Fault-crossing tunnel anti-seismic toughness supporting structure and construction method

Abstract

The invention discloses a fault-crossing tunnel anti-seismic toughness supporting structure and a construction method, the fault-crossing tunnel anti-seismic toughness supporting structure comprises a plurality of combined anchor rods, and further comprises a secondary lining layer, a waterproof damping interlayer 3 and a primary lining which are sequentially arranged from inside to outside of a tunnel hole, the primary lining, the waterproof damping interlayer and the secondary lining layer surround the inside of the hole by a circle, and the primary lining is closely attached to the wall surface of the tunnel hole. By arranging the combined anchor rods and the prefabricated linings, damage of earthquakes and fault slippage to the tunnel structure is reduced, the anti-seismic performance and post-earthquake recoverability of the tunnel supporting structure are improved, and the overall anti-seismic toughness of the tunnel is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel earthquake resistance, and in particular relates to an earthquake-resistant toughness support structure for a cross-fault tunnel and a construction method. Background Art

[0002] With the increasing number of transportation tunnel construction projects, due to the limitations of terrain conditions, tunnels will inevitably pass through earthquake-prone areas and fault zones. Experience shows that earthquakes may cause faults to slip, resulting in damage to tunnels crossing the faults.

[0003] Most of the existing tunnel seismic reinforcement technologies tend to enhance the existing structural strength, such as increasing the lining thickness, grouting reinforcement, etc. Even after adopting such reinforcement technologies, large damage or deformation will still occur under the action of earthquakes, and it is difficult to repair them to a usable level after the earthquake, which seriously affects the smooth flow of traffic lifelines.

[0004] In recent years, the concept of building seismic resilience has been promoted. Building seismic resilience refers to the ability of a building to maintain and restore its original building functions after a set level of earthquake. Traditional tunnel reinforcement methods can only meet the earthquake safety function, and the post-earthquake recoverability is poor. How to enhance the seismic resilience of cross-fault tunnels has become an important issue that needs to be solved in tunnel engineering construction. Summary of the invention

[0005] The purpose of the present invention is to provide a cross-fault tunnel seismic toughness support structure and construction method, which reduces the damage to the tunnel structure caused by earthquakes and fault slips through combined anchor rods and prefabricated assembled linings, improves the seismic performance and post-earthquake recoverability of the tunnel support structure, and enhances the overall seismic toughness of the tunnel.

[0006] The present invention adopts the following technical solution: a combined anchor rod, comprising an anchor cable and an anchor rod body arranged front and back in the same axial direction, wherein the anchor cable and the anchor rod body are connected via a steel strand connector (15);

[0007] The steel strand connector includes an anchor sleeve, an anchor cable sleeve and a clamp. The anchor sleeve is a cylinder with open ends at the front and rear ends, and its rear end is threadedly connected to the front end of the anchor rod body; its front end is connected to the anchor cable sleeve through a stud bolt;

[0008] The anchor cable sleeve is a shell structure with both front and rear ends open, the front end of which is a conical cavity with the tip facing forward, and the rear end is a cylindrical cavity;

[0009] A clamp is arranged in the conical cavity. The clamp is a truncated cone with its small head facing forward. A through hole is opened along the central axis of the truncated cone. An anchor cable is axially connected in the through hole. When the rock and soil deform, the clamp moves forward and the anchor cable grows, mobilizing the bearing capacity of the deep surrounding rock.

[0010] Furthermore, the front end of the anchor cable is axially connected with a cone head; the rear end of the anchor rod body is threadedly connected with an anchor head nut, and an anchor pad is coaxially sleeved on the anchor rod body and in front of the anchor head nut.

[0011] The cone head is located at the bottom of the borehole, and the bottom of the borehole is located in the deep surrounding rock; the anchor rod body passes through the primary lining and is connected to the primary lining, and the anchor plate at the rear end is attached to the tunnel wall and is screwed and fixed by the anchor head nut.

[0012] Furthermore, a plurality of grouting holes are arranged on the rear section of the anchor rod body, and the rear end of the anchor rod body is used to be connected to the grouting device. Grouting is performed through the rear end of the anchor rod body, and the slurry overflows from the plurality of grouting holes and seeps into the rock and soil.

[0013] Furthermore, a plurality of grout-stopping brushes are coaxially sleeved outside the front section of the anchor rod body and arranged at intervals in front and behind; each grout-stopping brush comprises a connecting sleeve and a fixing sleeve coaxially sleeved together, wherein the fixing sleeve is outside; the connecting sleeve is coaxially sleeved outside the anchor rod body; the grout-stopping brush is used to prevent the rear end grout from entering the anchor cable section;

[0014] Each slurry-stopping brush also includes a protective plate, a multi-layer steel wire layer and a pressing plate stacked in sequence from outside to inside. The protective plate, the pressing plate and the multi-layer steel wire layer are all shell structures, and the rear section is an outward-expanding trumpet shape, all of which are coaxially sleeved outside the connecting sleeve, and the front section is located inside the fixed tube, and the outward-expanding trumpet section is located outside the fixed tube; the inner side is close to the connecting sleeve;

[0015] Under the action of the slurry, the pressing plate bends backward, and the end portion extends toward the inner wall of the borehole and adheres to the inner wall of the borehole to block the slurry.

