High-water-pressure karst tunnel supporting structure and construction method thereof

Abstract

The invention discloses a high-water-pressure karst tunnel supporting structure and a construction method thereof, and relates to the technical field of tunnel supporting. The supporting structure comprises a primary supporting outer layer which is arranged on a rock wall on the surface of a wall body after tunnel excavation; the waterproof layer is arranged on the inner side of the initial-stage shotcrete-anchor support outer layer; the stress transfer layer is arranged on the inner side of the waterproof layer and comprises a first steel arch frame and a second steel arch frame, a plurality of supporting mechanisms and stress transfer mechanisms are arranged between the first steel arch frame and the second steel arch frame at intervals, and the supporting mechanisms and the stress transfer mechanisms are evenly distributed in the circumferential direction of the tunnel surrounding rock; the supporting structure has excellent waterproof performance and efficient stress coping capacity and can better adapt to dynamic deformation of surrounding rock.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel support, and particularly to a support structure for a high - water - pressure karst tunnel and its construction method. Background Technique

[0002] With the rapid development of transportation infrastructure construction, tunnel engineering is increasingly widely used in complex geological conditions such as mountainous areas. Among them, high - water - pressure karst tunnels account for a high proportion. The geological structure in karst areas is complex and changeable, with rich karst forms such as underground caves and rivers, frequent groundwater activities and high water pressure. Under the action of high water pressure in karst areas, ensuring the long - term safety of the lining structure is a major problem. Problems such as lining cracking and invert failure caused by high water pressure are increasing, and more seriously, it may lead to local tunnel collapses. Therefore, how to ensure the stability of the tunnel structure is particularly important.

[0003] Traditional tunnel support structures gradually expose many deficiencies when facing the complex working conditions of high - water - pressure karst tunnels.

[0004] (1) Traditional initial support usually only uses simple shotcrete or a small amount of wire mesh combined with rock bolts. Although it can provide preliminary support to a certain extent, under the long - term action of high water pressure, the shotcrete is prone to cracking, spalling and other phenomena, which cannot ensure the sealing and durability of the support structure, resulting in serious groundwater leakage problems and further deteriorating the surrounding rock conditions.

[0005] (2) Traditional waterproof layers mostly use single waterproof materials such as waterproof membranes. However, in a high - water - pressure karst environment, due to large surrounding rock deformation, the waterproof layer is easily torn and damaged, resulting in waterproof failure. Moreover, the connection between these waterproof layers and the surrounding rock and support structure is not tight and stable enough, and it is difficult to adapt to the dynamic deformation of the surrounding rock, and cannot effectively prevent the intrusion of groundwater.

[0006] (3) The steel arch support in traditional support structures only simply provides rigid support. When the surrounding rock pressure is unevenly distributed, the local stress on the steel arch is too large, and it is prone to distortion, deformation or even breakage, and cannot evenly disperse the pressure in the entire circumferential direction, greatly reducing the overall stability of the support structure. Summary of the Invention

[0007] Aiming at the above - mentioned existing problems, the present invention aims to provide a support structure for a high - water - pressure karst tunnel and its construction method, which has excellent waterproof performance, high - efficiency stress - response ability and can better adapt to the dynamic deformation of the surrounding rock.

[0008] The main idea of the technical solution adopted by the present invention: By setting the outer layer of the primary support, the surface of the surrounding rock is quickly sealed, and the deformation of the surrounding rock is initially controlled. By setting a waterproof layer outside the outer layer of the primary support, the water-stop rubber absorbs water and swells, and the support anchor, spring and buckle in the fixing mechanism cooperate. According to the dynamic absorption of water and swelling of the water-stop rubber, the support anchor can be adaptively stabbed into the surrounding rock or the outer layer of the primary support, enhancing the connection tightness and comprehensively coping with the waterproof problem under high water pressure. By arranging a support mechanism and a stress transfer mechanism at intervals between the first steel arch and the second steel arch, the received radial force is converted into the axial force of the cable stretching, and then the pressure is dispersed along the circumferential direction by means of the arched structure of the steel arch, effectively resolving the complex and changeable stress impact in the high water pressure karst environment.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A high water pressure karst tunnel support structure, comprising: An outer layer of primary support, arranged on the rock wall on the surface of the tunnel wall after excavation; A waterproof layer, arranged inside the outer layer of the initial shotcrete support; A stress transfer layer, arranged inside the waterproof layer, including a first steel arch and a second steel arch. A plurality of support mechanisms and stress transfer mechanisms are arranged at intervals between the first steel arch and the second steel arch, and the plurality of support mechanisms and stress transfer mechanisms are evenly distributed along the circumferential direction of the tunnel surrounding rock; Wherein, the support mechanism is used to provide rigid support for the support structure while releasing a certain amount of surrounding rock deformation; the stress transfer mechanism is used to transfer the radial force applied by the external surrounding rock to the support structure into the axial force along the steel arch, and disperse the pressure along its arched structure to the entire circumferential direction.

