A support structure, building and construction method for a foundation pit with upper soil layer and lower soft rock

Abstract

The present invention belongs to the technical field of civil engineering for urban rail transit, and specifically relates to a support structure, a building and a construction method for a soft rock foundation pit with an upper soil layer and a lower part. The technical scheme is as follows: a support structure for a soft rock foundation pit with an upper soil layer and a lower part, comprising retaining piles, wherein the diameter of the upper section of the retaining piles is greater than the diameter of the lower section of the retaining piles. A building for a soft rock foundation pit with an upper soil layer and a lower part, comprising a support structure and several layers of building main bodies. A construction method for a building for a soft rock foundation pit with an upper soil layer and a lower part, comprising the following steps: S1: drilling with drill bits of different hole diameters; S2: placing a steel cage in the drill hole and pouring concrete underwater; S3: excavating a foundation pit; erecting several support steels and laying several anchor cables; S4: constructing several layers of building main bodies in the foundation pit. The present invention provides a support structure, a building and a construction method for a soft rock foundation pit with an upper soil layer and a lower part, which is economical and can improve construction efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of urban rail transit civil engineering, and specifically relates to a supporting structure, a building and a construction method of a foundation pit with a soft rock in a lower part and an upper soil layer. Background Art

[0002] Subway stations generally adopt the open cut and build method. As the open cut is buried shallowly, the integrity of the structure, the waterproofing effect of the structure and the additional waterproof layer can be guaranteed, and the construction is convenient, the project cost is low, the construction period is easy to control, and the geological conditions are not high. If the ground conditions are good, the open cut and build method is preferred. In the open cut and build method, bored piles plus internal support or anchor cables are a commonly used support type.

[0003] Due to the densification of subway lines and the increase in transfer stations, many ultra-deep foundation pits with a depth of more than 25m have appeared in the foundation pits of subway stations. Especially in areas such as Chengdu, many ultra-deep foundation pits have passed through the upper soil layer or gravel layer, and the maximum depth is within the range of soft rock layer. Soft rock layers have better stability and do not need to use oversized retaining piles. Conventional design support structures use the support form and size parameters of pure soil layers or gravel layers, resulting in a certain degree of waste. In addition, larger retaining piles are used in both the upper soil layer and the lower soft rock layer, resulting in low construction efficiency. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the purpose of the present invention is to provide a support structure, building and construction method for a foundation pit with upper soil layer and lower soft rock layer which is economical and can improve construction efficiency.

[0005] The technical solution adopted by the present invention is:

[0006] A support structure for a foundation pit with an upper soil layer and a lower soft rock layer, comprising retaining piles, wherein the upper section of the retaining piles is located in the soil layer, and the lower section of the retaining piles extends into the rock layer. The diameter of the upper section of the retaining piles is greater than the diameter of the lower section of the retaining piles, and reinforcement is arranged inside the retaining piles. If the diameter of the upper section of the retaining piles is greater than the diameter of the lower section of the retaining piles, the amount of reinforced concrete can be reduced by reducing the diameter of the section of the retaining piles extending into the rock layer while meeting the requirements of strength and the like, thereby saving money. In addition, since the diameter of the lower section of the retaining piles is reduced, the time for making a steel cage is shortened, and the efficiency of pouring concrete is improved.

[0007] As a preferred embodiment of the present invention, the lower section of the retaining pile is connected with a plurality of anchor cables, and the upper sections of the retaining piles on both sides are connected with support steel, which is beneficial to the protection of shallow pipelines and surrounding buildings. The lower part of the retaining pile is supported by anchor cables, which can improve the efficiency of foundation pit excavation and is beneficial to the anti-floating of underground structures. The upper and lower sections of the retaining pile of the present invention adopt different support forms, which can further improve the economy and efficiency of foundation pit excavation while ensuring the support effect.

[0008] As a preferred solution of the present invention, the upper section of the retaining pile is aligned with the lower section of the retaining pile on the soil facing side, a fertilizer groove is formed on the soil facing side of the lower section of the retaining pile, and the anchor cable is connected to the fertilizer groove on the soil facing side of the lower section of the retaining pile. Since the side wall is arranged vertically, a fertilizer groove of a certain width will be left between the side wall and the lower section of the retaining pile. The fertilizer groove between the side wall and the retaining pile can be used as an anchor cable fertilizer groove to avoid the situation where the anchor cable fertilizer groove occupies space alone.

