Self-adaptive yielding support structure for large-deformation soft rock tunnel and construction method thereof

Abstract

The application discloses a self-adaptive yielding support structure for a large-deformation soft rock tunnel and a construction method thereof. The structure comprises a partitioned yielding primary lining and a self-adaptive yielding anchoring device arranged outside the partitioned yielding primary lining. The self-adaptive yielding anchoring device comprises a yielding anchor cable device, a rubber layer, a micro-fiber grouting layer and a self-repairing cement-clay grouting layer. The yielding anchor cable device comprises a first sleeve, an anchor cable, an elastic corrugated hose and a second sleeve. The partitioned yielding primary lining can be divided into multiple partitions on a tunnel cross section to adapt to the uneven deformation of various soft rock tunnels. The partitioned yielding primary lining is prefabricated and spliced by a plurality of annular UHPC lining pieces, a UHPC web and a high-damping rubber layer. The secondary lining is a cast-in-situ UHPC lining layer formed by UHPC moulding. The application can effectively constrain the large deformation of a deep-buried soft rock tunnel, improve the resistance-yielding capacity of the support structure and solve the support problem of uneven deformation of surrounding rock.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soft rock tunnel support, in particular to a self-adaptive yielding support structure for large-deformation soft rock tunnel and a construction method thereof. BACKGROUND

[0002] Weak lithology or high content of water-absorbing minerals is the material basis for soft surrounding rock to be pregnant with disasters, which is prone to large deformation of swelling or extrusion under the coupling of rock mass characteristics and occurrence environment. In addition, the large deformation of deep-buried soft rock tunnel has time-dependent characteristics, which lags behind the construction of the support structure. Therefore, the instability and large deformation of soft surrounding rock often occur during the operation of the tunnel, and engineering problems such as damage of the initial support of shotcrete, distortion of the internal steel arch, and cracking of the secondary lining often occur, which seriously threatens the operation safety of the tunnel, and the diseases often occur in deep-buried tunnels, making the rescue difficulty and the later repair cost difficult to estimate. Therefore, effective support measures need to be taken for the soft surrounding rock during tunnel construction.

[0003] In view of the urgent engineering problem of easy deformation and large deformation of the surrounding rock of deep-buried soft rock tunnel, the traditional support measures often use to increase the stiffness of the overall lining structure to enhance the support resistance of the large-deformation surrounding rock, which is unscientific and uneconomical. In recent years, engineering and technical personnel have gradually developed various types of prestressed anchors and yielding anchors, which have achieved certain results in the active and passive restriction of soft rock deformation. However, with the continuous intensification of the deformation of the surrounding rock, the anchoring layer where the anchor is located is prone to slip, debonding, and even dislocation from the surrounding rock, resulting in the loss of the anchoring effect of the anchor / anchor, in addition, the primary lining will also be plastically damaged under the action of the large surrounding rock pressure.

[0004] In view of this, in order to effectively constrain the large deformation of deep-buried soft rock tunnel, improve the resistance yielding capacity of the support structure, and solve the engineering problem of supporting unevenly deformed surrounding rock, a self-adaptive yielding support structure for large-deformation soft rock tunnel and a construction method thereof are proposed to achieve this purpose. SUMMARY

[0005] The purpose of the embodiments of the present application is to provide a self-adaptive yielding support structure for large-deformation soft rock tunnel and a construction method thereof, which realizes the constraint of large deformation of deep-buried soft rock tunnel, improves the resistance yielding capacity of the support structure, and solves the support problem of unevenly deformed surrounding rock, thereby solving at least one technical problem involved in the background art.

[0006] In order to solve the above technical problems, the present application is implemented as follows:

[0007] The embodiment of the application provides a self-adaptive yielding support structure for a large-deformation soft rock tunnel, which comprises a partitioned yielding primary lining and a self-adaptive yielding anchoring device arranged outside the partitioned yielding primary lining, one end of the self-adaptive yielding anchoring device is fixed to the partitioned yielding primary lining, and the other end is embedded in surrounding rock, the self-adaptive yielding anchoring device comprises a yielding anchor device, a micro-fiber grouting layer wrapped around two ends of the yielding anchor device, a self-repairing cement-clay grouting layer wrapped around a middle section of the yielding anchor device, and a rubber layer assembled on the yielding anchor device and used for spacing the micro-fiber grouting layer and the self-repairing cement-clay grouting layer; the yielding anchor device comprises, from far to near, a first sleeve, a second sleeve, an anchor cable arranged in the first sleeve and the second sleeve respectively, and a stretchable corrugated hose arranged on the anchor cable and located between the first sleeve and the second sleeve; the interiors of the first sleeve and the second sleeve are both evacuated to form a vacuum cavity, and an arc-shaped handle is arranged above the top of the vacuum cavity; the anchor cable comprises a variable cross-section section located in the vacuum cavity of the first sleeve and the second sleeve and an equal cross-section section connecting the two variable cross-section sections; the vertex of the variable cross-section section is connected with the arc-shaped handle through a high-damping spring;

[0008] The partitioned yielding primary lining is prefabricated and spliced by a plurality of annular UHPC lining pieces, UHPC web walls and high-damping rubber layers, the annular UHPC lining pieces are arranged on the two sides of the UHPC web walls and the high-damping rubber layers; the bottom of the second sleeve is connected with the annular UHPC lining piece.

