CN113356889B - Box type reinforcing method for advanced drill pipe right above tunnel - Google Patents

Abstract

A box type reinforcing method for an advance drill pipe right above a tunnel belongs to the technical field of foundation pit excavation and reinforcement. The drill pipe consists of a hollow drill bit and one or more connecting pipes; the hollow drill bit is composed of a conical head and a circular steel pipe which are manufactured into a whole, inner threads and outer threads are arranged on the inner wall and the outer wall of the conical head, the outer threads are positive threads, the inner threads are reverse threads, inner connecting threads I are arranged at the tail end of the inner wall of the circular steel pipe, inner connecting threads II are arranged at one end of the inner wall of the connecting pipe, and outer connecting threads are arranged at the other end of the outer wall of the connecting pipe; a plurality of first slurry outlet consolidation holes are formed in the cylinder and the connecting pipe; when the number of the connecting pipes is one, the hollow drill bit is in threaded connection with the connecting pipes; when the number of the connecting pipes is multiple, every two adjacent connecting pipes are connected through threads to form a splicing connecting pipe, and the splicing connecting pipe is connected with the hollow drill bit in a screwing manner; during grouting, the sleeve valve grouting pipe is arranged in the drill pipe and is in tight fit with the drill pipe. The method is used for reinforcing the right upper part of the existing subway tunnel.

Description

A box-type reinforcement method for the advanced drilling pipe directly above the tunnel

technical field

The invention belongs to the technical field of foundation pit excavation and reinforcement, and in particular relates to a box-type reinforcement method for an advanced drilling pipe directly above a tunnel.

Background technique

The development of urban underground rail transit can effectively support and lead the expansion of urban spatial layout and drive the economic development around the subway. Therefore, various engineering activities around the existing operating subway tunnels will become more and more frequent, and the accompanying subway Adjacent to the deep and large foundation pit project is inevitable. In order to ensure the safety of subway tunnels, many countries and regions have given control standards for the stress and deformation of subway tunnels. There is also a lack of systematic research on the protection measures of existing subway tunnel structures. At present, it is mostly limited to reducing the deformation of the foundation pit itself to reduce the risk of excessive tunnel deformation, such as the research on the excavation of the sub-silo of the foundation pit. Such methods often lack initiative, and once the subway tunnel is greatly deformed during the construction process, it will be difficult to remedy and control the further deformation of the subway tunnel. Therefore, it is necessary to propose a new reinforcement method for the excavation construction above the subway tunnel.

In addition, the grouting effect of the existing grouting device is relatively simple, and grouting holes need to be pre-drilled in the grouting reinforcement area. The grouting effect is not ideal, and it is easy to leak grouting or the grouting pressure cannot achieve the expected purpose. In addition, the shape of the grouting aggregate after grouting cannot be controlled, and even the grouting aggregate appears concentrated and agglomerated or slightly loose, which cannot achieve the effect of uniform grouting. For some special grouting reinforcement projects, directional grouting cannot be achieved, and only circumferential grouting can be performed, which is likely to cause waste of grouting and increase construction costs.

SUMMARY OF THE INVENTION

One of the objectives of the present invention is to solve the above-mentioned problems in the prior art, and provide a box-type reinforcement method for the advance drilling pipe just above the tunnel, which can effectively achieve the purpose of protecting the subway tunnel.

The second purpose of the present invention is to solve the above problems existing in the existing grouting device, and provide a grouting device for advancing the drill pipe just above the tunnel to meet the advanced grouting reinforcement effect of the advanced box reinforcement method.

In order to solve the above-mentioned technical problems, the technical scheme adopted by the present invention is as follows:

A grouting device for an advanced drilling pipe just above a tunnel, comprising a sleeve valve grouting pipe and a drill pipe; the drill pipe is composed of a hollow drill bit and one or more connecting pipes; the hollow drill bit is made of an integrated cone The head is composed of a round steel pipe, the inner and outer walls of the cone head are provided with inner and outer threads, the outer threads arranged on the outer wall of the cone head are positive spiral threads, and the inner threads arranged on the inner wall of the cone head are reversed screw thread, the rear end of the inner wall of the circular steel pipe is provided with an inner connection thread 1, one end of the inner wall of the connection pipe is provided with an inner connection thread 2, and the other end of the outer wall of the connection pipe is provided with an outer connection thread; and the connecting pipe are provided with a number of slurry consolidation holes;

When the number of connecting pipes is one, the inner connecting thread 1 of the hollow drill bit is screwed and connected with the outer connecting thread of the connecting pipe; The external connection thread is screwed and connected to form a spliced connection pipe, and the outer connection thread of the connection pipe at any end of the spliced connection pipe is screwed together with the inner connection thread of the hollow drill bit; when grouting, the sleeve valve grouting pipe It is arranged in the drill pipe and the two are tightly fitted.

