows a large octagonal working pit support member of the present invention. H-shaped steel cross braces 3 are tied between the long side and the short side of the inner wall of the working pit protective wall 1. Two pairs of H-shaped steel cross braces 3 are provided in each layer of the working pit protective wall 1, and are distributed up and down on the inner wall of each layer of the working pit protective wall 1. A stiffening brace is further tied to one pair of diagonally distributed H-shaped steel cross braces 3. The stiffening brace is a connecting ring welded along the middle of the H-shaped steel cross brace 3. A pair of stiffening braces are horizontally buckled on the connecting ring, and the other ends are respectively connected between the long side and the short side of the inner wall of the working pit protective wall 1, forming a cross structure with the H-shaped steel cross brace 3, so that the structure is relatively stable, safe and reliable.

[0059] The H-shaped steel cross brace 3 connects the octagonal working pit retaining wall 1 which is connected in blocks into a whole, and the multiple layers of working pit retaining walls 1 are connected by fasteners or pins 4 to form a working pit retaining wall 1 with a multi-layer structure.

[0060] like Figure 5 , Figure 6As shown, the working pit protection wall 1 of the present invention is applied to various pipeline jacking or directional drilling construction. The pipeline jacking entrance and exit holes 9 (pipeline laying direction) of the directional drilling construction are made of casting or steel parts separately, and a lower inner arc frame 7 is set on the upper part of the jacking entrance and exit holes 9, and an upper inner arc frame 8 is set on the lower part of the jacking pipe. This method is convenient for installation and disassembly; it is divided into two types with a total height of 3m and 4m, and a wall thickness of 300mm. The hole for directional drilling can be directly reserved on the supporting member.

[0061] In the present invention, the octagonal working pit support components are made of steel components, each layer is divided into at least 4 blocks (or 4 sections), and the wall thickness is 200-300mm. The inner and outer walls of each component are welded with steel plate stiffeners; the horizontal inclination angle of the contact surface of two adjacent blocks in each layer is 45°, and the two are connected by H-shaped steel cross braces, and the vertical spacing of the connection points is not less than 1m; the upper and lower layers are connected by clamps and fasteners (or pins), and the clamps and fasteners (or pins) are evenly arranged on each component, and the upper and lower layers are matched with each other.

[0062] The octagonal working pit support components are made of composite materials (such as steel-belt polyethylene, steel-belt polypropylene, etc.). The inner and outer surfaces of the working pit wall 1 are both corrugated, which is convenient for good stress conditions during construction. The ring stiffness is not less than 16-25kN / m 2 (i.e. SN16~SN25) or city-A level. Each layer is divided into at least 4 blocks (or 4 sections), and the maximum spacing between the inner and outer peaks (i.e. wall thickness) is 200~300mm. The connection method between blocks and layers of this type of working pit support components is the same as that of steel components.

[0063] The opening of the octagonal working pit supporting the top pipe (in the direction of pipeline laying) is made of casting or steel components separately. The inner arc structure of the upper and lower parts is conducive to installation and disassembly. The total height is 3m and 4m, and the wall thickness is 300mm. The opening for directional drilling can be reserved directly on the supporting component.

[0064] 10mm to 20mm thick rubber wear pads are added between the horizontal (45-degree contact surface) and vertical directions of the octagonal working pit support components to facilitate installation and disassembly, reduce collision and wear between components, and extend the service life of the components.