[0009] Optionally, the outer periphery of the first sleeve and the second sleeve is provided with a gourd-shaped resistance piece for enhancing the mechanical bite force of the micro-fiber grouting layer.

[0010] Optionally, the inner wall of the first sleeve and the second sleeve is shaped into a circular truncated cone section and a neck section extending from the two circular truncated cone sections; the circular truncated cone section and the neck section are both provided with a high-damping rubber thin layer for enhancing the contact friction force with the anchor cable.

[0011] Optionally, the first sleeve is further provided with an arc-shaped anchor head.

[0012] Optionally, the bottom of the second sleeve is provided with an arc-shaped bend matched with the surface shape of the annular UHPC lining piece, and a first bolt hole and a first grouting hole are symmetrically arranged.

[0013] Optionally, the annular UHPC lining piece is provided with a second bolt hole matched with the first bolt hole, and is further provided with a second grouting hole matched with the first grouting hole; the annular UHPC lining piece is matched and docked with the second sleeve through a high-strength bolt.

[0014] Optionally, a secondary lining is arranged in the inner side of the partition pressure-relief primary lining, and the secondary lining is a cast-in-situ UHPC lining layer formed by UHPC molding.

[0015] Optionally, the micro-fiber grouting layer is filled with high-performance fiber grouting material, and the high-performance fiber grouting material is composed of and has the following weight fractions: 52.5 grade Portland cement 380-420 parts; secondary fly ash 19-21 parts; first-grade silica ash 11-18 parts; S95 grade slag 36-48 parts; high-performance water reducing agent 4-5 parts; hybrid short fibers 20-33 parts; and water 66-95 parts.

[0016] The high-performance water reducing agent is a polycarboxylic acid type water reducing agent with a water-reducing rate of 23-32%.

[0017] The hybrid short fibers are formed by doping three basalt fibers with lengths of 2.5 mm, 5.0 mm and 7.5 mm at a mass ratio of 2:3:1, and the length-diameter ratio of the basalt fibers is constant at 55.

[0018] Optionally, the self-repairing cement-clay grouting layer is filled with cement-clay based grouting material, and the cement-clay based grouting material is composed of and has the following weight fractions: clay 470-540 parts; 42.5 grade Portland cement 23-27 parts; secondary fly ash 10-14 parts; water glass 38-45 parts; water 165-178 parts; type I microcapsules 10-15 parts; and type II microcapsules 15-26 parts.

[0019] The mineral composition of the clay is approximately the same as that of soft rock, so as to realize coordinated deformation of the self-repairing cement-clay grouting layer and the soft rock tunnel surrounding rock.

[0020] The modulus of the water glass is 1.5-2.1.

[0021] The type I microcapsules contain a composite repair agent formed by mixing epoxy resin and diluted water glass at a mass ratio of 1:2, and the modulus of the diluted water glass is 3.1-3.5.

[0022] The type II microcapsules contain magnesium oxide expanding agent.

[0023] The type I or type II microcapsules are ruptured along with expansion and cracking of the self-repairing cement-clay grouting layer (4), and then repair the micro-fissures.

[0024] The application further provides a construction method of the self-adaptive pressure-relief supporting structure for a large-deformation soft rock tunnel.

[0025] Step one: according to the actual soft rock tunnel design results to determine the adaptive yielding anchor and the parameters of the partition yielding primary lining, and the corresponding size of the yielding anchor device, rubber layer, annular UHPC lining piece, UHPC abdominal wall and high damping rubber layer are prefabricated in the factory, then the high damping rubber layer is pasted on both sides of the UHPC abdominal wall to complete the assembly;

[0026] Step two: tunnel excavation, drill anchor holes matched with the adaptive yielding anchor, and clean the holes, then install the adaptive yielding anchor, so that the first sleeve is embedded in the stable deep surrounding rock, then inject high-performance fiber grouting material to complete the construction of the first sleeve external micro-fiber grouting layer, then install the rubber layer, then continue to inject cement-clay based grouting material to complete the construction of the self-healing cement-clay grouting layer, install the rubber layer at the same time, and finally complete the construction of the second sleeve external micro-fiber grouting layer with high-performance fiber grouting material;

[0027] Step three: install the UHPC abdominal wall and high damping rubber layer which have been pre-assembled on both sides of the tunnel section and fix them with temporary supports, then install a ring-shaped UHPC lining piece, then continue to install the UHPC abdominal wall and high damping rubber layer on its right side, and then complete the fixation of the ring-shaped UHPC lining piece and make it tightly adhere to the tunnel surrounding rock, and use high-strength bolts to connect the second sleeve with the ring-shaped UHPC lining piece;

[0028] Step four: repeat step three until the partition yielding primary lining is closed, and supplement the micro-fiber grouting layer outside the second sleeve through the first grouting hole and the second grouting hole;

[0029] Step five: repeat steps two to four along the longitudinal extension direction of the tunnel to complete the construction of the partition yielding primary lining;

[0030] Step six: formwork, erect reinforcement, use ultra-high performance concrete to complete the construction of the cast-in-place UHPC lining layer, and remove the temporary supports of the high-damping rubber layer, vacuum cavity, high-damping spring, UHPC abdominal wall and high-damping rubber layer, and the adaptive yielding support structure for large deformation soft rock tunnels is finally constructed.

