Supporting structure and method for tunnel crossing fault fracture zone

Abstract

The invention provides a supporting structure and a supporting method for a tunnel to pass through a fault fracture zone. The supporting structure comprises a supporting reinforcing structure which is arranged in a non-collapsed hole section and a collapsed area hole section of the front edge of a collapsed area in the direction of the tunnel. The supporting and reinforcing structure in the collapse area tunnel section is connected with a pipe pile and comprises a permanent lining structure arranged on the inner side of the supporting and reinforcing structure, and the permanent lining structure is in a shell shape similar to the inner wall of a tunnel. The multiple pipe piles are arranged along the hole periphery of the collapse area at intervals, the longitudinal length of the pipe piles covers the longitudinal range of the whole collapse area, one end of each pipe pile is supported in the non-collapse hole section, and the other end of each pipe pile is supported in a stable rock mass behind the collapse area; the plurality of tubular piles are fixedly connected with the peripheral loose collapse body through grouting to form an integral structure; and the pile body part is arranged in the pipe pile. It is guaranteed that the collapse area is safely spanned, the technical problem that the large-fault collapse area is poor in self-stabilization capacity is solved, and the construction risk is reduced.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering technology, specifically to a support structure and support method for tunnels traversing fault fracture zones. Background Technology

[0002] During tunnel excavation using the drill-and-blast method, collapses are a common phenomenon and one of the main risks threatening the safety of construction workers. When a tunnel crosses a large fault, if the filling material within the fault zone is loose, especially under steep-angle fault conditions, the collapse area is highly susceptible to instability. As the soil in the collapse area changes from a relatively compact filling state to a loose accumulation state, its volume increases accordingly. Therefore, if the post-collapse state is not disturbed, the collapse area usually will not expand indefinitely. However, clearing the collapse area could potentially lead to further expansion of the collapse, or even trigger a roof fall, seriously threatening construction safety.

[0003] In traditional pipe roof crossing implementation schemes, the pipe roof is not an independent supporting structure, but rather forms an integral arch effect by consolidating with the surrounding rock mass. Therefore, the effectiveness of this scheme is closely related to the grouting quality. Facing large-scale fault collapses, controlling the grouting quality of the pipe roof is quite challenging. On the one hand, the good connectivity of the slag mass means that improper control of the grouting volume can easily lead to voids inside the pipe roof, potentially causing it to break during excavation. On the other hand, increasing the grouting pressure to ensure adequate filling within the pipe roof can easily lead to cross-contamination of grout, resulting in poor treatment outcomes and significantly increased costs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the first objective of this invention is to provide a support structure for tunnels traversing fault fracture zones. This invention ensures safe crossing of collapse zones, solves the technical problem of poor self-stabilization in large fault collapse zones, and reduces construction risks.

[0005] In a first aspect, the present invention provides a support structure for tunnels traversing fault fracture zones, comprising:

[0006] The support and reinforcement structure is set along the tunnel direction in the non-collapsed tunnel section at the front edge of the collapse area and in the tunnel section in the collapse area; the support and reinforcement structure in the tunnel section in the collapse area is connected to the pipe piles and includes a permanent lining structure set on its inner side.

[0007] Multiple pipe piles are arranged at intervals around the tunnel perimeter in the collapsed area, with their longitudinal length covering the entire longitudinal range of the collapsed area. One end of each pipe pile is supported in the uncollapsed tunnel section, and the other end is supported in the stable rock mass behind the collapsed area. The multiple pipe piles are consolidated with the surrounding loose collapsed body through grouting to form an integral structure.

[0008] The pile body component is located inside the pipe pile.

[0009] As a preferred technical solution of the present invention: an arch frame for the non-collapsed area is set in the non-collapsed tunnel section at the front edge of the collapsed area. The arch frame for the non-collapsed area is connected to the tunnel wall by anchor bolts and reinforced anchor bolts. The inner wall of the tunnel section for the non-collapsed area is covered with wire mesh and sprayed with concrete.