[0009] As a preferred solution of the present invention, a cap beam is provided on the top of the retaining pile.

[0010] A building with an upper soil layer and a lower soft rock foundation pit includes retaining piles on both sides, wherein the upper section of the retaining piles is located in the soil layer, and the lower section of the retaining piles extends into the rock layer. The diameter of the upper section of the retaining piles is greater than the diameter of the lower section of the retaining piles, and reinforcement is arranged inside the retaining piles; and several layers of building bodies are arranged between the retaining piles on both sides. If the diameter of the upper section of the retaining piles is greater than the diameter of the lower section of the retaining piles, then the amount of reinforced concrete can be reduced by reducing the diameter of the section of the retaining piles extending into the rock layer while meeting the requirements of strength and the like, thereby saving money. In addition, since the diameter of the lower section of the retaining piles is reduced, the time for making the steel cage is shortened, and the efficiency of pouring concrete is improved.

[0011] As a preferred embodiment of the present invention, the main building includes side walls and floor slabs, and the floor slabs of the bottom layer protrude from the side walls. The upper section of the retaining piles is aligned with the lower section of the retaining piles on the soil-facing side, and a fertilizer trough is formed between the soil-repelling side of the lower section of the retaining piles and the main building, and blocks are built in the fertilizer trough. Therefore, the blocks in the fertilizer trough can press down the protruding parts of the bottom layer of the floor slab, which is beneficial to the anti-floating of the main building. A crown beam is provided on the top of the retaining piles, and a capping beam made of micro-expansive concrete is provided between the crown beam and the top floor slab of the main building. Therefore, the capping beam can also serve the purpose of anti-floating for the main building.

[0012] A construction method for a building with an upper soil layer and a lower soft rock foundation pit, comprising the following steps:

[0013] S1: Drilling is performed using drill bits with different hole diameters. The hole diameter in the rock layer is smaller than the hole diameter in the soil layer.

[0014] S2: Place a steel cage in the borehole and pour concrete underwater to form retaining piles. Construct cap beams and retaining walls on top of the retaining piles.

[0015] S3: excavating the foundation pit; and in the process of excavating the foundation pit, erecting a number of supporting steels between the upper sections of the retaining piles on both sides, and driving a number of anchor cables at the lower sections of the retaining piles;

[0016] S4: construct several layers of building structure in the foundation pit and remove the supporting steel in the process;

[0017] S5: Remove the retaining wall, relocate the pipelines and backfill the top floor of the building.

[0018] The diameter of the upper section of the retaining pile is larger than the diameter of the lower section of the retaining pile. Under the condition of meeting the strength and other requirements, the amount of reinforced concrete can be reduced by reducing the diameter of the retaining pile extending into the rock layer, which saves money. In addition, since the diameter of the lower section of the retaining pile is reduced, the time for making the steel cage is shortened and the efficiency of pouring concrete is improved.

[0019] As a preferred embodiment of the present invention, in step S3, when the foundation pit is excavated to 0.5m below the center line of the support steel to be erected, the excavation is stopped and the support steel is erected in time; when the foundation pit is excavated to 0.5m below the position of the anchor cable to be installed, the excavation is stopped and the anchor cable is installed in time.

[0020] As a preferred solution of the present invention, in step S4, the floor slab of the main building is constructed first, and then the side walls of the main building are constructed; the protruding side walls of the floor slab of the bottom layer are arranged, the upper section of the retaining piles is aligned with the lower section of the retaining piles on the soil-facing side, a fertilizer trough is formed between the soil-repelling side of the lower section of the retaining piles and the main building, and concrete is poured into the fertilizer trough to form blocks. Therefore, the blocks in the fertilizer trough can press down the protruding parts of the floor slab of the bottom layer, which is beneficial to the anti-floating of the main building. A top beam is constructed between the top floor slab and the crown beam of the main building. The protruding side walls of the floor slab of the bottom layer and the arrangement of the crown beam and the top beam both serve the purpose of anti-floating of the main building.

[0021] The beneficial effects of the present invention are:

[0022] 1. The diameter of the upper section of the retaining pile of the present invention is greater than the diameter of the lower section of the retaining pile. Under the condition of meeting the requirements of strength, the diameter of the retaining pile extending into the rock layer can be reduced, so as to reduce the amount of reinforced concrete and save money. In addition, since the diameter of the lower section of the retaining pile is reduced, the time for making the steel cage is shortened and the efficiency of pouring concrete is improved.