[0031] The beneficial effects of the present application are as follows:

[0032] (1) The design of the present application is reasonable, the adaptive yielding anchor and the partition yielding primary lining adaptively yield together, and the support resistance of the support structure is continuously enhanced with the increase of the slip amount, and the allowed yielding deformation amount is large, thanks to the setting of the anchor cable variable cross-section section, neck section, high-damping rubber layer, vacuum cavity, high-damping spring, UHPC abdominal wall and high-damping rubber layer and other components;

[0033] (2) The primary lining of the partitioned pressure relief can be divided into multiple partitions on the cross section according to the physical and mechanical properties of soft rock and the cross section size of the tunnel, which can adapt to the uneven deformation of various soft rock tunnels.

[0034] (3) The mineral composition of the raw materials used in the self-healing cement-clay grouting layer is roughly the same as that of the surrounding rock, so that the anchor cable section of the self-adaptive pressure-yielding anchor can deform in tandem with the surrounding rock. At the same time, the anchor cable device can adapt to various working conditions such as stratum displacement and uneven deformation of soft rock.

[0035] (4) The ring-shaped UHPC lining sheet, UHPC belly wall and cast-in-place UHPC lining layer are all prefabricated or cast-in-place using UHPC as raw material. Due to its high mechanical properties and toughness, it can effectively reduce the cross-sectional size of the components and leave enough space for large deformation of the surrounding rock without increasing the tunnel excavation cross-sectional size. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments 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, wherein:

[0037] Figure 1 This is a schematic diagram of the adaptive pressure relief support structure of this application;

[0038] Figure 2 for Figure 1 Enlarged view of section A;

[0039] Figure 3 This is a schematic diagram of the adaptive pressure relief anchor of this application;

[0040] Figure 4 This is a schematic diagram of the structure of the pressure-relief anchor cable device in this application;

[0041] Figure 5 This is a schematic diagram of the structure of the first sleeve in this application;

[0042] Figure 6 This is a schematic diagram of the structure of the second sleeve in this application;

[0043] Figure 7 A schematic diagram of the spatial structure where the primary and secondary linings of this application are matched and connected in a zoned pressure-relief manner.

[0044] Figure 8 For along Figure 7 Cross-sectional view of line 1-1 in the middle;

[0045] Figure 9Fig. 1 is a structural schematic diagram of a pressure-released anchor cable device when the anchor cable of the present application is in a slipping and pressure-released state;

[0046] Figure 10 Fig. 2 is a structural schematic diagram of an adaptive pressure-released support structure when the adaptive pressure-released anchorage of the present application cooperates with the pressure-released primary lining of the partition pressure-released;

[0047] Figure 11 Fig. 3 is a structural schematic diagram of an adaptive pressure-released support structure when the surrounding rock of the soft rock tunnel of the present application undergoes uneven deformation.

[0048] In the drawings, 1 is a pressure-released anchor cable device, 2 is a rubber spacer, 3 is a micro-fiber grouting layer, 4 is a self-repairing cement-clay grouting layer, 5 is an annular UHPC lining piece, 6 is a UHPC abdominal wall, 7 is a high-damping rubber layer, 8 is a high-strength bolt, 9 is a cast-in-situ UHPC lining layer, 11 is a first sleeve, 111 is an arc-shaped anchor head, 112 is a circular truncated cone section, 113 is a neck section, 114 is a high-damping rubber thin layer, 12 is an anchor cable, 121 is a variable cross-section section, 122 is a constant cross-section section, 13 is an expansion bellows, 14 is a second sleeve, 141 is a first bolt hole, 142 is a first grouting hole, 15 is a gourd-shaped resistance piece, 16 is a valve, 17 is a vacuum cavity, 18 is an arc-shaped handle, 19 is a high-damping spring, 51 is a second bolt hole, and 52 is a second grouting hole. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0050] The terms "first", "second", and the like in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than that illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally a category, not limited to the number of objects, for example, the first object can be one or more. In addition, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / ", generally indicates that the front and rear associated objects are in an "or" relationship.

[0051] Please refer to Figures 1-11As shown in the embodiment of this application, an adaptive pressure relief support structure for large deformation soft rock tunnels is a composite structure composed of adaptive pressure relief anchors, partitioned pressure relief primary lining, and secondary lining. One end of the adaptive pressure relief anchor is fixed to the partitioned pressure relief primary lining, and the other end is embedded in the weak surrounding rock to constrain the deformation of the tunnel surrounding rock. The arrangement angle and number are determined according to the bearing deformation requirements of the soft rock tunnel.