[0010] Through the above technical solution, further: The waterproof layer includes: A steel pipe, with both ends open, placed vertically, and a number of small holes are opened on the shell; A rigid sleeve, sleeved inside the steel pipe, with both ends open, a layer of expanded perlite is arranged on the inner layer, and 2 fixing mechanisms with opposite tails are arranged inside, and a water-stop rubber is arranged on the side of the two fixing mechanisms away from the port; Wherein, the gap between the steel pipe and the steel sleeve is filled with water-stop rubber.

[0011] Through the above technical solution, further: The fixing mechanism includes: A support anchor, with a cavity structure inside, a number of barbs are arranged at the front end and the front end of the barbs is open, and a support anchor buckle is arranged at the front end of the support anchor; A first spring, sleeved on the tail end of the support anchor; The perlite buckle is arranged on the inner wall of the expanded perlite layer and cooperates with the support anchor buckle to make the initial state of the spring in a compressed state.

[0012] Wherein, the water-stop rubber on the side of the fixing mechanism away from the port starts to absorb water and expand into the support anchor and begins to push the first spring. When the thrust force for pushing the first spring is greater than the restoring force provided by the mutual engagement of the support anchor buckle and the perlite buckle to the first spring, the support anchor ejects and pierces into the nearest layer wall.

[0013] Through the above technical solutions, further: The stress transfer mechanism includes: There are 2 stress transfer units, which are arranged between the first steel arch and the second steel arch and are respectively fixedly connected to the first steel arch and the second steel arch, and are used to receive and transfer the radial force applied by the external surrounding rock to the support structure.

[0014] There are 2 cable fixing units, which are relatively arranged between the stress transfer units and are fixedly connected to the stress transfer units, and are used to receive the radial force from the stress transfer units and convert it into an axial force along the steel arch.

[0015] Through the above technical solutions, further: The stress transfer unit includes: The steel plate is fixedly arranged on the steel arch, and cylindrical channels are opened on both sides, and the middle of the cylindrical channel is open; The connecting rod is arranged inside the cylindrical channel and can slide along its axial direction; The second spring is fixedly arranged on both sides inside the cylindrical channel, and one side away from the two ends of the cylindrical channel is respectively fixedly connected to both ends of the connecting rod; The support rod is fixedly arranged in the middle of the connecting rod and extends obliquely upward and is fixedly connected to the cable fixing unit; Wherein, the steel plate receives the radial force from the outer surrounding rock to the first steel arch and the second steel arch, and the connecting rod and the support rod can rotate or slide axially inside the cylindrical channel according to the external force situation.

[0016] Through the above technical solutions, further: The cable fixing unit includes: The cable diverter is a disc-shaped solid structure, and an annular groove is opened on the disc, as well as an inlet and an outlet allowing the cable to enter and exit; The cable is arranged inside the annular groove and is used to receive stresses at different positions and angles and convert the radial force into an axial force that stretches the cable.

[0017] The fixed rods, including two of them, have a cavity structure inside and are symmetrically and penetratingly arranged outside the cable diverter through spherical hinges. An opening is provided on the spherical hinge and is communicated with the inside of the fixed rod; The piston push rod penetrates through the inside of the fixed rod. The piston push rod is threadedly connected to the support rod and is used to receive the radial force so that the piston push rod moves axially along the fixed rod; The third spring is sleeved on the piston push rod and is used to buffer and stabilize the pressure of the piston push rod along with the cable; Among them, after the piston push rod receives the displacement and force transmitted from the support rod, it will move towards the direction of the cable diverter until the cable is pressed into the annular groove of the cable diverter. At this time, due to the effect of the spherical hinge, the fixed rod and the piston push rod will rotate arbitrarily along with the direction of the force, and the force will be distributed on the part where the cable contacts the groove and is transmitted axially from the inlet to the outlet along the annular groove of the cable, so that the cable generates tensile deformation.

[0018] Through the above technical solutions, further: The support mechanism includes: The support plates, including two of them, namely the upper support plate and the lower support plate, are respectively fixedly connected to the first steel arch and the second steel arch; There are multiple steel columns arranged in the middle of the upper support plate and the lower support plate. The lower end of the steel column is fixedly connected to the lower support plate, and the upper end of the steel column is elastically connected to the upper support plate through the fourth spring.

[0019] Through the above technical solutions, further: The outer layer of the initial support includes a steel mesh and shotcrete.

[0020] Through the above technical solutions, further: The first steel arch includes an arched layer and anchor bolts. The arched layer is composed of several I-beams, and the anchor bolts are distributed circumferentially along the arched layer. The anchor bolts are anchored in the tunnel surrounding rock and are fixedly connected to the arched layer.

