Supporting structure for long-distance deeply-buried TBM inclined shaft water-rich complex rock stratum and working method

Abstract

The invention belongs to the technical field of tunnel supporting, and discloses a supporting structure of a long-distance deeply-buried TBM inclined shaft water-rich complex rock stratum and a working method.The supporting structure comprises graded yielding control anchor rods, anchor cables, a steel bar row, a steel bar net and a sprayed concrete layer, and the steel bar row, the steel bar net and the sprayed concrete layer are sequentially arranged on the tunnel surrounding rock surface from outside to inside; the graded yielding control anchor rod comprises a rod body, an outer ring, a yielding sleeve and an inner ring. In an initial state, the rear end of the rod body presses the inner ring on the rear port of the inner cavity of the yielding sleeve through a nut; the front end of the yielding sleeve extends into the drill hole and tightly presses the outer ring on the surrounding rock on the outer side of the drill hole; primary yielding friction fit is formed between the inner ring and an inner cavity of the yielding sleeve; and the front end of the yielding sleeve is in secondary yielding friction fit with the outer ring. The method has the advantages that the bearing capacity of the surrounding rock is fully exerted, and passive support is converted into active support; the graded yielding control anchor rods and the anchor cables are jointly supported, and the supporting structure is good in integrity and high in strength.

Description

Technical Field

[0001] The present invention belongs to the technical field of tunnel support, and particularly relates to a support structure and working method for a long-distance deep-buried TBM inclined shaft in a water-rich complex rock stratum. Background Art

[0002] Water-rich sandstone belongs to soft rock, which has low strength, is easy to weather, has strong water sensitivity, softens when encountering water, has argillaceous cementation, and is prone to swelling, softening and even disintegration under the action of water, resulting in large displacements of the surrounding rock of the roadway and coal and rock dynamic disasters such as roof falls and collapses.

[0003] The elastoplastic or viscoelastoplastic mechanical behavior of poor rock mass under the action of engineering disturbance leads to surrounding rock failure and instability phenomena such as large deformations, spalling of the tunnel wall, and collapses of the inclined shaft, posing a serious threat to the excavation and construction of the inclined shaft.

[0004] The design of bolt support parameters still mainly relies on engineering experience, and there is still a lack of a generally recognized initial bolt support design method, which cannot make good use of the adaptability to different strata and causes waste of support materials.

[0005] In view of the complex engineering environment and the deformation characteristics of the TBM inclined shaft, starting from the perspective of changing the stress state of the surrounding rock and promoting the common bearing of the support and the surrounding rock, an integrated bolt-mesh-shotcrete support scheme of "bolt (cable) + steel mesh + shotcrete" is proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a support structure and working method for a long-distance deep-buried TBM inclined shaft in a water-rich complex rock stratum according to the deficiencies of the above-mentioned existing technologies. The support structure is provided with a graded yielding control bolt, a cable, a steel bar row, and a steel mesh on the surrounding rock of the tunnel, and forms an integral body through a shotcrete layer; in addition, by the friction forces between the yielding sleeve and the inner ring and between the yielding sleeve and the outer ring, a primary yielding friction fit and a secondary yielding friction fit are formed to achieve the effect of "first control - then yield - then control - then yield" on the surrounding rock, so as to release the surrounding rock deformation, reduce the surrounding rock pressure, and improve the stress of the surrounding rock.

[0007] The purpose of the present invention is achieved by the following technical solutions: A support structure for a long-distance deep-buried TBM inclined shaft in a water-rich complex rock stratum, the support structure includes a graded yielding control bolt, a cable, and a steel bar row, a steel mesh, and a shotcrete layer sequentially arranged from the inside to the outside on the surrounding rock surface of the tunnel, and the steel mesh is fixed on the surrounding rock surface by the graded yielding control bolt and the cable; The stepped yielding control bolt includes a bolt body, an outer ring, a yielding sleeve and an inner ring; in the initial state, the rear end of the bolt body presses the inner ring against the rear port of the inner cavity of the yielding sleeve through a nut; the front end of the yielding sleeve extends into the drill hole and presses the outer ring against the surrounding rock outside the drill hole; a primary yielding friction fit is formed between the inner ring and the inner cavity of the yielding sleeve; a secondary yielding friction fit is formed between the front end of the yielding sleeve and the outer ring; wherein, the frictional force of the secondary yielding friction fit is greater than that of the primary yielding friction fit.

