A method for preventing and reinforcing uneven settlement of the external retaining wall of an underground garage

Abstract

The present invention discloses a method for preventing and reinforcing uneven settlement of the retaining wall outside an underground garage, belonging to the technical field of preventing and reinforcing settlement of underground structures, and comprising the following steps: determining the side for preventing and reinforcing settlement of the retaining wall outside the underground garage; determining the number and positions of the arrangement of micro steel pipe piles; driving the micro steel pipe piles on the side for preventing and reinforcing settlement, wherein the micro steel pipe piles are driven in a vertical or inclined manner, and the micro steel pipe piles are driven in a way of driving one pile every three piles skipped; arranging a reinforced concrete pile cap at the top of the vertical micro steel pipe piles, and connecting the reinforced concrete pile cap with the strip foundation of the underground garage to form an integral body; drilling holes in the retaining wall outside the underground garage, and pouring the inclined micro steel pipe piles and the hole wall of the retaining wall outside the underground garage tightly with grouting material to form an integral body.

Description

Technical Field

[0001] The present invention belongs to the technical field of settlement prevention and reinforcement of underground structures, and particularly relates to a method for preventing and reinforcing uneven settlement of an external retaining wall of an underground garage. Background Art

[0002] The statements herein only provide background art related to the present invention and do not necessarily constitute prior art.

[0003] At present, with the rapid development of the construction industry, there are many problems in the foundation scheme. Due to special strata, groundwater influence and other reasons, foundation settlement occurs. Among them, building settlement has always been a very important issue in the civil engineering industry. Generally speaking, a small amount or uniform settlement is generally allowed, while a large non-uniform settlement will bring very serious consequences to the project, such as structural damage, reduced bearing capacity, and at the same time, the safety and service performance of the building will be reduced, bringing discomfort and safety hazards to users and the surrounding people. If the building is severely eccentric, it may also cause the instability of the building foundation, and the consequences will be even more serious. Therefore, for a building with uneven settlement, in order to restore its safety and service functions, it is necessary to effectively prevent and reinforce its foundation.

[0004] The current reinforcement methods mainly achieve the purpose of settlement prevention and reinforcement by simply grouting the foundation under the existing foundation or by setting bored cast-in-place piles, micro-piles or root piles on both sides of the walls and columns on the upper part of the foundation to connect with the foundation. The existing settlement prevention methods are applicable to the reinforcement of conventional independent foundations or raft foundations with construction space, but for the external retaining wall of a high-rise building underground garage where one side is indoors and the other side is backfill soil, it is very difficult to use the existing settlement prevention and reinforcement techniques. Its main disadvantages are as follows:

[0005] 1. For the existing reinforcement measures, the pile foundations are symmetrically arranged on both sides of the foundation, as shown in Figures 1(a) and 1(b). Otherwise, it is easy to be eccentric after reinforcement and cannot meet the effective reinforcement requirements. However, for the external retaining wall of a building underground garage, one side is indoors and the other side is outdoor backfill soil, and it is impossible to arrange the pile foundations symmetrically.

[0006] 2. Symmetrical arrangement of pile foundations requires a large amount of earth excavation, and then settlement prevention and reinforcement construction of pile foundations are carried out on both sides of the external retaining wall of the basement respectively, thus increasing the construction period, causing long-term disturbance of the strata, and increasing the settlement rate of the external retaining wall of the high-rise building underground garage, resulting in further development of the uneven settlement of the external retaining wall of the underground garage, and even making it impossible to control the settlement rate and inclination of the high-rise building underground garage, and finally may cause serious engineering accidents.

[0007] 3. For the indoor and outdoor sites after excavation, due to the restrictions of construction space and strata factors, large equipment cannot be constructed.