A box-type reinforcement method for realizing the advanced drilling pipe directly above the tunnel by utilizing a grouting device for the advanced drilling pipe directly above the tunnel, the reinforcement method comprises the following steps:

Step 1: First, according to the subway tunnel protection red line, build the fencing piles on both sides of the foundation pit outside the subway tunnel protection red line, carry out the excavation of the first stage foundation pit on both sides of the subway tunnel, and require the lower ends of the fencing piles on both sides of the foundation pit to go deep the bottom of a subway tunnel;

Step 2: When excavating the first-stage foundation pit beyond the protection red line of the subway tunnel, construct the isolation piles on both sides of the subway tunnel at the same time. The minimum horizontal distance between the isolation piles and the outermost side of the subway tunnel is not less than 3 meters. The isolation pile effectively protects the subway tunnel to reduce the lateral displacement of the subway tunnel caused by the excavation of the foundation pits on both sides of the subway tunnel;

Step 3: When the first-phase foundation pits on both sides of the subway tunnel are excavated to the structural level and the bottom plate is poured, the drilling pipe is used to carry out lateral long-distance drilling construction. The positive screw thread is used to drill into the soil, and the reverse screw thread on the inner wall of the hollow drill bit is used to rotate the soil body during the drilling process out of the pipe body. , drill to the isolation pile on the same side as the end point; after that, clean the soil in the drill pipe, fasten the sleeve valve grouting pipe into the drill pipe, and at the same time as the sleeve valve grouting pipe is grouted, the slurry is grouted through the sleeve valve The grouting consolidation hole 2 of the pipe continuously penetrates into the surrounding soil to achieve the effect of grouting reinforcement. At the same time, the slurry infiltrated into the soil is connected with the slurry in the connecting pipe to form a steel pipe concrete pile with tree branches. Each time a row of drilling is completed, a corresponding waist beam is established, so that the drilling pipe and the retaining piles on both sides of the foundation pit are connected as a whole, which can effectively prevent the lateral displacement of the subway tunnel;

Step 4: When the first-phase foundation pit floor on both sides of the subway tunnel has been poured and the lateral drilling pipes have been drilled, the first-phase structural construction will be carried out to form a stacking effect; First, the rotary spray reinforcement pile construction is carried out directly above the subway tunnel, and then the soil excavation is carried out directly above the subway tunnel. The soil between the isolation piles shall be excavated. When the level of the bottom floor of the negative layer is reached, the grading shall be carried out and the excavation shall be continued until the bottom level of the rotary spray reinforcement pile is excavated. The construction of the temporary platform for equipment parking shall be carried out, and the drilling shall be started. Pipe operation, after top drilling to the specified position, clean the soil in the drill pipe, fasten the sleeve valve grouting pipe into the drill pipe for grouting; after the construction of the drill pipe is completed, carry out grading and backfill soil, and when the backfill reaches the rotary injection After the top of the pile is reinforced, the equipment is parked on a temporary platform, and then the drill pipe construction on the top is carried out. When the top drill pipe construction is completed, a box-type reinforcement structure is formed above the subway tunnel; In construction, connect the base plate of the negative ground floor with the retaining piles on both sides of the foundation pit and the tunnel isolation piles as a whole;

Step 5: After the government completes the pouring of the base plate of the first basement, the construction of the roof of the structure of the upper basement, including the temporary reinforcement of rib walls, is carried out after the symmetrical excavation of the partial floor and the silo. After the completion, carry out the symmetrical excavation of the other unexcavated parts in layered, striped and skipped warehouses. After the soil between the enclosure piles and the isolation piles on both sides of the foundation pit is excavated and the structural construction is completed, all the structural parts will be excavated. connected as a complete whole.