[0008] The steel bar row is composed of a plurality of longitudinal steel bars and is distributed at intervals in the circumferential direction. The steel bar mesh presses the steel bar row against the surrounding rock surface, and the shotcrete layer is sprayed on the surrounding rock surface to consolidate the stepped yielding control bolt, the cable bolt, the steel bar row, the steel bar mesh and the shotcrete layer into an integral structure.

[0009] The main body of the yielding sleeve is a cylindrical barrel, the front end of the barrel is provided with a conical end, and the rear end of the barrel is provided with the radially protruding limiting ring; a through hole for the bolt body to pass through is opened in the center of the conical end, and the aperture of the through hole is the same as the outer diameter of the bolt body.

[0010] The outer ring includes a fixed yielding ring, a ring platform, an adjustable yielding member, a chute, a guiding ring and a driving assembly; the ring platform is arranged along the outer circumferential edge of the front end face of the fixed yielding ring, and the inner circumferential wall surface of the fixed yielding ring is a longitudinally variable diameter section and fits the conical end; four groups of adjustable yielding members are arranged at intervals in the circumferential direction. The adjustable yielding member includes an adjustable yielding arc section, a connecting rod and a guiding contact head. The rod body of the connecting rod is assembled in the chute to guide the radial sliding of the connecting rod. The two ends of the connecting rod are respectively connected to the adjustable yielding arc section and the guiding contact head. The inner arc surface of the adjustable yielding arc section fits the conical end, and the guiding contact head makes sliding contact with the inner circle of the guiding ring. Four groups of guiding variable diameter sections are arranged on the inner circle of the guiding ring, and each group of guiding variable diameter sections corresponds to one guiding contact head. The guiding variable diameter section includes a small inner diameter section, a transition section and a large inner diameter section arranged in sequence; the guiding ring is driven to rotate by the driving assembly.

[0011] An outer toothed ring is provided on the outer wall surface of the guide ring. An annular guide groove is provided on the front end surface of the fixed yielding ring. A convex rail is provided on the rear end surface of the guide ring. The convex rail on the guide ring is correspondingly and fittingly installed in the annular guide groove to form a rotational guiding support for the rotation of the guide ring. The driving assembly includes a hydraulic telescopic rod and a straight rack fixedly arranged on the rod body of the hydraulic telescopic rod. The outer toothed ring on the guide ring is driven by the meshing transmission of the straight rack to drive the guide ring to rotate.

[0012] A pressure sensor for monitoring the surrounding rock pressure is provided on the rod body. The pressure sensor is connected and controlled with the controller of the hydraulic telescopic rod. Based on the surrounding rock pressure data monitored by the pressure sensor, it is used to control whether the driving assembly drives the guide ring to rotate. In the initial state, the transition section on the guide ring is in contact with the guide contact head. When it is necessary to increase the friction between the outer ring and the yielding sleeve, rotate the guide ring so that the small inner diameter section is in contact with the guide contact head and press the adjustable yielding arc section against the conical end head. When it is necessary to reduce the friction between the outer ring and the yielding sleeve, rotate the guide ring so that the large inner diameter section is in contact with the guide contact head to release the pressing of the adjustable yielding arc section against the conical end head.

[0013] The fixed yielding ring and the ring platform jointly enclose to form an equipment installation groove space. The thicknesses of the adjustable yielding member, the chute, the guide ring, and the driving assembly are all smaller than the height of the ring platform.

