Foundation pit supporting structure crossing pipeline and construction method

Abstract

The invention relates to the technical field of foundation pit construction, in particular to a foundation pit supporting structure crossing pipelines and a construction method. The structure comprises a foundation pit, foundation pit fender posts and a pipeline and further comprises a plurality of steel plates located in the foundation pit, the foundation pit fender posts are located on the two sides of the pipeline, the steel plates and the pipeline are located on different horizontal planes, and the two ends of each steel plate are connected with the foundation pit fender posts on the two sides of the pipeline respectively. By means of the structural design, pipeline relocation can be avoided under the condition that the foundation pit construction safety is guaranteed. According to the construction method, layer-by-layer excavation is adopted for foundation pit excavation in the peripheral range of the pipeline, steel plates are arranged layer by layer for retaining protection, earthwork around the upper portion and the lower portion of the pipeline is effectively protected, the foundation pit supporting design construction problem in the upper portion and the lower portion of the existing underground pipeline and in the adjacent range is solved, and pipeline relocation and transformation are avoided under the condition that foundation pit construction safety is guaranteed; the construction method is suitable for various foundation pit maintenance mechanisms, and is simple, high in construction efficiency, high in practicability and low in construction cost.

Description

Technical Field

[0001] The invention relates to the technical field of foundation pit construction, and in particular to a foundation pit supporting structure spanning a pipeline and a construction method. Background Art

[0002] The retaining structures, groundwater control, and environmental protection measures required to ensure the safety and stability of the underground space formed by excavation from the ground during the construction of underground structures are called foundation pit projects. At present, there are thousands of foundation pit projects being excavated every day at home and abroad. Especially in cities, foundation pit excavation is like heart surgery, with many restrictions and complicated underground pipelines. If you are not careful, it will lead to serious safety accidents. Therefore, in the design and construction of foundation pit projects, underground pipelines are the key points that affect the plan. The foundation pit support design around the pipeline is difficult and risky. If the retaining structure is too close to the pipeline, it is easy to damage the existing pipeline. If it is too far away from the pipeline, it cannot effectively protect the earthwork around the pipeline. If it is not handled properly, it is very easy to cause foundation pit instability accidents, and the consequences are extremely serious. At present, in the construction of foundation pit projects, before the foundation pit construction across the existing pipeline, the pipelines within the affected range are usually temporarily relocated to avoid the above problems. However, pipeline relocation has problems such as high project cost, poor economic efficiency, long construction period, and great negative impact on society (water and electricity outages for residents) and the environment.

[0003] There are few studies on foundation pit support schemes for crossing pipelines at home and abroad. Among them, patent CN 219863037U proposes a support structure that can be used for crossing pipelines. The support structure is mainly composed of two groups of support panels and support rods. However, the following shortcomings are found in this scheme: 1. The support structure has low rigidity and is only suitable for small foundation pits with shallow depths; 2. It cannot be constructed and used under gravel and gravel strata and hard soil conditions; 3. During the insertion process, it is difficult to control the distance between the support plate and the pipeline, which can easily damage the pipeline; 4. The support structure can only protect the soil above the pipeline. When the foundation pit excavation depth is greater than the pipeline burial depth, the soil below the pipeline cannot be effectively protected; 5. The overall applicability is not strong.

[0004] In view of this, this case arose to address the above-mentioned issues. Summary of the invention

[0005] The purpose of the present invention is to solve the problems in the prior art that the foundation pit support design in the foundation pit construction crossing the existing pipeline is difficult and risky, and the pipeline relocation has the problems of high engineering cost and long time, and to propose a foundation pit support structure and construction method crossing the pipeline.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A foundation pit support structure spanning a pipeline comprises a foundation pit, foundation pit retaining piles and a pipeline, and also comprises a plurality of steel plates located in the foundation pit, wherein the foundation pit retaining piles are located on both sides of the pipeline, the steel plates and the pipeline are on different horizontal planes, and the two ends of the steel plates are respectively connected to the foundation pit retaining piles on both sides of the pipeline.