[0065] In the specific implementation of the present invention, the octagonal working pit support component and its installation construction process are made of casting or steel or composite materials and are constructed by reverse construction method, including:

[0066] Dig vertically downward from the ground along the working pit position of the jacking pipe or directional drilling, dig a working pit with the same height and area of ​​the working pit retaining wall, splice four working pit retaining walls, buckle the H-shaped steel cross braces, and form an octagonal working pit support component; rubber water stop strips (or rubber wear pads) are added between the component blocks (or sections) and layers;

[0067] Then dig vertically downward to dig a layer of working pit, and assemble a layer of working pit support components by means of clamps, fasteners or pins; the maximum height of each layer shall not exceed 2m;

[0068] Support from top to bottom in sequence until the predetermined design elevation is reached, and then reinforced concrete bottom sealing is carried out;

[0069] After the excavation of the entire working pit and the assembly of supports are completed, the laying direction of the two lowest layers of pipelines is replaced with the special section of the opening, and the single side is replaced in sequence;

[0070] After the installation and construction of the pipeline and ancillary facilities are completed, the working pit support components are dismantled in sequence from the bottom, backfilling and dismantling in layers until they reach the ground; all the working pit support components are dismantled, and the prefabricated parts of the working pit support structure are transported back for inspection and maintenance to ensure safety and reliability during the next assembly.

[0071] The octagonal working pit supporting component of the present invention is divided into layers and blocks, and is suitable for working pits with a width of 4m to 8m and a length of 4m to 9.5m; the height of each layer is 1.5m and 2m (the entrance section is specially made, with a height of 3m and 4m), with a minimum of 4 layers (the total assembly depth is not less than 6m); each layer is divided into at least 4 blocks (or 4 sections), and the maximum length of a single component is about 4.5m.

[0072] During on-site construction, finished components (casting, steel or composite materials) can be used, which are manufactured in layers and blocks, assembled on-site, and disassembled after construction. They are easy to transport, hoist, inspect and maintain off-site, are not easily deformed, and have safe and reliable structures that can be reused. Each component includes the main structure, connectors (clamps, latches, fasteners, etc.), and support parts.

[0073] The size of the working pit is divided according to the diameter of the drainage (rainwater, sewage) pipeline. It is also applicable to professional pipelines such as water supply, heat, gas, and power, communication culverts, etc. See Table 1 below for details:

[0074] Table 1 List of working pit dimensions for pipe jacking construction

[0075]

[0076] The data in the above table only show the common working pit sizes and the range of applicable pipe diameters. According to the sizes of prefabricated components of the working pit, the net sizes of the working pit plane can be assembled into various specifications, including 6m×5m, 6m×6m, 7.5m×4m, 7.5m×5m, 8m×8m, 9.5m×5m, 9.5m×6m, etc. The specific sizes can be adjusted according to the actual situation on site during construction and the equipment used.

[0077] Table 2 List of working pit dimensions for directional drilling construction

[0078]

[0079] like Figure 7 , Figure 8 Shown is the internal structure and three-dimensional view of the single-layer finite element calculation model of the working pit support structure of the present invention.

[0080] like Fig. 9 , Fig.10 The figure shows the single-layer stress cloud map and deformation structure cloud map of the working pit support structure of the present invention when the burial depth is 16-18m. According to the stress cloud map, it can be seen that the stress of the components in about 85.8% of the structure is less than 341MPa, and the stress in about 79.8% of the structure is less than 256MPa. The remaining areas with higher stress are all located at the boundaries and local intersections of components, which are model errors or normal stress concentration phenomena, and can be solved by structural measures.

[0081] According to the deformation cloud map, the maximum inward displacement in the long side direction is 42mm, and the deformations in other positions are not large. At the same time, the buckling stability of the structure is calculated. By reasonably setting the internal support, the stability of the structure can be effectively guaranteed.

[0082] Through the above analysis, this structural form can meet the construction process requirements; and this structure is widely used in various pipeline jacking or directional drilling construction, which can shorten the construction period and improve production efficiency while ensuring safety.