[0014] A working method of a support structure for any of the long-distance deep-buried TBM inclined shaft water-rich complex rock formations involves the following steps: S1: Drill advance grouting holes in the surrounding rock in front of the TBM excavation for advance reinforcement. S2: After the TBM completes the excavation of the surrounding rock, drill holes in the surrounding rock to install the graded yielding control bolt and cable. The graded yielding control bolt includes a rod body, an outer ring, a yielding sleeve, and an inner ring. Among them, the drilling is divided into two steps. The first step is to drill a hole according to the diameter of the rod body. The second step is to ream the hole on the basis of the first drilled hole according to the outer diameter of the barrel of the yielding sleeve, and the reaming depth is the length of the yielding sleeve. While installing the graded yielding control bolt, lay a steel bar row and a steel mesh on the surface of the surrounding rock. The steel mesh presses the steel bar row against the surface of the surrounding rock, and the steel mesh is fixed on the surface of the surrounding rock through the graded yielding control bolt, the steel mesh, and steel rivets. S3: During the deformation process of the surrounding rock, when the surrounding rock pressure is greater than the frictional force of the first-level yielding friction fit, the rod drives a first-level yielding movement between the inner ring and the inner cavity of the yielding sleeve until the inner ring moves to the end of the inner cylinder of the yielding sleeve and stops; When the surrounding rock pressure is greater than the frictional force of the second-level yielding friction fit, the rod drives a second-level yielding movement between the front end of the yielding sleeve and the outer ring and moves into the borehole until the limiting ring protruding outward at the rear end of the yielding sleeve abuts against the outer ring and then stops moving; S4: After completing the installation and support processes of the graded yielding control bolt, the surface of the surrounding rock is sprayed and reinforced to consolidate the graded yielding control bolt, the cable bolt, the steel bar row, the steel bar mesh, and the shotcrete layer into an integral structure.

[0015] The advantages of the present invention are: (1) Give full play to the bearing capacity of the surrounding rock itself, and transform passive support into active support; the graded yielding control bolt and the cable bolt jointly support, the support structure has good integrity and high support strength; make a reasonable selection of the support scheme in combination with the monitoring results of the surrounding rock deformation of the roadway, play an efficient support role, and save support materials at the same time; (2) The graded yielding control bolt makes full use of the graded failure characteristics of the surrounding rock, thus maximizing the self-stabilizing ability of the surrounding rock, eliminating the need for repeated maintenance, and saving support materials; (3) The outer ring that undergoes a second-level yielding friction fit with the yielding sleeve is provided with an adjustable yielding member on the basis of the fixed yielding ring, and can flexibly adjust the yielding amount based on the surrounding rock pressure to meet the requirements of different deformation amounts on site. Description of the Drawings

[0016] Figure 1 It is a schematic diagram of the support structure of the tunnel surrounding rock in the present invention; Figure 2 For the present invention Figure 1 Partial enlarged view at A in; Figure 3 It is a side view of the graded yielding control bolt on the surrounding rock in the present invention; Figure 4 It is a side view of the graded yielding control bolt undergoing a first-level yielding movement on the surrounding rock in the present invention; Figure 5 It is a side view of the graded yielding control bolt undergoing a second-level yielding movement on the surrounding rock in the present invention; Figure 6 It is a detailed local structure drawing at the outer ring of the graded yielding control bolt in the present invention; Figure 7 For the present invention Figure 6 Schematic diagram B-B in; Figure 8 This is the detailed local structure diagram of the adjustable yielding component inside the outer ring in the present invention, where the conical end is not tightly pressed. Figure 9 In the present invention Figure 8 Schematic diagram of C-C.

[0017] As Figures 1-9 , each mark in the figure is respectively: Surrounding rock 1, rod body 2, inner ring 3, yielding sleeve 4, outer ring 5, nut 6, steel bar row 7, steel bar mesh 8, anchor cable 9, shotcrete layer 10; Conical end 41, cylinder body 42, limit ring 43; Fixed yielding ring 51, adjustable yielding component 52, adjustable yielding arc section 52a, connecting rod 52b, guiding contact head 52c, sliding groove 53, guiding ring 54, small inner diameter section 54a, transition section 54b, large inner diameter section 54c, external teeth 55, ring platform 56, telescopic driving rod 57, straight rack 58, annular guiding groove 59. Specific embodiments

[0018] The features of the present invention and other related features will be further described in detail below with reference to the accompanying drawings through embodiments, so as to facilitate the understanding of those skilled in the same industry: Embodiment: As Figures 1-9 shown, this embodiment specifically relates to a support structure for a long-distance deep-buried TBM inclined shaft in a water-rich complex rock stratum. The support structure includes a stepped yielding control bolt, an anchor cable 9, and a steel bar row 7, a steel bar mesh 8, and a shotcrete layer 10 that are sequentially arranged from the inside to the outside on the surrounding rock surface of the tunnel.

