A method for preventing subway tunnel from shifting

Abstract

The present invention relates to a method for preventing a subway tunnel from shifting, comprising the following steps: the first step is to form a hole: a plurality of pipe pile connection holes are set on the tunnel segment of the subway tunnel; the second step is to connect the outer steel pipe; the third step is to remove the flexible sealing bag: an operator extends his hand from one end of the outer steel pipe located in the subway tunnel into the outer steel pipe to push the through hole cover plate outward and make the flexible sealing bag extend from the pipe pile connection hole to the outside of the outer steel pipe, and the flexible sealing bag is turned over to face the inner surface outward during the process of extending from the pipe pile connection hole; the fourth step is to form a filling core. The present invention has a method for preventing a subway tunnel from shifting when the subway is constructed in a soft soil area, which solves the problem that a subway tunnel made by an existing construction method is prone to "drifting" when passing through a soft soil area.

Description

Technical Field

[0001] The invention relates to the technical field of subway tunnel construction, and in particular to a method for preventing a subway tunnel from shifting. Background Art

[0002] With the development of cities and the progress of society, the pressure of urban traffic has gradually increased, and the construction of subways has gradually increased, and various construction problems will be encountered. During the construction process, the excavation posture of the shield machine in the soft soil layer is difficult to control. After the tunnel is formed, the soft soil cannot provide a large force to the tunnel, and "drift" occurs during the operation of the subway. The instability of the tunnel has a great impact on driving. There is a lot of silt in the strata in many areas. It is very difficult to control the excavation posture and the linear control of the formed tunnel during shield construction. Therefore, how to ensure that the construction quality is in a controllable state and improve the construction quality prompts engineering and technical personnel to solve it according to the actual situation.

[0003] When the shield machine is used in the construction of muddy strata, the control of shield excavation parameters, segment assembly, selection, and excavation in different strata are all important reasons for the displacement of the formed tunnel. In order to prevent excessive settlement during the construction period of the shield tunnel, especially during the operation period, which will affect driving, it is necessary to reinforce the soft soil at the bottom of the shield tunnel so that the soft soil within the tunnel has sufficient foundation bearing capacity and reduce the displacement (drift) of the shield tunnel during the operation period. This is an urgent problem to be solved when the subway tunnel passes through the soft soil area. Summary of the invention

[0004] The present invention aims to provide a method for preventing a subway tunnel from shifting when the subway is constructed in a soft soil area, thereby solving the problem that a subway tunnel constructed by an existing construction method is prone to "drifting" when passing through a soft soil area.

[0005] The above technical problems are solved by the following technical solutions: a method for preventing subway tunnel displacement, characterized in that the first step is to form holes: a plurality of pipe pile connection holes are set on the tunnel segments of the subway tunnel; the second step is to connect the outer steel pipe: the outer steel pipe is passed from the subway tunnel through the pipe pile connection holes to the outside of the subway tunnel, a positioning block and a plurality of steel pipe through holes that penetrate the inside of the outer steel pipe are provided on the outer peripheral surface of one end of the outer steel pipe connected to the subway tunnel, the steel pipe through holes are sealed and docked with the open end of the flexible sealing bag, the steel pipe through holes are provided with through hole covers that can only be opened toward the outside of the outer steel pipe, the flexible sealing bag is located inside the outer steel pipe, the positioning blocks are abutted against the inner surface of the subway tunnel, the through hole covers are located outside the subway tunnel, the outer steel pipe is connected to the pipe pile connection holes The two ends of the outer steel pipe are sealed and fixed together; the third step is to remove the flexible sealing bag: the operator extends his hand from one end of the outer steel pipe located in the subway tunnel into the outer steel pipe to push the through-hole cover plate outward and make the flexible sealing bag extend from the through-hole of the steel pipe to the outside of the outer steel pipe. During the process of extending the through-hole of the steel pipe, the flexible sealing bag turns over so that the inner surface faces outward; the fourth step is to form a filling core: concrete is poured in the outer steel pipe, and a filling core is formed after the concrete is solidified. The concrete enters the flexible sealing bag through the pipe pile connection hole to bulge the sealing bag. After the concrete in the flexible sealing bag is solidified, it forms an external booster block that abuts against the outer peripheral surface of the subway tunnel together with the flexible sealing bag. The concrete in the flexible sealing bag is poured together with the concrete in the outer steel pipe; the filling core and the outer steel pipe constitute an anti-settling pile. This technical solution can make it possible for the outer steel pipe to be easily passed through the through hole of the steel pipe part during construction even though the flexible sealing bag is connected to the outer steel pipe part, without expanding the gap between the through hole of the steel pipe part and the outer light pipe, which makes it difficult to prevent the mud from entering the connection between the outer steel pipe and the subway tunnel during construction; it can also make the anti-settling pile not only fixed by bonding between the outer steel pipe and the connection hole of the steel pipe part after it is made, but also form an external auxiliary stopper to cooperate with the positioning block for clamping and fixing, which can not only make the fixation more reliable, but also improve the ability of the connection between the anti-settling pile and the tunnel wall to resist the torsional force generated by the swing of the anti-settling tunnel, so that the connection is not easily damaged. The flexible sealing bag is set up, so that it does not take up space when folded, and the shape is controllable after unfolding. The way of disassembling the elastic sheet is easy to cause the phenomenon of expansion transition and rupture. The through-hole cover plate is set up and the through-hole cover plate can only be opened outward, which can prevent the soft mud (silt) on the outside of the outer steel pipe from entering the outer steel pipe before grouting, so that the flexible sealing bag cannot be conveniently and reliably moved to the outside of the outer steel pipe. The position of the steel pipe without a hole is designed so that the sealed flexible bag can be withdrawn by inserting a hand into the outer steel pipe from the subway tunnel, which can improve the convenience during construction. By setting anti-settlement piles on the pipe segments, the subway tunnel can be effectively prevented from "drifting".