[0010] As a preferred technical solution of the present invention: the pipe pile includes a follower steel pipe with multiple grouting holes opened on the borehole wall, the surface of the follower steel pipe is fixed to the loose collapsed body, and the pile body component is placed inside the follower steel pipe.

[0011] As a preferred technical solution of the present invention: the pile body component includes a seamless steel pipe and a steel bar bundle disposed inside the seamless steel pipe. The steel bar bundle is composed of multiple steel bars. The two ends of the steel bar bundle are fixed to the two ends of the seamless steel pipe. The ends of the seamless steel pipe are closed and filled with cement mortar.

[0012] As a preferred technical solution of the present invention: a plurality of positioning supports are welded at intervals along the axial direction on the outer side of the reinforcing bar bundle; the positioning supports have an outer contour that matches the inner wall of the seamless steel pipe and an inner contour that matches the reinforcing bar; the reinforcing bar is positioned at a set position inside the seamless steel pipe by means of the positioning supports.

[0013] As a preferred technical solution of the present invention: multiple rows of collapse zone arch frames and secondary arches are provided in the collapse zone tunnel section, the collapse zone arch frames are connected to the pipe piles through the secondary arches, and the permanent lining structure is provided on the inner side of the multiple rows of collapse zone arch frames.

[0014] As a preferred technical solution of the present invention: a backfill concrete pumping pipe is provided on the permanent lining structure, and the cavity above the arch of the support and reinforcement structure in the collapsed tunnel section is filled with backfill concrete.

[0015] As a preferred technical solution of the present invention: the exposed tunnel face arch in the collapsed tunnel section is provided with advanced support.

[0016] Secondly, a second objective of the present invention is to provide a support method for tunnels traversing fault fracture zones, utilizing the aforementioned support structure, dividing the support structure into several phases of construction, and including the following steps:

[0017] S1. Maintain the state of the collapse formed in front of the tunnel face when the tunnel collapses inside the excavated tunnel, and use the accumulated collapse body to form a working platform;

[0018] S2. Construct arch frames in the non-collapsed tunnel section at the front edge of the collapse zone and combine them with system sprayed anchor support for joint reinforcement to form a first-phase support and reinforcement structure.

[0019] S3. Drilling is carried out through the collapsed area using the casing drilling process. After drilling is completed, the casing steel pipe is retained as a permanent support and grouting channel. One end of the casing steel pipe is supported in the designated tunnel section of the first-stage support and reinforcement structure, and the other end is supported in the stable rock mass behind the collapsed area. Then, a seamless steel pipe with reinforcing bars is inserted into the casing steel pipe as a pile component, and step-by-step grouting consolidation is performed: first, cement mortar is injected into the seamless steel pipe and allowed to solidify to form a core load-bearing structure. Then, grout is injected into the annular gap around the pipe through the casing steel pipe. This grout fills the pipe and permeates into the surrounding loose collapsed body, so that the surrounding loose collapsed body and the pipe pile are consolidated into an integral structure.

[0020] S4. After the pipe pile construction is completed, the next phase of support and reinforcement structure construction will be carried out in the tunnel section of the collapsed area. During the construction of the new phase of support and reinforcement structure, the lower slag in the tunnel section of the collapsed area will be locally grouted to form a first-phase slag consolidation grouting section with temporary stabilization effect. Then, the first-phase slag consolidation grouting section will be locally excavated. After the excavation, the tunnel section within the range of the first-phase slag consolidation grouting section will be promptly erected with the collapsed area arch frame and secondary arch.

[0021] S5. Repeat the construction process of step S4, and based on the previous support and reinforcement structure, construct the subsequent support and reinforcement structures in sequence until crossing the tunnel section of the collapse area.

[0022] S6. After all the debris in the collapsed area has been cleared, advance support is applied to the exposed tunnel face arch, and under the protection of the advance support, the tunnel face is finally repaired.