[0021] A construction method for supporting a high-water-pressure karst tunnel includes the following steps: Step 1, after excavating the tunnel, the outer layer of the initial support is timely laid on the inner wall surface of the surrounding rock. First, lay the steel mesh to make it fit the rock wall, and then spray concrete onto the steel mesh to cover the steel mesh and tightly combine it with the rock wall to form an initially stable support structure and initially control the deformation of the surrounding rock.

[0022] Step 2, set a waterproof layer on the outer layer of the initial support: sleeve the rigid casing inside the steel pipe, set expanded perlite and a fixing mechanism inside the steel casing, and then fill it with water-stop rubber to complete the construction of the waterproof layer.

[0023] Step 3, erect the steel arch support structure: First, install the first steel arch, anchor the anchor rod into the tunnel surrounding rock and firmly fix it to its arched layer, and then install the second steel arch at a suitable position inside the first steel arch.

[0024] Step 4, uniformly install the support mechanism along the circumferential direction of the tunnel surrounding rock between the first steel arch and the second steel arch.

[0025] Step 5, install 2 stress transfer units between the first steel arch and the second steel arch, one fixed on the first steel arch and the other fixed on the second steel arch. The 2 stress transfer units are installed opposite to each other, and the stress transfer units are installed at intervals with the support mechanism so that they can receive and transfer the radial force exerted by the external surrounding rock on the support structure.

[0026] Step 6, install a cable fixing unit between the 2 stress transfer units so that it can receive the radial force from the stress transfer unit and convert it into an axial force along the steel arch, and then disperse the pressure along the arched structure to the entire circumferential direction.

[0027] The beneficial effects of the present invention are as follows: 1. On the one hand, the support structure of the present invention can release a certain amount of surrounding rock deformation, avoid damage to the support structure due to excessive deformation of the surrounding rock, and give the surrounding rock an appropriate "release space"; on the other hand, it can provide rigid support for the entire support system to ensure the stability of the tunnel during the deformation process of the surrounding rock.

[0028] 2. The stress transfer unit can accurately receive the radial force exerted by the external surrounding rock, and with the synergistic effect of the connecting rod, the second spring and the support rod, it can flexibly adjust its own structure to adapt to external forces of different sizes and directions, ensuring the smooth transfer of force. The cable fixing unit further cleverly converts the radial force into an axial force along the steel arch, and through components such as the cable diverter, the cable and the supporting piston push rod and the third spring, it efficiently disperses the pressure along the arched structure to the entire circumferential direction, enhancing the overall compressive stability of the support structure and effectively resisting the pressure from all directions of the surrounding rock.

[0029] 3. From the outer layer of the primary support to the waterproof layer and then to the stress transfer layer, the structural layers are closely connected and complement each other. The steel mesh of the outer layer of the primary support is closely attached to the rock wall by shotcrete, providing a solid foundation for the installation of the subsequent waterproof layer and stress transfer layer and initially controlling the deformation of the surrounding rock. The waterproof layer not only realizes the stability of its own structure but also is closely connected to the outer layer of the primary shotcrete support to prevent the waterproof layer from shifting or falling off due to tunnel vibration or water pressure impact. The stress transfer layer is organically combined with the waterproof layer and the outer layer of the primary support, and each component works together to build a comprehensive and multi-layered stable support system to ensure the safety of tunnel construction and operation. Description of the Drawings

[0030] Figure 1 Schematic diagram of the high - water - pressure karst tunnel support structure of the present invention; Figure 2 Schematic diagram of the waterproof layer structure of the present invention; Figure 3 Schematic diagram of the positional relationship between the steel pipe and the fixing mechanism of the present invention; Figure 4 Schematic diagram of the structure of a single fixing mechanism of the present invention; Figure 5 For the present invention Figure 1 Partial enlarged schematic diagram at position A; Figure 6 Schematic diagram of the structure of the stress transfer unit of the present invention; Figure 7 Schematic diagram of the structure of the cable fixing unit of the present invention; Figure 8 Schematic diagram of the connection relationship of the cable fixing unit of the present invention; Figure 9 Schematic three - dimensional structure diagram of the support mechanism of the present invention; Figure 10 Front - view structure schematic diagram of the support mechanism of the present invention.

[0031] Wherein: 1. Outer layer of primary support; 2. Waterproof layer; 201. Steel pipe; 202. Steel sleeve; 2021. Expanded perlite; 203. Waterproof rubber; 3. Fixing mechanism; 301. Anchor support; 3011. Spiked head; 302. Anchor support buckle; 303. First spring; 304. Perlite buckle; 4. Stress transfer layer; 401. First steel arch; 4011. Anchor bolt; 402. Second steel arch; 5. Stress transfer mechanism; 6. Stress transfer unit; 601. Steel plate; 6011. Cylindrical channel; 602. Connecting rod; 603. Second spring; 604. Support rod; 7. Cable fixing unit; 701. Cable splitter; 7011. Annular groove; 7012. Inlet; 7013. Outlet; 702. Cable; 703. Fixing rod; 704. Piston push rod; 705. Third spring; 706. Cross lock; 707. Ball joint; 7071. Opening; 8. Support mechanism; 801. Upper support plate; 802. Lower support plate; 803. Steel column; 804. Fourth spring. Detailed implementation manners

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and illustrated herein can be arranged and designed in various different configurations.