[0006] Preferably, in the fourth step, the inner steel pipe is first passed through the outer steel pipe, the outer steel pipe and the inner steel pipe are both round pipes, an annular cavity surrounding the outer periphery of the inner steel pipe is formed between the outer steel pipe and the inner steel pipe, an outer steel pipe end wall is provided at one end of the outer steel pipe away from the tunnel, the outer steel pipe end wall closes the outer steel pipe so that the outer steel pipe becomes a blind pipe, an inner steel pipe end wall is provided at one end of the inner steel pipe away from the tunnel, the inner steel pipe end wall closes the inner steel pipe so that the inner steel pipe becomes a blind pipe; in the process of filling concrete, the inner steel pipe is first filled with concrete and then the concrete is filled into the annular cavity, in the process of filling the concrete into the inner steel pipe, the inner steel pipe is rotated in the outer steel pipe, and then the concrete is filled into the annular cavity, the concrete in the annular cavity is solidified to form a cement bonding layer bonding the inner steel pipe and the outer steel pipe together, the concrete in the inner steel pipe is solidified to form a concrete inner core, and the cement bonding layer, the inner steel pipe and the concrete inner core constitute the filling core. This technical solution realizes the rotation of the inner steel pipe to accelerate the compaction speed of the concrete inner core when grouting to form the anti-settling pile.

[0007] Preferably, a spherical crown-shaped support protrusion is provided on the inner surface of the end wall of the outer steel pipe portion, and a spherical pit is provided on the outer surface of the end wall of the inner steel pipe portion. The inner steel pipe is supported in the outer steel pipe by being sleeved on the support protrusion by the pit. A gap is provided between the bottom wall of the outer steel pipe portion and the bottom wall of the inner steel pipe portion. The support protrusion and the pit are spherically matched and abutted together. When the inner steel pipe is rotated in the outer steel pipe, the inner steel pipe is supported on the support protrusion to rotate; the cement bonding layer extends into the gap. It can improve the patency when rotating the inner steel pipe. The spherical matching and abutting together can increase the contact area and reduce wear.

[0008] Preferably, the outer peripheral surface of the inner steel pipe is provided with a plurality of supporting convex strips extending axially along the circumference of the inner steel pipe, and the inner steel pipe is sealed and supported in the outer steel pipe by the supporting convex strips, and the supporting convex strips isolate the annular cavity from a plurality of strip holes distributed along the circumference of the inner steel pipe, and the lower ends of all the strip holes are connected; in the process of injecting concrete into the annular cavity, one end of the strip hole located in the subway tunnel is connected to the exhaust equipment for exhaust, and concrete is injected from the other end of the strip hole located in the subway tunnel until all the strip holes are filled with concrete, and then the exhaust is stopped. The reliability of grouting into the annular cavity is improved.