[0023] S7. After passing through the collapsed section, in accordance with the overall construction requirements, the permanent lining structure will be constructed. A backfill concrete pumping pipe will be reserved on the permanent lining structure, and after the permanent lining structure construction is completed, pumped concrete will be used to backfill the cavity between the permanent lining structure and the pipe pile.

[0024] The beneficial effects provided by this invention are as follows:

[0025] 1. This invention utilizes a pipe pile system to form a reliable longitudinal "bridge" within the collapsed area, and its cooperation with the transverse support and reinforcement structure directly transfers the upper load to the stable rock mass at both ends. This fundamentally changes the stress mechanism of the support structure, enabling safe and proactive crossing of the collapsed area. It greatly reduces the risk of secondary collapse and roof fall during excavation, and ensures the safety of construction personnel and equipment.

[0026] 2. This invention incorporates seamless steel pipes and reinforcing bar bundles within the core steel pipe, ultimately forming a high-strength reinforced concrete pipe pile. This avoids the risk of breakage caused by voids in grouting, common in traditional pipe roofs. The structure boasts strong integrity and a load-bearing capacity far superior to traditional methods, providing a solid guarantee for subsequent excavation and permanent lining.

[0027] 3. The support method of this invention adopts a phased and purpose-specific grouting strategy. By combining confined grouting around the pipe piles with localized pre-consolidation grouting of the slag, it effectively solves the industry problems of easy grout loss and cross-contamination, achieving precise and controllable grouting range. This ensures effectiveness while reducing waste and subsequent excavation difficulty. The method has clear steps, strong operability, and a high success rate, effectively shortening the construction period for handling such geological disasters and reducing indirect losses caused by work stoppages due to accidents. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a diagram showing the state of stability during a collapse inside the tunnel.

[0030] Figure 2 A schematic plan view of the arrangement of pipe piles in a landslide area provided in an embodiment of the present invention;

[0031] Figure 3 This is a schematic plan view of the support and reinforcement structure for the tunnel section in the collapse area provided in an embodiment of the present invention;

[0032] Figure 4 This is a state diagram of the tunnel after the collapse body has been cleared, as provided in an embodiment of the present invention.

[0033] Figure 5 This is a state diagram of the collapsed area after crossing, provided in an embodiment of the present invention.

[0034] Figure 6 This is a schematic diagram of the structure after the support structure has been constructed, as provided in an embodiment of the present invention.

[0035] Figure 7 This is a typical cross-sectional view of the support structure provided in an embodiment of the present invention;

[0036] Figure 8 The diagram shows the construction of a pipe pile as provided in an embodiment of the present invention.

[0037] Attached reference numerals: 1. Working face during collapse; 6. Temporarily stable zone; 7. Relaxation zone; 8. Slag mass; 9. Anchor bolt support; 10. Wire mesh and shotcrete; 11. Arch frame in non-collapse zone; 12. Reinforced anchor bolt; 13. Pipe pile; 14. Integral structure; 15. Slag consolidation grouting section; 16. Arch frame in collapse zone; 17. Secondary arch; 18. Advance support; 19. Working face after fault crossing; 20. Backfill concrete; 21. Permanent lining structure; 1301. Casing steel pipe; 1302. Seamless steel pipe; 1303. Reinforcing steel; 1304. Triangular brace; 1305. Grouting hole; 1306. Pipe pile mortar; 1307. Casing grout. Detailed Implementation

[0038] To enable those skilled in the art to better understand the technical solutions of the present invention, preferred embodiments of the present invention are described below in conjunction with specific examples. However, it should be understood that the accompanying drawings are for illustrative purposes only and should not be construed as limiting the present invention. For better illustration of this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable that some well-known structures and their descriptions may be omitted in the drawings for those skilled in the art. The positional relationships described in the drawings are for illustrative purposes only and should not be construed as limiting the present invention.