The beneficial effects of the present invention relative to the prior art are:

The traditional excavation methods directly above the subway are basically post-reinforcement measures or the cost of reinforcement construction is too high, or the prevention and reinforcement effect is not ideal. The present invention is advanced reinforcement, that is, before the excavation and unloading of the soil directly above the subway tunnel, the advanced prevention and control reinforcement is carried out on the reserved soil above the tunnel, so that when the formal excavation and unloading are carried out directly above the subway tunnel in the later stage, the tunnel structure is already in Security status. And a new grouting device is adopted, which can not only carry out advance drilling and reinforcement before the excavation of the soil directly above the subway tunnel, but also perform directional grouting in combination with the sleeve valve pipe, and the grouting slurry can be injected from the drill pipe. The grouting consolidation hole overflows directionally, and directional grouting reinforcement is carried out to reduce the use of grout, which can reduce the construction cost and greatly improve the reinforcement effect.

Description of drawings

Fig. 1 is the axonometric view 1 of the hollow drill bit;

Fig. 2 is the axonometric view 2 of the hollow drill bit;

Fig. 3 is the axonometric view 1 of the connecting pipe;

Figure 4 is a second axonometric view of the connecting pipe;

Figure 5 is a schematic view of the drill pipe before assembly;

Figure 6 is a schematic diagram of a box-type reinforcement structure;

7 is a schematic diagram of a layered, strip-hopping, and warehouse-hopping symmetrical excavation structure;

Fig. 8 is the schematic diagram of the drill pipe operation during the construction of the equipment parking temporary platform;

FIG. 9 is a front cross-sectional view of the sleeve valve grout pipe. The downward pointing arrow in the figure indicates the grouting direction.

The names and labels of the components involved in the above drawings are as follows:

Reverse rotation thread 1, positive rotation thread 2, slurry consolidation hole 1 3, inner connection thread 1 4, outer connection thread 5, inner connection thread 2 6, subway tunnel 7, positioning ring 8, rotary spray reinforcement pile 9, underground Bottom layer 10, equipment parking temporary platform 11, isolation pile 12, enclosure pile 18, temporary reinforcement rib wall 20, grading 25, drill pipe 26, 6-point steel pipe 27, connecting piece 1 28, slurry stop ring 1 29 , Steel pipe opening 30, grouting ring 2 31, pointed bottom 32, connecting piece 2 33, grouting pipe opening 34, PVC grouting pipe 35.

Detailed ways

Embodiment 1: As shown in Figures 1-5 and 9, the present embodiment discloses a grouting device for drilling pipe ahead of the tunnel directly above, including a sleeve valve grouting pipe (in the prior art) and a drilling pipe 26; the drill pipe 26 is composed of a hollow drill bit and one or more connecting pipes; the hollow drill bit is composed of a conical head and a circular steel pipe made as one body, and the inner and outer walls of the conical head are provided with inner and outer walls. External thread, the external thread arranged on the outer wall of the cone head is a forward thread 2, the inner thread arranged on the inner wall of the cone head is a reverse rotation thread 1, and the rear end of the inner wall of the circular steel pipe is provided with an inner connecting thread 1 . 4. One end of the inner wall of the connecting pipe is provided with an inner connecting thread 2 6, and the other end of the outer wall of the connecting pipe is provided with an external connecting thread 5; both the circular steel pipe and the connecting pipe are provided with several slurry consolidation holes 1 3 ;

When the number of connecting pipes is one, the inner connecting thread 4 of the hollow drill bit is screwed and connected with the outer connecting thread 5 of the connecting pipe; when the number of connecting pipes is multiple, every two adjacent connecting pipes pass through the inner connecting thread. Two 6 and external connecting thread 5 are screwed and connected to form a spliced connecting pipe, and the external connecting thread 5 of the connecting pipe located at any end in the splicing connecting pipe is screwed and connected with the inner connecting thread 1 4 of the hollow drill bit (using Kaishan KG420S crawler type The down-the-hole drilling rig drills the drill pipe 26); during grouting, the sleeve valve grouting pipe (in the prior art) is arranged in the drill pipe 26 and the two are tightly matched (through the sleeve valve grouting pipe provided The positioning ring 8 on the outer wall of the grouting pipe is tightly connected with the inner wall of the connecting pipe of the drill pipe 26).

Further, the hollow drill bit and the connecting pipe are both steel pipes.