[0016] Furthermore, a plurality of fixing holes are provided on the side wall of the fixing cylinder and are spaced around it, and a plurality of connecting holes are provided on the protective plate, the clamping plate and the multiple steel wire layers at positions corresponding to the fixing holes. The fixing holes and the connecting holes at the same position form a group of holes, and each group of holes is provided with fixing bolts to fix the clamping plate, the multiple steel wire layers and the protective plate to the fixing cylinder.

[0017] The present invention also discloses a cross-fault tunnel seismic toughness support structure, comprising a plurality of the above-mentioned combined anchor rods, and also comprising a secondary lining layer, a waterproof shock-absorbing insulation layer and a primary lining arranged in sequence from the inside of the tunnel to the outside, wherein the primary lining, the waterproof shock-absorbing insulation layer and the secondary lining layer are arranged in a circle in the tunnel, wherein:

[0018] The secondary lining layer includes an integral secondary lining and a multi-ring segmented assembled secondary lining which are connected in the longitudinal direction. The integral secondary lining is used to be arranged in the area outside the fault fracture zone, and the multi-ring segmented assembled secondary lining is used to be arranged in the fault fracture zone;

[0019] The multiple rings of segmented assembled secondary linings are sequentially arranged in a longitudinal direction, and each ring of the segmented assembled secondary linings includes a plurality of assembled concrete segments and a plurality of shear rubber segments, the assembled concrete segments and the shear rubber segments are arranged at intervals, and the adjacent assembled concrete segments and the shear rubber segments are fitted and connected;

[0020] Each of the prefabricated concrete sections includes an inverted arch block, which is U-shaped and has left and right arms with different heights. Taking the inverted arch block as a reference, its left or right side is sequentially connected to the side wall B block and the arch waist B block, and its right or left side is sequentially connected to the side wall A block and the arch waist A block, and a capping block is connected between the arch waist B block and the arch waist A block.

[0021] Furthermore, in two adjacent prefabricated concrete sections, the left and right arms of the inverted arch block are arranged in opposite directions, and the capping block, arch waist B block, side wall B block, arch waist A block and side wall A block are correspondingly arranged in opposite directions on the left and right sides and upward, wherein the capping block is located on the left or right side of the designed center line of the tunnel, so that when assembled into the prefabricated concrete section, the joints between the corresponding blocks are not on the same longitudinal line.

[0022] Furthermore, each shear rubber segment is annular and consistent with the shape of the adjacent assembled concrete segment; each shear rubber segment includes a polytetrafluoroethylene rubber plate layer and a thin steel plate layer stacked together in the longitudinal direction.

[0023] The present invention also discloses a construction method of the above-mentioned cross-fault tunnel seismic ductile support structure, comprising the following steps:

[0024] Step S1, excavate a tunnel chamber, drill multiple holes in the tunnel wall, and the bottom of each hole is located in the deep surrounding rock; insert a combined anchor rod into each hole, with the cone head located at the bottom of the hole, and each stopper brushes the shallow surrounding rock section close to the deep surrounding rock in the hole; the anchor plate is attached to the surface of the rock and soil in the tunnel, and the anchor head nut is screwed to fix the combined anchor rod;

[0025] Grouting is performed from the rear end of the anchor rod body, and the slurry overflows from the grouting hole and penetrates into the rock and soil. At the same time, the slurry that has not penetrated in time flows to the grout-stopping brush. Under the action of the slurry, the pressing plate bends backward, and its end is attached to the borehole wall. The slurry overflowing from the end of the pressing plate and the borehole wall is blocked by the multiple steel wire layers. At the same time, the protective plate supports the multiple steel wire layers. The slurry overflowing from the previous grout-stopping brush is blocked by the adjacent grout-stopping brushes in turn.

[0026] Step S2, installing a steel arch frame and a steel mesh close to the excavated tunnel wall, spraying concrete after forming, and forming a primary lining; the rear end of the anchor rod body is fixedly connected to the primary lining;

[0027] Step S3, attaching a waterproof and shock-absorbing insulation layer to the inner surface of the primary lining;

[0028] Step S4, installing a ring of segmented assembled secondary lining in the fault fracture zone area, installing an inverted arch block at the bottom of the tunnel hole, with its left arm high and right arm low, taking the inverted arch block as a reference, connecting the side wall B block and the arch waist B block in sequence on its left side, and connecting the side wall A block and the arch waist A block in sequence on its right side, connecting the arch waist B block on the left side with the arch waist A block on the right side through a capping block, and the capping block is located on the right side of the tunnel design centerline, completing the installation of a ring of assembled concrete segments; attaching the shear rubber segment to the segmented assembled secondary lining and installing it;

[0029] The adjacent ring segmented assembled secondary lining is installed on the installed shear rubber segment, and an inverted arch block is installed at the bottom of the tunnel hole, with its left arm being low and its right arm being high. With the inverted arch block as a reference, its left side is sequentially connected to the side wall A block and the waist A block, and its right side is sequentially connected to the side wall B block and the waist B block. The waist B block is connected to the waist A block through a capping block, and the capping block is located on the left side of the tunnel design centerline, thus completing the installation of a ring of assembled concrete segments; the shear rubber segment is installed on the segmented assembled secondary lining;

[0030] Repeat the above installation until the installation of the segmented assembled secondary lining in the fault fracture zone is completed;

[0031] Step S5: construct an integrated secondary lining in the tunnel outside the fault fracture zone, with one end of the integrated secondary lining attached to the shear rubber section at the inner end of the fault fracture zone.