[0033] The inventors' research found that traditional initial support usually only uses simple sprayed concrete or a small amount of steel mesh in combination with anchor rods, which cannot ensure the sealing and durability of the support structure; traditional waterproof layers are mostly laid with a single waterproof material, which is easily torn and damaged, resulting in waterproof failure, and the connection between these waterproof layers and the surrounding rock and support structure is not tight and stable enough, making it difficult to adapt to the dynamic deformation of the surrounding rock; the steel arch support in the traditional support structure is locally subjected to excessive force, and is prone to twisting, deformation or even breakage, and cannot disperse the pressure to the entire circumference, which greatly reduces the overall stability of the support structure.

[0034] Based on the above findings, the present application proposes a high-pressure karst tunnel support structure and a construction method thereof. From the initial support outer layer to the waterproof layer, and then to the stress transfer layer, the various structural layers are closely connected and complement each other. The steel mesh of the initial support outer layer and the sprayed concrete are tightly attached to the rock wall, providing a solid foundation for the subsequent installation of the waterproof layer and the stress transfer layer, and preliminarily controlling the deformation of the surrounding rock. The waterproof layer not only achieves the stability of the waterproof layer's own structure, but is also tightly connected to the initial sprayed anchor support outer layer to prevent the waterproof layer from shifting or falling off due to tunnel vibration or water pressure shock. The stress transfer layer is organically combined with the waterproof layer and the initial support outer layer, and each component works together to build a comprehensive, multi-level stable support system to ensure the safety of tunnel construction and operation. Example 1

[0035] The present application discloses an initial support structure for a tunnel.

[0036] In the embodiment of the present invention, Figures 1 to 10 As shown, the initial support structure of the tunnel includes an initial support outer layer 1, which is arranged on the rock wall on the wall surface after the tunnel is excavated. The initial support outer layer 1 includes a steel mesh and shotcrete. The steel mesh is a mesh structure woven by crisscrossing steel bars. Steel bars with a diameter of 6-12 mm are used, and the grid spacing is 100-300 mm. The steel mesh is laid first and then the concrete is shotcreted to form a complete support structure. The steel mesh enhances the integrity and tensile strength of the concrete, while the shotcrete provides sealing and supporting effects. The two complement each other and jointly improve the stability and durability of the support structure, so as to achieve the purpose of quickly sealing the surrounding rock surface and preliminarily controlling the deformation of the surrounding rock.

[0037] A waterproof layer 2 is provided on the inner side of the outer layer 1 of the initial support to prevent groundwater from seeping into the tunnel interior. The waterproof layer 2 includes a steel pipe 201 with both ends open and vertically placed, and a number of small holes are provided on the shell. A steel casing 202 is sleeved inside the steel pipe 201, with both ends of the steel casing 202 open. A layer of expanded perlite 2021 is provided on the inner layer of the steel casing 202, which can absorb part of the water when the surrounding rock seeps water, enhance the expansion effect of the water-stop rubber, and at the same time, the porous structure of the expanded perlite 2021 can provide a certain buffer and support when the fixing mechanism 3 is activated, ensuring that the water-stop rubber 203 pops out smoothly and is in close contact with the surrounding rock. The space between the steel pipe 201 and the steel casing 202 is filled with water-stop rubber 203. The water-stop rubber 203 is a high-special rubber with the property of absorbing water and expanding. When water seeps in the tunnel, the water-stop rubber 203 will quickly absorb water and expand, with its volume and mass increasing several times, and it will expand out from the small holes of the steel pipe shell to block the leakage point and prevent water from continuing to seep into the tunnel interior, forming a dense water-stop barrier. Two fixing mechanisms 3 are provided inside the steel casing 202. The tails of the two fixing mechanisms 3 are arranged oppositely at both ends of the steel casing 202. The fixing mechanism 3 includes a support anchor 301 with a cavity structure inside. A number of barbs 3011 are provided at the front end. The barbs 3011 are conical and open at the front end, which are used to enhance the connection between the waterproof layer 2 and the outer layer 1 of the initial support. A support anchor buckle 302 is also provided at the front end of the support anchor 301. A first spring 303 is sleeved at the tail end of the support anchor 301. A perlite buckle 304 is provided on the inner wall of the expanded perlite layer, which cooperates with the support anchor buckle 302 to form a mechanical locking structure. In the initial state, the support anchor buckle 302 and the perlite buckle 304 are engaged with each other to ensure that the first spring 303 remains in a compressed state in the initial state and prevent the support anchor 301 from ejecting prematurely. A water-stop rubber 203 is provided on the side of the fixing mechanism 3 away from the two ends of the steel casing 202. When water seeps in the tunnel, the water-stop rubber 203 starts to absorb water and expand. As the water-stop rubber 203 expands, the water-stop rubber 203 will enter the support anchor 301 and gradually push the first spring 303. When the water-stop rubber 203 expands to a certain extent, the thrust generated by it will exceed the restoring force provided by the engagement of the support anchor buckle 302 and the perlite buckle 304 to the first spring 303, the support anchor buckle 302 and the perlite buckle 304 will separate, and the first spring 303 releases energy to push the support anchor 301 to move forward. The barbs 3011 at the front end of the support anchor 301 will penetrate into the nearest inner and outer layer walls, firmly fixing the waterproof layer 2 between the outer layer 1 of the initial support and the stress transfer layer 4, enabling the waterproof layer 2 to automatically adjust when the surrounding rock deforms or seeps water, ensuring the effectiveness of the water-stop system.