[0019] As Figure 1 , 2 shown, the stepped yielding control bolts and the anchor cables 9 are distributed at intervals in the circumferential direction of the surrounding rock 1 and penetrate deep into the surrounding rock 1 for anchoring; the steel bar row 7 is composed of several longitudinal steel bars and is distributed at intervals in the circumferential direction of the tunnel surrounding rock 1. The steel bar mesh 8 presses and fixes the steel bar row 7 on the surrounding rock surface. The fixation between the steel bar mesh 8 and the surrounding rock surface is realized through steel bar rivets (not shown in the figure), stepped yielding control bolts, and anchor cables 9. The shotcrete layer 10 is sprayed on the surrounding rock surface to consolidate the stepped yielding control bolts, anchor cables 9, steel bar row 7, steel bar mesh 8, and the shotcrete layer 10 into an integral structure. Among them, the combination of the steel bar mesh 8 and the steel bar row 7 constitutes the steel bar framework of the concrete integral structure.

[0020] As Figures 1-9 shown, the stepped yielding control bolt includes a rod body 2, an outer ring 5, a yielding sleeve 4, and an inner ring 3.

[0021] As Figure 3 , 4, as shown in Figs. 5, the main body of the yielding sleeve 4 is a cylindrical barrel 42. A conical end 41 is provided at the front end of the barrel 42, and a radially outward protruding limiting ring 43 is provided at the rear end of the barrel 42. A through hole for the rod body 2 to pass through is provided at the center of the conical end 41, and the diameter of the through hole is the same as the outer diameter of the rod body 2. The outer diameter of the conical end 41 gradually narrows and becomes smaller longitudinally (in the direction towards the surrounding rock 1).

[0022] As Figure 3 , 4 , 5, 6, 7, 8, 9, the outer ring 5 includes a fixed yielding ring 51, a ring platform 56, an adjustable yielding member 52, a sliding groove 53, a guiding ring 54 and a driving assembly. The ring platform 56 is arranged along the annular outer edge of the front end face of the fixed yielding ring 51, and the two together enclose a groove space for installing and arranging each component. The thickness of each of the foregoing components is less than the height of the ring platform 56. During installation, the fixed yielding ring 51 and the ring platform 56 are buckled on the surrounding rock 1 to prevent the components in the groove space from being damaged by extrusion.

[0023] As Figure 3 , 4 , 5, 6, 7, 8, 9, the inner circumferential wall surface of the fixed yielding ring 51 is a longitudinally variable diameter section and fits the conical end 41. As Figure 6 , 7 , 8, 9, four groups of adjustable yielding members 52 are arranged at intervals in the circumferential direction. The adjustable yielding member 52 includes an adjustable yielding arc section 52a, a connecting rod 52b and a guiding contact head 52c. The rod body of the connecting rod 52b is assembled in the sliding groove 53 to conduct radial sliding guidance on the connecting rod 52b. The two ends of the connecting rod 52b are respectively connected to the adjustable yielding arc section 52a and the guiding contact head. The inner arc surface of the adjustable yielding arc section 52a can fit on the conical end 41. The guiding contact head 52c is in sliding contact with the inner circle of the guiding ring 54. Four groups of guiding variable diameter sections are provided on the inner circle of the guiding ring 54, and each group of guiding variable diameter sections corresponds to one guiding contact head 52c. The guiding variable diameter section includes a small inner diameter section 54a, a transition section 54b and a large inner diameter section 54c arranged in sequence. The rotation of the guiding ring 54 is driven by the driving assembly.