[0009] Preferably, the tunnel segment is a prefabricated concrete part, and the pipe pile connection hole is a prefabricated hole formed in the process of manufacturing the tunnel segment; before the pipe pile connection hole is connected to the anti-settling pile, a plug is sealed and connected in the pipe pile connection hole, and the pipe pile connection hole is formed by removing the plug in the first step. This can avoid drilling a through hole for the steel pipe on site when connecting the anti-settling pile, which causes construction inconvenience and damage to the segment.

[0010] Preferably, the outer end of the plug is provided with an outer flange located outside the subway tunnel, the inner end is provided with a threaded section, the threaded section extends into the subway tunnel, the plug sleeve is provided with a sealing ring, the sealing ring is clamped by the outer flange and the outer peripheral surface of the subway tunnel to seal and connect the plug with the pipe pile connection hole; in the first step, the plug is opened by pushing the plug toward the outside of the subway tunnel. The sealing reliability when sealing the pipe pile connection hole is good and the sealing is convenient to achieve, and it is convenient to open.

[0011] Preferably, a locking nut is threadedly connected to the threaded section, and the locking nut abuts against the inner surface of the subway tunnel, so as to prevent the pipe pile connection hole from losing its sealing function due to impact with the plug when the anti-settling pile is not connected.

[0012] Preferably, the inner end of the pipe pile connection hole is provided with an annular boss surrounding the pipe pile connection hole and arranged on the inner surface of the subway tunnel, and the end surface of the annular boss is provided with an annular support plane extending along the circumference of the pipe pile connection hole, the annular support plane is perpendicular to the threaded section, and the locking nut is supported on the annular support plane, so that the force is uniform when tightening the locking nut.

[0013] Preferably, an annular steel gasket is cast on the annular boss, and the end surface of the annular steel gasket constitutes the annular supporting plane, which can improve the connection strength.

[0014] Preferably, the pipe pile connection hole is a tapered hole with a small inner end and a large outer end, and the plug is a tapered head with a small inner end and a large outer end, and the plug is sealed and connected with the conical surface of the pipe pile connection hole. When the pipe segment is made as a standard part, there will be unused pipe pile connection holes. In this case, the pipe pile connection holes need to be sealed for a long time. In this case, the technical solution can effectively prevent the outer flange from being damaged when the plug is plugged due to soil pressure and internal pressure, causing the plug to lose its sealing function.

[0015] Preferably, the peripheral surface of the plug is provided with a plurality of annular connection grooves extending along the circumference of the plug, the annular connection grooves are distributed along the axial direction of the plug, and an adhesive ring formed by curing concrete is provided in the annular connection groove, and the plug is sealed and fixed with the pipe pile connection hole through the adhesive ring. During the manufacturing process, the concrete is filled into the annular connection groove when the plug is assembled into the pipe pile connection hole, and then the plug is inserted into the pipe pile connection hole for assembly, so that sealing can be achieved labor-savingly during connection.

[0016] Preferably, the plug is a concrete structure, a steel core extending out of the inner end of the plug is pre-buried in the inner end of the plug, and the threaded section is arranged on the steel core, which can ensure the thread strength of the threaded section and reduce material costs.

[0017] Preferably, the upper ends of the anti-settling piles are connected together through a steel connecting frame located in the subway tunnel. The inner ends of the anti-settling piles are supported together by the steel connecting frame, and can bear force together, thereby reducing the force on the connection between the anti-settling piles and the pipe segments and preventing damage.

[0018] Preferably, the steel connection frame includes a plurality of steel rods whose one ends are connected to the filling core of the anti-settling pile in a one-to-one correspondence and steel support ribs connecting the other ends of all the steel rods together; when making the filling core, the steel rods are inserted into the concrete forming the filling core before the concrete solidifies, and after the concrete solidifies, the steel rods are cast together with the filling core to achieve the connection between the steel rods and the filling core. This can improve the convenience and reliability of the connection between the steel connection frame and the anti-settling pile.

[0019] Preferably, the steel rod and the steel supporting ribs are welded together.

[0020] Preferably, the steel pipe is inserted into the pipe pile connection hole, and the steel pipe and the pipe pile connection hole are sealed and fixed together, which can improve the bending strength of the connection between the anti-settlement pile and the pipe segment.

