A tunnel anchoring structure with anti-blast and wave resistance and a construction method thereof

Abstract

The application discloses an anti-blast and anti-wave tunnel anchoring structure and a construction method, belongs to the technical field of tunnel surrounding rock anti-blast support, and comprises a group anchor rod and a protection component, wherein the group anchor rod comprises a central anchor rod assembly and a plurality of peripheral anchor rod assemblies which are arranged outside the central anchor rod assembly, and the protection component is embedded in the surrounding rock outside the group anchor rod. The protection component is used for absorbing and dissipating the energy of the blast stress wave, the group anchor rod is used for dispersively transmitting the residual impact load to the surrounding rock, and the protection component and the group anchor rod are cooperatively matched to realize the graded anti-blast support on the surrounding rock, so that the support reliability and the anti-blast safety of the tunnel surrounding rock under the strong dynamic load working condition are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of blast-resistant support technology for tunnel surrounding rock, specifically a blast-resistant wave-damping tunnel anchoring structure and construction method. Background Technology

[0002] As transportation tunnels, underground civil defense caverns, and deep mine roadways continue to expand into deeper and more complex geological areas, tunnel excavation blasting and external impact explosions generate high-intensity stress waves that propagate within the rock mass, causing surrounding rock loosening and inducing disasters such as spalling, collapse, and support failure, seriously threatening tunnel construction and long-term safety. Currently, the mainstream tunnel support system primarily uses full-length bonded mortar anchors and hollow grouting anchors. These anchors mainly rely on grout bonding to achieve surrounding rock anchoring. Their structural design focuses on bearing static surrounding rock pressure and does not specifically address the blocking and dissipation of explosive stress waves. Therefore, they have significant shortcomings under strong dynamic load conditions and are unable to withstand complex and variable external instantaneous impact loads.

[0003] Existing tunnel anchor support structures are mostly independent single structures. The forces on each anchor are dispersed and the coordination is poor. When subjected to external impact, the load cannot be effectively transferred and dispersed, which easily leads to problems such as overload fracture of a single anchor, debonding of the anchorage interface, and cracking and falling off of the grout, resulting in local support failure and subsequent chain-like instability and failure of the surrounding rock.

[0004] At present, some impact-resistant anchor bolts are improved by focusing on the energy absorption of a single anchor bolt, but a systematic group anchor bolt collaborative protection system has not been formed. This makes it impossible to achieve graded dissipation and overall dispersion of impact loads, resulting in limited resistance to external impacts and difficulty in meeting the needs of tunnel blast-resistant support. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to propose a tunnel anchoring structure and construction method for blast-resistant wave-damping, which achieves graded blast resistance through the coordinated cooperation of group anchor bolts and protective components, effectively improving the support reliability and blast-resistant safety of tunnel surrounding rock under strong dynamic load conditions.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a tunnel anchoring structure for blast resistance and wave blocking, comprising a group of anchor bolts and protective components. The group of anchor bolts includes a central anchor bolt assembly and several peripheral anchor bolt assemblies arranged around the outside of the central anchor bolt assembly. The protective components are embedded in the surrounding rock outside the group of anchor bolts.

[0007] As a further improvement to the technical solution, the protective component is a protective cylinder made of aluminum foam, and the outer surface of the protective cylinder is coated with a polyurea layer. The protective cylinder is embedded in the annular mounting groove of the surrounding rock and surrounds the outside of the group of anchor bolts.

[0008] As a further improvement to the technical solution, the protective component is a grid frame, which includes a plurality of first partitions arranged in a ring along the longitudinal direction of the tunnel. A second partition group is arranged between two adjacent first partitions. The second partition group includes a plurality of second partitions distributed circumferentially. Each second partition is perpendicular to the first partition. The second partitions in two adjacent second partition groups are staggered. A plurality of circumferential grooves for installing the first partitions are opened in the surrounding rock along the longitudinal direction of the tunnel. A plurality of longitudinal grooves for installing the second partitions are opened between two adjacent circumferential grooves. The first partitions and the second partitions are made of aluminum foam and their outer surfaces are coated with a polyurea layer.