[0052] The adaptive pressure relief anchor includes a pressure relief anchor device 1, a microfiber grouting layer 3 wrapped around both ends of the pressure relief anchor device 1, a self-healing cement-clay grouting layer 4 wrapped around the middle section of the pressure relief anchor device 1, and a rubber separator 2 assembled on the pressure relief anchor device 1 and used to separate the microfiber grouting layer 3 and the self-healing cement-clay grouting layer 4.

[0053] The pressure-relief anchor cable device 1 includes, from far to near, a first sleeve 11, a second sleeve 14, an anchor cable 12 with its two ends respectively disposed in the first sleeve 11 and the second sleeve 14, and a telescopic corrugated hose 13 sleeved on the anchor cable 12 and located between the first sleeve 11 and the second sleeve 14.

[0054] Both the first sleeve 11 and the second sleeve 14 are provided with gourd-shaped anti-blocking components 15 that enhance the mechanical interlocking force with the microfiber grouting layer 3 on their outer periphery. Both have vacuum chambers 17 formed inside by air valves 16, and are provided with arc-shaped handles 18 on the top.

[0055] Specifically, the arc-shaped handle 18 is fixedly connected to the first sleeve 11 and the second sleeve 14 by molding or welding.

[0056] The first sleeve 11 is also provided with an arc-shaped anchor head 111 protruding from the outside to further enhance the anchoring force with the microfiber grouting layer 3.

[0057] In addition, the outer edges of the first sleeve 11 and the second sleeve 14 are both arc-shaped, similar to the design of the gourd-shaped resistive component 15. This is to avoid stress concentration caused by sharp corners on the device and to minimize the original cracks in the microfiber grouting layer 3 and the self-healing cement-clay grouting layer 4.

[0058] The inner walls of the first sleeve 11 and the second sleeve 14 are both formed with frustum sections 112 and neck sections 113 extending towards each other from the two frustum sections 112; a high-damping rubber thin layer 114 is provided on the frustum sections 112 and the neck sections 113 to enhance the contact friction with the anchor cable 12.

[0059] The anchor cable 12 includes a variable cross-section section 121 located in the vacuum cavity 17 of the first sleeve 11 and the second sleeve 14 respectively, and an equal cross-section section 122 connecting the two variable cross-section sections 121; the vertex of the variable cross-section section 121 is connected with the arc-shaped handle 18 by a high-damping spring 19 to improve the resistance of the yielding anchor cable device 1.

[0060] The telescopic corrugated hose 13 is wrapped outside the anchor cable 12 to serve as a protective layer.

[0061] The bottom of the second sleeve 14 is shaped with an arc-shaped bending matched with the surface shape of the annular UHPC lining piece 5, and symmetrically provided with a first bolt hole 141 and a first grouting hole 142.

[0062] The anchor cable 12 is made of a plurality of annular steel wires through bending, rotating, tight binding and other processes, and is generally in the shape of "8"; in the natural extension state, the variable cross-section section 121 of the anchor cable 12 is located in the vacuum cavity 17 and in contact with the high-damping rubber thin layer 114 of the circular truncated cone section 112; and the equal cross-section section 122 is interposed between the neck section 113 of the first sleeve 11 and the neck section 113 of the second sleeve 14 and closely adheres to the high-damping rubber thin layer 114 of the neck section 113.

[0063] The steel wires of the variable cross-section section 121 are all variable cross-section, and the diameter becomes larger as closer to the vertex, which makes the yielding resistance of the anchor cable 12 gradually increase with the increase of the slip amount, and provides stronger supporting resistance for the unstable surrounding rock.

[0064] Specifically, the diameter of the steel wires of the variable cross-section section 121 is about 1.05-1.25 times of that of the equal cross-section section 122, which can prevent the anchor cable 12 from slipping out of the neck section 113 when stressed and yielding, and can ensure that the vacuum cavity 17 is always in a vacuum environment by closely adhering to the neck section 113, thereby providing stronger supporting resistance for the yielding process of the yielding anchor cable device 1.

[0065] The first sleeve 11 is embedded in the stable deep surrounding rock, and its slip deformation amount is negligible, which can be regarded as a fixed end; when the anchor cable 12 is subjected to the swelling effect of soft rock, the variable cross-section section 121 slips and yields in the vacuum cavity 17 of the first sleeve 11 and the second sleeve 14, and part of the variable cross-section section 121 gradually enters the neck section 113 by extruding the high-damping rubber thin layer 114, and the maximum slip amount at both ends is about 15-20 cm; the second sleeve 14 cooperates with the annular UHPC lining piece 5 to yield, and the maximum slip amount is about 30-40 cm.

[0066] The rubber partition layer 2 is arranged between the micro-fiber grouting layer 3 and the self-repairing cement-clay grouting layer 4 to isolate the grouting partition; specifically, the rubber partition layer 2 is a hollow circular ring with a thickness of about 2-4 cm, the outer circle diameter of which is consistent with the diameter of the anchor hole, and the inner circle diameter of which is consistent with the diameter of the equal cross-section section 122.