[0008] Preferably, the foundation pit retaining piles are more than 1 meter away from the pipeline.

[0009] Preferably, the plurality of steel plates are parallel up and down and have their left and right ends respectively fixedly connected to foundation pit retaining piles closest to the pipeline.

[0010] Preferably, the foundation pit retaining pile adopts a reinforced concrete retaining structure, a steel bar is implanted in the foundation pit retaining pile, one end of the steel bar is exposed from the foundation pit retaining pile and the end of the steel bar is threaded, the steel plate is provided with holes corresponding to the steel bar and is sleeved on the steel bar through the holes, and also includes nuts, and the steel plate is fixed to the foundation pit retaining pile through the nuts. More specifically, the foundation pit retaining pile adopts a bored cast-in-place pile, and the steel bar is multiple.

[0011] Preferably, the foundation pit retaining piles are protected by steel structures, and the steel plates are welded and fixed to the foundation pit retaining piles. More specifically, the foundation pit retaining piles are Larsen steel sheet piles.

[0012] A construction method for a foundation pit support structure across a pipeline comprises the following steps:

[0013] S1, explore the underground pipelines within the foundation pit to determine the plane position and buried depth of the pipelines;

[0014] S2, level the site and conduct surveying and setting out;

[0015] S3, construct foundation pit retaining piles, use full casing construction, avoid using soil squeezing piles, and keep the foundation pit retaining piles at a certain distance from the pipeline; preferably more than 1 meter, and the distance can be appropriately reduced under precise mechanical control;

[0016] S4, construction crown beam;

[0017] S5, excavate the foundation pit to the bottom of the first support, and construct the first support of the foundation pit;

[0018] S6, dig 0.5-0.7 meters downward, set a steel plate protection distance, set a steel plate protection, and fix the two ends of the steel plate to the foundation pit retaining piles on both sides of the pipeline;

[0019] S7, repeat S6, excavate layer by layer, set up steel plate protection layer by layer until the pipeline is located, use manual excavation around the pipeline, and take protective measures for the pipeline. The pipeline protection adopts the "supporting" scheme, the pipeline is placed on the bracket, and the bracket is connected to the crown beams on both sides through the suspension member;

[0020] S8, after the pipeline protection is completed, continue to dig downwards, repeat S6, excavate layer by layer, and set up steel plate protection layer by layer until the second support bottom, and set up the waist beam and the second support;

[0021] S9, continue to excavate downwards, repeat S8 until the excavation reaches the bottom of the foundation pit;

[0022] S10, after the internal structure of the foundation pit is completed, the lowest steel plate is removed, and the foundation pit is backfilled with earth within the range of the lowest steel plate; the second-to-last steel plate is removed, and then the foundation pit is backfilled with earth within the range of the second-to-last steel plate, from bottom to top, the steel plates are removed layer by layer, and the earth is backfilled layer by layer until it reaches the ground.

[0023] Compared with the prior art, the present invention provides a foundation pit support structure and construction method for crossing pipelines, which has the following beneficial effects:

[0024] 1) The foundation pit retaining piles of the present invention are located on both sides of the pipeline and are more than 1 meter away from the pipeline. Since the foundation pit retaining piles are driven deeply, no matter the pipeline is above or below the bottom of the foundation pit, the structural design can ensure that the foundation pit retaining piles avoid the pipeline. Inside the foundation pit, the two ends of the steel plate are respectively connected to the foundation pit retaining piles on both sides of the pipeline. Several steel plates are horizontally arranged between the foundation pit retaining piles on both sides of the pipeline. The steel plates and the pipelines are at different horizontal planes for avoiding the pipeline for construction. Between the foundation pit retaining piles on both sides of the pipeline, several steel plates are arranged for support and protection, which effectively protects the earth around the upper and lower parts of the pipeline, and ensures the foundation pit support and protection between the foundation pit retaining piles on both sides of the pipeline, which not only improves the safety of foundation pit construction, but also avoids pipeline relocation and ensures the normal use of the pipeline.