[0021] Preferably, a concrete water-proof layer is poured on the bottom of the subway tunnel, and the concrete water-proof layer completely covers the upper ends of the steel connection frame and the anti-settling piles, which can prevent leakage at the connection and prevent rust on exposed steel parts.

[0022] Preferably, a concrete anti-seepage layer is poured on the bottom of the subway tunnel, and the concrete anti-seepage layer completely covers the parts of the steel connecting frame and the anti-settlement piles located in the subway tunnel.

[0023] The invention has the following advantages: by arranging the anti-settling piles on the pipe segments, the subway tunnel can be effectively prevented from drifting, and the anti-settling piles of the structure can be formed by grouting in the subway tunnel. Compared with the ground grouting reinforcement measures, there is no need to set up temporary enclosures, dig and abandon soil for equipment to enter the site, which can shorten the construction period and reduce the cost; because the invention is constructed in the subway tunnel, the impact on road traffic, the noise impact on the surrounding living areas, and the large amount of dust generated during the transportation of abandoned soil can be avoided during construction, and a certain amount of solid waste pollution is reduced; the pipe pile connection hole of the pipe segment is prefabricated and closed by a plug, and when connecting with the anti-settling pile, the plug is opened to form a grouting hole for forming and connecting the anti-settling pile, which can avoid the impact damage to the pipe segment caused by the opening of the hole; the steel pipe of the grouting pipe has two layers and can rotate, so that the concrete inner core can be quickly compacted when the anti-settling pile is made; the anti-settling pile can form an external power-assisting block for clamping the pipe segment, so that the connection between the anti-settling pile and the pipe segment has a strong ability to resist the prying of the anti-settling pile. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a process flow chart of the present invention;

[0025] Figure 2 It is a schematic diagram of a subway tunnel when the outer steel pipe and the tunnel segment in the first embodiment are connected together;

[0026] Figure 3 for Figure 2 A local enlarged schematic diagram of point A;

[0027] Figure 4 This is a schematic diagram of a subway tunnel manufactured in Example 1;

[0028] Figure 5 For anti-settlement piles Figure 4 A schematic cross-sectional view of the B-B direction;

[0029] Figure 6 for Figure 4 A local enlarged schematic diagram of point C;

[0030] Figure 7 This is a schematic diagram when the pipe pile connection hole is not connected to the anti-settlement pile, that is, it is not opened;

[0031] Figure 8 This is a schematic diagram of the subway tunnel produced in Example 2.