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0040] like Figure 1 As shown, the fault fracture zone includes, from top to bottom, a temporarily stable zone 6, a relaxed zone 7, and a collapsed debris body 8, as follows: Figures 2 to 8As shown, the present invention provides a support structure for a tunnel traversing a fault fracture zone, including a support and reinforcement structure disposed along the tunnel direction in the non-collapsed tunnel section at the leading edge of the collapse zone and in the collapsed tunnel section; the support and reinforcement structure in the collapsed tunnel section is connected to pipe piles 13 and includes a permanent lining structure 21 disposed on its inner side. In this embodiment, the permanent lining structure 21 is a reinforced concrete structure with a shell shape similar to the inner wall of the tunnel; multiple pipe piles 13 are arranged at intervals along the perimeter of the collapsed zone, their longitudinal length covering the entire longitudinal range of the collapsed zone, and the pipe piles 13 cover the entire collapsed area, and not less than In the tunnel's arch and more than half of the sidewalls on both sides, the spacing between adjacent pipe piles 13 is generally 30-40cm, extending outward at an angle of 10°-15° along the tunnel axis. One end of each pipe pile 13 is supported in the uncollapsed tunnel section, and the other end is supported in the stable rock mass behind the collapsed area, with an anchoring depth of not less than 3m in the stable rock mass. The multiple pipe piles 13 are grouted to form an integral structure 14 with the surrounding loose collapsed body. The grout concentration is adjusted according to the mortar consumption feedback during the grouting process, and water glass and other quick-setting agents are added appropriately. The pile body components are set inside the pipe piles 13.

[0041] "The section of the tunnel that has not collapsed at the leading edge of the landslide area" refers to, for example... Figure 1 The area shown is the excavated area (excavated tunnel) in front of the tunnel face 1 or the collapsed area at the time of the collapse, while "behind the collapsed area" refers to the area that has already been excavated. Figure 1 This part of the tunnel awaiting excavation.

[0042] Multiple pipe piles 13 are consolidated with the surrounding loose collapsed material through grouting to form an integral structure, which can effectively seal the gaps between the pipe piles 13 and prevent blockage or local collapse during the excavation of the lower tunnel. In order to control the excessive diffusion of grout to the lower slag body 8, avoid material waste and increase the difficulty of subsequent slag body 8 removal, an appropriate amount of quick-setting agent is added to the grout for this part.

[0043] Multiple rows of non-collapsed arch frames 11 are installed within the non-collapsed tunnel section at the leading edge of the collapsed area. These non-collapsed arch frames 11 are connected to the tunnel wall via anchor bolt supports 9 and reinforcing anchor bolts 12. The inner wall of the non-collapsed tunnel section is covered with wire mesh and shotcrete 10. In this embodiment, the reinforcing anchor bolts 12 are concentrated near the collapsed area, and the arrangement range of the anchor bolt supports 9 is larger than the arrangement range of the reinforcing anchor bolts 12. The ends of the reinforcing anchor bolts 12 form hooks to anchor the non-collapsed arch frames 11, improving the integrity of the arch frames and the surrounding rock.

[0044] The pipe pile 13 includes a follower steel pipe 1301 with multiple grouting holes 1305 on the borehole wall. The surface of the follower steel pipe 1301 is fixed to the loose collapsed body, and the pile body components are placed inside the follower steel pipe 1301.

[0045] In this embodiment, the root tube 1301 is a steel pipe with a diameter of not less than 150 mm, and its wall is provided with dense grouting holes 1305. The grouting holes 1305 are evenly distributed in the circumferential direction with no less than 6 holes per circle, and the axial spacing is not greater than 20 cm. Subsequently, a seamless steel pipe 1302 with a diameter of 108 mm is inserted into the root tube 1301.