[0032] The beneficial effects of the present invention are as follows: 1. The anchor rod body of the combined anchor rod can be grout-injected to reinforce the shallow surrounding rock of the tunnel. One end of the anchor cable is located in the deep surrounding rock with a stable structure. When the shallow surrounding rock is deformed, the anchor cable can mobilize the bearing capacity of the deep surrounding rock, and at the same time, the advantages of anchor rod and anchor cable support are brought into play, and the anchoring effect is stronger. 2. The segmented assembled secondary lining is used in the fault fracture zone and within 30m nearby. The secondary lining is segmented, and a shear rubber segment is arranged between each two segments of assembled concrete segments, which enhances the overall shear resistance of the segmented assembled secondary lining, prevents the fault slip caused by the earthquake from causing damage to the tunnel, and at the same time, the post-earthquake recovery cost of the segmented assembled secondary lining is low, and the repair operation is simple, and only the blocks and shear rubber segments that have lost their functions due to earthquake damage need to be replaced. 3. The waterproof and shock-absorbing insulation layer is used to replace the traditional geotextile and waterproof board to absorb earthquake energy, and at the same time, it swings with the raised ribs under the action of the earthquake to consume earthquake energy. The post-earthquake waterproof and shock-absorbing insulation layer has a certain reset ability, which improves the overall seismic toughness of the tunnel structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of a seismic ductile support structure for a tunnel across a fault;

[0034] Figure 2 It is a schematic diagram of the combined anchor rod;

[0035] Figure 3 It is a structural schematic diagram of a steel stranded wire connector;

[0036] Figure 4 A cross-sectional view of a grout-stopping brush;

[0037] Figure 5 This is a cross-sectional view of a seismic ductile support structure for a tunnel across a fault.

[0038] Figure 6 This is a schematic diagram of the decomposition of a seismic ductile support structure for a tunnel across a fault;

[0039] Figure 7 Schematic diagram of segmented assembled secondary lining Figure 1 ;

[0040] Figure 8 Schematic diagram of segmented assembled secondary lining Figure 2 ;

[0041] Fig. 9 This is a schematic diagram of a waterproof and shock-absorbing insulation layer;

[0042] Among them: 1. Anchoring system; 11. Anchor head nut; 12. Anchor pad; 13. Anchor rod body; 14. Stop grout brush; 141. Connecting sleeve; 142. Protective plate; 143. Steel wire layer; 144. Pressing plate; 145. Fixing bolt; 146. Fixing tube; 15. Steel strand connector; 151. Anchor sleeve; 152. Stud bolt; 153. Anchor cable sleeve; 154. Clamp;

[0043] 16. Anchor cable; 17. Cone head; 2. Primary lining; 3. Waterproof and shock-absorbing insulation layer; 31. Waterproof board; 32. High damping rubber layer; 33. Geotextile; 4. Secondary lining; 41. Integrated secondary lining; 42. Segmented assembled secondary lining; 421. Assembled concrete segment; 4211. Capping block; 4212. Arch waist block A; 4213. Arch waist block B; 4214 Side wall block A; 4215. Side wall block B; 4216. Invert block; 422. Shear rubber segment; 5. Fault fracture zone. DETAILED DESCRIPTION

[0044] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] The present invention discloses a combined anchor rod, such as Figure 1 As shown, it includes an anchor cable 16 and an anchor rod body 13 arranged front and back in the same axial direction, and the anchor cable 16 and the anchor rod body 13 are axially connected through a steel strand connector 15;

[0046] like Figure 2As shown, the strand connector 15 includes an anchor sleeve 151, an anchor cable sleeve 153 and a clamp 154. The anchor sleeve 151 is a cylinder with open ends at both ends. Internal threads are arranged on the inner walls of the front and rear ends of the cylinder. The rear end is threadedly connected with the front end of the anchor rod body 13; the front end is connected with the anchor cable sleeve 153 through a stud bolt 152. External threads are arranged on the outer walls of the front and rear ends of the stud bolt 152. The stud bolt 152 is threadedly connected with the anchor rod body 13 and the anchor cable sleeve 153.

[0047] The anchor cable sleeve 153 is a shell structure with open ends at both ends, and includes a conical cavity, a large cylindrical cavity and a small cylindrical cavity from front to back, and the inner wall of the small cylindrical cavity is provided with an internal thread;

[0048] The tip of the conical cavity faces forward and is connected to the outside; a clamp 154 ​​is arranged in the connecting cavity where the conical cavity and the large cylindrical cavity are connected; the clamp 154 ​​is a truncated cone, and the truncated cone is smaller than the connecting cavity; the small end of the truncated cone faces forward, and a through hole is opened along the central axis of the truncated cone, and an anchor cable 16 is sleeved in the through hole. When the rock and soil deform, the clamp 154 ​​moves forward, the anchor cable 16 grows, and the rock and soil body is supported by the reverse force of the anchor cable 16, while the bearing capacity of the deep surrounding rock is mobilized, thereby enhancing the support effect.

