Anti-displacement subway tunnel structure based on soft foundation

Abstract

The present invention relates to a displacement-preventing subway tunnel structure based on soft ground, which includes a subway tunnel surrounded by tunnel segments and a number of anti-settlement piles. One end of each anti-settlement pile is hermetically and fixedly connected to a pipe pile connection hole. The anti-settlement pile includes an outer steel pipe and an inner steel pipe disposed inside the outer steel pipe. An annular cavity surrounding the inner steel pipe is formed between the outer steel pipe and the inner steel pipe. The annular cavity is filled with a cement bonding layer, and the inner steel pipe is filled with a concrete core. The outer steel pipe becomes a blind pipe, and the inner steel pipe is also a blind pipe. The outer steel pipe and the inner steel pipe are fixed together through the cement bonding layer. The present invention has the advantage of preventing displacement when constructed in soft soil areas, and solves the problem that existing subway tunnels are prone to "drift" when constructed in soft soil areas.

Description

Technical Field

[0001] The present invention relates to the technical field of subway tunnel construction, and particularly to an anti-displacement subway tunnel structure based on soft foundation. Background Art

[0002] With the development of cities and the progress of society, the pressure on urban transportation has gradually increased. Subsequently, the construction of subways has gradually increased, and various construction problems will be encountered. During the construction process, it is difficult to control the tunneling attitude of the shield machine in soft soil layers. After the tunnel is formed, since the soft soil cannot provide a large force to the tunnel, "drift" occurs during the operation of the subway. The instability of the tunnel has a great impact on train operation. There is a large amount of silt in the strata in many areas, and it is very difficult to control the tunneling attitude and the alignment of the formed tunnel during shield construction. Therefore, the problem of how to ensure that the construction quality is in a controllable state and improve the construction quality urges engineers to solve it according to the actual situation.

[0003] During the construction of the shield machine in the silt stratum, the control of shield tunneling parameters, the assembly and selection of segments, and the tunneling in different strata are all important reasons for the deviation of the formed tunnel. To prevent excessive settlement during the construction period, especially during the operation period of the shield tunnel and affect train operation, it is necessary to reinforce the soft soil at the bottom of the shield tunnel, so that the soft soil within the tunnel range has sufficient bearing capacity of the foundation, and at the same time reduce the displacement (drift) of the shield tunnel during the operation period, which 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 an anti-displacement subway tunnel structure based on soft foundation that can prevent displacement when constructed in soft soil areas, and solves the problem that the existing subway tunnels are prone to "drift" when constructed in soft soil areas.

[0005] The above technical problems are solved by the following technical solutions: A displacement-preventing subway tunnel structure based on soft ground, including a subway tunnel surrounded by tunnel segments and a number of anti-settlement piles. The tunnel segments are provided with a number of pile connection holes, and one end of each anti-settlement pile is hermetically and fixedly connected in one of the pile connection holes. The anti-settlement piles are located outside the subway tunnel. The anti-settlement pile includes an outer steel pipe and an inner steel pipe inserted into the outer steel pipe. Both the outer steel pipe and the inner steel pipe are circular 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. The annular cavity is filled with a cement bonding layer formed by curing cement slurry. The inner steel pipe is filled with a concrete core. The end of the outer steel pipe away from the tunnel is provided with an outer steel pipe end wall, and the outer steel pipe end wall closes the outer steel pipe to make the outer steel pipe a blind pipe. The end of the inner steel pipe away from the tunnel is provided with an inner steel pipe end wall, and the inner steel pipe end wall closes the inner steel pipe to make the inner steel pipe a blind pipe. The outer steel pipe and the inner steel pipe are fixed together by the cement bonding layer. The construction method of the anti-settlement pile is as follows: Set a number of pile connection holes on the tunnel segments of the subway tunnel, pass the outer steel pipe through the pile connection holes from the inside of the subway tunnel to the outside of the subway tunnel, and hermetically and fixedly connect the outer steel pipe with the pile connection holes. Pass the inner steel pipe into the outer steel pipe so that an annular cavity surrounding the outer periphery of the inner steel pipe is formed between the outer steel pipe and the inner steel pipe. Fill the inner steel pipe with concrete and then fill the annular cavity with concrete. During the process of filling the inner steel pipe with concrete, rotate the inner steel pipe inside the outer steel pipe. The concrete in the annular cavity cures to form a cement bonding layer that bonds the inner steel pipe and the outer steel pipe together. The concrete in the inner steel pipe cures to form a concrete core. The cement bonding layer, the inner steel pipe and the concrete core constitute a filling core, and the filling core and the outer steel pipe constitute the anti-settlement pile. Through the setting of anti-settlement piles on the segments, this technical solution can effectively prevent the "drift" of the subway tunnel. This technical solution can realize rotating the inner steel pipe during grouting to form the anti-settlement pile to accelerate the compaction speed of the concrete core.