[0046] The pile body component includes a seamless steel pipe 1302 and a steel bar bundle disposed within the seamless steel pipe 1302. One end of the seamless steel pipe 1302 inserted into the root steel pipe 1301 is sealed. The steel bar bundle is composed of multiple steel bars 1303. The two ends of the steel bar bundle are fixed to the two ends of the seamless steel pipe 1302. Cement mortar is poured into the seamless steel pipe 1302 to form a pipe pile mortar body 1306. The water-cement ratio of the cement mortar is about 0.5:1, which means it has a certain fluidity while maintaining a high viscosity.

[0047] On the outside of the reinforcing bar bundle, a plurality of positioning supports are welded at intervals along its axial direction; the positioning supports have an outer contour that matches the inner wall of the seamless steel pipe 1302 and an inner contour that matches the reinforcing bar 1303; the reinforcing bar 1303 is positioned at a predetermined position inside the seamless steel pipe 1302 by the positioning supports.

[0048] In this embodiment, the positioning support is specifically a triangular brace 1304. This triangular brace 1304 is formed by bending or welding a steel plate, and the curvature of its three corners matches the inner wall curvature of the seamless steel pipe 1302, thus achieving a tight fit. A longitudinal steel bar 1303 is welded to the inner wall of each corner of the triangular brace 1304, and these steel bars 1303 together constitute the steel bar bundle.

[0049] Multiple rows of collapse zone arch frames 16 and secondary arches 17 are installed in the collapsed zone tunnel section. The collapsed zone arch frames 16 are connected to the pipe piles 13 through the secondary arches 17. The permanent lining structure 21 is installed on the inner side of the multiple rows of collapsed zone arch frames 16.

[0050] A backfill pumping concrete pipe is installed on the permanent lining structure 21. The cavity above the arch of the support and reinforcement structure in the collapsed tunnel section is filled with backfill concrete 20 to ensure the contact state between the lining and the surrounding area.

[0051] The exposed working face within the collapsed tunnel section (i.e. Figure 5 After the interrupted layer crosses the tunnel face 19), the top arch is equipped with advanced support 18. In this embodiment, the advanced support 18 can be advanced anchor, advanced small pipe, or pipe roof, etc., depending on the geological conditions exposed at the tunnel face.

[0052] A support method for tunnels traversing fault fracture zones utilizes the aforementioned support structure, which is constructed in several phases, and includes the following steps:

[0053] S1. Maintain the state of the collapse formed in front of the working face 1 when the tunnel collapses inside the excavated tunnel, and use the accumulated collapse body to form a working platform.

[0054] S2. Construct the non-collapsed arch frame 11 in the designated tunnel section at the front edge of the collapse zone and combine it with the system sprayed anchor support for joint reinforcement to form the first-phase support and reinforcement structure.

[0055] S3. Drilling is carried out through the collapsed area using the casing drilling process. After drilling is completed, the casing steel pipe 1301 is retained as a permanent support and grouting channel. One end of the casing steel pipe 1301 is supported in the designated tunnel section of the first-stage support and reinforcement structure, and the other end is supported in the stable rock mass behind the collapsed area. Then, a seamless steel pipe 1302 with steel reinforcement bundles is inserted into the casing steel pipe 1301 as a pile component, and step-by-step grouting consolidation is performed: first, cement mortar is injected into the seamless steel pipe 1302 and allowed to solidify to form a core bearing structure. Then, grout is injected into the annular gap around the casing through the casing steel pipe 1301 to form a casing grouting body 1307. This grout fills the inside of the pipe and penetrates into the surrounding loose collapsed body, so that the surrounding loose collapsed body and the pipe pile 13 are consolidated into an integral structure 14.

[0056] S4. After the construction of pipe pile 13 is completed, the phased excavation of slag 8 will be planned according to the internal characteristics of the collapsed body revealed by the borehole. The next phase of support and reinforcement structure construction will be carried out in the tunnel section of the collapsed area. During the construction of the new phase of support and reinforcement structure, the lower slag 8 in the tunnel section of the collapsed area will be locally grouted to form the first phase of slag consolidation grouting section 15 with temporary stabilization. Then, the first phase of slag consolidation grouting section 15 will be locally excavated. After the excavation, the collapsed area arch frame 16 and secondary arch 17 will be erected in the tunnel section within the range of the first phase of slag consolidation grouting section 15. Finally, the wire mesh and shotcrete operations will be carried out.