[0025] 2) The construction method of the present invention adopts layer-by-layer excavation in the foundation pit around the pipeline, and steel plates are set layer by layer for support and protection, which overcomes the difficulties in the design and construction of foundation pit support above and below the existing underground pipelines and in the vicinity, improves the safety of foundation pit construction, avoids pipeline relocation, and ensures the normal use of the pipeline. The construction method is simple and improves construction efficiency;

[0026] 3) In the present invention, the steel plate is fixedly connected to the foundation pit retaining piles on both sides of the pipeline for support and protection. The structure and method can be used for foundation pit retaining piles of various supporting structures, and there is no restriction on the buried depth and type of pipelines. It has a wide range of applications, multiple application scenarios, and strong practicality;

[0027] 4) After the internal structure of the foundation pit is completed in the present invention, the steel plate can be dismantled and recycled, which greatly saves the cost of the foundation pit project.

[0028] Therefore, a foundation pit support structure and construction method for crossing pipelines can not only ensure the safety of foundation pit construction, but also avoid pipeline relocation. The method is simple to construct, low in cost, widely applicable, with many application scenarios and strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the structure of a foundation pit support structure spanning a pipeline according to the present invention from a top view;

[0030] Figure 2 It is a front cross-sectional view of a pipeline below the bottom of a foundation pit of a foundation pit support structure spanning a pipeline according to the present invention;

[0031] Figure 3 The present invention is a front cross-sectional view of a pipeline of a foundation pit support structure spanning the pipeline above the bottom of the foundation pit.

[0032] Figure 4 A schematic diagram of the structure of the connection between the steel plate of the foundation pit support structure spanning the pipeline and the reinforced concrete enclosure structure of the present invention

[0033] Figure 5 It is a schematic diagram of the enlarged structure of the connection between the steel plate and the reinforced concrete enclosure structure of a foundation pit supporting structure spanning a pipeline according to the present invention.

[0034] In the figure: 1-steel plate; 2-pipeline; 3-foundation pit retaining piles; 4-crown beam; 5-support; 6-waist beam; 7-rebar; 8-nut. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "lower end", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0037] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0039] Example 1

[0040] like Figure 1-3 As shown, a foundation pit support structure crossing a pipeline includes a foundation pit, foundation pit retaining piles 3 and a pipeline 2, and also includes a plurality of steel plates 1 located in the foundation pit, the foundation pit retaining piles 3 are located on both sides of the pipeline 2, the steel plates 1 and the pipeline 2 are at different horizontal planes, and the two ends of the steel plates 1 are respectively connected to the foundation pit retaining piles 3 on both sides of the pipeline 2. The steel plates 1 and the pipeline 2 are at different horizontal planes to avoid the pipeline 2 for construction, and between the foundation pit retaining piles 3 on both sides of the pipeline 2, a plurality of steel plates 1 are arranged for support and protection, which effectively protects the earth around the upper and lower parts of the pipeline 2, and ensures the foundation pit support and protection between the foundation pit retaining piles 3 on both sides of the pipeline 2, which not only improves the safety of the foundation pit construction, but also avoids the relocation of the pipeline 2, and ensures the normal use of the pipeline 2.

[0041] Furthermore, the foundation pit retaining pile 3 is more than 1 meter away from the pipeline 2. Since there is a certain error in the detection of the pipeline 2, this distance can ensure that the foundation pit retaining pile 3 can avoid the pipeline 2 during construction to protect the pipeline.

[0042] Furthermore, a plurality of steel plates 1 are parallel to each other in the vertical direction and the left and right ends are respectively fixedly connected to the foundation pit retaining piles 3 which are closest to the pipeline 2 .

[0043] like Figure 2As shown, when the pipeline 2 is located below the bottom of the foundation pit, several steel plates 1 are located above the pipeline 2 and are arranged parallel to each other in the foundation pit, and the two ends of the steel plates 1 are respectively connected to the foundation pit retaining piles 3 on the left and right sides of the pipeline 2, effectively protecting the earth around the upper and lower parts of the pipeline 2 and ensuring the support and protection between the foundation pit retaining piles 3 on both sides of the pipeline 2 in the foundation pit.