[0008] 4. For simple grouting reinforcement at the foundation bottom alone, it is very difficult to control the grouting range and the grouting volume. Moreover, if the foundation soil is loess stratum, it will cause disturbance to the stratum below the foundation, resulting in secondary settlement of the foundation. Summary of the Invention

[0009] Aiming at the uneven settlement of the external retaining wall of the existing building underground garage under special conditions such as poor and special strata, the existing settlement prevention and reinforcement technologies are restricted by site conditions, construction space and stratum factors and cannot be implemented or cannot quickly achieve the purpose of settlement prevention and reinforcement. The purpose of the present invention is to provide a method for preventing and reinforcing the uneven settlement of the external retaining wall of an underground garage. A combined pile foundation of vertical and inclined micro steel pipe piles is arranged on the top of the indoor foundation of the external retaining wall of the existing building underground garage, and a reinforced concrete pile cap structure is arranged on the top of the piles, so that the external retaining wall of the basement is connected to the micro steel pipe piles through an external pile cap, so as to achieve the purpose of quickly preventing and reinforcing settlement.

[0010] In order to achieve the above purpose, the present invention is realized through the following technical solutions:

[0011] In the first aspect, the present invention provides a method for preventing and reinforcing the uneven settlement of the external retaining wall of an underground garage, including the following steps:

[0012] Determine the settlement prevention and reinforcement side of the external retaining wall of the underground garage;

[0013] Determine the arrangement quantity and position of the micro steel pipe piles;

[0014] Drive the micro steel pipe piles on the settlement prevention and reinforcement side. The micro steel pipe piles are driven vertically or obliquely, and the micro steel pipe piles are driven in a skip-driving method of driving one pile every three piles;

[0015] Set a reinforced concrete pile cap on the top of the vertical micro steel pipe piles, and the reinforced concrete pile cap is connected with the strip foundation of the underground garage to form a whole;

[0016] Drill holes in the external retaining wall of the underground garage, and the inclined micro steel pipe piles and the hole wall of the external retaining wall of the underground garage are filled and compacted with grouting material to form a whole.

[0017] As a further technical solution, the process of determining the settlement prevention and reinforcement side is as follows:

[0018] According to the settlement and deformation conditions of the external retaining wall of the existing building underground garage, determine the position with larger settlement of the building, and determine it as the settlement prevention and reinforcement side of the external retaining wall of the underground garage.

[0019] As a further technical solution, the process of determining the arrangement quantity and position of the micro steel pipe piles is as follows:

[0020] Calculate the bearing capacity of the foundation in the settlement prevention area of the retaining wall outside the underground garage of the building based on the current loads, backfill soil, and settlement conditions of the retaining wall on the basement exterior of the existing building, and determine the quantity and location of the micro steel pipe piles.

[0021] As a further technical solution, the vertical micro steel pipe piles are driven vertically downward from the strip foundation of the underground garage, and the pile tips at the bottoms of the vertical micro steel pipe piles pass through the backfill soil behind the retaining wall outside the underground garage of the existing building and enter the undisturbed soil layer at the base of the underground garage of the existing building.

[0022] As a further technical solution, the inclined micro steel pipe piles are driven obliquely downward from the strip foundation of the underground garage, and the pile tips at the bottoms of the inclined micro steel pipe piles enter the undisturbed soil layer at the base of the underground garage of the existing building.

[0023] As a further technical solution, during the driving process of the micro steel pipe piles, first construct the micro steel pipe piles in the areas with larger settlement, and the pile top elevation is set at a certain distance above the bottom surface of the strip foundation of the underground garage.

[0024] As a further technical solution, the reinforced concrete pile cap structure is connected to the strip foundation of the underground garage by implanting steel bars, and the bottom elevation of the reinforced concrete pile cap is the same as the top elevation of the strip foundation; the reinforced concrete pile cap is provided with stress steel bars and stirrups, and the surface of the strip foundation is roughened and an interface agent is applied before pouring the concrete.

[0025] As a further technical solution, steel pipe positioners are arranged at intervals along the whole pile body of the inclined micro steel pipe piles, and grouting pipes are arranged at the positions of the steel pipe positioners, and secondary grouting of cement slurry is carried out on the pile body of the inclined micro steel pipe piles through the grouting pipes.

[0026] As a further technical solution, an enlarged hole is set at the connection position between the pile top of the inclined micro steel pipe pile and the strip foundation, and inclined holes are drilled in both the retaining wall outside the underground garage and the strip foundation to communicate with the enlarged hole at the pile head part, so that the inclined micro steel pipe pile and the hole wall of the retaining wall outside the underground garage are filled and compacted with grouting material, and the connection is restored through the wall steel bars.