[0057] Furthermore, the consolidation grouting of the slag body is implemented segment by segment according to the excavation progress. The purpose of consolidation grouting of slag body 8 is to enhance the temporary self-stability of the slag body 8 to be excavated. Since the upper slag body 8 in the collapsed tunnel section provides lower support for the pipe pile 13, consolidation grouting can prevent the upper slag body 8 from continuously collapsing during excavation, thereby effectively shortening the suspended span of the lower part of the pipe pile 13, thus reducing the load borne by the pipe pile 13 and improving the overall safety of the construction process. In order to control the grout diffusion range, an appropriate amount of quick-setting agent is added to the grout in this part of the grouting.

[0058] S5. Repeat the construction process of step S4, and based on the previous support and reinforcement structure, construct the subsequent support and reinforcement structures in sequence until crossing the tunnel section of the collapse area.

[0059] S6. After all the debris 8 in the collapsed area has been cleared, advance support 18 is applied to the exposed tunnel face arch, and the tunnel face is then repaired under the protection of the advance support 18.

[0060] S7. After passing through the collapsed section, in accordance with the overall construction requirements, the permanent lining structure 21 is constructed. A backfill concrete pumping pipe is reserved on the permanent lining structure 21, and after the construction of the permanent lining structure 21 is completed, pumped concrete is used to backfill the cavity between the permanent lining structure and the pipe pile 13.

[0061] Based on the description and accompanying drawings of this invention, those skilled in the art can easily manufacture or use the support structure and support method for tunnels crossing fault fracture zones according to this invention, and can achieve the positive effects described in this invention.

[0062] Unless otherwise specified, in this invention, terms such as "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe orientation or positional relationships in this invention are for illustrative purposes only and should not be construed as limiting this invention. For those skilled in the art, the specific meaning of the above terms can be understood in conjunction with the accompanying drawings and according to the specific circumstances.

[0063] Unless otherwise explicitly specified and limited, the terms "set up," "connected," and "linked" in this invention should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A support structure for tunnels traversing fault fracture zones, characterized in that: include: The support and reinforcement structure is set along the tunnel direction in the non-collapsed tunnel section at the front edge of the collapse area and in the tunnel section in the collapse area; the support and reinforcement structure in the tunnel section in the collapse area is connected to the pipe piles and includes a permanent lining structure set on its inner side, the permanent lining structure being shell-shaped similar to the inner wall of the tunnel. Multiple pipe piles are arranged at intervals around the tunnel perimeter in the collapsed area, with their longitudinal length covering the entire longitudinal range of the collapsed area. One end of each pipe pile is supported in the uncollapsed tunnel section, and the other end is supported in the stable rock mass behind the collapsed area. The multiple pipe piles are consolidated with the surrounding loose collapsed body through grouting to form an integral structure. The pile body component is located inside the pipe pile.

2. The support structure for tunnels crossing fault fracture zones according to claim 1, characterized in that: An arch frame for the non-collapsed area is installed in the non-collapsed tunnel section at the leading edge of the collapsed area. The non-collapsed area arch frame is connected to the tunnel wall through anchor bolt support and reinforced anchor bolts. The inner wall of the non-collapsed area tunnel section is covered with wire mesh and sprayed with concrete.

3. The support structure for tunnels crossing fault fracture zones according to claim 1, characterized in that: The pipe pile includes a steel pipe with multiple grouting holes on the borehole wall, the surface of the steel pipe being fixed to the loose collapsed body, and the pile body components being placed inside the steel pipe.