[0006] Preferably, on the outer peripheral surface of one end of the outer steel pipe connected to the subway tunnel, there are positioning blocks and several steel pipe part through holes penetrating the inside of the outer steel pipe. The steel pipe part through holes are hermetically butted with the open end of the flexible sealing bag. The positioning blocks are abutted against the inner surface of the subway tunnel. The flexible sealing bag is located outside the outer steel pipe, and the inner surface of the flexible sealing bag faces outward. The flexible sealing bag is filled with concrete. After the concrete in the flexible sealing bag cures, it forms an external assisting stop block with the flexible sealing bag whose outer peripheral surfaces are abutted together. The concrete in the flexible sealing bag is poured together with the cement bonding layer. The method for manufacturing the external assisting stop block is as follows: During the process of passing the outer steel pipe from inside the subway tunnel through the pipe pile connection hole to the outside of the subway tunnel, the flexible sealing bag is located inside the outer steel pipe. The steel pipe part through hole is provided with a through hole cover plate that can only be opened towards the outside of the outer steel pipe, and the through hole cover plate is located outside the subway tunnel. After the positioning blocks are abutted against the inner surface of the subway tunnel, the operator reaches into the outer steel pipe from the end of the outer steel pipe located inside the subway tunnel to push open the through hole cover plate and make the flexible sealing bag extend out of the outer steel pipe from the pipe pile connection hole. During the process of the flexible sealing bag extending out of the pipe pile connection hole, it is turned inside out with the inner surface facing outward. During the process of filling concrete into the annular cavity, the concrete enters the flexible sealing bag through the steel pipe part through hole to bulge the sealing bag, thus realizing the filling of the flexible sealing bag with concrete. In this technical solution, during the construction process, even though there is a flexible sealing bag connected to the outer steel pipe, it is convenient to pass through the steel pipe part through hole without expanding the gap between the steel pipe part through hole and the outer light pipe, which makes it difficult to prevent mud from entering the connection between the outer steel pipe and the subway tunnel during construction. It can also make the anti-settlement pile, after being manufactured, not only fixed by the bonding between the outer steel pipe and the steel pipe part connection hole, but also form an external assisting stop block to cooperate with the positioning blocks for clamping and fixing. In this way, not only can the fixing be more reliable, but also the ability of the anti-settlement pile to resist the torsional force generated by the swing of the anti-settlement tunnel at the connection with the tunnel wall can be improved, making the connection less likely to be damaged. The setting of the flexible sealing bag can make it not occupy space when folded, and its shape can be controlled after unfolding. The way of disassembling the elastic sheet is prone to the phenomenon of excessive expansion and rupture. The through hole cover plate is provided and can only be opened outward, which can prevent the soft soil (silty soil) outside from entering the outer steel pipe before the outer steel pipe is grouted, so that the flexible sealing bag cannot be conveniently and reliably moved to the outside of the outer steel pipe. The position of the non-through hole of the steel pipe is designed to be the position where the operator can reach into the outer steel pipe from inside the subway tunnel to withdraw the flexible sealing bag, which can improve the convenience during construction.