[0049] The front end of the anchor cable 16 is axially connected with a cone head 17; the anchor rod body 13 is a hollow round tube with a closed front end and an open rear end, and an external thread is provided at the rear end thereof, which is threadedly connected with the anchor head nut 11, and a plurality of grout-stopping brushes 14 are coaxially sleeved outside the front section thereof, and the plurality of grout-stopping brushes 14 are arranged at intervals in front and back, and each grout-stopping brush 14 is welded and fixed to the anchor rod body 13. An anchor pad 11 is coaxially sleeved on the anchor rod body 13 and located in front of the anchor head nut 11.

[0050] The cone head 17 is located at the bottom of the borehole, and the bottom of the borehole is located in the deep surrounding rock; the anchor rod body 13 passes through the primary lining 2 and is connected to the primary lining 2, and the anchor plate 12 at the rear end is attached to the tunnel wall and is screwed and fixed by the anchor head nut 11.

[0051] like Figure 3 As shown, a plurality of grouting holes are arranged on the anchor rod body 13 and behind the grouting brush 14 at the rear end. The rear end of the anchor rod body 13 is used to connect with the grouting device. Grouting is performed through the rear end of the anchor rod body 13. The grouting overflows from the plurality of grouting holes and penetrates into the rock and soil. The grouting brush 14 is used to prevent the rear end grout from entering the anchor cable 16 section.

[0052] Each grout-stopping brush 14 includes a connecting sleeve 141 and a fixed sleeve 146 coaxially sleeved together, wherein the fixed sleeve 146 is outside, its front end is closed, and the rear end is open, and the length of the rear end is shorter than the length of the connecting sleeve 141; the front and rear ends of the connecting sleeve 141 are both open; the connecting sleeve 141 is coaxially sleeved outside the anchor rod body 13.

[0053] The protective plate 142, the pressing plate 144 and the multi-layer steel wire layer 143 are all shell structures, and from front to back, they all include a cylindrical section and an outwardly expanded horn section connected axially. The cylindrical section is coaxially sleeved outside the connecting sleeve 141, and the cylindrical section is located inside the fixed cylinder 146, and the outwardly expanded horn section is located outside the fixed cylinder. With the area close to the connecting sleeve 141 as the inner part, the pressing plate 144, the multi-layer steel wire layer 143 and the protective plate 142 are arranged in sequence from the inside to the outside. On the side wall of the fixed cylinder 146, a plurality of fixing holes are provided at intervals around the side wall. On the protective plate 142, the pressing plate 144 and the multi-layer steel wire layer 143, a plurality of connecting holes are provided at positions corresponding to the fixing holes. The fixing holes and connecting holes at the same position form a group of holes, and each group of holes is sleeved with a fixing bolt 145 to achieve the fixing of the pressing plate 144, the multi-layer steel wire layer 143 and the protective plate 142 to the fixed cylinder 146. The multi-layer steel wire layer 143 is composed of a plurality of stacked steel wire layers. The included angle between the outer expansion section and the connecting sleeve 141 is 55°.

[0054] The connecting sleeve 141 is made of 5 mm thick stainless steel; the protection plate 142 is made of 2 mm thick stainless steel plate; the pressing plate 144 is made of 3 mm thick high manganese wear-resistant steel plate; the multi-layer steel wire layer 143 includes 3 layers of 15 mm thick single steel wire layers.

[0055] Under the force of the slurry, the outer expansion section of the pressing plate 144 is bent backward, and the end portion extends toward the inner wall of the borehole and adheres to the inner wall of the borehole to block the slurry. The slurry overflowing from the end portion of the pressing plate 144 and the borehole wall is blocked by the multi-layer steel wire layer 143, and at the same time, the protection plate 142 supports the multi-layer steel wire layer 143; the slurry overflowing from the previous slurry-stopping brush 14 is blocked by the adjacent slurry-stopping brushes 14 in turn.

[0056] The invention discloses a cross-fault tunnel seismic toughness support structure, which is suitable for strengthening cross-fault tunnel support operations in earthquake-prone areas and improving the seismic toughness of the tunnel.

[0057] A seismic ductile support structure for a tunnel across a fault, such as Figure 4-6 As shown, it includes a plurality of the above-mentioned combined anchor rods, and also includes a secondary lining layer 4, a waterproof shock-absorbing insulation layer 3 and a primary lining 2 which are arranged in sequence from the inside of the tunnel to the outside. The primary lining 2, the waterproof shock-absorbing insulation layer 3 and the secondary lining layer 4 are arranged in a circle in the tunnel, wherein the part close to the rock and soil layer is the outside, and the primary lining 2 is in close contact with the tunnel wall.