[0038] On the inner side of the waterproof layer 2, there is a stress transfer layer 4, which includes a first steel arch 401 and a second steel arch 402. Both the first steel arch 401 and the second steel arch 402 are composed of several I-beams, forming an arch structure that can withstand a large surrounding rock pressure. The first steel arch 401 includes an arch layer and bolts 4011. The bolts 4011 are distributed along the circumference of the arch layer. The bolts 4011 are anchored in the tunnel surrounding rock and fixedly connected to the arch layer. Between the first steel arch 401 and the second steel arch 402, there are multiple support mechanisms 8 and stress transfer mechanisms 5 arranged at intervals. The multiple support mechanisms 8 and stress transfer mechanisms 5 are evenly distributed along the circumference of the tunnel surrounding rock. The support mechanism 8 is used to provide rigid support for the support structure while releasing a certain amount of surrounding rock deformation; the stress transfer mechanism 5 is used to transfer the radial force exerted by the external surrounding rock on the support structure into an axial force along the steel arch, and disperse the pressure along its arch structure to the entire circumferential direction.

[0039] The stress transfer mechanism 5 includes stress transfer units 6, with 2 of them, arranged between the first steel arch 401 and the second steel arch 402, and fixedly connected to the first steel arch 401 and the second steel arch 402 respectively, for receiving and transferring the radial force exerted by the external surrounding rock on the support structure.

[0040] The stress transfer unit 6 includes a steel plate 601, which is welded to the first steel arch 401 or the second steel arch 402, for receiving the radial force from the outer surrounding rock on the first steel arch 401 and the second steel arch 402. On both sides of the steel plate 601, there are cylindrical channels 6011, and the middle of the cylindrical channels 6011 is open. Inside the cylindrical channels 6011, there is a connecting rod 602. The connecting rod 602 can rotate in the cylindrical channels 6011 and slide along its axial direction. On both sides inside the cylindrical channels 6011, there are second springs 603 welded. The sides of the second springs 603 away from the two ends of the cylindrical channels 6011 are respectively welded to the two ends of the connecting rod 602. In the middle of the connecting rod 602, there is a support rod 604 fixedly arranged. The support rod 604 extends obliquely upward and is fixedly connected to the cable fixing unit 7. When the external surrounding rock exerts a radial force on the steel arch, the steel plate 601 first receives this radial force and transfers it to the connecting rod 602. The connecting rod 602 rotates or slides axially in the cylindrical channels 6011 according to the direction of this stress, compressing or stretching the second springs 603. At this time, the support rod 604 will slide inside the cylindrical channels 6011 according to the external force situation and transfer the force to the cable fixing unit 7. Through this mechanism, the radial force is effectively transferred and redirected to the cable fixing unit 7.