[0067] The micro-fiber grouting layer 3 is wrapped outside the first sleeve 11 and the second sleeve 14, and is formed by pouring high-performance fiber grouting material.

[0068] Specifically, the composition and weight fraction of the high-performance fiber grouting material are as follows: 52.5 grade Portland cement 380-420 parts; secondary fly ash 19-21 parts; first grade silica ash 11-18 parts; S95 grade slag 36-48 parts; high-performance water reducing agent 4-5 parts; hybrid short fiber 20-33 parts; and water 66-95 parts. The high-performance water reducing agent is a polycarboxylic acid type water reducing agent with a water reducing rate of 23%-32%; the hybrid short fiber is made of three kinds of basalt fibers with lengths of 2.5 mm, 5.0 mm and 7.5 mm in a mass ratio of 2:3:1, and the length-diameter ratio of the basalt fibers used is constant at 55.

[0069] The self-repairing cement-clay grouting layer 4 is wrapped outside the stretchable corrugated hose 13, and is formed by pouring cement-clay based grouting material. Specifically, the composition and weight fraction of the cement-clay based grouting material are as follows: clay 470-540 parts; 42.5 grade Portland cement 23-27 parts; secondary fly ash 10-14 parts; water glass 38-45 parts; water 165-178 parts; type I microcapsule 10-15 parts; and type II microcapsule 15-26 parts. The mineral composition of the clay is substantially the same as that of soft rock, so as to realize the coordinated deformation of the self-repairing cement-clay grouting layer 4 and the soft rock tunnel surrounding rock.

[0070] The modulus of the water glass is 1.5-2.1.

[0071] The type I microcapsule contains a composite repair agent, and the composite repair agent is made by mixing epoxy resin and dilute water glass in a mass ratio of 1:2.

[0072] Specifically, the modulus of the dilute water glass is 3.1-3.5, the type II microcapsule contains magnesium oxide expanding agent, and the type I or type II microcapsule is ruptured along with the expansion and cracking of the self-repairing cement-clay grouting layer 4, thereby repairing the micro-fissures.

[0073] The partition pressure-relieving primary lining can be divided into three, five or seven partitions in the cross section according to the physical and mechanical properties of soft rock and the size of the tunnel cross section, so as to adapt to the uneven deformation of various soft rock tunnels.

[0074] Referring to Figures 7-8In the embodiment, the partitioned yielding primary lining is divided into three partitions. The partitioned yielding primary lining is prefabricated and spliced by a plurality of annular UHPC lining pieces 5, UHPC web walls 6 and high-damping rubber layers 7.

[0075] It needs to be further explained that a plurality of the partitioned yielding primary linings are also arranged in the longitudinal direction of the tunnel. The UHPC web walls 6 of the partitioned yielding primary linings in the longitudinal direction are shorter than the UHPC web walls 6 arranged along the cross section of the tunnel, but have the same function, that is, cooperating with the high-damping rubber layers 7 to constrain and limit the deformation of the annular UHPC lining pieces 5.

[0076] The annular UHPC lining pieces 5 are arranged on both sides of the UHPC web walls 6 and the high-damping rubber layers 7, and the annular UHPC lining pieces 5 in different partitions push each other to provide stronger support for the primary lining, which can significantly reduce the cross-sectional size of the primary lining and the secondary lining, reduce the cost of the tunnel lining structure, and save enough space for adapting to the large deformation of soft rock.

[0077] Specifically, the thickness of the annular UHPC lining piece 5 is 9-13 cm, and the thickness of the UHPC web wall 6 is 10-16 cm.

[0078] The annular UHPC lining piece 5 is provided with a second bolt hole 51 matched with the first bolt hole 141, and is also provided with a second grouting hole 52 matched with the first grouting hole 142.

[0079] The annular UHPC lining piece 5 is matched and connected with the second sleeve 14 through the high-strength bolt 8.

[0080] The high-damping rubber layer 7 is arranged on both sides of the UHPC web wall 6, and the height of the high-damping rubber layer 7 is 2 / 3-3 / 4 of the height of the UHPC web wall 6.

[0081] The cross section of the high-damping rubber layer 7 is a right trapezoid, and the included angle between the inclined waist and the bottom side of the side connected with the annular UHPC lining piece 5 is about 45°-70°, so as to realize resistance increase and yielding.

[0082] The secondary lining is a cast-in-situ UHPC lining layer 9 formed by UHPC molding. Specifically, the thickness of the cast-in-situ UHPC lining layer 9 is 15-23 cm.

[0083] After the UHPC web wall 6 is assembled, the steel bars matched with the cast-in-situ UHPC lining layer 9 are arranged to enhance the integrity of the partitioned yielding primary lining and the secondary lining.