[0023] 2. Since the side wall is set vertically, there will be a certain gap between the side wall and the lower part of the retaining pile. The gap between the side wall and the retaining pile can be used as an anchor fertilizer trough to avoid the situation where the anchor fertilizer trough occupies space alone.

[0024] 3. The upper part of the retaining pile is supported by supporting steel, and the rigidity of the supporting steel is greater than that of the anchor cable, which is beneficial to the protection of surrounding buildings. The lower part of the retaining pile is supported by anchor cables, which can improve the efficiency of foundation pit excavation and help the underground structure to resist floating. The upper and lower parts of the retaining pile of the present invention adopt different support forms, which can improve the economy and efficiency of foundation pit excavation while ensuring the support effect.

[0025] 4. The bottom plate of the main building is cantilevered. During the use of the underground station, the fertilizer groove between the retaining piles and the main building is filled with molds to form blocks. The bottom plate of the main building is pressed by the blocks in the fertilizer groove to prevent the main building from floating up. In addition, the crown beam and the top beam can press the main building from above, further improving the anti-floating ability of the main building. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the support structure of the present invention;

[0027] Figure 2 It is a structural schematic diagram of the building of the present invention;

[0028] Figure 3 It is a schematic diagram of the structure of retaining piles.

[0029] In the figure, 1-retaining piles; 2-reinforcement; 3-anchor cables; 4-supporting steel; 5-cap beam; 6-building body; 7-top beam; 8-blocks; 9-anti-floating beam; 51-retaining wall; 61-side wall; 62-floor slab. DETAILED DESCRIPTION

[0030] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0031] Embodiment 1:

[0032] like Figure 1 As shown, a support structure for a foundation pit with an upper soil layer and a lower soft rock layer includes a retaining pile 1, wherein the upper section of the retaining pile 1 is located in the soil layer, and the lower section of the retaining pile 1 extends into the rock layer. The diameter of the upper section of the retaining pile 1 is greater than the diameter of the lower section of the retaining pile 1. Reinforcement 2 is provided in the retaining pile 1, and a cap beam 5 is provided on the top of the retaining pile 1. The diameter of the upper section of the retaining pile 1 of the present invention is greater than the diameter of the lower section of the retaining pile 1. Under the condition of meeting the requirements of strength, by reducing the diameter of the section of the retaining pile 1 extending into the rock layer, the amount of reinforced concrete can be reduced, thereby saving money. In addition, since the diameter of the lower section of the retaining pile 1 is reduced, the time for making a steel cage is shortened, and the efficiency of pouring concrete is improved.

[0033] The lower section of the retaining pile 1 is connected to a plurality of anchor cables 3, and the upper sections of the retaining piles 1 on both sides are connected to support steels 4. The upper section of the retaining pile 1 is supported by support steels 4, and the rigidity of the support steels 4 is greater than that of the anchor cables 3, which is beneficial to the protection of surrounding buildings. The lower section of the retaining pile 1 is supported by anchor cables 3, which can improve the efficiency of foundation pit excavation and is beneficial to the anti-floating of underground structures. The upper and lower sections of the retaining pile 1 of the present invention adopt different support forms, which can further improve the economy and efficiency of foundation pit excavation while ensuring the support effect.

[0034] The upper section of the retaining pile 1 is aligned with the lower section of the retaining pile 1 on the soil facing side, and a fertilizer groove is formed on the soil facing side of the lower section of the retaining pile 1, and the anchor cable 3 is connected to the fertilizer groove on the soil facing side of the lower section of the retaining pile 1. Since the side wall 61 is arranged vertically, a certain gap will be left between the side wall 61 and the lower section of the retaining pile 1. The gap between the side wall 61 and the retaining pile 1 can be used as a fertilizer groove for the anchor cable 3, avoiding the situation where the fertilizer groove for the anchor cable 3 occupies space alone.

[0035] Among them, Figure 3 As shown, longitudinal main reinforcement, spiral stirrups and stiffening reinforcement are arranged in the reinforcement 2 in the retaining pile 1. The reinforcement 2 is evenly distributed in the retaining pile 1. The anchor cable 3 is arranged at the back soil side of the lower section of the retaining pile 1, and the other end of the anchor cable 3 is obliquely extended to the soil side of the lower section of the retaining pile 1 and fixed.