Further, the plurality of pulping and consolidation holes-3 are all round holes (the diameter of the round holes, the number and density of the openings can be changed according to actual needs).

Embodiment 2: As shown in FIGS. 1-9 , this embodiment is a box-type reinforcement method for realizing the advanced drilling pipe directly above the tunnel by using the grouting device described in Embodiment 1. The reinforcement method includes the following steps:

Step 1: First, according to the protection red line of the subway tunnel 7, build the supporting piles 18 on both sides of the foundation pit outside the protection red line of the subway tunnel 7, carry out the excavation of the first-stage foundation pit on both sides of the subway tunnel 7, and require the surrounding walls on both sides of the foundation pit. The lower end of the guard pile 18 goes deep into the bottom of the subway tunnel 7 (a number of waist beams can be appropriately set according to the excavation depth of the foundation pit);

Step 2: When excavating the first-phase foundation pit beyond the protection red line of the subway tunnel 7, construct the isolation piles 12 on both sides of the subway tunnel 7 at the same time, and the minimum horizontal distance between the isolation piles 12 and the outermost side of the subway tunnel 7 is not less than 3 meters. , set up multiple rows of isolation piles 12 (preferably set up four rows of isolation piles 12), effectively protect the subway tunnel 7, to reduce the lateral displacement of the subway tunnel 7 caused by the excavation of the foundation pit on both sides of the subway tunnel 7;

Step 3: When the first-phase foundation pits on both sides of the subway tunnel 7 are excavated to the structural level and the bottom plate (here the bottom plate refers to the first-phase foundation pit floor on both sides of the subway tunnel 7) is poured, the drilling pipe 26 is used to carry out lateral Drilling to a long distance (the lateral drilling distance can be maintained at about 20m-25m) (the diameter of the outer wall of the connecting pipe of the drill pipe 26 is slightly smaller than the diameter of the outer wall of the enclosure piles 18 on both sides of the foundation pit, or the diameter can be adjusted according to the needs of the construction structure) , First use the hollow drill bit to drill, the positive spiral thread 2 on the outer wall of the hollow drill bit is used to drill into the soil, and the reverse spiral thread 1 on the inner wall of the hollow drill bit is used to rotate the soil during the drilling process out of the pipe body. The drilling of the hollow drill bit makes the splicing connection pipe continuously and continuously drilled until the isolation pile 12 on the same side is the end point; after that, the soil in the drill pipe 26 is cleaned, and the sleeve valve grouting pipe is fastened and put into the drill pipe 26 At the same time, with the grouting of the sleeve valve grouting pipe (different soil quality, the grouting pressure is also different. For example, when grouting in sand, considering the grouting pressure of split grouting, it should usually be controlled at 0.2-0.5 MPa; if it is in cohesive soil, the grouting pressure should be controlled within 0.2-0.3MPa; if cement mortar is used as the slurry, the slump should be controlled within 25-75mm, and the grouting pressure should be 1 -7MPa. If the slump is relatively small, the grouting pressure can take the upper limit. If the cement-water glass double-liquid fast-setting grout is used, the grouting pressure should be less than 1MPa), and the grout passes through the sleeve valve. The grouting consolidation hole 2 of the grouting pipe continuously penetrates into the surrounding soil to achieve the effect of grouting reinforcement. At the same time, the grouting infiltrated into the soil and the grouting in the connecting pipe are connected to form a steel pipe concrete pile with tree branches. Each time the drill pipe 26 completes a row of drilling, a corresponding waist beam is established, so that the drill pipe 26 is connected with the surrounding piles 18 on both sides of the foundation pit as a whole, effectively preventing the lateral displacement of the subway tunnel;