[0084] The annular UHPC lining piece 5, the UHPC abdominal wall 6 and the cast-in-situ UHPC lining layer 9 are all prefabricated from ultra-high performance concrete (UHPC) through processes such as reinforcement, mold building and steam curing. Specifically, the ultra-high performance concrete is mixed from 52.5 grade Portland cement, high-purity quartz sand with SiO2≥99.5%, first-grade fly ash, S105 grade slag, first-grade silica fume, water and polycarboxylate superplasticizer in a mass ratio of 1:1.15:0.08:0.13:0.18:0.21:0.023.

[0085] Specific slip and pressure release process and resistance increase principle are as follows:

[0086] When the soft rock tunnel surrounding rock expands or extrudes, referring to Figure 9 The variable cross-section section 121 of the anchor cable 12 slips and releases pressure in the vacuum cavity 17 of the first sleeve 11 and the second sleeve 14, and part of the variable cross-section section 121 gradually enters the neck section 113 by extruding the high-damping rubber layer 114, and the resistance of the pressure release gradually increases with the increase of the slip amount, which provides stronger support resistance for the unstable surrounding rock. In addition, the vacuum cavity 17 and the high-damping spring 19 constrain the deformation of the anchor cable 12 that slips, thereby improving the resistance and pressure release level of the pressure release anchor device 1. At the same time, the second sleeve 14 in the deformation surrounding rock zone and the annular UHPC lining piece 5 adaptively and cooperatively release pressure, and the UHPC abdominal wall 6 and the high-damping rubber layer 7 at both ends constrain and limit the deformation of the annular UHPC lining piece 5.

[0087] Figure 10 For the adaptive pressure release anchoring piece and the adaptive pressure release primary lining in the adaptive pressure release supporting structure when the soft rock tunnel surrounding rock uniformly deforms, Figure 11 For the adaptive pressure release supporting structure when the soft rock tunnel surrounding rock deforms unevenly.

[0088] In order to realize the above-mentioned adaptive pressure release supporting structure for large deformation soft rock tunnel, the present application provides a construction method based on the above-mentioned adaptive pressure release supporting structure for large deformation soft rock tunnel, comprising the following steps:

[0089] Step one: according to the design results of the actual soft rock tunnel, the parameters of the adaptive pressure release anchoring piece and the adaptive pressure release primary lining are determined, and the corresponding size of the pressure release anchor device 1, the rubber separation layer 2, the annular UHPC lining piece 5, the UHPC abdominal wall 6 and the high-damping rubber layer 7 are prefabricated in the factory, and then the high-damping rubber layer 7 is pasted on both sides of the UHPC abdominal wall 6 to complete the assembly;

[0090] Step two: tunnel excavation, drilling anchor holes for adaptive yielding anchor at the same time, hole cleaning, then installing adaptive yielding anchor, so that the first sleeve 11 is embedded in the stable deep surrounding rock, then injecting high-performance fiber grouting material to complete the construction of the first sleeve 11 external micro-fiber grouting layer 3, followed by installing rubber layer 2, then continue to inject cement-clay based grouting material to complete the construction of the self-repairing cement-clay grouting layer 4, while installing rubber layer 2, finally using high-performance fiber grouting material to complete the construction of the second sleeve 14 external micro-fiber grouting layer 3;

[0091] Step three: installing pre-assembled UHPC web 6 and high-damping rubber layer 7 on both sides of the tunnel section, and fixing with temporary support, then installing a ring-shaped UHPC lining piece 5, followed by continuing to install UHPC web 6 and high-damping rubber layer 7 on its right side, thereby completing the fixation of the ring-shaped UHPC lining piece 5 and making it tightly adhere to the tunnel surrounding rock, while using high-strength bolts 8 to connect the second sleeve 14 with the ring-shaped UHPC lining piece 5;

[0092] Step four: repeating step three until the partition yielding primary lining is closed, while supplementing the micro-fiber grouting layer 3 outside the second sleeve 14 through the first grouting hole 142 and the second grouting hole 52;

[0093] Step five: repeating steps two to four along the longitudinal extension direction of the tunnel to complete the construction of the partition yielding primary lining;

[0094] Step six: formwork setting, steel bar erection, using ultra-high performance concrete to complete the construction of the cast-in-place UHPC lining layer 9, and removing the temporary support for fixing the ring-shaped UHPC lining piece 5, UHPC web 6 and high-damping rubber layer 7, thereby finally completing the construction of the adaptive yielding support structure for large deformation soft rock tunnel.

[0095] The beneficial effects of the present application are as follows:

[0096] (1) The design of the present application is reasonable, the adaptive yielding anchor and the partition yielding primary lining adaptively yield together, benefiting from the setting of anchor cable variable cross-section section, neck section, high-damping rubber thin layer, vacuum cavity, high-damping spring, UHPC web and high-damping rubber layer, etc., the support resistance of the support structure is continuously enhanced with the increase of the slip amount, and the allowed yielding deformation amount is large;

[0097] (2) The partition yielding primary lining can be divided into multiple partitions on the cross section according to the physical and mechanical properties of soft rock and the size of the tunnel section, which can adapt to the uneven deformation of various soft rock tunnels;

[0098] (3) The mineral composition of the raw materials used for the self-repairing cement-clay grouting layer is roughly the same as that of the surrounding rock, which enables the anchor cable section of the self-adapting pressure-relieving anchor to deform cooperatively with the surrounding rock, and the setting of the anchor cable device can adapt to various working conditions such as stratum dislocation and uneven deformation of soft rock;

[0099] (4) The annular UHPC lining piece, the UHPC abdominal wall and the cast-in-situ UHPC lining layer are all prefabricated or cast in-situ from UHPC as the raw material, and due to the super-high mechanical properties and toughness, the component cross-sectional size can be effectively reduced, and sufficient pressure-relieving deformation space is left for the large-deformation surrounding rock without increasing the tunnel excavation cross-sectional size.