[0024] A circle of external teeth 55 is provided on the outer wall surface of the guiding ring 54. An annular guide groove 59 is provided on the front end face of the fixed yielding ring 51. A convex rail is provided on the rear end face of the guiding ring 54. The convex rail on the guiding ring 54 is correspondingly and fittingly installed in the annular guide groove 59 to provide rotational guiding support for the rotation of the guiding ring 54. The driving assembly includes a hydraulic telescopic rod 57 and a straight rack 58 fixedly arranged on the rod body of the hydraulic telescopic rod 57. The external teeth 55 on the guiding ring 54 are meshed and driven by the straight rack 58 to drive the guiding ring 54 to rotate.

[0025] As Figures 1-9As shown in the figure, the working method of the support structure for the water-rich complex rock stratum of the long-distance deep-buried TBM inclined shaft in this embodiment includes the following steps: (S1) Drill advanced grouting holes in the surrounding rock 1 in front of the TBM excavation for advanced reinforcement, improve the mechanical properties of the surrounding rock, give full play to the self-stabilizing effect of the surrounding rock, and improve the self-stability.

[0026] The specific method of advanced grouting is as follows: First, according to the advanced prediction information, use an advanced drill to drill an advanced hole through the hole in the TBM cutter head, and then connect a grouting pump for advanced grouting. In order to improve the grouting effect, replace the cement mortar with superfine cement-sodium silicate double-fluid grout to ensure the injection range and grouting pressure, reduce the water inflow into the surrounding rock 1 to a certain extent, and improve the physical and mechanical properties of the surrounding rock of the soft rock roadway, such as compressive strength, tensile strength, shear strength, etc., which helps to achieve uniform bearing. According to the loosening range of the surrounding rock 1, the grouting holes are 300-400 mm deeper than the loosening range of the surrounding rock 1.

[0027] (S2) After the TBM finishes excavating the surrounding rock 1, drill holes in the surrounding rock 1 to install the graded yielding control bolt and the cable bolt 9. Among them, the installation steps of the graded yielding control bolt are as follows: Drill a hole in the surrounding rock 1 based on the diameter of the bolt body 2. On this basis, ream the rear end of the first drilled hole according to the outer diameter of the cylinder body 42 of the yielding sleeve 4, and the reaming depth is the length of the yielding sleeve 4, so that the yielding sleeve 4 can extend into the reamed part during the subsequent graded yielding process; after reaming, install the graded yielding control bolt, and the graded yielding control bolt includes a bolt body 2, an outer ring 5, a yielding sleeve 4 and an inner ring 3.

[0028] It should be noted that while installing the graded yielding control bolt, lay the steel rib row 7 and the steel mesh 8 on the surface of the surrounding rock 1. The specific steps are as follows: Arrange the longitudinal steel rib rows 7 at intervals along the circumferential direction on the surface of the surrounding rock 1, and temporarily limit and fix the steel rib rows 7 manually or by means of a support. Then lay the steel mesh 8 to press the steel rib rows 7 against the surface of the surrounding rock 1, and then drive steel rivets into the surrounding rock 1 to permanently fix the steel mesh 8. At the same time, sequentially install the graded yielding control bolt and the cable bolt 9 in the surrounding rock 1. The outer ring 5 at the rear end of the graded yielding control bolt 9 can press and fix the steel mesh 8 ( Figure 3 、 4 、5 omits the steel mesh 8), in addition, the rear end of the cable bolt 9 can also press and fix the steel mesh 8 as a supplement.

[0029] S3: Perform graded yielding between the graded yielding control bolt and the surrounding rock 1, specifically as follows: In the initial state, the rear end of the rod body 2 presses the inner ring 3 against the inner cavity rear port of the yielding sleeve 4 through a nut 6; the front end of the yielding sleeve 4 extends into the borehole and presses the outer ring 5 against the surrounding rock 1 outside the borehole; a primary yielding friction fit is formed between the inner ring 3 and the inner cavity of the yielding sleeve 4; a secondary yielding friction fit is formed between the front end of the yielding sleeve 4 and the outer ring 5; wherein, the frictional force of the secondary yielding friction fit is greater than that of the primary yielding friction fit. It should be noted that, in order to ensure sufficient frictional force, an interference fit is adopted between the inner ring 3 and the inner cavity of the yielding sleeve 4, and an interference fit is also adopted between the outer ring 5 and the yielding sleeve 4, and when relative sliding occurs between the yielding sleeve 4 and the outer ring 5, the yielding sleeve 4 will cause radial extrusion on the inner ring of the fixed yielding ring 51 of the outer ring 5.