[0058] The anchor cable 16 of each combined anchor rod is inserted into the rock and soil, the cone head 17 is located at the bottom of the borehole, and the bottom of the borehole is located in the deep surrounding rock; the end of the anchor cable 16 passes through the primary lining 2 and is connected to the primary lining 2, and the anchor plate 12 at the rear end is attached to the surface of the rock and soil in the hole and is screwed and fixed by the anchor head nut 11.

[0059] The secondary lining layer 4 includes an integrated secondary lining 41 and a multi-ring segmented assembled secondary lining 42. The integrated secondary lining 41 is used to be set in an area outside the fault fracture zone. The integrated secondary lining 41 is constructed in sections, and a plurality of connection holes are arranged at intervals around the end side wall of the integrated secondary lining 41.

[0060] The multi-ring segmented assembled secondary lining 42 is used to be set in the fault fracture zone area, which is the area within 30m of the fault fracture zone; the multi-ring segmented assembled secondary lining 42 is arranged in sequence in the longitudinal direction; when the segmented assembled secondary lining 42 and the integrated secondary lining 41 are connected, a shear rubber segment 422 is arranged between the segmented assembled secondary lining 42 and the integrated secondary lining 41. The fault fracture zone area and the area outside the fault fracture zone area are connected to form the entire operation area.

[0061] like Figure 7 and 8 As shown, the assembled concrete segment 421 and the shear rubber segment 422 are both annular and consistent with the shape of the tunnel hole in a circumferential direction, and are used to fit the inner wall and bottom of the tunnel hole.

[0062] Each assembled concrete segment 421 includes an inverted arch block 4216, which is U-shaped, and the heights of the left and right arms are different; with the inverted arch block 4216 as a reference, the left or right side thereof is sequentially connected to the side wall B block 4215 and the waist B block 4213, the right or left side thereof is sequentially connected to the side wall A block 4214 and the waist A block 4212, and the waist B block 4213 and the waist A block 4212 are connected to the capping block 4211. The inverted arch block 4216 is enclosed in a ring, surrounding the tunnel hole for one week.

[0063] The capping block 4211, the arch waist B block 4213, the side wall B block 4215, the arch waist A block 4212 and the side wall A block 4214 are all arc-shaped, which are consistent with the curvature of the tunnel holes at their respective locations. The inverted arch block 4216 is arc-shaped, which is consistent with the design size. The capping block 4211, the arch waist B block 4213, the side wall B block 4215, the arch waist A block 4212, the side wall A block 4214 and the inverted arch block 4216 are all provided with connecting holes. Joints are formed between adjacent blocks, and each joint is sealed with a penetrating crystallization coating.

[0064] In two adjacent prefabricated concrete sections 421, the left and right arms of the inverted arch block 4216 are arranged in opposite directions, and the capping block 4211, the arch waist B block 4213, the side wall B block 4215, the arch waist A block 4212 and the side wall A block 4214 are arranged in opposite directions in the left and right directions upwards, wherein the capping block 4211 is located on the left or right side of the tunnel design centerline, so that when the prefabricated concrete section 421 is assembled, the joints between the corresponding blocks are not on the same longitudinal line. The left or right arm of the inverted arch block 4216 is flush with the structural design baseline, and the other end is 2 to 3 meters higher than the structural design baseline; the inner arc lengths of the capping block 4211, the arch waist A block 4212, the arch waist B block 4213, the side wall A block 4214 and the side wall B block 4215 are S1, S2, S3, S4, S5 respectively, and the arc length ratio is S1:S2:S3:S4:S5=1:2:2:2.5:2.5. The structural design baseline is given when the tunnel is designed. The capping block 4211, the arch waist B block 4213, the side wall B block 4215, the arch waist A block 4212, the side wall A block 4214 and the invert block 4216 are prefabricated outside the tunnel and transported to the tunnel.

[0065] Since the arch bears the greatest pressure, the size of the capping block 4211 is the smallest among all the blocks, so it cannot be located at a position that crosses the arch, and at the same time, it is necessary to ensure that the joints of adjacent blocks are not at the arch.

[0066] The anti-seepage grade of each prefabricated concrete segment 421 is S10, the concrete strength grade is C50, the length of each ring along the length direction of the tunnel is 1.5m, the thickness of the prefabricated concrete segment 421 is the same as the thickness of the integrated secondary lining, and the curvature of each block matches the curvature of the integrated secondary lining.

[0067] Each shear rubber segment 422 is annular and consistent with the shape of the adjacent prefabricated concrete segment 421; each shear rubber segment 422 includes a polytetrafluoroethylene rubber layer and a thin steel layer stacked together in the longitudinal direction, the polytetrafluoroethylene rubber layer includes a plurality of polytetrafluoroethylene rubber plates stacked together in sequence in the longitudinal direction; the thin steel layer includes a plurality of thin steel plates stacked together in sequence in the longitudinal direction; each polytetrafluoroethylene rubber plate has a thickness of 5 mm in the longitudinal direction; each thin steel plate has a thickness of 5 mm in the longitudinal direction. Multiple polytetrafluoroethylene rubber plates and thin steel plates are inlaid, bonded, and vulcanized to form a 30 mm thick shear rubber layer 422. The shear rubber segment 422 is prefabricated outside the tunnel and transported to the tunnel when it is required to be installed.