[0009] As a further improvement to the technical solution, the group of anchor bolts includes a central anchor bolt assembly and six peripheral anchor bolt assemblies evenly distributed circumferentially outside the central anchor bolt assembly. Both the central and peripheral anchor bolt assemblies include an anchor bolt body, an anchor bolt cluster end tie rod, multiple anchor bolt cluster ends, and an anchor bolt cluster end limiter. One end of the anchor bolt body used to insert into the anchor bolt hole drilled in the surrounding rock is defined as the front end, and the other end as the rear end. The front end face of the anchor bolt body of the central anchor bolt assembly is connected to six anchor bolt cluster ends evenly distributed circumferentially. An anchor bolt cluster end limiter is installed on the anchor bolt cluster end. The front end of the anchor bolt cluster end tie rod passes through the anchor bolt cluster end limiter, and its rear end extends into the axial channel of the anchor bolt body and protrudes from the rear end of the anchor bolt body. The front end of the anchor bolt cluster end tie rod is provided with a compression part, located on the front side of the space enclosed by the anchor bolt cluster ends. The outer side of the front end of the anchor bolt body is also provided with a hole for inserting the anchor bolt body into the anchor bolt hole. Then, the limiting part can be locked at the front end of the anchor bolt hole; when the anchor bolt cluster end pull rod is pulled backward, the extrusion part extrudes the anchor bolt cluster end. Under the reaction force provided by the limiting part, the anchor bolt cluster end of the central anchor bolt assembly bends toward the corresponding peripheral anchor bolt assembly. Among the three anchor bolt cluster ends of the peripheral anchor bolt assembly, the middle anchor bolt cluster end bends toward the central anchor bolt assembly, and the two anchor bolt cluster ends on both sides bend toward the adjacent peripheral anchor bolt assembly respectively. The extrusion part of the peripheral anchor bolt assembly has a boss on the rear side, which faces one of the anchor bolt cluster ends on both sides. The orthographic projections of the anchor bolt cluster ends of the central anchor bolt assembly and the peripheral anchor bolt assembly on the reference plane perpendicular to the axial direction of the anchor bolt body overlap and are spaced apart axially. The orthographic projections of the two anchor bolt cluster ends between adjacent peripheral anchor bolt assemblies overlap on the reference plane perpendicular to the axial direction of the anchor bolt body and are spaced apart axially, forming an overall force-bearing skeleton.

[0010] As a further improvement to the technical solution, the anchor bolt cluster end limiter is provided with a central positioning hole and several peripheral positioning holes evenly distributed around the central positioning hole. The anchor bolt cluster end tie rod passes through the central positioning hole, and the anchor bolt cluster ends pass through the corresponding peripheral positioning holes respectively. The anchor bolt cluster ends are fixedly connected to the anchor bolt cluster end limiter at the position where they pass through the peripheral positioning holes.

[0011] As a further improvement to the technical solution, a positioning steel bar is provided between the anchor cluster end limiter of the peripheral anchor bolt assembly and the front end of the anchor bolt body.

[0012] As a further improvement to the technical solution, the anchor bolt cluster end includes a plain round steel bar. On the plain round steel bar located at the front end of the anchor bolt cluster end limiter, multiple metal reinforcing collars are spaced apart along its length direction. The rear end of the plain round steel bar is connected to the front end face of the anchor bolt body.

[0013] As a further improvement to the technical solution, the anchor bolt cluster end tie rod includes a tie rod body and an extrusion part in the shape of an inverted frustum disposed at the front end of the tie rod body. The orthographic projection of the extrusion part on a reference plane perpendicular to the axial direction of the anchor bolt body at least partially coincides with the orthographic projection of the metal reinforcing collar on the reference plane.

[0014] As a further improvement to the technical solution, the limiting part includes a tension support limiter, a tension support, and an elastic element. The tension support limiter is located on the outer side of the front end of the anchor rod body to limit the opening angle of the tension support. On the anchor rod body located at the rear end of the tension support limiter, multiple grooves are evenly opened along its circumference. The tension support is hinged in the groove. An elastic element is also provided between the tension support and the bottom of the groove. Under the action of the elastic element, the tension support opens radially and is locked at the front end of the anchor rod hole to limit the displacement of the anchor rod body in the rearward direction and provide a reaction force for pulling the tie rod at the end of the anchor rod cluster.