[0032] In the figure: anti-settlement pile 1, tunnel segment 2, subway tunnel 3, outer steel pipe 4, inner steel pipe 5, cement bonding layer 6, concrete inner core 8, outer steel pipe end wall 7, inner steel pipe end wall 9, supporting protrusion 10, gap 11, plug 12, outer flange 13, threaded section 14, sealing ring 15, locking nut 16, annular boss 17, annular steel gasket 18, annular supporting plane 19, bonding ring 20, steel core 21, supporting protrusion 22, strip hole 23, positioning block 24, steel pipe through hole 25, flexible sealing bag 26, through hole cover 27, overlapping step 28, external power assist stopper 29, inner surface 30 of flexible sealing bag, filling core 31, concrete in flexible sealing bag 32, steel connecting frame 33, steel rod 34, steel supporting rib 35, concrete anti-seepage layer 36. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example 1, see Figures 1 to 7A method for preventing a subway tunnel from shifting comprises the following steps: a first step, forming a hole: a plurality of pipe pile connection holes are set on a tunnel segment 2 of a subway tunnel 3; a second step, connecting an outer steel pipe: an outer steel pipe 4 is passed from the inside of the subway tunnel to the outside of the subway tunnel through the pipe pile connection hole, a positioning block 24 and a plurality of steel pipe through holes 25 penetrating the inside of the outer steel pipe are provided on the outer peripheral surface of one end of the outer steel pipe connected with the subway tunnel, the steel pipe through hole is sealed and butted with the open end of a flexible sealing bag 26, the steel pipe through hole is provided with a through hole cover plate 27 which can only be opened toward the outside of the outer steel pipe, the flexible sealing bag is located inside the outer steel pipe, the positioning block is butted with the inner surface of the subway tunnel, the through hole cover plate is located outside the subway tunnel, and the outer steel pipe is sealed and fixedly connected with the pipe pile connection hole. ; The third step is to remove the flexible sealing bag: the operator extends his hand from one end of the outer steel pipe located in the subway tunnel into the outer steel pipe to push the through-hole cover plate outward and make the flexible sealing bag extend from the through-hole of the steel pipe to the outside of the outer steel pipe. In the process of extending the through-hole of the steel pipe, the flexible sealing bag turns over so that the inner surface 30 of the flexible sealing bag faces outward; The fourth step is to form a filling core: concrete is poured in the outer steel pipe, and a filling core 31 is formed after the concrete solidifies. The concrete enters the flexible sealing bag through the pipe pile connecting hole to bulge the sealing bag. After the concrete 32 in the flexible sealing bag is solidified, it forms an outer booster stopper 29 that abuts against the outer peripheral surface of the subway tunnel together with the flexible sealing bag. The concrete in the flexible sealing bag is poured together with the concrete in the outer steel pipe; the filling core and the outer steel pipe constitute an anti-settling pile 1. Specifically: in the fourth step, the inner steel pipe 5 is first inserted into the outer steel pipe, the outer steel pipe and the inner steel pipe are both round pipes, and an annular cavity surrounding the outer periphery of the inner steel pipe is formed between the outer steel pipe and the inner steel pipe. An outer steel pipe end wall 7 is provided at one end of the outer steel pipe away from the tunnel, and the outer steel pipe end wall closes the outer steel pipe so that the outer steel pipe becomes a blind pipe. An inner steel pipe end wall 9 is provided at one end of the inner steel pipe away from the tunnel, and the inner steel pipe end wall closes the inner steel pipe so that the inner steel pipe becomes a blind pipe; in the process of filling concrete, the inner steel pipe is first filled with concrete and then filled into the annular cavity. In the process of filling concrete into the inner steel pipe, the inner steel pipe is rotated in the outer steel pipe, and then the concrete is filled into the annular cavity. The concrete in the annular cavity is solidified to form a cement bonding layer 6 that bonds the inner steel pipe and the outer steel pipe together. The concrete in the inner steel pipe is solidified to form a concrete inner core 8. The cement bonding layer, the inner steel pipe and the concrete inner core constitute the filling core. A spherical crown-shaped supporting protrusion 10 is provided on the inner surface of the end wall of the outer steel pipe portion, and a spherical pit is provided on the outer surface of the end wall of the inner steel pipe portion. The inner steel pipe is supported in the outer steel pipe by being sleeved on the supporting protrusion through the pit. A gap 11 is provided between the bottom wall of the outer steel pipe portion and the bottom wall of the inner steel pipe portion. The supporting protrusion and the pit spherically fit and abut against each other. When the inner steel pipe is rotated in the outer steel pipe, the inner steel pipe is supported and rotated on the supporting protrusion; the cement bonding layer extends into the gap.The outer circumferential surface of the inner steel pipe is provided with a plurality of support ribs 22 extending axially along the circumference of the inner steel pipe. The inner steel pipe is sealed and supported in the outer steel pipe by the support ribs. The support ribs isolate the annular cavity from a plurality of strip holes distributed along the circumference of the inner steel pipe. The lower ends of all the strip holes are connected. In the process of injecting concrete into the annular cavity, one strip hole located at one end of the subway tunnel is connected to the exhaust equipment for exhaust. At the same time, concrete is injected from the remaining strip holes located at one end of the subway tunnel until all the strip holes are filled with concrete and then the exhaust is stopped. The tunnel segment is a prefabricated concrete part, and the pipe pile connection hole is a prefabricated hole formed in the process of making the tunnel segment. Before the pipe pile connection hole is connected to the anti-settling pile, a plug 12 is sealed and connected in the pipe pile connection hole. In the first step, the pipe pile connection hole is formed by removing the plug. The outer end of the plug is provided with an outer flange 13 located outside the subway tunnel, and the inner end is provided with a threaded section 14, the threaded section extends into the subway tunnel, and the plug sleeve is provided with a sealing ring 15, which is clamped by the outer flange and the outer peripheral surface of the subway tunnel to seal the plug with the pipe pile connection hole; in the first step, the plug is opened by pushing the plug toward the outside of the subway tunnel. The pipe pile connection hole is a conical hole with a small inner end and a large outer end, and the plug is a conical head with a small inner end and a large outer end. The plug is sealed and connected with the conical surface of the pipe pile connection hole. A locking nut 16 is threadedly connected on the threaded section. The locking nut is in contact with the inner surface of the subway tunnel. Specifically: the inner end of the pipe pile connection hole is provided with an annular boss 17 surrounding the pipe pile connection hole and arranged on the inner surface of the subway tunnel, and an annular steel gasket 18 is cast on the annular boss. The end surface of the steel gasket constitutes an annular support plane 19 extending along the circumference of the pipe pile connection hole, and the annular support plane is perpendicular to the threaded section, and the locking nut is supported on the annular support plane. The peripheral surface of the plug is provided with a plurality of annular connecting grooves extending along the circumference of the plug. The annular connecting grooves are distributed along the axial direction of the plug. An adhesive ring 20 formed by curing concrete is provided in the annular connecting groove. The plug is sealed and fixed with the pipe pile connection hole through the adhesive ring. When opening the plug, unscrew the locking nut, knock the threaded section outward to crack the adhesive ring, and then remove the plug. The plug is a concrete structure. The inner end of the plug is pre-buried with a steel core 21 extending out of the inner end of the plug, and the threaded section is arranged on the steel core.