[0041] The stress transfer mechanism 5 further includes two oppositely arranged cable fixing units 7 (with the direction of the outlet 7013 as a reference), which are arranged between the stress transfer units 6 and fixedly connected to the stress transfer units 6, and are used to receive the radial force from the stress transfer units 6 and convert it into the axial force along the steel arch. The cable fixing unit 7 includes a cable diverter 701, which is a disk-shaped solid structure. An annular groove 7011 is formed on the disk, and an inlet 7012 and an outlet 7013 for allowing the cable 702 to enter and exit are provided. Cross locks 706 are arranged at the inlet 7012 and the outlet 7013 for fixing the cable 702. The cable is a high molecular carbon fiber composite cable. The function of the cable diverter 701 is to enable the cable 702 to receive forces from different directions. Specifically, a thick cable enters the annular groove 7011 of the cable diverter 701 from the inlet 7012 and is divided into several thin cables. The several thin cables are divided into two parts and respectively surround the annular groove 7011 for half a week along the upper and lower directions of the opening. Finally, each part of the thin cables is re-stranded at the outlet and converges again to form a thick cable, so as to receive stresses at different positions and angles and convert the radial force into the axial force that stretches the cable 702. Fixing rods 703 are symmetrically and penetratively arranged outside the cable diverter 701 through ball joints 707. There are two fixing rods 703, and their interiors are all cavity structures. An opening 7071 is formed on the ball joint 707 and communicates with the interior of the fixing rod 703 to provide a moving space for the piston push rod 704. A piston push rod 704 is slidably arranged through and inside the fixing rod 703. The external thread of the piston push rod 704 is in threaded connection with the internal thread of the support rod 604 to receive the radial force, so that the piston push rod 704 moves axially along the fixing rod 703. A third spring 705 is sleeved on the piston push rod 704 to buffer and stabilize the piston push rod 704 against the pressure of the cable 702. When the radial force transmitted by the support rod 604 acts on the piston push rod 704, the piston push rod 704 will move inside the fixing rod 703 towards the direction where the cable diverter 701 is located and flexibly adjust its direction according to the direction of the force until the cable 702 is pressed into the annular groove 7011 of the cable diverter 701 for fixing the cable 702 and transmitting the stress. At this time, the radial force will be evenly distributed on the part where the cable 702 contacts the annular groove 7011 and converted into the axial force that stretches itself, and the forces in all directions are coordinated and balanced during the process of the thin cables converging and re-stranding into a thick cable.Finally, the radial force distributed at the contact part of the cable 702 and the annular groove 7011 is transmitted from the inlet 7012 of the cable 702 to the outlet 7013 along the direction of the inlet 7012 of the cable 702, causing the cable 702 to produce tensile deformation, achieving the successful conversion of the complex and variable radial force into the tensile force along the axis of the cable 702, and then dispersing the force along the axis of the steel arch through the cable 702, greatly enhancing the ability of the support structure to cope with the radial force of the surrounding rock and ensuring the overall stability of the tunnel.

[0042] Taking the stress transfer mechanism 5 at the highest point of the tunnel as an example for analysis, the specific situation is as follows: When the external surrounding rock exerts a radial pressure on the support structure, the first steel arch 401 and the second steel arch 402 will apply the radial pressure to the stress transfer units 6 at the upper and lower ends. The stress transfer unit 6 transfers the radial force to the piston push rod 704 through the support rod 604. The piston push rod 704 will move inside the fixed rod 703 towards the direction where the cable diverter 701 is located and flexibly adjust its direction according to the direction of the force until the cable 702 is pressed into the annular groove 7011 of the cable diverter 701. At this time, the cable 702 will be stretched from the inlet 7012 to the outlet 7013, achieving the purpose of converting the radial force into the axial tensile force of the cable 702. Since the two cable fixing units 7 in the stress transfer mechanism 5 are relatively arranged with reference to the direction of the outlet 7013, the stress transfer mechanism 5 at the highest point will stretch the cable 702 towards the place where the outlets 7013 of the two cable fixing units 7 are close to each other, thereby realizing the conversion of the radial force between the stress transfer mechanism 5 at the highest point and the stress transfer mechanisms 5 on its adjacent sides into the axial tensile force of its cable 702. At the same time, the stress transfer mechanism 5 at the highest point of the tunnel may also play a role in reversely supporting the stress transfer mechanisms 5 on its adjacent sides. Therefore, the stress transfer mechanism 5 will transfer the radial force applied by the tunnel into the axial force along the steel arch, disperse the pressure along its arch structure to the entire circumferential direction, and provide reverse support for each other.

[0043] The support mechanism 8 includes two support plates, namely the upper support plate 801 fixedly connected to the first steel arch 401 and the lower support plate 802 fixedly connected to the second steel arch 402. The support plates provide rigid support for the entire support structure to prevent excessive deformation of the surrounding rock. Steel columns 803 are fixedly connected to the positions near the four corners of the lower support plate 802. One end of a fourth spring 804 is welded to the upper end of the steel column 803, and the other end of the fourth spring 804 is welded to the upper support plate 801, which is used to allow the surrounding rock to undergo slight deformation within a certain range and avoid the failure of the support structure due to excessive deformation of the surrounding rock.

[0044] In a possible implementation manner, a lining layer is further provided inside the stress transfer layer 1, which is used to enhance the waterproof performance, improve the overall strength of the structure, protect the internal structure and improve the durability.

[0045] The present application discloses a construction method for a high-water-pressure karst tunnel, which is used for constructing the supporting structure of the above-mentioned high-water-pressure karst tunnel, and includes the following steps: Step 1, after the tunnel is excavated, the outer layer 1 of the initial support is promptly laid on the inner wall surface of the surrounding rock. First, the steel mesh is laid to make it fit the rock wall, and then concrete is sprayed onto the steel mesh to cover the steel mesh and be tightly combined with the rock wall, forming an initially stable support structure to initially control the deformation of the surrounding rock.