[0015] Based on the above structure, this invention proposes a construction method for an anti-blast wave tunnel anchoring structure, comprising the following steps: S1. First, based on the physical and mechanical properties of the rock mass and the support requirements, determine the length of each individual anchor rod in a group of anchor rods. Since tunnel and underground cavern excavation is mostly carried out by blasting, even under the same geological conditions, different blasting designs and construction methods may result in different loosening ranges of the surrounding rock. Therefore, the determination of the length of each individual anchor rod must be carried out through on-site experiments. The thickness of the loosened zone of the surrounding rock is determined by on-site sonic wave velocity testing, and the radius R of the plastic zone is obtained. The length of each individual anchor rod is calculated using the following formula: L = R + L0 + L1 + L2, where R is the radius of the plastic zone, L0 is the anchoring length extending into the intact rock mass (L0≥0.5m in hard rock, L0≥1.0m in soft rock or under high ground stress), L1 is the length of the anchor rod cluster end (L1≥0.3m), and L2 is the exposed length of the pad, i.e., the length of the rear end of the anchor rod extending beyond the outer side of the outer ring pad, used for installing the nut (L2 is taken as 0.15m). S2. Based on the equilibrium calculation of the surrounding rock's stable plastic zone, and taking into account the synergistic effect of the group anchor bolts, the distribution design of the group anchor bolts is carried out with the basic principle of preventing local collapse arches. The maximum spacing between rows of group anchor bolts is S. max ≤0.5L ＇ L ＇ The effective anchorage length of the anchor rod body excluding exposed sections; based on the maximum spacing between groups of anchor rods, several groups of anchor rods are arranged along the longitudinal and circumferential directions of the tunnel to form an anchorage support system covering the entire tunnel cross section; S3. Drill the central anchor bolt hole in the surrounding rock using a reaming drill. The initial drilling length is R + L0, and the minimum drilling diameter is φ45, φ48, or φ52 mm. When the anchor bolt body is a custom specification, the drilling diameter should be at least 20 mm larger than the anchor bolt body diameter. At the bottom of the central anchor bolt hole, form a front-end reaming cavity through multi-stage reaming. The reaming section length is L1 + L2, and the reaming diameter should be at least 0.3 m. Then drill several peripheral anchor bolt holes. The peripheral anchor bolt assembly uses the same specification anchor bolt body as the central anchor bolt assembly, and the drilling length is also the same. All peripheral anchor bolt holes are connected to the front-end reaming cavity. S4. Insert the central anchor bolt assembly into the central anchor bolt hole, so that the limiting part of the central anchor bolt assembly passes through the front end opening of the central anchor bolt hole and stops at the front end opening. Pull the anchor bolt cluster end pull rod backward so that the anchor bolt cluster end of the central anchor bolt assembly bends radially in the front enlarged cavity. S5. Insert the peripheral anchor bolt assemblies into the corresponding peripheral anchor bolt holes, so that the limiting part of the peripheral anchor bolt assembly passes through the front end opening of the corresponding peripheral anchor bolt hole and is stuck at the front end opening. Pull the anchor bolt cluster connection end pull rod of the peripheral anchor bolt assembly respectively, so that the anchor bolt cluster connection end of the peripheral anchor bolt assembly is bent radially in the front enlarged cavity. S6. Grouting is performed on the anchor bolts of the central anchor bolt assembly and the peripheral anchor bolt assembly, respectively, into the central anchor bolt hole, the peripheral anchor bolt hole and the front end enlarged cavity. S7. Seal the openings of the central anchor bolt hole and each peripheral anchor bolt hole respectively. Pass the rear ends of the central anchor bolt assembly and the peripheral anchor bolt assembly through the inner ring pad and the anchor bolt assembly pad in sequence, and then lock the outer ring pad with nuts. S8. After the group of anchor bolts is installed, a protective component is installed around the group of anchor bolts. If the protective component is a protective cylinder, the cylinder drill is used to drill into the surrounding rock along the axis of the central anchor bolt assembly to form an annular installation groove. The drilling depth of the cylinder drill is at least 1 / 3 of the length of the anchor bolt body, and the diameter of the cylinder drill is not less than twice the diameter of the outer circle of the cross section of the group of anchor bolts. The protective cylinder is then embedded in the annular installation groove and fixed. If the protective component is a grid cylinder frame, a chain grooving machine is used to groove the groove perpendicular to the tunnel surrounding rock surface. During grooving, an annular groove is opened along the longitudinal direction of the tunnel at the centerline position between two adjacent rows of group anchor bolts, and a longitudinal groove is opened along the circumferential direction of the tunnel at the centerline position between two adjacent columns of group anchor bolts. The longitudinal groove and the annular groove intersect to form a grid structure. Then, the grid cylinder frame is placed into the grid structure and fixed.