[0035] Embodiment 2 is different from Embodiment 1 in that:

[0036] See also Figure 8, the upper ends of the anti-settlement piles are connected together through a steel connecting frame 33 located in the subway tunnel. The steel connecting frame includes a plurality of steel rods 34 whose one ends are cast in the concrete core of the anti-settlement piles one by one and steel support bars 35 connecting the other ends of all the steel rods together. The steel rods and the steel support bars are welded together. A concrete anti-seepage layer 36 is cast on the bottom of the subway tunnel. The concrete anti-seepage layer completely covers the steel connecting frame and the anti-settlement piles located in the subway tunnel. The specific process of casting the steel rods with the concrete core is as follows: when making the filling core, the steel rods are inserted into the concrete in the inner steel pipe before the concrete in the inner steel pipe is solidified, and the steel rods are cast together with the filling core after the concrete is solidified to achieve the connection between the steel rods and the filling core.

[0037] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preventing a subway tunnel from shifting, characterized in that: The first step is to form a hole: a plurality of pipe pile connection holes are set on the tunnel segment of the subway tunnel; the second step is to connect the outer steel pipe: the outer steel pipe is passed from the subway tunnel through the pipe pile connection hole to the outside of the subway tunnel, and a positioning block and a plurality of steel pipe through holes that penetrate the inside of the outer steel pipe are provided on the outer peripheral surface of one end of the outer steel pipe connected to the subway tunnel, and the steel pipe through hole is sealed and connected with the open end of the flexible sealing bag, and the steel pipe through hole is provided with a through hole cover that can only be opened to the outside of the outer steel pipe, and the flexible sealing bag is located inside the outer steel pipe, and the positioning block is abutted against the inner surface of the subway tunnel, and the through hole cover is located outside the subway tunnel, and the outer steel pipe is sealed and fixedly connected with the pipe pile connection hole; the third step is to remove the flexible sealing bag, and the positioning block is abutted against the inner surface of the subway tunnel, and the through hole cover is located outside the subway tunnel, and the outer steel pipe is sealed and fixedly connected with the pipe pile connection hole; Sealing bag: The operator reaches into the outer steel pipe from one end of the outer steel pipe located in the subway tunnel by hand to push open the through-hole cover plate and extend the flexible sealing bag from the through-hole of the steel pipe to the outside of the outer steel pipe. The flexible sealing bag turns over with the inner surface facing outward during the process of extending the through-hole of the steel pipe. The fourth step is to form a filling core: pour concrete in the outer steel pipe, and the filling core is formed after the concrete solidifies. The concrete enters the flexible sealing bag through the pipe pile connecting hole to bulge the sealing bag. After the concrete in the flexible sealing bag is solidified, it forms an external booster block that abuts against the outer peripheral surface of the subway tunnel together with the flexible sealing bag. The concrete in the flexible sealing bag is poured together with the concrete in the outer steel pipe. The filling core and the outer steel pipe constitute an anti-settling pile.