4. The support structure for tunnels crossing fault fracture zones according to claim 1, characterized in that: The pile body component includes a seamless steel pipe and a steel bar bundle inside the seamless steel pipe. The steel bar bundle is composed of multiple steel bars, and the two ends of the steel bar bundle are fixed to the two ends of the seamless steel pipe. The ends of the seamless steel pipe are closed and filled with cement mortar.

5. The support structure for tunnels traversing fault fracture zones according to claim 4, characterized in that: On the outside of the reinforcing bar bundle, a plurality of positioning supports are welded at intervals along its axial direction; the positioning supports have an outer contour that matches the inner wall of the seamless steel pipe and an inner contour that matches the reinforcing bar; the reinforcing bar is positioned in a predetermined position inside the seamless steel pipe by means of the positioning supports.

6. The support structure for tunnels crossing fault fracture zones according to claim 1, characterized in that: Multiple rows of collapse zone arch frames and secondary arches are installed inside the collapsed zone tunnel section. The collapse zone arch frames are connected to the pipe piles through the secondary arches, and the permanent lining structure is installed on the inner side of the multiple rows of collapse zone arch frames.

7. The support structure for tunnels crossing fault fracture zones according to claim 1, characterized in that: The permanent lining structure is equipped with a backfill pumping concrete pipe, and the cavity above the arch of the support and reinforcement structure in the collapsed tunnel section is filled with backfill concrete.

8. The support structure for tunnels crossing fault fracture zones according to claim 1, characterized in that: The exposed tunnel face arch in the collapsed section is equipped with advanced support.

9. A support method for tunnels crossing fault fracture zones, characterized in that, Using the support structure described in claims 1-8 for support, the support structure is divided into several phases of construction, and includes the following steps: S1. Maintain the state of the collapse formed in front of the tunnel face when the tunnel collapses inside the excavated tunnel, and use the accumulated collapse body to form a working platform; S2. Construct arch frames in the non-collapsed tunnel section at the front edge of the collapse zone and combine them with system sprayed anchor support for joint reinforcement to form a first-phase support and reinforcement structure. S3. Drilling is carried out through the collapsed area using the casing drilling process. After drilling is completed, the casing steel pipe is retained as a permanent support and grouting channel. One end of the casing steel pipe is supported in the designated tunnel section of the first-stage support and reinforcement structure, and the other end is supported in the stable rock mass behind the collapsed area. Then, a seamless steel pipe with reinforcing bars is inserted into the casing steel pipe as a pile component, and step-by-step grouting consolidation is performed: first, cement mortar is injected into the seamless steel pipe and allowed to solidify to form a core load-bearing structure. Then, grout is injected into the annular gap around the pipe through the casing steel pipe. This grout fills the pipe and permeates into the surrounding loose collapsed body, so that the surrounding loose collapsed body and the pipe pile are consolidated into an integral structure. S4. After the pipe pile construction is completed, the next phase of support and reinforcement structure construction will be carried out in the tunnel section of the collapsed area. During the construction of the new phase of support and reinforcement structure, the lower slag in the tunnel section of the collapsed area will be locally grouted to form a first-phase slag consolidation grouting section with temporary stabilization effect. Then, the first-phase slag consolidation grouting section will be locally excavated. After the excavation, the tunnel section within the range of the first-phase slag consolidation grouting section will be promptly erected with the collapsed area arch frame and secondary arch. S5. Repeat the construction process of step S4, and based on the previous support and reinforcement structure, construct the subsequent support and reinforcement structures in sequence until crossing the tunnel section of the collapse area. S6. After all the debris in the collapsed area has been cleared, advance support is applied to the exposed tunnel face arch, and the tunnel face is then repaired under the protection of the advance support. S7. After passing through the collapsed section, in accordance with the overall construction requirements, the permanent lining structure will be constructed. A backfill concrete pumping pipe will be reserved on the permanent lining structure, and after the permanent lining structure construction is completed, pumped concrete will be used to backfill the cavity between the permanent lining structure and the pipe pile.

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