[0016] Based on the aforementioned technical solution, the present invention has the following beneficial effects: (1) The anchor cluster ends of the central anchor assembly and the peripheral anchor assembly of the present invention are bent radially by the compression of the anchor cluster end pull rod, so that the central anchor assembly and the anchor cluster ends of the peripheral anchor assembly overlap on the orthogonal projection part on the reference plane perpendicular to the axial direction of the anchor rod body to form an integral load-bearing skeleton. After grouting, the grout forms a wrapping and solidification of the integral load-bearing skeleton. The anchoring force of the group anchors comes from the synergistic cooperation of the mechanical interlocking of the anchor cluster ends, the group cooperative bearing and the grout wrapping and solidification, which significantly improves the overall pull-out resistance and impact resistance of the group anchors, avoids the problem of uneven load distribution and edge anchors being pulled out first due to overload in the traditional dispersed anchor layout. At the same time, since the integral load-bearing skeleton distributes the load to different parts of the surrounding rock, it avoids stress concentration at the same section of the anchor root, effectively reducing the risk of cracking and debonding of the grouting layer.

[0017] (2) This invention forms a collaborative working mechanism of external absorption and internal transmission, and graded blast resistance through the coordinated cooperation of group anchor bolts and protective components. The protective components, as the first line of defense, use aluminum foam to absorb and dissipate the energy of the explosion stress wave; the remaining impact load after being attenuated by the aluminum foam is transmitted to the group anchor bolts, and further evenly dispersed and transmitted to the surrounding rock by the overall stress skeleton, realizing the graded dissipation and overall dispersion of the impact load, effectively improving the blast resistance safety of the tunnel surrounding rock under strong dynamic load conditions.

[0018] (3) The present invention designs the distribution of group anchor bolts based on the equilibrium calculation of the surrounding rock stability plastic zone, and the maximum spacing between the group anchor bolts Smax ≤ 0.5 L.＇ (L) ＇ (The effective anchorage length of the anchor rod body excluding exposed sections) Several groups of anchor rods are arranged along the longitudinal and circumferential directions of the tunnel, so that adjacent groups of anchor rods form a continuous load-bearing structure covering the entire tunnel cross section, avoiding the occurrence of local collapse arches and significantly improving the integrity and stability of the support system.

[0019] (4) The present invention can flexibly select protective cylinder or grid frame as protective component according to the actual needs of the project. Both forms are made of foam aluminum and the outer surface is coated with polyurea layer to adapt to different tunnel cross-section shapes and construction conditions.

[0020] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in conjunction with the accompanying drawings. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural schematic diagram of a first embodiment of an anti-blast wave tunnel anchoring structure according to the present invention; Figure 2 for Figure 1 Enlarged view of point I; Figure 3 This is a three-dimensional structural schematic diagram of a second embodiment of the blast-resistant and wave-damping tunnel anchoring structure of the present invention; Figure 4 This is a three-dimensional structural diagram of a group of anchor bolts for a tunnel anchoring structure with blast resistance and wave blocking according to the present invention. Figure 5 This is a three-dimensional structural schematic diagram of the central anchor bolt assembly of a tunnel anchoring structure for blast resistance and wave blocking according to the present invention. Figure 6 This is a three-dimensional structural diagram of the peripheral anchor bolt assembly of a blast-resistant and wave-damping tunnel anchoring structure according to the present invention. Figure 7 This is a three-dimensional structural diagram of the group of anchor bolts of the tunnel anchoring structure of the present invention, after the ends of the anchor bolt clusters are bent to form an integral load-bearing skeleton. Figure 8 for Figure 7 A magnified view of section II; Figure 9 This is a schematic diagram of the three-dimensional structure of the outer ring pad. Figure 10 This is a three-dimensional structural diagram of the anchor cluster end tie rod of the peripheral anchor bolt assembly of the blast-resistant and wave-damping tunnel anchoring structure of the present invention. Reference numerals: 1. Group of anchor bolts; 2. Protective component; 21. Protective cylinder; 22. Grid frame; 2201. First partition; 2202. Second partition; 11. Central anchor bolt assembly; 12. Peripheral anchor bolt assembly; 101. Anchor bolt body; 102. Anchor bolt cluster end tie rod; 1021. Extrusion part; 1022. Tie rod body; 1023. Boss; 103. Anchor bolt cluster end; 104. 1. Plain round steel bar; 1032. Metal reinforced collar; 104. Anchor bolt cluster end limiter; 1041. Central positioning hole; 1042. Peripheral positioning hole; 105. Limiting part; 1051. Tensile support limiter; 1052. Tensile support; 1053. Elastic element; 1054. Groove; 121. Positioning steel bar; 13. Inner ring pad; 14. Anchor bolt group pad; 15. Outer ring pad. Detailed Implementation

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings.