[0027] As a further technical solution, the vertical micro steel pipe piles are driven downward from the top surface of the strip foundation, and the inclined micro steel pipe piles are constructed at the intersection of the root of the retaining wall outside the underground garage and the strip foundation. A water stop steel plate is arranged at the pile top of the micro steel pipe piles to prevent groundwater seepage damage.

[0028] The beneficial effects of the present invention are as follows:

[0029] The method for preventing and controlling differential settlement of the external retaining wall of an underground garage in the present invention adopts a combined form of vertical and inclined micro steel pipe piles, which are only arranged on one side of the strip foundation inside the garage. The inclined micro steel pipe piles can decompose the force, providing not only vertical supporting force but also horizontal component force. Through secondary grouting of the pile body, the foundation of the outdoor backfill soil side is strengthened, which can avoid the eccentric force of the foundation caused by uneven arrangement of pile foundations and the additional settlement of the foundation after reinforcement.

[0030] In the method for preventing and controlling differential settlement of the external retaining wall of an underground garage in the present invention, the upper load of the external retaining wall of the underground garage is transmitted to the vertical and inclined micro steel pipe piles through a reinforced concrete pile cap, and then transmitted to the foundation through the micro steel pipe piles. The force transmission path is clear and the load transmission is reasonable. After the construction of the connection structure between the external retaining wall of the underground garage and the micro steel pipe piles, the external wall of the underground garage can achieve the purpose of rapid settlement prevention and reinforcement, and can effectively control the post-construction settlement in the later stage.

[0031] In the method for preventing and controlling differential settlement of the external retaining wall of an underground garage in the present invention, the micro steel pipe piles have a small hole-forming diameter and are suitable for various special strata, such as miscellaneous fill, loess or karst strata with karst caves or string of karst caves. The construction has little disturbance to the existing foundation and foundation, and the construction cost is low.

[0032] In the method for preventing and controlling differential settlement of the external retaining wall of an underground garage in the present invention, the pile layout positions are all at the top of the indoor foundation of the external retaining wall of the existing building basement, which can avoid a large amount of earth excavation outside the external retaining wall of the basement. Brief Description of the Drawings

[0033] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0034] Figure 1(a) is a schematic diagram of the existing reinforcement measures in the background technology;

[0035] Figure 1(b) is a schematic diagram of another existing reinforcement measure in the background technology;

[0036] Figure 2 is a schematic diagram of the method for preventing and controlling differential settlement of the external retaining wall of an underground garage in the present invention;

[0037] Figure 3 is a schematic sectional view of the reinforcement of the external retaining wall of an underground garage of an existing building in the present invention;

[0038] Figure 4 is a schematic diagram of the reinforcement of the vertical micro steel pipe piles of the strip foundation of the external retaining wall of an underground garage of an existing building in the present invention;

[0039] Figure 5It is a schematic diagram of the reinforcement of the strip foundation of the retaining wall outside the underground garage of the existing building by inclined micro steel pipe piles in the present invention;

[0040] Figure 6 It is a schematic diagram of the implanting of steel bars for the reinforced concrete pile cap of the newly added micro steel pipe piles in the present invention;

[0041] Figure 7 It is a schematic diagram of the reinforcement of the reinforced concrete pile cap of the newly added micro steel pipe piles in the present invention;

[0042] Figure 8 It is a large-scale drawing of the newly added micro steel pipe piles in the present invention;

[0043] Figure 9 It is a diagram of the relative position relationship between the reinforcement of the newly added micro steel pipe micro piles and the existing building and the underground garage plane in the present invention;

[0044] In the figure: The distances or dimensions between each part are exaggerated for showing the positions of each part, and the schematic diagram is only for illustration;

[0045] Among them, 1. Retaining wall outside the underground garage, 2. Strip foundation, 3. Reinforced concrete waterproof board of the underground garage, 4. Roof slab of the underground garage, 5. Reinforced concrete pile cap, 6. Backfill soil, 7. Vertical micro steel pipe piles, 8. Inclined micro steel pipe piles, 9. Original soil layer at the bottom of the underground garage of the existing building, 10. Waterstop steel plate, 11. Steel pipe positioner, 12. Steel bars, 13. Reaming at the pile head part, 14. Stress-bearing steel bars, 15. Stirrups, 16. Grouting pipe. Specific implementation mode