[0030] During the deformation process of the surrounding rock 1, when the surrounding rock pressure gradually becomes greater than the frictional force of the primary yielding friction fit (i.e., the frictional force between the inner ring 3 and the yielding sleeve 4), the rod body 2 drives a primary yielding movement between the inner ring 3 and the inner cavity of the yielding sleeve 4. As the inner ring 3 moves towards the inside of the surrounding rock 1, the deformation energy of the surrounding rock is gradually released during the movement, and the increasing speed of the surrounding rock pressure slows down. When the surrounding rock pressure is equal to the working resistance of the rod body 2, the yielding movement stops and the yielding process ends; when the surrounding rock pressure is greater than the frictional force of the primary yielding friction fit, the primary yielding process continues until the inner ring 3 moves to the end of the inner barrel of the yielding sleeve 4 and stops.

[0031] If the deformation of the surrounding rock continues to develop after the primary yielding ends, then the surrounding rock pressure will continue to increase. At this time, if the surrounding rock pressure has not increased to the frictional force of the secondary yielding friction fit, the rod body 2 will deform to release the deformation energy of the surrounding rock; when the surrounding rock pressure increases to be greater than the frictional force of the secondary yielding friction fit, relative sliding occurs between the outer ring 5 and the yielding sleeve 4, and the secondary yielding process begins. The rod body 2 drives the conical end 41 of the yielding sleeve 4 to move deeper into the surrounding rock 1 and into the reamed part of the borehole; as the yielding process continues, the deformation energy of the surrounding rock is released, and the increasing amplitude of the surrounding rock pressure slows down. When it is equal to the secondary yielding working resistance (the frictional force of the secondary yielding friction fit), the yielding process stops, and the surrounding rock pressure and the support resistance reach equilibrium, and the deformation of the surrounding rock is controlled during the staged yielding process. Finally, when the limiting ring 43 protruding from the rear end of the yielding sleeve 4 abuts against the outer ring 5, the movement stops.

[0032] It should be noted that a pressure sensor for monitoring the surrounding rock pressure (not shown in the figure) is provided on the rod body 2. The pressure sensor is connected and controlled with the controller of the hydraulic telescopic rod 57. Based on the surrounding rock pressure data monitored by the pressure sensor, it controls whether the driving assembly drives the guide ring 54 to rotate. That is, during secondary yielding, if the surrounding rock pressure is less than the secondary yielding working resistance, the rod body 2 will deform to release the surrounding rock deformation energy. If the rod body 2 is continuously deformed, it will also be an unsafe process. Therefore, an adjustable yielding member 52 is required to adjust the secondary yielding working resistance between the outer ring 5 and the yielding sleeve 4. The specific description is as follows: In the initial state, the transition section 54b on the guide ring 54 is in contact with the guide contact head 52c; when it is necessary to increase the friction force between the outer ring 5 and the yielding sleeve 4, rotate the guide ring 54 so that the small inner diameter section 54a is in contact with the guide contact head 52c and press the adjustable yielding arc section 52a against the conical end 41. Thus, under the guidance of the chute 55, the adjustable yielding arc section 52a is pressed against the conical end 41, thereby increasing the secondary yielding working resistance; when it is necessary to reduce the friction force between the outer ring 5 and the yielding sleeve 4, rotate the guide ring 54 so that the large inner diameter section 54c is in contact with the guide contact head 52c to release the pressing of the adjustable yielding arc section 52a against the conical end 41. When the conical end 41 is pulled deep into the surrounding rock, the adjustable yielding arc section 52a will not block the conical end 41.