[0100] It should be noted that in this document, the terms "comprise", "comprising", or any other variant thereof are intended to cover non-exclusive inclusions, such that processes, methods, articles, or apparatuses that comprise a list of elements are not limited to those elements, but can also include other elements not expressly listed, or inherent to such processes, methods, articles, or apparatuses. Without more limitations, the element defined by the phrase "comprising a" does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0101] In addition, it should be noted that the scope of the methods and systems in the embodiments of the present application is not limited to performing functions in the order shown or discussed, but can also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described methods can be performed in an order different from that described, and various steps can also be added, omitted, or combined. In addition, the features described with reference to certain examples can be combined in other examples.

[0102] The embodiments of the present application are described above in combination with the drawings, but the present application is not limited to the above-described specific embodiments, and the above-described specific embodiments are only illustrative, not restrictive, and those skilled in the art can make many forms under the inspiration of the present application without departing from the scope of the present application and the scope protected by the claims, which are all within the protection of the present application.

Claims

1. An adaptive pressure relief support structure for large deformation soft rock tunnels, characterized in that, The system includes a partitioned pressure-relief primary lining and an adaptive pressure-relief anchor installed on the outside of the partitioned pressure-relief primary lining. One end of the adaptive pressure-relief anchor is fixed to the partitioned pressure-relief primary lining, and the other end is embedded in the surrounding rock. The adaptive pressure-relief anchor includes a pressure-relief anchor cable device (1), a microfiber grouting layer (3) wrapped around both ends of the pressure-relief anchor cable device (1), a self-healing cement-clay grouting layer (4) wrapped around the middle section of the pressure-relief anchor cable device (1), and a rubber separator (2) assembled on the pressure-relief anchor cable device (1) and used to separate the microfiber grouting layer (3) and the self-healing cement-clay grouting layer (4). The pressure-relief anchor cable device (1) includes, from far to near, a first sleeve (11), a second sleeve (14), and two ends respectively set on the first sleeve (11) and the second sleeve (14). The second sleeve (14) contains an anchor cable (12) and a telescopic corrugated hose (13) sleeved on the anchor cable (12) and located between the first sleeve (11) and the second sleeve (14); the interiors of the first sleeve (11) and the second sleeve (14) are both evacuated by a valve (16) to form a vacuum chamber (17), and an arc-shaped handle (18) is provided above the top of the vacuum chamber (17); the anchor cable (12) includes a variable cross-section section (121) located in the vacuum chamber (17) of the first sleeve (11) and the second sleeve (14) respectively, and an equal cross-section section (122) connecting the two variable cross-section sections (121); the apex of the variable cross-section section (121) is connected to the arc-shaped handle (18) by a high-damping spring (19); The partitioned pressure relief initial lining is prefabricated and spliced ​​from several annular UHPC lining pieces (5), UHPC belly wall (6) and high damping rubber layer (7). The annular UHPC lining pieces (5) are arranged on both sides of the UHPC belly wall (6) and the high damping rubber layer (7). The bottom of the second sleeve (14) is connected to the annular UHPC lining pieces (5).

2. The adaptive pressure relief support structure for large deformation soft rock tunnels according to claim 1, characterized in that, Both the first sleeve (11) and the second sleeve (14) are provided with gourd-shaped anti-blocking components (15) that enhance the mechanical interlocking force with the microfiber grouting layer (3) on their outer periphery.

3. The adaptive pressure relief support structure for large deformation soft rock tunnels according to claim 2, characterized in that, The inner walls of the first sleeve (11) and the second sleeve (14) are both formed with a frustum section (112) and a neck section (113) extending from the two frustum sections (112) towards each other; both the frustum section (112) and the neck section (113) are provided with a thin layer of high-damping rubber (114) to enhance the contact friction with the anchor cable (12).

4. The adaptive pressure relief support structure for large deformation soft rock tunnels according to claim 2, characterized in that, The first sleeve (11) also has an arc-shaped anchor head (111) protruding from the outside.

5. The adaptive pressure relief support structure for large deformation soft rock tunnels according to claim 4, characterized in that, The bottom of the second sleeve (14) is provided with an arc-shaped bend that matches the surface shape of the annular UHPC lining sheet (5), and is symmetrically provided with a first bolt hole (141) and a first grouting hole (142).