[0007] Preferably, a spherical crown-shaped support protrusion is provided on the inner surface of the end wall of the outer steel pipe part, and a concave pit with a spherical surface structure is provided on the outer surface of the end wall of the inner steel pipe part. The inner steel pipe is sleeved on the support protrusion through the concave pit and supported inside the outer steel pipe. A gap is provided between the bottom wall of the outer steel pipe part and the bottom wall of the inner steel pipe part. The support protrusion and the concave pit are in spherical surface fit and abutted together. When the inner steel pipe is rotated inside the outer steel pipe, the inner steel pipe is supported on the support protrusion for rotation; the cement bonding layer extends into the gap. This can improve the smoothness when rotating the inner steel pipe. The spherical surface fit and abutment together can increase the contact area and reduce wear.

[0008] Preferably, a plurality of support ribs extending axially along the circumferential direction of the inner steel pipe are provided on the outer circumferential surface of the inner steel pipe. The inner steel pipe is hermetically supported inside the outer steel pipe through the support ribs. The support ribs isolate the annular cavity into a plurality of strip-shaped holes distributed along the circumferential direction of the inner steel pipe, and the lower ends of all the strip-shaped holes communicate. During the process of injecting concrete into the annular cavity, while one strip-shaped hole at one end of the subway tunnel is docked with a gas extraction device for gas extraction, concrete is injected into all the strip-shaped holes from the other strip-shaped holes at one end of the subway tunnel until all the strip-shaped holes are filled with concrete, and then the gas extraction is stopped. This can improve the reliability when grouting into the annular cavity.

[0009] Preferably, the tunnel segment is a concrete precast member, and the pipe pile connection hole is a precast hole formed during the production of the tunnel segment; before connecting the pipe pile connection hole to the anti-settlement pile, a plug is hermetically connected inside the pipe pile connection hole. During use, the plug is removed to form the pipe pile connection hole. This can avoid punching through the through hole of the steel pipe part on-site when connecting the anti-settlement pile, resulting in inconvenient construction and damage to the segment due to hole opening.

[0010] Preferably, the outer end of the plug is provided with an outward flange located outside the subway tunnel, and the inner end is provided with a threaded section that extends into the subway tunnel. The plug is sleeved with a sealing ring, and the sealing ring is clamped between the outward flange and the outer circumferential surface of the subway tunnel to hermetically connect the plug to the pipe pile connection hole. During use, the plug is pushed towards the outside of the subway tunnel to open the plug. The sealing reliability is good when sealing the pipe pile connection hole and it is convenient to achieve sealing, and it is also 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. This can prevent the plug from being impacted when the anti-settlement pile is not connected, resulting in the loss of the sealing function of the pipe pile connection hole.

[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 steel support ribs and a plurality of steel rods, one end of the steel rods is connected to the filling core of the anti-settling piles one by one, and the other ends of the steel rods are connected together through the steel support ribs. 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.

[0019] Preferably, the steel connection frame includes a plurality of steel bars connected one by one to the filling cores of the settlement-resistant piles at one end and a steel support bar connecting the other ends of all the steel bars together; when manufacturing the filling cores, the steel bars are inserted into the concrete forming the filling cores before the concrete solidifies, and after the concrete solidifies, the steel bars are cast together with the filling cores to realize the connection between the steel bars and the filling cores. This can improve the convenience and reliability of the connection between the steel connection frame and the settlement-resistant piles.

[0020] Preferably, the steel bars and the steel support bar are welded together.

[0021] Preferably, the steel pipe penetrates into the pipe pile connection hole, and the steel pipe is hermetically fixed to the pipe pile connection hole. This can improve the anti-bending strength at the connection between the settlement-resistant pile and the segment.

[0022] Preferably, a concrete anti-seepage layer is poured on the bottom inside the subway tunnel, and the concrete anti-seepage layer completely covers the upper ends of the steel connection frame and the settlement-resistant piles. This can not only prevent leakage at the connection, but also prevent the steel parts from being exposed and rusting.

[0023] Preferably, a concrete anti-seepage layer is poured on the bottom inside the subway tunnel, and the concrete anti-seepage layer completely covers the parts of the steel connection frame and the settlement-resistant piles located inside the subway tunnel.