[0033] S4: After completing the installation and support process of the graded yielding control bolt, spray mortar on the surface of the surrounding rock to form a shotcrete layer 10. The shotcrete layer 10 consolidates the graded yielding control bolt, the cable 9, the steel bar row 7, and the steel bar mesh 8 into an integral structure.

[0034] The advantages of this embodiment are: (1) Give full play to the self-bearing capacity of the surrounding rock and transform passive support into active support; the graded yielding control bolt and the cable jointly support, with good integrity of the support structure and high support strength; select a reasonable support plan in combination with the monitoring results of the surrounding rock deformation of the roadway, play an efficient support role, and save support materials at the same time; (2) The graded yielding control bolt makes full use of the graded failure characteristics of the surrounding rock, thus maximizing the self-stabilizing ability of the surrounding rock, eliminating the need for repeated maintenance, and saving support materials; (3) The outer ring that undergoes secondary yielding friction cooperation with the yielding sleeve is provided with an adjustable yielding member on the basis of the fixed yielding ring, and can flexibly adjust the yielding amount based on the surrounding rock pressure to meet the requirements of different deformation amounts on site.

Claims

1. A support structure for a long-distance deep-buried TBM inclined shaft in a water-rich complex rock stratum, characterized in that The support structure includes stepwise yielding control bolts, cable bolts, and a steel bar row, a steel bar mesh, and a shotcrete layer that are sequentially arranged from the inside to the outside on the surrounding rock surface of the tunnel. The steel bar mesh is fixed to the surrounding rock surface by the stepwise yielding control bolts and the cable bolts; The stepwise yielding control bolt includes a bolt body, an outer ring, a yielding sleeve, and an inner ring. In the initial state, the rear end of the bolt body presses the inner ring against the rear port of the inner cavity of the yielding sleeve through a nut. The front end of the yielding sleeve extends into the drill hole of the surrounding rock and presses the outer ring against the surrounding rock outside the drill hole. A first-level yielding friction fit is formed between the inner ring and the inner cavity of the yielding sleeve. A second-level yielding friction fit is formed between the front end of the yielding sleeve and the outer ring. Among them, the frictional force of the second-level yielding friction fit is greater than the frictional force of the first-level yielding friction fit.

2. The support structure for a long-distance deep-buried TBM inclined shaft in a water-rich complex rock stratum according to claim 1, characterized in that The steel bar row is composed of several longitudinal steel bars and is distributed at intervals in the circumferential direction. The steel bar mesh presses the steel bar row against the surrounding rock surface. The shotcrete layer is sprayed on the surrounding rock surface to consolidate the stepwise yielding control bolts, the cable bolts, the steel bar row, the steel bar mesh, and the shotcrete layer into an integrated structure.

3. The support structure for a long-distance deep-buried TBM inclined shaft in a water-rich complex rock stratum according to claim 1, characterized in that The main body of the yielding sleeve is a cylindrical barrel. A conical end is provided at the front end of the barrel, and a radially protruding limiting ring is provided at the rear end of the barrel. A through hole for the bolt body to pass through is opened in the center of the conical end, and the diameter of the through hole is the same as the outer diameter of the bolt body.

4. A support structure for a long-distance deep-buried TBM inclined shaft in a water-rich complex rock stratum according to claim 3, characterized in that The outer ring includes a fixed yielding ring, a ring platform, an adjustable yielding member, a sliding groove, a guiding ring, and a driving assembly. The ring platform is arranged along the circumferential outer edge of the front end surface of the fixed yielding ring. The inner wall surface of the inner circle of the fixed yielding ring is a longitudinally variable diameter section and fits the conical end. Four groups of adjustable yielding members are arranged at intervals in the circumferential direction. The adjustable yielding member includes an adjustable yielding arc section, a connecting rod, and a guiding contact head. The rod body of the connecting rod is assembled in the sliding groove to provide radial sliding guidance for the connecting rod. The two ends of the connecting rod are respectively connected to the adjustable yielding arc section and the guiding contact head. The inner arc surface of the adjustable yielding arc section fits the conical end. The guiding contact head is in sliding contact with the inner circle of the guiding ring. Four groups of guiding variable diameter sections are arranged on the inner circle of the guiding ring, and each group of guiding variable diameter sections corresponds to one guiding contact head. The guiding variable diameter section includes a small inner diameter section, a transition section, and a large inner diameter section arranged in sequence. The guiding ring is driven to rotate by the driving assembly.