[0044] like Figure 3 As shown, when the pipeline 2 is located above the bottom of the foundation pit, the steel plate 1 needs to be set away from the horizontal plane where the pipeline 2 is located. Several steel plates 1 are respectively located above and below the pipeline 2 and are parallel to each other. The two ends of the steel plate 1 are respectively connected to the foundation pit retaining piles 3 on the left and right sides of the pipeline 2, which effectively protects the earth around the upper and lower parts of the pipeline 2 and ensures the support and protection between the foundation pit retaining piles 3 on both sides of the pipeline 2 in the foundation pit.

[0045] Furthermore, the foundation pit retaining pile 3 is enclosed by a steel structure, and the steel plate 1 is welded and fixed to the foundation pit retaining pile 3. More specifically, the foundation pit retaining pile 3 is a Larsen steel sheet pile. The structure is easy to construct and has a simple fixing method.

[0046] In this embodiment 1, the foundation pit retaining structure adopts steel structure retaining, and steel sheet piles are taken as an example. The underground pipeline 2 is a rainwater pipe with a diameter of 0.8m and a buried depth of 2.5m. The specific implementation process is as follows:

[0047] S1, collect the as-built drawings of the existing pipeline 2, and combine with the on-site geophysical exploration to find out in detail that the underground pipeline 2 is a water supply pipe with a diameter of 0.8m and a buried depth of 2.5m;

[0048] S2, level the construction site, conduct on-site layout according to the design, and determine the location of the steel sheet piles;

[0049] S3, construct steel sheet pile enclosure structure, the net distance between steel sheet pile and rainwater pipeline 2 is 1.0m, the steel sheet pile near pipeline 2 is constructed by static pressure pile sinking to prevent vibration construction from damaging pipeline 2; the net distance between bored piles on both sides of pipeline 2 is 2.8m;

[0050] S4, dig 0.7m downwards, construct steel purlins, and erect the first steel support 5. The steel support is made of φ609 steel pipe support.

[0051] S5. A steel plate 1 is promptly installed above the pipeline 2 for protection. The size of the steel plate 1 is 5.0m×0.6m×0.02m (length×width×thickness). Both ends of the steel plate 1 are firmly welded to the steel sheet piles.

[0052] S6, excavate downward layer by layer, with each layer excavated to a depth of 0.7m, and set steel plate 1 protection layer by layer according to step S5 until the position of pipeline 2, carefully excavate the area around pipeline 2 manually, and set support hoisting protection for pipeline 2 according to the design;

[0053] S7, after the protection of the pipeline 2 is completed, continue to dig downward layer by layer, with an excavation depth of 0.7m for each layer, and continue to repeat step S5 until the bottom of the second support 5, and set the waist beam 6 and the second support 5;

[0054] S8, continue to excavate downward layer by layer, repeating step S5 until the excavation reaches the bottom of the foundation pit;

[0055] S9, construct the main structure inside the foundation pit in time. After the main structure is completed, remove the lowest steel plate 1 and backfill the soil within the range of the lowest steel plate 1; remove the second-to-last steel plate 1, and then backfill the soil within the range of the second-to-last steel plate 1, and so on, from bottom to top, remove all steel plates 1 layer by layer for recycling and reuse, recycle the steel pipe support 5 and waist beam 6, surrounding purlins, etc. layer by layer, backfill the soil layer by layer until the ground, recycle the steel sheet piles, and complete the foundation pit and structure construction across the pipeline 2.

[0056] Example 2

[0057] like Figure 1-5 As shown, the difference between this embodiment and embodiment 1 is that the foundation pit retaining pile 3 adopts a reinforced concrete retaining structure, a plurality of steel bars 7 are implanted in the foundation pit retaining pile 3, one end of the steel bar 7 leaks out of the foundation pit retaining pile 3 and the end of the steel bar 7 leaks out of the threaded end, the steel plate 1 is provided with holes corresponding to the steel bars 7 and is sleeved on the steel bars 7 through the holes, and also includes nuts 8, and the steel plate 1 is fixed to the foundation pit retaining pile 3 through the nuts 8. More specifically, the foundation pit retaining pile 3 adopts bored cast-in-place piles. A plurality of steel bars 7 are implanted in the foundation pit retaining pile 3, and the connection through the plurality of steel bars 7 is more stable. The structure is easy to construct, and the fixing method is simple, which is convenient for the later disassembly of the steel plate 1.