[0036] Embodiment 2:

[0037] like Figure 2 As shown, a building with an upper soil layer and a lower soft rock foundation pit includes retaining piles 1 on both sides, the upper section of the retaining piles 1 is located in the soil layer, the lower section of the retaining piles 1 extends into the rock layer, the diameter of the upper section of the retaining piles 1 is larger than the diameter of the lower section of the retaining piles 1, and reinforcement 2 is arranged in the retaining piles 1; several layers of building main body 6 are arranged between the retaining piles 1 on both sides.

[0038] In this embodiment, the diameter of the upper section of the retaining pile 1 is greater than the diameter of the lower section of the retaining pile 1. Under the condition of meeting the strength and other requirements, by reducing the diameter of the retaining pile 1 extending into the rock layer, the amount of reinforced concrete can be reduced, saving economy. In addition, since the diameter of the lower section of the retaining pile 1 is reduced, the time for making the steel cage is shortened and the efficiency of pouring concrete is improved.

[0039] During the excavation of the foundation pit, the upper part of the retaining pile 1 is supported by the support steel 4, which has a greater rigidity than the anchor cable 3, which is beneficial to the protection of surrounding buildings. When laying the building body 6, the support steel 4 is gradually removed to ensure the safety of the entire construction process. The lower part of the retaining pile 1 is supported by the anchor cable 3, which can improve the excavation efficiency of the foundation pit and is beneficial to the anti-floating of the underground structure.

[0040] The upper section of the retaining pile 1 is aligned with the lower section of the retaining pile 1 on the soil facing side, and the anchor cable 3 is connected to the soil-repelling side of the lower section of the retaining pile 1. Since the side wall 61 is arranged vertically, a certain gap will be left between the side wall 61 and the lower section of the retaining pile 1. The gap between the side wall 61 and the retaining pile 1 can be used as a groove for the anchor cable 3, avoiding the situation where the groove for the anchor cable 3 occupies space alone. After the anchor cable 3 is installed, the gap between the side wall 61 and the lower section of the retaining pile 1 is filled with concrete.

[0041] The building body 6 includes side walls 61 and floor slabs 62, and the bottom floor slab 62 is protruding from the side walls 61. The upper section of the retaining pile 1 is aligned with the lower section of the retaining pile 1 on the soil-facing side, and a fertilizer trough is formed between the soil-repelling side of the lower section of the retaining pile 1 and the building body 6, and blocks 8 are built in the fertilizer trough. Therefore, the blocks 8 in the fertilizer trough can press down the protruding parts of the bottom floor slab 62, which is beneficial to the anti-floating of the building body 6. A crown beam 5 is arranged on the top of the retaining pile 1, and a capping beam 7 made of micro-expansive concrete is arranged between the crown beam 5 and the top floor slab 62 of the building body 6. Therefore, the capping beam 7 and the crown beam 5 can also serve the purpose of anti-floating for the building body 6. An anti-floating beam 9 is also arranged between the block 8 and the upper section of the retaining pile 1 to further improve the anti-floating effect of the building body 6 and the retaining pile 1.

[0042] like Figure 3 As shown, longitudinal main reinforcement, spiral stirrups and stiffening reinforcement are arranged in the reinforcement 2 in the retaining pile 1. The reinforcement 2 is evenly distributed in the retaining pile 1. The anchor cable 3 is arranged at the back soil side of the lower section of the retaining pile 1, and the other end of the anchor cable 3 is obliquely extended to the soil side of the lower section of the retaining pile 1 and fixed.

[0043] Embodiment 3:

[0044] A construction method for a building with an upper soil layer and a lower soft rock foundation pit, comprising the following steps:

[0045] S1: Drilling is performed using drill bits with different hole diameters. The hole diameter in the rock layer is smaller than the hole diameter in the soil layer.

[0046] S2: Place a steel cage in the borehole and perform underwater concrete pouring to form retaining piles 1; construct cap beams 5 and retaining walls 51.

[0047] S3: excavating a foundation pit; and in the process of excavating the foundation pit, a number of support steels 4 are set up between the upper sections of the retaining piles 1 on both sides, and a number of anchor cables 3 are driven in the lower sections of the retaining piles 1.