5. The support structure for a long-distance deep-buried TBM inclined shaft in a water-rich complex rock stratum according to claim 4, wherein A circle of external teeth is provided on the outer wall surface of the guiding ring. An annular guide groove is provided on the front end surface of the fixed yielding ring. A convex rail is provided on the rear end surface of the guiding ring. The convex rail on the guiding ring is correspondingly and matingly installed in the annular guide groove to provide rotational guiding support for the rotation of the guiding ring. The driving assembly includes a hydraulic telescopic rod and a straight rack fixedly arranged on the rod body of the hydraulic telescopic rod. The external teeth on the guiding ring are meshed and driven by the straight rack to drive the guiding ring to rotate.

6. The support structure for a long-distance deep-buried TBM inclined shaft in a water-rich complex rock stratum according to claim 5, characterized in that The rod body is provided with a pressure sensor for monitoring the surrounding rock pressure. The pressure sensor is connected and controlled with the controller of the hydraulic telescopic rod, and based on the surrounding rock pressure data monitored by the pressure sensor, it controls whether the driving assembly drives the guide ring to rotate; In the initial state, the transition section on the guide ring is in contact with the guide contact head; When it is necessary to increase the friction between the outer ring and the yielding sleeve, rotate the guide ring so that the small inner diameter section is in contact with the guide contact head and press the adjustable yielding arc section against the conical end head; when it is necessary to reduce the friction between the outer ring and the yielding sleeve, rotate the guide ring so that the large inner diameter section is in contact with the guide contact head to release the pressing of the adjustable yielding arc section against the conical end head.

7. The support structure for a long-distance deep-buried TBM inclined shaft in a water-rich complex rock stratum according to claim 5, characterized in that The fixed yielding ring and the ring platform jointly enclose a space for equipment installation grooves. The thicknesses of the adjustable yielding member, the chute, the guide ring, and the driving assembly are all smaller than the height of the ring platform.

8. A working method of a support structure for a long-distance deep-buried TBM inclined shaft in a water-rich complex rock stratum as described in any one of claims 1-7, characterized in that The working method includes the following steps: S1: Drill advanced grouting holes in the surrounding rock in front of the TBM excavation for advanced reinforcement; S2: After the TBM completes the excavation of the surrounding rock, drill holes in the surrounding rock to install the graded yielding control bolt and cable. The graded yielding control bolt includes a rod body, an outer ring, a yielding sleeve, and an inner ring; among them, the drilling is divided into two steps. The first step is to drill a hole according to the diameter of the rod body, and the second step is to ream the hole on the basis of the drilled hole according to the outer diameter of the barrel of the yielding sleeve. The reaming depth is the length of the yielding sleeve; While installing the graded yielding control bolt, lay a steel bar row and a steel mesh on the surface of the surrounding rock. The steel mesh presses the steel bar row against the surface of the surrounding rock, and the steel mesh is fixed on the surface of the surrounding rock through the graded yielding control bolt, the steel mesh, and steel rivets; S3: During the deformation process of the surrounding rock, when the surrounding rock pressure is greater than the friction force of the first-level yielding friction fit, the rod body drives the inner ring to move in a first-level yielding manner between the inner cavity of the yielding sleeve until the inner ring moves to the inner barrel end of the yielding sleeve and stops; When the surrounding rock pressure is greater than the friction force of the second-level yielding friction fit, the rod body drives the front end of the yielding sleeve to move in a second-level yielding manner with the outer ring and move into the drill hole until the limiting ring protruding from the rear end of the yielding sleeve abuts against the outer ring and then stops moving; S4: After completing the installation and support process of the graded yielding control bolt, spray-grout and reinforce the surface of the surrounding rock to consolidate the graded yielding control bolt, the cable, the steel bar row, the steel mesh, and the shotcrete layer into an integral structure.

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