[0046] It should be noted that the following detailed description is illustrative and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0047] In a typical implementation mode of the present invention, as shown in Figure 1, a method for stopping and reinforcing the uneven settlement of the retaining wall outside the underground garage is proposed. This stopping and reinforcing method is applicable to the foundation of the retaining wall outside the underground garage of existing high-rise buildings under various stratum conditions; among them, the foundation form of the retaining wall 1 outside the high-rise building underground garage is a strip foundation 2, and the foundation of the retaining wall outside the high-rise building underground garage adopts a natural foundation or a composite foundation; different strata are mainly collapsible loess, miscellaneous fill, and karst strata, and areas where there are beaded karst caves underground and are extremely sensitive to construction disturbance and prone to large settlement.

[0048] Specifically, the method for stopping and reinforcing the uneven settlement of the retaining wall outside the underground garage of the present invention includes the following steps:

[0049] 1) Based on the settlement deformation of the external retaining wall of the underground garage of the existing building, determine the location with relatively large settlement of the building, and identify this as the side for settlement prevention and reinforcement of the external wall of the underground garage;

[0050] The location with relatively large settlement of the building here refers to the side with relatively large settlement deformation at the bottom of the building.

[0051] In this embodiment, an underground garage roof slab 4 and overlying soil are provided on the top of the underground garage. The side of the underground garage is the external retaining wall 1 of the underground garage. An underground garage reinforced concrete waterproof slab 3 is provided at the bottom of the underground garage. A strip foundation 2 is provided at the corner where the external retaining wall 1 of the underground garage and the underground garage reinforced concrete waterproof slab 3 are connected.

[0052] 2) According to the current load, backfill soil 6, and settlement situation of the external retaining wall of the basement of the existing building, calculate the bearing capacity of the foundation in the settlement prevention area of the external retaining wall of the building's underground garage. At the same time, in combination with the structural characteristics of the building's underground garage, determine the quantity and location of the micro steel pipe piles; the diameter, bearing capacity, concrete strength, etc. of the micro steel pipe piles are calculated according to the corresponding technical specifications;

[0053] In the preferred solution, the diameter of the micro steel pipe pile is preferably taken as 220 mm. The pile length needs to be determined in combination with special stratum conditions. The pile tip needs to penetrate the miscellaneous fill, loess, or karst caves or string of karst caves in the karst stratum, and the pile tip enters the hard stratum. The strength of the micro steel pipe pile body should not be lower than M30, and the steel pipe model is determined in combination with the single pile bearing capacity. The center distance of the micro steel pipe piles from the inner side of the external retaining wall of the underground garage is not less than 0.6 m, and the pile top elevation is 100 mm above the bottom surface of the strip foundation 2.

[0054] In this embodiment, the micro steel pipe piles are driven into the side for settlement prevention and reinforcement of the underground garage external wall in a vertical or inclined manner. The micro steel pipe piles are driven downward from the strip foundation 2. Among them, the vertical micro steel pipe piles 7 are driven vertically downward from the strip foundation 2. The bottom pile tip of the vertical micro steel pipe piles 7 penetrates the backfill soil 6 behind the external retaining wall of the existing building's underground garage and enters the original soil layer 9 at the bottom of the existing building's underground garage. A reinforced concrete pile cap 5 is provided at the top of the vertical micro steel pipe piles 7. The reinforced concrete pile cap 5 and the strip foundation 2 are tightly connected by steel bars 12. The entire pile body of the vertical micro steel pipe piles 7 is provided with steel pipe positioners 11 at intervals. The inclined micro steel pipe piles 8 are driven downward obliquely from the strip foundation 2. The bottom pile tip of the inclined micro steel pipe piles 8 enters the original soil layer 9 at the bottom of the existing building's underground garage. An enlarged hole 13 is provided at the connection position between the top of the inclined micro steel pipe piles 8 and the strip foundation. The entire pile body of the inclined micro steel pipe piles 8 is provided with steel pipe positioners 11 at intervals.

[0055] 3) According to the pile position layout of the vertical micro steel pipe piles and the inclined micro steel pipe piles, the micro steel pipe piles are driven by the "one pile driven every three piles" skip driving method with an interval of three piles for every one pile driven, so as to reduce the disturbance of construction to the foundation and the stratum;

[0056] During the driving process of the micro steel pipe piles, the micro steel pipe piles in the area with larger settlement should be constructed first, and the pile top elevation is 100 mm above the bottom surface of the strip foundation.