Step 4: When the first-phase foundation pit floor casting on both sides of the subway tunnel 7 is completed, and the lateral drilling pipe 26 completes the drilling, the first-phase structural construction is carried out (the first-phase structural construction mainly includes the beams of the main structure of the building, Columns, floors, shear walls, etc.) to form a stacking effect (this will help alleviate the hysteresis effect of soil rebound caused by unloading of the foundation pit); after that, the soil directly above the subway tunnel 7 is reinforced, first in the subway Rotary spray reinforcement piles 9 are constructed just above the tunnel 7, and then the soil excavation is carried out directly above the subway tunnel 7. The layered and striped vaulting is used for symmetrical excavation. First, the enclosure piles 18 and isolation piles 12 on both sides of the foundation pit are carried out. During the excavation of the soil between, when the level of the bottom floor 10 is reached, the grading 25 is carried out and the excavation continues downward until the bottom level of the rotary spray reinforcement pile 9 is excavated, and the construction of the temporary platform 11 for equipment parking is carried out. Start the operation of the drill pipe 26 (the diameter of the outer wall of the drill pipe 26 is 500mm, and the appropriate size can also be adjusted according to the conditions of the foundation pit project). The pipe is fastened and put into the drill pipe 26 for grouting (the soil quality is different, the grouting pressure is also different); when the construction of the drill pipe 26 is completed, the grading 25 is backfilled (the soil with better soil quality can be selected to replace the original soil , can also directly backfill the original soil), when backfilling to the top of the rotary jet reinforcement pile 9, the equipment is parked on the temporary platform 11, and then the top drill pipe 26 construction is carried out, when the top drill pipe 26 construction is completed, since then , a box-type reinforcement structure is formed above the subway tunnel 7; the construction of the underground negative first floor 10 is carried out afterwards, and the underground negative first floor 10 is connected with the enclosure piles 18 on both sides of the foundation pit and the tunnel isolation pile 12 as a whole ( In this way, a back pressure structure with large stiffness is formed);

Step 5: After the government completes the pouring of the base plate 10 on the first floor of the ground, the construction of the top plate of the structure on the upper first floor is carried out, including the temporary reinforcement of the rib wall 20 (this is more than the traditional reinforcement. The rigidity of the structure is large, and the self-weight of the upper structure can also be equivalent to an effective stacking load, which can effectively prevent the subway tunnel 7 from floating due to excavation); when the construction of the roof of the negative layer structure is completed, the other unexcavated parts are layered. Symmetrical excavation is carried out in strips and vaults. After the soil between the enclosure piles 18 and the isolation piles 12 on both sides of the foundation pit is excavated and the structural construction is completed, all structural parts (including the enclosure piles 18 on both sides of the foundation pit, The connection between the isolation pile 12 and the base plate 10) of the negative ground floor is a complete whole.

The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Equivalent replacements or changes to the inventive concept shall all fall within the protection scope of the present invention.

Claims (2)

1. A box type reinforcing method of a forepoling pipe right above a tunnel is realized by utilizing a grouting device of the forepoling pipe right above the tunnel, wherein the grouting device comprises a sleeve valve grouting pipe and a drilling pipe (26); the drill pipe (26) consists of a hollow drill bit and one or more connecting pipes; the hollow drill bit is composed of a cone head and a round steel pipe which are manufactured into a whole, inner threads and outer threads are arranged on the inner wall and the outer wall of the cone head, the outer threads arranged on the outer wall of the cone head are positive-rotation threads (2), the inner threads arranged on the inner wall of the cone head are negative-rotation threads (1), inner connecting threads I (4) are arranged at the tail end of the inner wall of the round steel pipe, inner connecting threads II (6) are arranged at one end of the inner wall of the connecting pipe, and outer connecting threads (5) are arranged at the other end of the outer wall of the connecting pipe; a plurality of slurry outlet consolidation holes I (3) are respectively arranged on the round steel pipe and the connecting pipe; when the number of the connecting pipes is one, the internal connecting thread I (4) of the hollow drill bit is screwed with the external connecting thread (5) of the connecting pipe; when the number of the connecting pipes is multiple, every two adjacent connecting pipes are connected in a screwing mode through an inner connecting thread II (6) and an outer connecting thread (5) to form a splicing connecting pipe, and the outer connecting thread (5) of the connecting pipe positioned at any end in the splicing connecting pipe is connected with an inner connecting thread I (4) of the hollow drill bit in a screwing mode; during grouting, the sleeve valve grouting pipe is arranged in the drill pipe (26) and is tightly matched with the drill pipe; the method is characterized in that: the reinforcing method comprises the following steps:

the method comprises the following steps: firstly, according to the protection red line of the subway tunnel (7), arranging fender posts (18) at two sides of a foundation pit outside the protection red line of the subway tunnel (7), excavating the foundation pit at one stage at two sides of the subway tunnel (7), and requiring the lower ends of the fender posts (18) at two sides of the foundation pit to be deep into the bottom of the subway tunnel (7);