[0068] A plurality of through holes are formed on the side wall of the shear rubber segment 422 in a circumferential direction. The positions of the through holes correspond to the positions of the connecting holes on each block. The through holes and the connecting holes at the same position are connected via bent bolt holes.

[0069] like Fig. 9As shown, the waterproof shock-absorbing insulation layer 3 is composed of a geotextile 33, a rubber layer 32, and a waterproof board 31 stacked in sequence, wherein the rubber layer material is silicone rubber mixed with nano-silicon dioxide, the rubber layer 32 includes a bottom plate, and the damping factor of the rubber layer material is not less than 0.4. The bottom plate is provided with raised ribs and grooves, and a plurality of raised ribs are arranged at intervals, each interval is a groove, and the direction of each raised rib is consistent with the width direction of the bottom plate. The thickness of the bottom plate is 5cm to 8cm, and the thickness of the raised ribs is 3 to 5cm. The waterproof shock-absorbing insulation layer is used to replace the traditional geotextile and waterproof board, and the material characteristics of the high-damping rubber absorb the seismic energy. At the same time, it swings with the raised ribs under the action of the earthquake to consume the seismic energy. After the earthquake, the waterproof shock-absorbing insulation layer has a certain reset ability, which improves the overall seismic toughness of the tunnel structure.

[0070] The present invention also discloses a construction method of the above-mentioned cross-fault tunnel seismic ductile support structure, comprising the following steps:

[0071] Step S1, excavate a tunnel chamber, drill multiple holes in the tunnel wall, and the bottom of each hole is located in the deep surrounding rock; insert two sets of cement rolls into each hole, push the cement rolls to the bottom of the hole with a steel drill, insert a combined anchor rod 1 into each hole, the cone head 17 is located at the bottom of the hole, and each grout-stopping brush 14 is placed in the shallow surrounding rock section close to the deep surrounding rock in the hole; the anchor plate 12 is attached to the surface of the rock and soil in the cave, and the anchor head nut 11 is screwed to fix the combined anchor rod 1;

[0072] Grouting is performed from the rear end of the anchor rod body 13, and the grout overflows from the grouting hole and penetrates into the rock and soil. At the same time, the grout that has not penetrated in time flows to the grout-stopping brush 14. Under the action of the grout, the pressing plate 144 is bent backward, and its end is attached to the borehole wall. The grout overflowing from the end of the pressing plate 144 and the borehole wall is blocked by the multi-layer steel wire layer 143. At the same time, the protective plate 142 supports the multi-layer steel wire layer 143; the grout overflowing from the previous grout-stopping brush 14 is blocked by the adjacent grout-stopping brushes 14 in turn;

[0073] Step S2, installing a steel arch frame and a steel mesh close to the excavated tunnel wall, spraying concrete after forming, and forming a primary lining 2; the rear end of the anchor rod body 13 is fixedly connected to the primary lining 2;

[0074] Step S3, attaching the waterproof and shock-absorbing insulation layer 3 to the inner surface of the primary lining 2;

[0075] Step S4, install a ring of segmented assembled secondary lining 42 in the fault fracture zone area, install an inverted arch block 4216 at the bottom of the tunnel hole, its left arm is high and the right arm is low, take the inverted arch block 4216 as a reference, its left side is connected to the side wall B block 4215 and the arch waist B block 4213 in sequence, and its right side is connected to the side wall A block 4214 and the arch waist A block 4212 in sequence, the arch waist B block 4213 on the left side is connected to the arch waist A block 4212 on the right side through the capping block 4211, and the capping block 4211 is located on the right side of the tunnel design center line, and the installation of a ring of assembled concrete segment 421 is completed; the shear rubber segment 422 is attached to the segmented assembled secondary lining 42;

[0076] The adjacent ring segmented assembled secondary lining 42 is installed on the installed shear rubber segment 422, and the inverted arch block 4216 is installed at the bottom of the tunnel hole, with its left arm being low and its right arm being high. With the inverted arch block 4216 as a reference, its left side is sequentially connected to the side wall A block 4214 and the waist A block 4212, and its right side is sequentially connected to the side wall B block 4215 and the waist B block 4213. The waist B block 4213 is connected to the waist A block 4212 through the capping block 4211, and the capping block 4211 is located on the left side of the tunnel design center line, thus completing the installation of a ring of assembled concrete segment 421; the shear rubber segment 422 is installed on the segmented assembled secondary lining 42;

[0077] Repeat the above installation until the installation of the segmented assembled secondary lining 42 in the fault fracture zone is completed;

[0078] Step S5: construct an integrated secondary lining 41 in the tunnel outside the fault fracture zone, and one end of the integrated secondary lining 41 is attached to the shear rubber section 422 at the inner end of the fault fracture zone.