[0058] refer to Figure 1 and Figure 3-5 In this embodiment 2, the foundation pit retaining pile 3 adopts a reinforced concrete retaining structure. Taking the underground pipeline 2 as a rainwater pipe, the pipeline 2 has a diameter of 0.6m and a burial depth of 3.2m as an example, the specific implementation process is as follows:

[0059] S1, explore the underground pipeline 2 within the scope of the foundation pit, collect the completion drawings of the existing pipeline 2, and combine the on-site geophysical exploration to find out in detail that the underground pipeline 2 is a rainwater pipe with a diameter of 0.6m and a buried depth of 3.2m;

[0060] S2, level the construction site, carry out on-site layout according to the design, and determine the location of bored piles;

[0061] S3, construction of bored piles, pile diameter 1.0m, bored piles and rainwater pipeline 2 net distance of 1.2m, bored piles near pipeline 2 position are constructed with casing to prevent maintenance pile construction from damaging the pipeline; bored piles on both sides of the pipeline net distance of 3.0m;

[0062] S4, erecting formwork, constructing reinforced concrete crown beam 4 and first support 5;

[0063] S5, after the crown beam 4 and the support 5 reach 70% of the design strength, dig 0.7m downwards and install the steel plate 1 for protection in time. The size of the steel plate 1 is 5.0m×0.6m×0.02m (length×width×thickness). The two ends of the steel plate 1 are respectively fixed on the foundation pit retaining piles 3 on both sides of the pipeline 2. φ25 ribbed steel bars 7 are implanted on the bored piles. The implantation length of the steel bar 7 is 0.6m. Six embedded steel bars are used at each location. The exposed ends of the embedded steel bars 7 are threaded. Corresponding holes are set on the steel plate 1. The threaded steel bars 7 are passed through and fixed with nuts 8;

[0064] S6, excavate downward layer by layer, with each layer excavation depth of 0.7m, and set up steel plate 1 protection layer by layer according to S5 until the position of pipeline 2. The surrounding area of ​​pipeline 2 is carefully excavated manually, and support hoisting protection is set for pipeline 2 according to the design;

[0065] S7, after the protection of pipeline 2 is completed, continue to dig downward layer by layer, with each layer excavated to a depth of 0.7m, and continue to repeat S5 until the bottom of the second support 5, and set the waist beam 6 and the second support 5;

[0066] S8, continue to excavate downward layer by layer, repeating step S7 until the excavation reaches the bottom of the foundation pit;

[0067] S9, construct the main structure inside the foundation pit in time. After the main structure is completed, remove the lowest steel plate 1, and backfill the foundation pit within the range of the lowest steel plate 1; remove the second-to-last steel plate 1, and then backfill the foundation pit within the range of the second-to-last steel plate 1, and so on, from bottom to top, remove all steel plates 1 layer by layer for recycling and reuse, and backfill the soil layer by layer until the ground is reached, completing the foundation pit and structure construction across the pipeline.

[0068] The construction method of the present invention adopts layer-by-layer excavation in the foundation pit excavation around the pipeline 2, and sets steel plates 1 layer by layer for support and protection, effectively protecting the earth around the upper and lower parts of the pipeline 2, overcoming the difficulties in the design and construction of foundation pit support above and below the existing underground pipeline 2 and the adjacent range, which not only improves the safety of foundation pit construction, but also avoids the relocation of the pipeline 2, ensuring the normal use of the pipeline 2. The construction method is simple and has high construction efficiency. It can be used for foundation pit retaining piles 3 of various support structures, and there is no restriction on the buried depth and type of the pipeline 2. It has a wide range of applications, multiple application scenarios, and strong practicality; and the steel plate 1 can be dismantled and recycled in the later stage, which greatly saves the cost of the foundation pit project.