[0057] Limited by the site and space conditions, a small geological drill can be selected as the construction equipment for the micro steel pipe piles. The inclined micro steel pipe piles can be constructed by slightly modifying the geological drill. The pile forming angle can be 0° - 20°. This equipment can reduce the construction disturbance to the formation and control the uneven settlement during construction. The inclined micro steel pipe piles are convenient for construction after being modified by the geological drill.

[0058] 4) To prevent the groundwater seepage damage during the later use process, a water stop steel plate 10 is set at the pile top of the micro steel pipe piles. The water stop steel plate can be made of a steel plate with a thickness of 5 mm.

[0059] 5) To connect the micro steel pipe piles with the foundation of the exterior wall of the existing building's underground garage into an integrated whole and ensure a clear and reliable force transmission path, a pile top reinforced concrete pile cap 5 needs to be newly added at the top of the vertical micro steel pipe piles 7. The structure of the reinforced concrete pile cap 5 needs to be connected with the strip foundation by means of planting steel bars to form an integral whole, ensuring that the upper load is transmitted to the foundation through the micro steel pipe piles. The newly added pile caps are all cast-in-place reinforced concrete, greatly enhancing the overall stiffness of the exterior wall structure in the area with larger settlement.

[0060] The micro steel pipe piles and the reinforced concrete pile caps form an external connection structure. The micro steel pipe piles are connected with the top of the strip foundation of the exterior wall of the existing building's underground through the planting of steel bars in the pile caps. The inclined micro steel pipe piles can reinforce the formation on the side of the backfill soil through secondary grouting on the pile side. For the original strip foundation to be reliably connected and transmit force with the newly added reinforced concrete pile caps, steel bars need to be planted on the top surface. The micro steel pipe piles are connected with the reinforced concrete pile caps according to the structural requirements. The detailed description of this part is as follows:

[0061] ① The vertical micro steel pipe piles are connected with the strip foundation of the exterior wall of the existing building's underground garage through the reinforced concrete pile cap 5. The structure of the reinforced concrete pile cap 5 is connected with the strip foundation 2 by planting steel bars. The bottom elevation of the reinforced concrete pile cap needs to be the same as the top elevation of the strip foundation.

[0062] ② The reinforced concrete pile cap is provided with stress-bearing steel bars 14 and stirrups 15. Before pouring the concrete, the surface of the strip foundation needs to be roughened, an interface agent is applied, and the steel bars are planted and anchored with planting glue to ensure reliable connection.

[0063] ③ The vertical micro steel pipe piles are constructed downward from the top surface of the strip foundation. The inclined micro steel pipe piles are constructed at the intersection of the root of the underground retaining exterior wall and the strip foundation, and secondary grouting of cement slurry is carried out on the pile body. The grouting pressure of the cement slurry is controlled at 0.5 MPa - 1 MPa to ensure clear and reliable force transmission. A grouting pipe 16 is set at the steel pipe locator of the inclined micro steel pipe pile, and grouting is carried out through the grouting pipe.

[0064] The retaining wall 1 outside the underground garage and the strip foundation 2 are both drilled with inclined holes to communicate with the enlarged holes 13 at the pile heads of the inclined micro steel pipe piles 8, so that the inclined micro steel pipe piles 8 and the hole walls of the retaining wall 1 outside the underground garage are filled and compacted with grouting material, and the connection is restored through the wall reinforcement.

[0065] 8) According to the reinforced concrete pile cap structure, construction is carried out according to the construction procedures such as implanting steel bars, binding steel bars, formwork support, and pouring concrete, so as to ensure that the external structure is integrally connected with the foundation of the retaining wall outside the existing building underground garage, so as to achieve the purpose of rapid settlement stopping and reinforcement.