[0048] When the foundation pit is excavated to 0.5m below the center line of the support steel 4 to be erected, stop excavation and erect the support steel 4 in time; when the foundation pit is excavated to 0.5m below the position of the anchor cable 3 to be installed, stop excavation and install the anchor cable 3 in time.

[0049] S4: construct several layers of building bodies 6 in the foundation pit, and remove the supporting steel 4 in the process. Specifically: excavate the foundation pit to the design elevation, construct the bottom floor slab 62 and part of the side wall 61; after the concrete of the bottom floor slab 62 reaches the design strength, construct the negative third floor side wall 61, the negative second floor slab 62, the middle longitudinal beam and the middle column; after the concrete of the negative second floor slab 62 reaches the design strength, construct the negative second floor side wall 61, the negative first floor slab 62, the middle longitudinal beam and the middle column; after the concrete of the negative first floor slab 62 reaches the design strength, remove the second supporting steel 4, and construct the negative first floor side wall 61, the top floor slab 62, the top longitudinal beam and the middle column.

[0050] During the construction of the main building 6, concrete is poured into the manure tank to form blocks (8), and an anti-floating beam 9 is constructed between the blocks and the upper section of the retaining pile 1. A top beam 7 is constructed between the top floor slab 62 of the main building 6 and the crown beam 5.

[0051] S5: After the top floor slab 62 and the side wall 61 reach the designed strength, the first supporting steel 4 is removed, the retaining wall 51 is removed, the foundation pit is backfilled, and the road surface is restored.

[0052] In this embodiment, the diameter of the upper section of the retaining pile 1 is greater than the diameter of the lower section of the retaining pile 1. Under the condition of meeting the strength and other requirements, by reducing the diameter of the retaining pile 1 extending into the rock layer, the amount of reinforced concrete can be reduced, saving economy. In addition, since the diameter of the lower section of the retaining pile 1 is reduced, the time for making the steel cage is shortened and the efficiency of pouring concrete is improved.

[0053] During the excavation of the foundation pit, the upper part of the retaining pile 1 is supported by the support steel 4, which has a greater rigidity than the anchor cable 3, which is beneficial to the protection of surrounding buildings. When laying the building body 6, the support steel 4 is gradually removed to ensure the safety of the entire construction process. The lower part of the retaining pile 1 is supported by the anchor cable 3, which can improve the excavation efficiency of the foundation pit and is beneficial to the anti-floating of the underground structure.

[0054] The upper section of the retaining pile 1 is aligned with the lower section of the retaining pile 1 on the soil facing side, and the anchor cable 3 is connected to the fertilizer groove on the soil-receiving side of the lower section of the retaining pile 1. Since the side wall 61 is arranged vertically, a certain gap will be left between the side wall 61 and the lower section of the retaining pile 1. The gap between the side wall 61 and the retaining pile 1 can be used as a fertilizer groove for the anchor cable 3, avoiding the situation where the fertilizer groove for the anchor cable 3 occupies space alone. After the anchor cable 3 is installed, the gap between the side wall 61 and the lower section of the retaining pile 1 is filled with concrete.

[0055] The building blocks 8 in the fertilizer tank can press down the protruding parts of the bottom floor slab 62, which is beneficial to the anti-floating of the building body 6. A cap beam 5 is arranged on the top of the retaining pile 1, and a capping beam 7 made of micro-expansive concrete is arranged between the capping beam 5 and the top floor slab of the building body 6. Therefore, the capping beam 7 and the capping beam 5 can also play the role of anti-floating for the building body 6. An anti-floating beam 9 is also arranged between the building blocks 8 and the upper section of the retaining pile 1 to further improve the anti-floating effect of the building body 6 and the retaining pile 1.

[0056] like Figure 3 As shown, longitudinal main reinforcement, spiral stirrups and stiffening reinforcement are arranged in the reinforcement 2 in the retaining pile 1. The reinforcement 2 is evenly distributed in the retaining pile 1. The anchor cable 3 is arranged at the back soil side of the lower section of the retaining pile 1, and the other end of the anchor cable 3 is obliquely extended to the soil side of the lower section of the retaining pile 1 and fixed.