[0069] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A foundation pit support structure for crossing a pipeline, comprising a foundation pit, foundation pit retaining piles and a pipeline, characterized in that: It also includes a plurality of steel plates located in the foundation pit, the foundation pit retaining piles are located on both sides of the pipeline, the steel plates and the pipeline are on different horizontal planes, and the two ends of the steel plates are respectively connected to the foundation pit retaining piles on both sides of the pipeline.

2. A foundation pit support structure for crossing a pipeline according to claim 1, characterized in that: The foundation pit retaining piles are more than 1 meter away from the pipeline.

3. A foundation pit support structure for crossing a pipeline according to claim 1, characterized in that: A plurality of steel plates are parallel up and down and the left and right ends are respectively fixedly connected to the foundation pit retaining piles closest to the pipeline.

4. A foundation pit support structure for crossing a pipeline according to claim 1, characterized in that: The foundation pit retaining pile adopts a reinforced concrete retaining structure, and steel bars are implanted in the foundation pit retaining pile. One end of the steel bar protrudes from the foundation pit retaining pile and the end of the steel bar is threaded. The steel plate is provided with holes corresponding to the steel bars and is sleeved on the steel bars through the holes. It also includes nuts, and the steel plate is fixed to the foundation pit retaining pile through the nuts.

5. A foundation pit support structure for crossing a pipeline according to claim 4, characterized in that: The foundation pit retaining piles are bored cast-in-place piles.

6. The foundation pit support structure for crossing pipelines according to claim 1 is characterized in that: The foundation pit retaining piles are enclosed by steel structures, and the steel plates are welded and fixed to the foundation pit retaining piles.

7. A foundation pit support structure for crossing a pipeline according to claim 6, characterized in that: The foundation pit retaining piles are Larsen steel sheet piles.

8. The construction method of a foundation pit support structure across a pipeline according to claims 1-7 is characterized in that: The following steps are involved: S1, explore the underground pipelines within the foundation pit to determine the plane position and buried depth of the pipelines; S2, level the site and conduct surveying and setting out; S3, construct foundation pit retaining piles, use full casing construction, avoid using soil squeezing piles, and keep the foundation pit retaining piles at a certain distance from the pipeline; S4, construction crown beam; S5, excavate the foundation pit to the bottom of the first support, and construct the first support of the foundation pit; S6, digging a certain distance downwards and installing a steel plate for protection, wherein both ends of the steel plate are respectively fixedly connected to the foundation pit retaining piles on both sides of the pipeline; S7, repeat S6, excavate layer by layer, set up steel plate protection layer by layer until the pipeline is located, use manual excavation around the pipeline, and take protective measures for the pipeline; S8, after the pipeline protection is completed, continue to dig downwards, repeat S6, excavate layer by layer, and set up steel plate protection layer by layer until the second support bottom, and set up the waist beam and the second support; S9, continue to excavate downwards, repeat S8 until the excavation reaches the bottom of the foundation pit; S10, after the internal structure of the foundation pit is completed, the lowest steel plate is removed, and the foundation pit is backfilled with earth within the range of the lowest steel plate; the second-to-last steel plate is removed, and then the foundation pit is backfilled with earth within the range of the second-to-last steel plate, from bottom to top, the steel plates are removed layer by layer, and the earth is backfilled layer by layer until it reaches the ground.

9. The construction method of a foundation pit support structure across a pipeline according to claim 8, characterized in that: In S3, the retaining piles of the foundation pit are more than 1 meter away from the pipeline. In S6, the excavation is 0.5-0.7 meters downward and steel plate protection is installed.

10. The construction method of a foundation pit support structure spanning a pipeline according to claim 8, characterized in that: The pipeline protection adopts the "supporting" solution, the pipeline is placed on the bracket, and the bracket is connected to the crown beams on both sides through suspension components.

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