[0066] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preventing and reinforcing uneven settlement of the external retaining wall of an underground garage, characterized in that, it includes the following steps: Determine the side for preventing and reinforcing the settlement of the external retaining wall of the underground garage; Determine the quantity and positions of the micro steel pipe piles; Drive the micro steel pipe piles on the side for preventing and reinforcing the settlement. The micro steel pipe piles are driven vertically or obliquely, and the micro steel pipe piles are driven in a way of driving one pile every three piles skipped; Set a reinforced concrete pile cap at the top of the vertical micro steel pipe pile, and the reinforced concrete pile cap is connected with the strip foundation of the underground garage to form an integral whole; Drill holes in the external retaining wall of the underground garage, and the inclined micro steel pipe pile and the hole wall of the external retaining wall of the underground garage are filled and compacted with grouting material to form an integral whole.

2. The method for preventing and reinforcing uneven settlement of the external retaining wall of the underground garage according to claim 1, characterized in that, the process of determining the side for preventing and reinforcing the settlement is as follows: According to the settlement deformation condition of the external retaining wall of the underground garage of the existing building, determine the position with larger settlement of the building, and determine it as the side for preventing and reinforcing the settlement of the external retaining wall of the underground garage.

3. The method for preventing and reinforcing uneven settlement of the external retaining wall of the underground garage according to claim 1, characterized in that, the process of determining the quantity and positions of the micro steel pipe piles is as follows: According to the current load, backfill soil and settlement condition of the external retaining wall of the basement of the existing building, calculate the bearing capacity of the foundation of the settlement prevention area of the external retaining wall of the underground garage of the building, and determine the quantity and positions of the micro steel pipe piles.

4. The method for preventing and reinforcing uneven settlement of the external retaining wall of the underground garage according to claim 1, characterized in that, The vertical micro steel pipe pile is driven vertically downward from the strip foundation of the underground garage, and the bottom pile end of the vertical micro steel pipe pile passes through the backfill soil behind the external retaining wall of the underground garage of the existing building and enters the original soil layer at the bottom of the underground garage of the existing building.

5. The method for preventing and reinforcing uneven settlement of the external retaining wall of the underground garage according to claim 1, characterized in that, The inclined micro steel pipe pile is driven obliquely downward from the strip foundation of the underground garage, and the bottom pile end of the inclined micro steel pipe pile enters the original soil layer at the bottom of the underground garage of the existing building.

6. The method for preventing and reinforcing uneven settlement of the external retaining wall of the underground garage according to claim 1, characterized in that, During the driving process of the micro steel pipe piles, first construct the micro steel pipe piles in the area with larger settlement, and the pile top elevation is at a set distance above the bottom surface of the strip foundation of the underground garage.

7. The method for preventing and reinforcing uneven settlement of the external retaining wall of the underground garage according to claim 1, characterized in that, The reinforced concrete pile cap structure is connected with the strip foundation of the underground garage by implanting steel bars, and the bottom elevation of the reinforced concrete pile cap is the same as the top elevation of the strip foundation; the reinforced concrete pile cap is provided with stress steel bars and stirrups, and the surface of the strip foundation is roughened and an interface agent is applied before pouring the concrete.

8. The method for preventing and reinforcing uneven settlement of the external retaining wall of the underground garage according to claim 1, characterized in that, Steel pipe positioners are arranged at intervals along the whole pile body of the inclined micro steel pipe pile, grouting pipes are arranged at the steel pipe positioners, and secondary grouting of cement slurry is carried out on the pile body of the inclined micro steel pipe pile through the grouting pipes.

9. The method for preventing and reinforcing uneven settlement of the external retaining wall of the underground garage according to claim 1, characterized in that, At the connection position between the top of the inclined micro steel pipe pile and the strip foundation, an enlarged hole is set at the pile head part. Inclined holes are drilled in the external retaining wall of the underground garage and the strip foundation to communicate with the enlarged hole at the pile head part, so that the inclined micro steel pipe pile and the hole wall of the external retaining wall of the underground garage are filled and compacted with grouting material, and the connection is restored through the wall reinforcement.

10. The method for preventing and controlling uneven settlement of the external retaining wall of the underground garage as described in claim 1, characterized in that, The vertical micro steel pipe pile is driven downward from the top surface of the strip foundation, and the inclined micro steel pipe pile is constructed at the intersection of the root of the external retaining wall of the underground garage and the strip foundation. A water stop steel plate is arranged at the top of the micro steel pipe pile to prevent groundwater from infiltrating and damaging.

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