[0024] The present invention has the following advantages: By arranging settlement-resistant piles on the segments, it can effectively prevent the subway tunnel from drifting, and the settlement-resistant piles of this structure can be formed by grouting inside the subway tunnel. Compared with the ground grouting reinforcement measures: there is no need to set up temporary enclosures, excavate and dispose of soil for the equipment to enter the site, which can shorten the construction period and reduce costs; since the present invention is constructed inside the subway tunnel, it can avoid affecting the road traffic during construction, avoid the noise impact on the surrounding living areas, avoid the large amount of dust generated during the transportation of the excavated soil, and reduce a certain amount of solid waste pollution; the pipe segment prefabricated pipe pile connection holes are closed by plugs, and when connecting with the settlement-resistant piles, the plugs can be opened to form grouting holes for forming and connecting the settlement-resistant piles, which can avoid the impact damage to the pipe segments caused by opening holes; the steel pipe of the grouting pipe is composed of two layers and can rotate, so that the inner core of the concrete can be quickly compacted when making the settlement-resistant piles; the settlement-resistant piles can form external assisting blocks for clamping the pipe segments, so that the connection between the settlement-resistant piles and the pipe segments has a strong ability to resist the prying of the settlement-resistant piles. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of Embodiment 1 of the present invention;

[0026] Figure 2 It is a schematic diagram when only the outer steel pipe is connected to the tunnel segment in Embodiment 1;

[0027] Figure 4 is Figure 1 a partial enlarged view at position C of

[0028] Figure 5 is Figure 1 the anti - settlement pile of Figure 1 a cross - sectional view along the B - B direction of

[0029] Figure 6 a schematic diagram when the pipe pile connection hole is not connected to the anti - settlement pile, that is, when it is not opened;

[0030] Figure 7 is a schematic diagram of Embodiment II of the present invention.

[0031] 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, end wall of outer steel pipe part 7, end wall of inner steel pipe part 9, support protrusion 10, gap 11, plug 12, flanging 13, threaded section 14, sealing ring 15, locking nut 16, annular convex platform 17, annular steel gasket 18, annular support plane 19, bonding ring 20, steel core 21, support rib 22, strip hole 23, positioning block 24, through hole of steel pipe part 25, flexible seal bag 26, through hole cover plate 27, lapping step 28, external assistance block 29, inner surface of flexible seal bag 30, filling core 31, concrete in flexible seal bag 32, steel connection frame 33, steel rod 34, steel support rib 35, concrete anti - seepage layer 36. Specific embodiments

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] Embodiment I, refer to Figures 1 to 6, A subway tunnel structure with anti-displacement function based on soft foundation, comprising a number of anti-settlement piles 1 and a subway tunnel 3 surrounded by tunnel segments 2. The tunnel segments are provided with a number of pile connection holes. One end of each anti-settlement pile is hermetically and fixedly connected to a pile connection hole. The anti-settlement piles are located outside the subway tunnel. The anti-settlement piles extend radially along the tunnel. The anti-settlement pile includes an outer steel pipe 4 and an inner steel pipe 5 inserted into the outer steel pipe. Both the outer steel pipe and the inner steel pipe are circular 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, and a cement bonding layer 6 solidified by concrete is filled in the annular cavity. A concrete core 8 is filled in the inner steel pipe. One end of the outer steel pipe away from the tunnel is provided with an outer steel pipe end wall 7, and the outer steel pipe end wall closes the outer steel pipe to make the outer steel pipe a blind pipe. One end of the inner steel pipe away from the tunnel is provided with an inner steel pipe end wall 9, and the inner steel pipe end wall closes the inner steel pipe to make the inner steel pipe a blind pipe. The outer steel pipe and the inner steel pipe are fixed together by the cement bonding layer. Before the cement bonding layer is formed, the inner steel pipe can rotate within the outer steel pipe. A spherical support protrusion 10 is provided on the inner surface of the outer steel pipe end wall. A spherical concave pit is provided on the outer surface of the inner steel pipe end wall. The inner steel pipe is supported within the outer steel pipe by sleeving the concave pit on the support protrusion. A gap 11 is provided between the bottom wall of the outer steel pipe and the bottom wall of the inner steel pipe, and the cement bonding layer extends into the gap. The support protrusion and the concave pit are in spherical mating contact with each other. A number of support ribs 22 extending axially along the circumferential direction of the inner steel pipe are provided on the outer peripheral surface of the inner steel pipe. The inner steel pipe is hermetically supported within the outer steel pipe by the support ribs. The support ribs isolate the annular cavity into a number of strip-shaped holes 23 distributed along the circumferential direction of the inner steel pipe, and the lower ends of all the strip-shaped holes are connected.