[0046] Step 2, a waterproof layer 2 is arranged on the outer layer 1 of the initial support: the steel sleeve 202 is sleeved inside the steel pipe 202, expanded perlite 2021 and a fixing mechanism 3 are arranged inside the steel sleeve 202, and then the water-stop rubber 203 is filled to complete the construction of the waterproof layer 2.

[0047] Step 3, erect the steel arch support structure: first install the first steel arch 401, anchor the bolt 4011 in the tunnel surrounding rock and firmly fix it to its arched layer, and then install the second steel arch 402 at an appropriate position inside the first steel arch 401.

[0048] Step 4, the support mechanism 8 is evenly installed circumferentially along the tunnel surrounding rock between the first steel arch 401 and the second steel arch 402.

[0049] Step 5, two stress transfer units 6 are installed between the first steel arch 401 and the second steel arch 402, one is fixed on the first steel arch 401 and the other is fixed on the second steel arch 402. The two stress transfer units 6 are installed opposite to each other, and the stress transfer unit 6 is installed at intervals with the support mechanism 8 so that it can receive and transfer the radial force exerted by the external surrounding rock on the support structure.

[0050] Step 6, a cable fixing unit 7 is installed between the two stress transfer units 6 so that it can receive the radial force from the stress transfer unit 6 and convert it into an axial force along the steel arch, and then disperse the pressure along the arched structure to the entire circumferential direction.

[0051] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A high - water - pressure karst tunnel support structure, characterized in that, Comprising: The outer layer of the initial support (1), which is arranged on the rock wall of the wall surface after the tunnel excavation; The waterproof layer (2), which is arranged on the inner side of the outer layer of the initial support (1); The stress transfer layer (4), which is arranged on the inner side of the waterproof layer (2), includes a first steel arch (401) and a second steel arch (402), and a plurality of support mechanisms (8) and stress transfer mechanisms (5) are arranged at intervals between the first steel arch (401) and the second steel arch (402), and the plurality of support mechanisms (8) and stress transfer mechanisms (5) are evenly distributed along the circumferential direction of the tunnel surrounding rock; Wherein, the support mechanism (8) is used to provide rigid support for the support structure while releasing a certain amount of surrounding rock deformation; The stress transfer mechanism (5) is used to transfer the radial force applied by the external surrounding rock to the support structure into an axial force along the steel arch, and disperse the pressure along its arched structure to the entire circumferential direction.

2. The high-water-pressure karst tunnel support structure according to claim 1, characterized in that: The waterproof layer (2) includes: The steel pipe (201), both ends of which are open, is placed vertically, and a number of small holes are opened on the shell; The rigid sleeve, which is sleeved inside the steel pipe (201), both ends of which are open, a layer of expanded perlite (2021) is arranged on the inner layer, and two fixing mechanisms (2) with opposite tails are arranged inside, and a water-stop rubber (203) is arranged on one side of the two fixing mechanisms (2) away from the port; Wherein, the gap between the steel pipe (201) and the steel sleeve (202) is filled with the water-stop rubber (203).

3. The support structure for a high-water-pressure karst tunnel according to claim 1, characterized in that: The fixing mechanism (3) includes: The anchor (301), the inside of which is a cavity structure, a number of barbs (3011) are arranged at the front end and the front end of the barbs (3011) is open, and an anchor buckle (302) is arranged at the front end of the anchor (301); The first spring (303), which is sleeved on the tail end of the anchor (301); The perlite buckle (304), which is arranged on the inner wall of the expanded perlite layer (2021) and cooperates with the anchor buckle (302) to make the initial state of the first spring (303) a compressed state; Wherein, the water-stop rubber (203) on one side of the fixing mechanism (3) away from the port starts to absorb water and expand into the inside of the anchor (301) and starts to push the first spring (303). When the thrust for pushing the first spring (303) is greater than the restoring force provided by the mutual engagement of the anchor buckle (302) and the perlite buckle (304) to the first spring (303), the anchor (301) ejects and pierces into the nearest layer wall.

4. A high - water - pressure karst tunnel support structure according to claim 1, characterized in that: The stress transfer mechanism (5) includes: The stress transfer units (6), there are 2 of them, which are arranged between the first steel arch (401) and the second steel arch (402), and are respectively fixedly connected with the first steel arch (401) and the second steel arch (402), and are used to receive and transfer the radial force applied by the external surrounding rock to the support structure; The cable fixing unit (7) has two, which are relatively arranged between the stress transfer units (6), fixedly connected to the stress transfer units (6), and are used to receive the radial force from the stress transfer units (6) and convert it into the axial force along the steel arch.