step two: when excavation of a first-stage foundation pit outside a protection red line of the subway tunnel (7) is carried out, isolation piles (12) on two sides of the subway tunnel (7) are simultaneously constructed, the minimum horizontal distance between the isolation piles (12) and the outermost side of the subway tunnel (7) is not less than 3m, a plurality of rows of isolation piles (12) are arranged, the subway tunnel (7) is effectively protected, and the lateral displacement of the subway tunnel (7) caused by excavation of the foundation pits on two sides of the subway tunnel (7) is reduced;

step three: after foundation pits at two sides of a subway tunnel (7) are excavated to a structural elevation and a bottom plate is poured, lateral long-distance drilling construction is carried out by using the drill pipe (26), firstly, a hollow drill bit is used for drilling, a forward thread (2) on the outer wall of the hollow drill bit is used for drilling a soil body, a reverse thread (1) on the inner wall of the hollow drill bit is used for rotating the soil body out of a pipe body in the drilling process, a splicing connecting pipe is continuously drilled in along with the drilling of the hollow drill bit, and the isolation pile (12) drilled to the same side is taken as a terminal point; then, cleaning soil in the drill pipe (26), fastening the sleeve valve grouting pipe into the drill pipe (26), simultaneously continuously infiltrating the grout into the surrounding soil body through the grout outlet consolidation holes of the sleeve valve grouting pipe along with the grouting of the sleeve valve grouting pipe to achieve the effect of grouting reinforcement, simultaneously connecting the grout infiltrating into the soil body with the grout in the connecting pipe to form a steel pipe concrete pile with tree branches, and establishing a corresponding waist beam when drilling the drill pipe (26) in each row, so that the drill pipe (26) and the fender posts (18) on two sides of the foundation pit are connected into a whole, and the lateral displacement of the subway tunnel is effectively prevented;

step four: when the first-stage foundation pit bottom plates on two sides of the subway tunnel (7) are poured and the lateral drill pipes (26) are drilled, first-stage structural construction is carried out to form a stacking effect; then, reinforcing the soil body right above the subway tunnel (7), constructing a rotary spraying reinforcing pile (9) right above the subway tunnel (7), excavating the soil body right above the subway tunnel (7), adopting layered strip skip symmetrical excavation, firstly excavating the soil body between a retaining pile (18) at two sides of a foundation pit and an isolation pile (12), continuously excavating a slope (25) when the soil body is excavated to the elevation of a bottom plate (10) at the underground negative layer until the bottom elevation of the rotary spraying reinforcing pile (9) is excavated, constructing an equipment parking temporary platform (11), starting the operation of a drill pipe (26), cleaning the soil in the drill pipe (26) after top drilling to the preset position, and tightly arranging a sleeve valve grouting pipe into the drill pipe (26) for grouting; after the construction of the drill pipe (26), carrying out slope releasing (25) backfill, after backfilling to the top of the jet grouting reinforcing pile (9), carrying out equipment parking temporary platform (11) operation, then carrying out the construction of the drill pipe (26) at the top, and after the construction of the drill pipe (26) at the top is finished, forming a box-type reinforcing structure above the subway tunnel (7); then, constructing an underground minus one-layer bottom plate (10), and connecting the underground minus one-layer bottom plate (10), the fender posts (18) at two sides of the foundation pit and the tunnel isolation piles (12) into a whole;

step five: after the underground negative layer bottom plate (10) is poured by local partial layer strip-by-strip skip symmetrical excavation, the construction of the upper negative layer structure top plate is carried out, including the construction of a temporary reinforcing rib wall (20); after the construction of the top plate with the negative layer of structure is finished, the layered strip-by-strip cabin-jumping symmetrical excavation of other non-excavated parts is carried out, after the soil between the fender piles (18) at the two sides of the foundation pit and the isolation piles (12) is excavated and the structure construction is finished, all the structural members are connected into a whole.

2. The box type reinforcing method for the advance drill pipe right above the tunnel according to claim 1, characterized in that: in the fourth step, the mode of reinforcing the soil body right above the subway tunnel (7) before excavation is as follows: the reinforcing method is characterized in that grouting reinforcement or deep mixing pile reinforcement is adopted, the reinforcing range is longitudinal reinforcement along the subway tunnel (7), and the reinforcing width is the area surrounded by the isolation piles (12) on the two sides of the subway tunnel (7).

Images