[0034] The tunnel segment is a precast concrete component, and the pipe pile connection hole is a precast hole formed during the production of the tunnel segment; before the pipe pile connection hole is connected to the anti-settlement pile, a plug 12 is hermetically connected inside the pipe pile connection hole. The outer end of the plug is provided with an outward 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 a sealing ring 15 is sleeved on the plug. The sealing ring is clamped by the outward flange and the outer peripheral surface of the subway tunnel to hermetically connect the plug and the pipe pile connection hole together. A locking nut 16 is threadedly connected to the threaded section. The locking nut abuts against the inner surface of the subway tunnel. Specifically: the inner end of the pipe pile connection hole is provided with an annular boss 17 arranged on the inner surface of the subway tunnel and surrounding the pipe pile connection hole, and an annular steel gasket 18 is cast on the annular boss. The end surface of the annular steel gasket constitutes an annular supporting plane 19 extending along the circumference of the pipe pile connection hole, and the annular supporting plane is perpendicular to the threaded section. The locking nut is supported on the annular supporting plane. The pipe pile connection hole is a tapered hole with a smaller inner end and a larger outer end, and the plug is tapered with a smaller inner end and a larger outer end. The plug is hermetically connected to the pipe pile connection hole by tapered surface fit. A plurality of annular connection grooves extending along the circumference of the plug are provided on the circumferential surface of the plug. The annular connection grooves are distributed along the axial direction of the plug, and an adhesive ring 20 formed by concrete curing is provided in the annular connection grooves. The plug is hermetically fixed to the pipe pile connection hole through the adhesive ring. When opening the plug, unscrew the locking nut, tap the threaded section outward to crack the adhesive ring, and then remove the plug. The plug is a concrete structure, and a steel core 21 extending out of the inner end of the plug is embedded at the inner end of the plug, and the threaded section is arranged on the steel core.

[0035] On the outer peripheral surface of one end of the outer steel pipe connected to the subway tunnel, a positioning block 24 and a plurality of steel pipe part through holes 25 penetrating through the inside of the outer steel pipe are provided. The steel pipe part through holes are hermetically butted against the open end of the flexible sealing bag 26. When the steel pipe part through holes are not opened, a through hole cover plate 27 that can only be opened towards the outside of the outer steel pipe is provided. The through hole cover plate is connected to the through hole cover plate only by overlapping on the overlapping step 28 at the outer end of the through hole cover plate, and the through hole cover plate is located outside the subway tunnel. The flexible sealing bag is located inside the outer steel pipe during the process of the outer steel pipe passing through the steel pipe part through holes. The positioning block abuts against the inner surface of the subway tunnel, and the outer steel pipe is hermetically and fixedly connected to the pipe pile connection hole. When the flexible sealing bag is located outside the outer steel pipe, its inner surface faces outward. During the pouring process, 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 cures, it forms an outer assisting block 29 that abuts against the outer peripheral surface of the subway tunnel together with the flexible sealing bag.