[0083] The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solution disclosed in the present invention, technicians in this field can make some substitutions and deformations to some technical features therein according to the disclosed technical content without creative labor, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. An octagonal working pit support member, characterized in that: The working pit retaining wall comprises a frame-shaped working pit retaining wall, wherein the frame-shaped working pit retaining wall is formed by connecting a frame-shaped plate and a straight plate to form an octagonal supporting member, wherein the frame-shaped plate and the straight plate are connected by symmetrically distributed H-shaped steel cross braces; the frame-shaped plate and the straight plate are connected to form an octagonal supporting member, wherein the connecting surface is inclined at 45°, and the inclination direction of each contact surface is the same; The working pit retaining wall comprises an inner layer and an outer layer of steel plates, a steel plate stiffening rib is arranged between the inner layer and the outer layer of steel plates, and an interlayer connecting piece connected to the adjacent layer of the working pit retaining wall is arranged at the bottom of the working pit retaining wall; The working pit retaining wall is connected by H-shaped steel cross braces, at least one pair of H-shaped steel cross braces is tied between the long side and the corner cutting member of the octagonal support member, and at least another pair of H-shaped steel cross braces is tied between the long side and the short side of the octagonal support member; a stiffening brace is further connected to the H-shaped steel cross brace tied between the long side and the short side; Adjacent octagonal support components are connected through interlayer connectors, and layer-by-layer excavation of the jacking pipe or directional drilling working pit is carried out, as well as reverse disassembly and recovery of the octagonal support components after excavation.

2. An octagonal working pit support member according to claim 1, characterized in that: The steel plate stiffening ribs are arranged at equal intervals between the inner and outer steel plates along the working pit protective wall.

3. The octagonal working pit support member according to claim 1, characterized in that: The steel plate stiffening ribs include a vertical plate and two horizontal stiffening rods connected therebetween. The vertical plate is welded at 90° along the inner and outer steel plate walls of the working pit guard wall; the two horizontal stiffening rods are respectively welded along the inner and outer steel plate walls of the working pit guard wall.

4. The octagonal working pit support member according to claim 1, characterized in that: The steel plate stiffening rib is a vertical frame plate, and the flanges at both ends of the frame plate are welded to the inner and outer steel plate walls of the working pit guard wall respectively.

5. An octagonal working pit support member according to claim 4, characterized in that: A rubber waterstop or rubber wear pad is provided between the butt joint surfaces.

6. The octagonal working pit support member according to claim 1, characterized in that: The outer surfaces of the inner and outer steel plates of the working pit protective wall are both corrugated.

7. The octagonal working pit support member according to claim 1, characterized in that: The H-shaped steel cross braces are tied between the four sides of the octagonal supporting member and the corner cutting member. At least four pairs of H-shaped steel cross braces are symmetrically distributed along the octagonal working pit retaining wall. The H-shaped steel cross braces are hung or threaded.

8. The octagonal working pit support member according to claim 1, characterized in that: The stiffening brace is a connecting ring welded along the middle of the H-shaped steel cross brace. A pair of stiffening braces are horizontally buckled on the connecting ring, and the other ends are respectively connected between the long side and the short side of the inner wall of the working pit guard wall to form a cross structure with the H-shaped steel cross brace.

9. An installation construction method using the octagonal working pit support member according to any one of claims 1 to 8, characterized in that: include: Dig vertically downward from the ground along the working pit position of the jacking pipe or directional drilling, dig a layer of working pit with the same height and area of ​​the working pit retaining wall, splice the working pit retaining wall, buckle the H-shaped steel cross brace, and form a layer of octagonal working pit support components; add rubber water stop strips or rubber wear pads between the component blocks, sections, and layers; Then dig vertically downward to dig a layer of working pit, and assemble a layer of working pit support components by means of clamps, fasteners or pins; the maximum height of each layer shall not exceed 2m; Support from top to bottom in sequence until the predetermined design elevation is reached, and then reinforced concrete bottom sealing is carried out; After the excavation of the working pit and the assembly of the supports are completed, the laying direction of the two bottom layers of pipelines is replaced with the special section of the hole, and the single side is replaced in sequence; After the installation and construction of the pipeline and ancillary facilities are completed, the working pit support components are backfilled and dismantled layer by layer starting from the bottom until the backfilling is completed and the working pit support components are recovered.

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