[0057] The present invention is not limited to the above-mentioned optional implementation modes. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that fall within the scope defined by the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A support structure for a foundation pit with an upper soil layer and a lower soft rock layer, characterized in that: The invention comprises a retaining pile (1), wherein the upper section of the retaining pile (1) is located in the soil layer, the lower section of the retaining pile (1) extends into the rock layer, and the diameter of the upper section of the retaining pile (1) is larger than the diameter of the lower section of the retaining pile (1); the lower section of the retaining pile (1) is connected to a plurality of anchor cables (3), and the upper sections of the retaining piles (1) on both sides are connected to support steel (4); the upper section of the retaining pile (1) is aligned with the lower section of the retaining pile (1) on the soil facing side, a fat groove is formed on the soil back side of the lower section of the retaining pile (1), and the anchor cable (3) is connected to the fat groove on the soil back side of the lower section of the retaining pile (1); the retaining pile (1) is provided with reinforcement (2), and the reinforcement (2) in the retaining pile (1) is provided with longitudinal main reinforcement, spiral stirrups and stiffening reinforcement.

2. The supporting structure of a foundation pit with an upper soil layer and a lower soft rock layer according to claim 1, characterized in that: A cap beam (5) is provided on the top of the retaining pile (1).

3. A building with an upper soil layer and a lower soft rock foundation pit, using the support structure of the upper soil layer and a lower soft rock foundation pit according to claim 1, characterized in that: It comprises retaining piles (1) on both sides, the upper section of the retaining piles (1) is located in the soil layer, the lower section of the retaining piles (1) extends into the rock layer, and the diameter of the upper section of the retaining piles (1) is greater than the diameter of the lower section of the retaining piles (1); and a plurality of layers of building bodies (6) are arranged between the retaining piles (1) on both sides.

4. The building of the foundation pit with upper soil layer and lower soft rock layer according to claim 3 is characterized in that: The building body (6) comprises side walls (61) and floor slabs (62), the bottom floor slab (62) is arranged to protrude from the side walls (61), the upper section of the retaining pile (1) is aligned with the lower section of the retaining pile (1) on the soil facing side, a fertilizer trough is formed between the soil facing side of the lower section of the retaining pile (1) and the building body (6), and blocks (8) are built in the fertilizer trough; a cap beam (5) is arranged on the top of the retaining pile (1), and a capping beam (7) made of micro-expansion concrete is arranged between the cap beam and the top floor slab (62) of the building body (6).

5. A construction method for a building with an upper soil layer and a lower soft rock foundation pit, used for constructing the building with an upper soil layer and a lower soft rock foundation pit as claimed in claim 3, characterized in that: The steps include: S1: Drilling is performed using drill bits with different hole diameters. The hole diameter in the rock layer is smaller than the hole diameter in the soil layer. S2: placing a steel cage in the borehole and pouring concrete underwater to form retaining piles (1), and constructing a cap beam (5) and a retaining wall (51) on the top of the retaining piles; S3: excavating a foundation pit; and during the excavation of the foundation pit, installing a plurality of support steels (4) between the upper sections of the retaining piles (1) on both sides, and installing a plurality of anchor cables (3) at the lower sections of the retaining piles (1); S4: constructing several layers of building structure (6) in the foundation pit, and removing the supporting steel (4) in the process; S5: demolish the retaining wall (51), relocate the pipelines, and backfill the top floor (62) of the building body (6) with soil.

6. The construction method of a building with an upper soil layer and a lower soft rock foundation pit according to claim 5, characterized in that: In step S3, when the foundation pit is excavated to 0.5 m below the center line of the support steel (4) to be installed, the excavation is stopped and the support steel (4) is installed in time; when the foundation pit is excavated to 0.5 m below the position of the anchor cable (3) to be installed, the excavation is stopped and the anchor cable (3) is installed in time.

7. The construction method of a building with an upper soil layer and a lower soft rock foundation pit according to claim 5 or 6, characterized in that: In step S4, the floor slab (62) of the building body (6) is first constructed, and then the side walls (61) of the building body (6) are constructed; the floor slab (62) of the bottom layer is arranged to protrude from the side walls (61), the upper section of the retaining pile (1) is aligned with the lower section of the retaining pile (1) on the soil facing side, a fertilizer trough is formed between the soil facing side of the lower section of the retaining pile (1) and the building body (6), and concrete is poured into the fertilizer trough to form a building block (8); and a top beam (7) is constructed between the top floor slab (62) of the building body (6) and the crown beam (5).

Images