[0036] The method for fabricating the present invention is as follows: First step, hole formation: several pipe pile connection holes are provided on the tunnel segments 2 of the subway tunnel 3; Second step, connecting the outer steel pipe: the outer steel pipe 4 is passed through the pipe pile connection holes from inside the subway tunnel to the outside of the subway tunnel. The through hole of the steel pipe part is provided with a through hole cover plate 27 that can only be opened towards the outside of the outer steel pipe. The flexible seal bag is located inside the outer steel pipe. The positioning block abuts against the inner surface of the subway tunnel. The through hole cover plate is located outside the subway tunnel. The outer steel pipe is hermetically and fixedly connected to the pipe pile connection holes; Third step, removing the flexible seal bag: the operator reaches into the outer steel pipe from one end of the outer steel pipe located inside the subway tunnel by hand, pushes open the through hole cover plate towards the outside of the outer steel pipe, so that the flexible seal bag extends out of the outer steel pipe through the pipe pile connection holes. During the process of the flexible seal bag extending out of the pipe pile connection holes, it is turned over so that the inner surface 30 of the flexible seal bag faces outwards; Fourth step, forming the filling core: concrete is poured into the outer steel pipe. After the concrete solidifies, a filling core 31 is formed. The concrete enters the flexible seal bag through the pipe pile connection holes and bulges the seal bag. After the concrete 32 inside the flexible seal bag solidifies, it forms an external assisting block 29 that abuts against the outer peripheral surface of the subway tunnel together with the flexible seal bag. The concrete inside the flexible seal bag is poured together with the concrete inside the outer steel pipe; The filling core and the outer steel pipe constitute the anti-settlement pile 1. Specifically: in the fourth step, the inner steel pipe 5 is first passed through the outer steel pipe, 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; During the process of filling concrete, the inner steel pipe is first filled with concrete and then concrete is filled into the annular cavity. During the process of filling the inner steel pipe with concrete, the inner steel pipe is rotated inside the outer steel pipe, and then concrete is filled into the annular cavity. The concrete inside the annular cavity solidifies to form a cement bonding layer 6 that bonds the inner steel pipe and the outer steel pipe together. The concrete inside the inner steel pipe solidifies to form a concrete inner core 8. The cement bonding layer, the inner steel pipe and the concrete inner core constitute the filling core. The inner steel pipe is supported inside the outer steel pipe by being sleeved on the support protrusion through the concave pit. When rotating the inner steel pipe inside the outer steel pipe, the inner steel pipe is supported on the support protrusion for rotation; During the process of injecting concrete into the annular cavity, a strip hole at one end of the subway tunnel is docked with the air extraction device for air extraction, and concrete is injected from the remaining strip holes at one end of the subway tunnel. After all the strip holes are filled with concrete, the air extraction is stopped. The tunnel segment is a precast concrete member, and the pipe pile connection hole is a precast hole formed during the fabrication of the tunnel segment; In the first step, the plug is opened by pushing the plug towards the outside of the subway tunnel. Specifically: when opening the plug, the locking nut is unscrewed, and the threaded section is knocked outwards so that the bonding ring cracks, and then the plug can be removed.

[0037] Embodiment 2, the difference from Embodiment 1 is:

[0038] See Figure 7, the upper ends of the anti-settlement piles are connected together through a steel connection frame 33 located in the subway tunnel. The steel connection frame includes steel support bars 35 and a number of steel rods 34. One end of each steel rod is correspondingly connected to the filling core of the anti-settlement pile, and the other ends of the steel rods are connected together through the steel support bars. The steel rods and the steel support bars are welded together. A concrete anti-seepage layer 36 is poured on the bottom inside the subway tunnel. The concrete anti-seepage layer completely covers the steel connection frame and the part of the anti-settlement pile located in the subway tunnel. The specific process of pouring the steel rods together with the concrete inner core is as follows: when making the filling core, the steel rods are inserted into the concrete inside the inner steel pipe before the concrete in the inner steel pipe solidifies, and after the concrete solidifies, the steel rods are poured together with the filling core to realize the connection between the steel rods and the filling core.