[0079] The present invention discloses a cross-fault tunnel seismic toughness support structure and construction method, which adopts a combined anchor rod, can grouting and reinforce the shallow surrounding rock of the tunnel, and the anchor cable can mobilize the bearing capacity of the deep surrounding rock, while giving full play to the advantages of anchor rod and anchor cable support, and the anchoring effect is stronger. At the same time, a segmented assembled secondary lining is used in the fault fracture zone and within 30m nearby, and a shear rubber segment 422 is set between adjacent assembled concrete segments 421, which enhances the overall shear resistance of the secondary lining and prevents fault slip caused by earthquakes from causing damage to the tunnel.

Claims

1. A combined anchor rod, characterized in that: It comprises an anchor cable (16) and an anchor rod body (13) arranged front and back in the same axial direction, wherein the anchor cable (16) and the anchor rod body (13) are connected via a steel strand connector (15); The stranded wire connector (15) comprises an anchor sleeve (151), an anchor cable sleeve (153) and a clamp (154); the anchor sleeve (151) is a cylinder with open ends at the front and rear ends, and its rear end is threadedly connected to the front end of the anchor rod body (13); Its front end is connected to the anchor cable sleeve (153) via a stud bolt (152); The anchor cable sleeve (153) is a shell structure with both front and rear ends open, the front end of which is a conical cavity with the tip facing forward, and the rear end is a cylindrical cavity; A clamp (154) is arranged in the conical cavity. The clamp (154) is a truncated cone with its small head facing forward. A through hole is opened along the central axis of the truncated cone. An anchor cable (16) is axially connected in the through hole. When the rock and soil deform, the clamp (154) moves forward and the anchor cable (16) grows, thereby mobilizing the bearing capacity of the deep surrounding rock.

2. A combined anchor rod as claimed in claim 1, characterized in that: The front end of the anchor cable (16) is axially connected to a cone head (17); the rear end of the anchor rod body (13) is threadedly connected to an anchor head nut (11); an anchor pad (11) is coaxially sleeved on the anchor rod body (13) and located in front of the anchor head nut (11). The cone head (17) is located at the bottom of the borehole, and the bottom of the borehole is located in the deep surrounding rock; the anchor rod body (13) passes through the primary lining (2) and is connected to the primary lining (2), and the anchor plate (12) at the rear end is attached to the tunnel wall and is screwed and fixed by the anchor head nut (11).

3. A combined anchor rod as claimed in claim 2, characterized in that: A plurality of grouting holes are arranged on the rear section of the anchor rod body (13); the rear end of the anchor rod body (13) is used to be connected to a grouting device; grouting is performed through the rear end of the anchor rod body (13); grout overflows from the plurality of grouting holes and infiltrates into the rock and soil.

4. A combined anchor rod as claimed in claim 3, characterized in that: A plurality of grout-stopping brushes (14) are coaxially sleeved outside the front section of the anchor rod body (13) and are spaced apart from each other. Each of the grout-stopping brushes (14) comprises a connecting sleeve (141) and a fixing sleeve (146) coaxially sleeved together, wherein the fixing sleeve (146) is outside. The connecting sleeve (141) is coaxially sleeved outside the anchor rod body (13). The grout-stopping brushes (14) are used to prevent the grout at the rear end from entering the anchor cable (16) section. Each of the slurry-stopping brushes (14) further comprises a protective plate (142), a multi-layer steel wire layer (143) and a pressing plate (144) which are stacked in sequence from the outside to the inside. The protective plate (142), the pressing plate (144) and the multi-layer steel wire layer (143) are all shell structures, and the rear section is in an outwardly expanding trumpet shape. They are all coaxially sleeved outside the connecting sleeve (141), and the front section is located inside the fixing tube (146), and the outwardly expanding trumpet section is located outside the fixing tube (146); the inner side is closer to the connecting sleeve (141); Under the action of the slurry, the pressing plate (144) bends backward, and the end portion extends toward the inner wall of the borehole and adheres to the inner wall of the borehole to block the slurry.

5. A combined anchor rod as claimed in claim 4, characterized in that: A plurality of fixing holes are provided on the side wall of the fixing cylinder (146) at intervals around the side wall, and a plurality of connecting holes are provided on the protective plate (142), the pressing plate (144) and the multi-layer steel wire layer (143) at positions corresponding to the fixing holes. The fixing holes and connecting holes at the same position form a group of holes, and each group of holes is provided with a fixing bolt (145) to fix the pressing plate (144), the multi-layer steel wire layer (143) and the protective plate (142) to the fixing cylinder (146).