2. A method for preventing subway tunnel displacement according to claim 1, characterized in that: In the fourth step, the inner steel pipe is first inserted into the outer steel pipe, the outer steel pipe and the inner steel pipe are both round pipes, an annular cavity surrounding the outer periphery of the inner steel pipe is formed between the outer steel pipe and the inner steel pipe, an outer steel pipe end wall is provided at one end of the outer steel pipe away from the tunnel, the outer steel pipe end wall closes the outer steel pipe so that the outer steel pipe becomes a blind pipe, and an inner steel pipe end wall is provided at one end of the inner steel pipe away from the tunnel, the inner steel pipe end wall closes the inner steel pipe so that the inner steel pipe becomes a blind pipe; in the process of filling concrete, the inner steel pipe is first filled with concrete and then filled into the annular cavity, in the process of filling the concrete into the inner steel pipe, the inner steel pipe is rotated in the outer steel pipe, the concrete in the annular cavity is solidified to form a cement bonding layer bonding the inner steel pipe and the outer steel pipe together, the concrete in the inner steel pipe is solidified to form a concrete inner core, and the cement bonding layer, the inner steel pipe and the concrete inner core constitute the filling core.

3. A method for preventing subway tunnel displacement according to claim 2, characterized in that: A spherical crown-shaped supporting protrusion is provided on the inner surface of the end wall of the outer steel pipe portion, and a spherical structured pit is provided on the outer surface of the end wall of the inner steel pipe portion. The inner steel pipe is supported in the outer steel pipe by being sleeved on the supporting protrusion by the pit. A gap is provided between the bottom wall of the outer steel pipe portion and the bottom wall of the inner steel pipe portion. The supporting protrusion and the pit spherically fit and abut against each other. When the inner steel pipe is rotated in the outer steel pipe, the inner steel pipe is supported on the supporting protrusion to rotate; the cement bonding layer extends into the gap.

4. A method for preventing a subway tunnel from shifting according to claim 2 or 3, characterized in that: The outer peripheral surface of the inner steel pipe is provided with a plurality of supporting convex strips extending axially along the circumference of the inner steel pipe. The inner steel pipe is sealed and supported in the outer steel pipe by the supporting convex strips. The supporting convex strips isolate the annular cavity into a plurality of strip holes distributed along the circumference of the inner steel pipe, and the lower ends of all the strip holes are connected. In the process of injecting concrete into the annular cavity, one end of a strip hole located at the subway tunnel is connected to the exhaust equipment for exhaust, while concrete is injected from the remaining strip holes located at one end of the subway tunnel until all the strip holes are filled with concrete, and then the exhaust is stopped.

5. The method for preventing subway tunnel displacement according to claim 1, characterized in that: The tunnel segment is a prefabricated concrete part, and the pipe pile connection hole is a prefabricated hole formed in the process of manufacturing the tunnel segment; before the pipe pile connection hole is connected to the anti-settlement pile, a plug is sealed in the pipe pile connection hole, and in the first step, the pipe pile connection hole is formed by removing the plug.

6. A method for preventing a subway tunnel from shifting according to claim 5, characterized in that: The outer end of the plug is provided with an outer flange located outside the subway tunnel, and the inner end is provided with a threaded section, and the threaded section extends into the subway tunnel. The plug sleeve is provided with a sealing ring, and the sealing ring is clamped by the outer flange and the outer peripheral surface of the subway tunnel to seal and connect the plug to the pipe pile connecting hole. In the first step, the plug is opened by pushing the plug toward the outside of the subway tunnel.

7. A method for preventing a subway tunnel from shifting according to claim 5 or 6, characterized in that: The pipe pile connection hole is a tapered hole with a small inner end and a large outer end, and the plug is a tapered head with a small inner end and a large outer end. The plug is matched with the tapered surface of the pipe pile connection hole and is sealed and connected together.

8. The method for preventing subway tunnel displacement according to claim 1, characterized in that: The upper ends of the anti-settling piles are connected together via a steel connecting frame located in the subway tunnel.

9. A method for preventing a subway tunnel from shifting according to claim 8, characterized in that: The steel connecting frame includes a plurality of steel rods whose one ends are connected one-to-one to the filling core of the anti-settling pile and steel supporting ribs connecting the other ends of all the steel rods together; when making the filling core, the steel rods are inserted into the concrete forming the filling core before the concrete is solidified, and after the concrete is solidified, the steel rods are poured together with the filling core to achieve the connection between the steel rods and the filling core.

10. A method for preventing a subway tunnel from shifting according to claim 8 or 9, characterized in that: A concrete water-proof layer is poured on the bottom of the subway tunnel, and the concrete water-proof layer completely covers the parts of the steel connecting frame and the anti-settling piles located in the subway tunnel.

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