5. The high - water - pressure karst tunnel support structure according to claim 4, characterized in that: The stress transfer unit (6) includes: A steel plate (601) fixedly arranged on the steel arch, with cylindrical channels (6011) opened on both sides, and the middle of the cylindrical channels (6011) is open; A connecting rod (602) arranged inside the cylindrical channel (6011) and capable of sliding along its axial direction; A second spring (603) fixedly arranged on both sides inside the cylindrical channel (6011), and the sides away from the two ports of the cylindrical channel (6011) are respectively fixedly connected to the two ends of the connecting rod (602); A support rod (604) fixedly arranged in the middle of the connecting rod (602), inclined upward and fixedly connected to the cable fixing unit (7); Among them, the steel plate (601) receives the radial force from the outer surrounding rock on the first steel arch (401) and the second steel arch (402), and the connecting rod (602) and the support rod (604) can rotate or slide axially inside the cylindrical channel (6011) according to the external force condition.

6. The high - water - pressure karst tunnel support structure according to claim 4, characterized in that: The cable fixing unit (7) includes: A cable diverter (701), a disc-shaped solid structure, with an annular groove (7011) opened on the disc, and an inlet (7012) and an outlet (7013) allowing the cable to enter and exit; A cable (702) arranged inside the annular groove, used to receive stresses at different positions and angles, and convert the radial force into the axial force that stretches the cable (702); Two fixing rods (703), with a cavity structure inside, symmetrically and penetratingly arranged outside the cable diverter (701) through spherical hinges (707), and an opening (7071) is opened on the spherical hinge (707) and communicated with the inside of the fixing rod (703); A piston push rod (704) penetratingly arranged inside the fixing rod (703), the piston push rod (704) is threadedly connected to the support rod (604), and is used to receive the radial force to make the piston push rod (704) move axially along the fixing rod (703); A third spring (705) sleeved on the piston push rod (704), used to buffer and stabilize the pressure of the piston push rod (704) along with the cable (702); Among them, after the piston push rod (704) receives the displacement and force transmitted from the support rod (604), it will move in the direction of the cable diverter (701) until the cable (702) is pressed into the annular groove (7011) of the cable diverter (701). At this time, due to the effect of the ball joint (707), the fixed rod (703) and the piston push rod (704) will rotate arbitrarily along with the direction of the force, and the force will be distributed on the part where the cable (702) contacts the annular groove (7011), and is transmitted along the axial direction of the cable annular groove (7011) from the inlet (7012) to the outlet (7013) to cause tensile deformation of the cable (702).

7. The high-water-pressure karst tunnel support structure according to claim 1, characterized in that: The support mechanism (8) includes: Support plates, there are 2 of them, namely the upper support plate (801) and the lower support plate (802), which are respectively fixedly connected to the first steel arch (401) and the second steel arch (402); Steel columns (803), there are multiple of them, arranged in the middle of the upper support plate (801) and the lower support plate (802). The lower end of the steel column (803) is fixedly connected to the lower support plate (802), and the upper end of the steel column (803) is elastically connected to the upper support plate (801) through the fourth spring (804).

8. A high-water-pressure karst tunnel support structure according to claim 1, characterized in that: The primary support outer layer (1) includes a steel mesh and shotcrete.

9. A high-water-pressure karst tunnel support structure according to claim 1, characterized in that: The first steel arch (401) includes an arched layer and anchor bolts (4011), and the anchor bolts (4011) are distributed along the circumferential direction of the arched layer. The anchor bolts (4011) are anchored in the tunnel surrounding rock and fixedly connected to the arched layer.

10. The construction method of the high-water-pressure karst tunnel support structure according to any one of claims 1 to 9, characterized in that It includes the following steps: Step 1, after the tunnel is excavated, the primary support outer layer (1) is timely laid on the inner wall surface of the surrounding rock. First, the steel mesh is laid to make it fit the rock wall, and then shotcrete is sprayed onto the steel mesh to cover the steel mesh and be closely combined with the rock wall to form a primary stable support structure and initially control the deformation of the surrounding rock; Step 2, set the waterproof layer (2) on the primary support outer layer (1): sleeved the rigid sleeve inside the steel pipe (201), set the expanded perlite (2021) and the fixing mechanism (2) inside the steel sleeve (202), and then fill it with the water-stop rubber (203) to complete the construction of the waterproof layer (2); Step 3, erect the steel arch support structure: first install the first steel arch (401), anchor the anchor bolts (4011) in the tunnel surrounding rock and firmly fix them to its arched layer, and then install the second steel arch (402) at a suitable position inside the first steel arch (401); Step 4, evenly install the support mechanism (8) along the circumferential direction of the tunnel surrounding rock between the first steel arch (401) and the second steel arch (402); Step 5, install 2 stress transfer units (6) between the first steel arch (401) and the second steel arch (402), one is fixed on the first steel arch (401), and the other is fixed on the second steel arch (402). The 2 stress transfer units (6) are installed oppositely, and the stress transfer units (6) are installed at intervals with the support mechanism (8) so that they can receive and transfer the radial force applied by the external surrounding rock to the support structure; Step 6: Install a cable fixing unit (7) between two stress transfer units (6) so that it can receive the radial force from the stress transfer unit (6) and convert it into an axial force along the steel arch, thereby dispersing the pressure along the arched structure in the entire circumferential direction.

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