[0039] Finally, it should be noted that the above are only the preferred embodiments of the present utility model and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features. 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 displacement-preventing subway tunnel structure based on soft ground, comprising a subway tunnel surrounded by tunnel segments, characterized in that, It also includes a number of anti-settlement piles. The tunnel segment is provided with a number of pile connection holes. One end of each anti-settlement pile is hermetically and fixedly connected to one of the pile connection holes. The anti-settlement piles are located outside the subway tunnel. The anti-settlement pile includes an outer steel pipe and an inner steel pipe inserted into the outer steel pipe. Both the outer steel pipe and the inner steel pipe are circular 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. The annular cavity is filled with a cement bonding layer solidified from cement slurry. The inner steel pipe is filled with a concrete core. The end of the outer steel pipe away from the tunnel is provided with an outer steel pipe end wall. The outer steel pipe end wall closes the outer steel pipe to make the outer steel pipe a blind pipe. The end of the inner steel pipe away from the tunnel is provided with an inner steel pipe end wall. The inner steel pipe end wall closes the inner steel pipe to make the inner steel pipe a blind pipe. The outer steel pipe and the inner steel pipe are fixed together through the cement bonding layer; on the outer peripheral surface of the end of the outer steel pipe connected to the subway tunnel, there are positioning blocks and a number of steel pipe through holes penetrating the inside of the outer steel pipe. The steel pipe through holes are hermetically butted against the open end of the flexible sealing bag. The positioning blocks are abutted against the inner surface of the subway tunnel. The flexible sealing bag is located outside the outer steel pipe. The inner surface of the flexible sealing bag faces outward. The flexible sealing bag is filled with concrete. After the concrete in the flexible sealing bag solidifies, it forms an outer assisting block whose outer peripheral surfaces are abutted together with the flexible sealing bag. The concrete in the flexible sealing bag is poured together with the cement bonding layer.

2. The anti-displacement subway tunnel structure based on soft foundation according to claim 1, characterized in that, On the inner surface of the outer steel pipe end wall, there is a spherical crown-shaped supporting protrusion. On the outer surface of the inner steel pipe end wall, there is a spherical concave pit. The inner steel pipe is supported in the outer steel pipe by sleeving the concave pit on the supporting protrusion. There is a gap between the bottom wall of the outer steel pipe part and the bottom wall of the inner steel pipe part. The supporting protrusion and the concave pit are in spherical mating contact. When the inner steel pipe is rotated in the outer steel pipe, the inner steel pipe is supported on the supporting protrusion for rotation; the cement bonding layer extends into the gap.

3. The anti-displacement subway tunnel structure based on soft foundation according to claim 1 or 2, characterized in that, On the outer peripheral surface of the inner steel pipe, there are a number of supporting ribs distributed circumferentially along the inner steel pipe and extending axially. The inner steel pipe is hermetically supported in the outer steel pipe through the supporting ribs. The supporting ribs isolate the annular cavity into a number of strip-shaped holes distributed circumferentially along the inner steel pipe. The lower ends of all the strip-shaped holes are connected.

4. The anti-displacement subway tunnel structure based on soft foundation according to claim 1 or 2, characterized in that, The tunnel segment is a precast concrete member. The pile connection holes are precast holes formed during the process of manufacturing the tunnel segment; before the pile connection holes are connected to the anti-settlement piles, a plug is hermetically connected in the pile connection holes.

5. The anti-displacement subway tunnel structure based on soft foundation according to claim 4, characterized in that, The outer end of the plug is provided with an outward flange located outside the subway tunnel, and the inner end is provided with a threaded section. The threaded section extends into the subway tunnel. The plug is sleeved with a sealing ring. The sealing ring is clamped by the outward flange and the outer peripheral surface of the subway tunnel to hermetically connect the plug to the pile connection hole.

6. The anti-displacement subway tunnel structure based on soft foundation according to claim 4, characterized in that, The pile connection holes are tapered holes with a smaller inner end and a larger outer end. The plug is a tapered head with a smaller inner end and a larger outer end. The plug is in tapered mating contact with the pile connection holes for hermetic connection.

7. The anti-displacement subway tunnel structure based on soft foundation according to claim 1 or 2, characterized in that, The upper ends of the anti-settlement piles are connected together through a steel connection frame located inside the subway tunnel.

8. The anti-displacement subway tunnel structure based on soft foundation according to claim 7, characterized in that, The steel connection frame includes steel support ribs and a plurality of steel rods. One end of each steel rod is correspondingly connected to the filling core of the anti-settlement pile, and the other ends of the steel rods are connected together through the steel support ribs.

9. The anti-displacement subway tunnel structure based on soft foundation according to claim 7, characterized in that, A concrete anti-seepage layer is poured on the bottom inside the subway tunnel, and the concrete anti-seepage layer completely covers the parts of the steel connection frame and the anti-settlement pile located inside the subway tunnel.

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