6. A seismic ductile support structure for a tunnel across a fault, characterized in that: A combined anchor rod comprising a plurality of claims 1 to 5, further comprising a secondary lining layer (4), a waterproof shock-absorbing insulation layer (3) and a primary lining (2) arranged in sequence from the inside of the tunnel to the outside, wherein the primary lining (2), the waterproof shock-absorbing insulation layer (3) and the secondary lining layer (4) are arranged circumferentially in the tunnel, wherein: The secondary lining layer (4) comprises an integral secondary lining (41) and a multi-ring segmented assembled secondary lining (42) which are bonded and connected in the longitudinal direction, wherein the integral secondary lining (41) is used to be arranged in an area outside the fault fracture zone area, and the multi-ring segmented assembled secondary lining (42) is used to be arranged in the fault fracture zone area; The multiple rings of segmented assembled secondary lining (42) are sequentially arranged in a longitudinal direction, each ring of the segmented assembled secondary lining (42) comprises a plurality of assembled concrete segments (421) and a plurality of shear rubber segments (422), the assembled concrete segments (421) and the shear rubber segments (422) are arranged at intervals, and adjacent assembled concrete segments (421) and shear rubber segments (422) are attached and connected; Each of the assembled concrete sections (421) comprises an inverted arch block (4216), which is U-shaped and has left and right arms of different heights. Taking the inverted arch block (4216) as a reference, the left or right side thereof is sequentially connected to a side wall B block (4215) and an arch waist B block (4213), and the right or left side thereof is sequentially connected to a side wall A block (4214) and an arch waist A block (4212), and a capping block (4211) is connected between the arch waist B block (4213) and the arch waist A block (4212).

7. The cross-fault tunnel seismic toughness support structure according to claim 6, characterized in that: In two adjacent prefabricated concrete sections (421), the left and right arms of the inverted arch block (4216) are arranged in opposite directions, and the capping block (4211), the arch waist B block (4213), the side wall B block (4215), the arch waist A block (4212) and the side wall A block (4214) are arranged in opposite directions in the left and right directions upward, wherein the capping block (4211) is located on the left or right side of the tunnel design center line, so that when the prefabricated concrete sections (421) are assembled, the joints between the corresponding blocks are not on the same longitudinal line.

8. The cross-fault tunnel seismic toughness support structure according to claim 7, characterized in that: Each of the shear rubber segments (422) is annular and consistent with the shape of the adjacent assembled concrete segment (421); each of the shear rubber segments (422) comprises a polytetrafluoroethylene rubber sheet layer and a thin steel sheet layer stacked together in the longitudinal direction.

9. A construction method for a cross-fault tunnel seismic toughness support structure as claimed in claim 6, 7 or 8, characterized in that: The steps include: Step S1, excavating a tunnel chamber, drilling multiple holes on the tunnel wall, the bottom of each hole being located at the deep surrounding rock; inserting a combined anchor rod (1) into each hole, the cone head (17) being located at the bottom of the hole, and each grout-stopping brush (14) being located at the shallow surrounding rock section close to the deep surrounding rock in the hole; the anchor pad (12) being attached to the tunnel wall in the cave, and the anchor head nut (11) being screwed to fix the combined anchor rod (1); Grouting is performed from the rear end of the anchor rod body (13), and the slurry overflows from the grouting hole and penetrates into the rock and soil. At the same time, the slurry that has not penetrated in time flows to the grout-stopping brush (14). Under the action of the slurry, the pressing plate (144) is bent backward, and its end is attached to the borehole wall. The slurry overflowing from the end of the pressing plate (144) and the borehole wall is blocked by the multi-layer steel wire layer (143). At the same time, the protective plate (142) supports the multi-layer steel wire layer (143); the slurry overflowing from the previous grout-stopping brush (14) is blocked by the adjacent grout-stopping brush (14) in turn; Step S2, installing a steel arch frame and a steel mesh close to the excavated tunnel wall, spraying concrete after forming, and forming a primary lining (2); the rear end of the anchor rod body (13) is fixedly connected to the primary lining (2); Step S3, attaching a waterproof and shock-absorbing insulation layer (3) to the inner surface of the primary lining (2); Step S4, installing a ring of segmented assembled secondary lining (42) in the fault fracture zone area, installing an inverted arch block (4216) at the bottom of the tunnel hole, wherein the left arm is high and the right arm is low, taking the inverted arch block (4216) as a reference, the left side is connected to the side wall B block (4215) and the arch waist B block (4213) in sequence, and the right side is connected to the side wall A block (4214) and the arch waist A block (4212) in sequence, the arch waist B block (4213) on the left side is connected to the arch waist A block (4212) on the right side through a capping block (4211), and the capping block (4211) is located on the right side of the tunnel design center line, thereby completing the installation of a ring of assembled concrete segments (421); attaching the shear rubber segment (422) to the segmented assembled secondary lining (42); The adjacent ring segmented assembled secondary lining (42) is installed on the installed shear rubber segment (422), and an inverted arch block (4216) is installed at the bottom of the tunnel hole, with its left arm being low and its right arm being high. With the inverted arch block (4216) as a reference, its left side is sequentially connected to the side wall A block (4214) and the waist A block (4212), and its right side is sequentially connected to the side wall B block (4215) and the waist B block (4213). The waist B block (4213) is connected to the waist A block (4212) through a capping block (4211), and the capping block (4211) is located on the left side of the tunnel design center line, thereby completing the installation of a ring of assembled concrete segments (421); the shear rubber segment (422) is installed on the segmented assembled secondary lining (42); Repeat the above installation until the installation of the segmented assembled secondary lining (42) in the fault fracture zone is completed; Step S5, constructing an integrated secondary lining (41) in the tunnel outside the fault fracture zone, wherein one end of the integrated secondary lining (41) is attached to the shear rubber section (422) at the inner end of the fault fracture zone.

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