6. The adaptive pressure relief support structure for large deformation soft rock tunnels according to claim 5, characterized in that, The annular UHPC lining plate (5) is provided with a second bolt hole (51) that matches the first bolt hole (141), and a second grouting hole (52) that matches the first grouting hole (142); the annular UHPC lining plate (5) and the second sleeve (14) are matched and connected by high-strength bolts (8).

7. The adaptive pressure relief support structure for large deformation soft rock tunnels according to claim 1, characterized in that, It also includes a secondary lining disposed inside the primary lining of the partition, wherein the secondary lining is a cast-in-place UHPC lining layer (9) formed by UHPC molding.

8. The adaptive pressure relief support structure for large deformation soft rock tunnels according to claim 1, characterized in that, The microfiber grouting layer (3) is formed by injecting high-performance fiber grouting material. The composition and weight parts of the high-performance fiber grouting material are as follows: 380-420 parts of 52.5 grade silicate cement; 19-21 parts of grade II fly ash; 11-18 parts of grade I silica fume; 36-48 parts of S95 grade slag; 4-5 parts of high-performance water-reducing agent; 20-33 parts of mixed short fibers; 66-95 parts of water. The high-performance water-reducing agent is a polycarboxylate-based water-reducing agent with a water reduction rate of 23% to 32%. The hybrid short fiber is made by mixing three types of basalt fibers with lengths of 2.5 mm, 5.0 mm, and 7.5 mm in a mass ratio of 2:3:1, and the aspect ratio of the basalt fibers used is constant at 55.

9. The adaptive pressure relief support structure for large deformation soft rock tunnels according to claim 1, characterized in that, The self-healing cement-clay grouting layer (4) is formed by grouting with cement-clay based grouting material. The composition and weight parts of the cement-clay based grouting material are as follows: 470-540 parts of clay; 23-27 parts of 42.5 grade silicate cement; 10-14 parts of grade II fly ash; 38-45 parts of water glass; 165-178 parts of water; 10-15 parts of type I microcapsules; 15-26 parts of type II microcapsules. The mineral composition of the clay is roughly the same as that of the soft rock, so as to achieve coordinated deformation of the self-healing cement-clay grouting layer (4) and the surrounding rock of the soft rock tunnel. The modulus of the water glass is 1.5 to 2.1; The type I microcapsule contains a composite repair agent, which is a mixture of epoxy resin and diluted water glass in a mass ratio of 1:2, and the modulus of the diluted water glass is 3.1 to 3.

5. The type II microcapsule contains a magnesium oxide expanding agent; The type I or type II microcapsules rupture as the self-healing cement-clay grouting layer (4) expands and cracks, thereby repairing the micro-cracks.

10. A construction method for an adaptive pressure relief support structure for large deformation soft rock tunnels as described in any one of claims 1-9, characterized in that, include: Step 1: Based on the design results of the actual soft rock tunnel, determine the parameters of the adaptive pressure relief anchor and the partitioned pressure relief primary lining, and prefabricate the corresponding size pressure relief anchor device (1), rubber partition (2), annular UHPC lining sheet (5), UHPC web (6) and high damping rubber layer (7) in the factory. Then, attach the high damping rubber layer (7) to both sides of the UHPC web (6) to complete the assembly. Step 2: Tunnel excavation, while drilling anchor holes for adaptive pressure relief anchors and cleaning the holes, then installing adaptive pressure relief anchors so that the first sleeve (11) is embedded in the stable deep surrounding rock, then injecting high-performance fiber grouting material to complete the construction of the micro-fiber grouting layer (3) outside the first sleeve (11), then installing the rubber partition (2), then continuing to inject cement-clay based grouting material to complete the construction of the self-healing cement-clay grouting layer (4), while installing the rubber partition (2), and finally using high-performance fiber grouting material to complete the construction of the micro-fiber grouting layer (3) outside the second sleeve (14); Step 3: Install the pre-assembled UHPC web (6) and high-damping rubber layer (7) on both sides of the tunnel section and fix them with temporary supports. Then install a ring-shaped UHPC lining piece (5). Next, continue to install the UHPC web (6) and high-damping rubber layer (7) on its right side to complete the fixing of the ring-shaped UHPC lining piece (5) and make it close to the tunnel surrounding rock. At the same time, use high-strength bolts (8) to fix the second sleeve (14) to the ring-shaped UHPC lining piece (5). Step 4: Repeat step 3 until the initial lining of the partition is closed by pressure relief, and at the same time, grout the microfiber grouting layer (3) outside the second sleeve (14) through the first grouting hole (142) and the second grouting hole (52); Step 5: Repeat steps 2 to 4 along the longitudinal direction of the tunnel to complete the construction of the initial lining with zoned pressure relief; Step 6: Set up formwork and erect steel bars. Use ultra-high performance concrete to complete the construction of the cast-in-place UHPC lining layer (9), and remove the temporary supports that fix the annular UHPC lining plate (5), UHPC belly wall (6) and high damping rubber layer (7). The adaptive pressure relief support structure for large deformation soft rock tunnel can then be completed.

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