[0023] This invention provides a tunnel anchoring structure and construction method for blast-resistant wave blocking. By setting up a group of anchor bolts 1 in the surrounding rock of the tunnel and embedding protective components 2 in the surrounding rock around the group of anchor bolts 1, the energy absorption and dissipation of the protective components 2 and the synergistic bearing of the group of anchor bolts 1 are used to form a graded blast-resistant system with external absorption and internal transmission, which effectively improves the support reliability and blast-resistant safety of the tunnel surrounding rock under strong dynamic load conditions.

[0024] In this invention, the direction in which the underground engineering extends towards the surface is defined as the vertical direction, and the direction perpendicular to the vertical direction is defined as the horizontal direction. The end of the anchor rod 101 that extends into the anchor hole is defined as the front end, and the end of the anchor rod 101 that protrudes from the anchor hole is defined as the rear end. The front end of all components refers to the direction towards the front end of the anchor rod 101, and the rear end of all components refers to the direction away from the front end of the anchor rod 101. "Axial" refers to the direction parallel to the axis of the anchor rod 101 itself, i.e., the direction from the front end to the rear end; "radial" refers to the direction perpendicular to the axis of the anchor rod 101 itself; and "reference plane perpendicular to the axial direction of the anchor rod 101" refers to a plane perpendicular to the axial direction of the group of anchor rods 1.

[0025] Reference Figure 1 , Figure 2 As a first embodiment of the present invention, a tunnel anchoring structure for blast resistance and wave blocking includes a group of anchor bolts 1 and a protective component 2 embedded in the annular mounting groove of the surrounding rock and surrounding the outside of the group of anchor bolts 1. In this embodiment, the protective component 2 is a protective cylinder 21, which is made of aluminum foam material and has a polyurea layer sprayed on its outer surface.

[0026] Reference Figure 4 , Figure 5 , Figure 6The group of anchor bolts 1 includes a central anchor bolt assembly 11 and six peripheral anchor bolt assemblies 12 that are evenly distributed around the central anchor bolt assembly 11 in the circumferential direction.

[0027] The central anchor bolt assembly 11 and the peripheral anchor bolt assembly 12 have basically the same structure, both including the anchor bolt body 101, the anchor bolt cluster end tie rod 102, the anchor bolt cluster end 103, and the anchor bolt cluster end limiter 104.

[0028] The anchor rod body 101 is a hollow rod made of hollow steel bars, with an internal axial channel serving as both a grouting channel and a tensioning channel for the anchor bolt cluster end tie rod 102. The end of the anchor rod body 101 used to insert into the anchor hole drilled in the surrounding rock is defined as the front end, and the other end as the rear end. The diameter of the anchor rod body 101 can be selected according to actual needs, with conventional values ​​being 25mm, 28mm, or 32mm, and a wall thickness of 6mm.

[0029] The anchor bolt assembly 11 has six circumferentially distributed anchor bolt cluster ends 103 connected to the front end face of the anchor bolt body 101. Each anchor bolt cluster end 103 includes a plain round steel bar 1031, and six metal reinforcing collars 1032 spaced apart along its length on the plain round steel bar 1031 located at the front end of the anchor bolt cluster end limiter 104. The rear end of the plain round steel bar 1031 is connected to the front end face of the anchor bolt body 101. The metal reinforcing collars 1032 are fixed to the plain round steel bar 1031 by spot welding. The diameter of the plain round steel bar 1031 is preferably 6 mm.

[0030] An anchor bolt cluster end limiter 104 is installed on the anchor bolt cluster end 103. The anchor bolt cluster end limiter 104 is disc-shaped and made of high-strength steel. It has a central positioning hole 1041 and peripheral positioning holes 1042 evenly distributed around the central positioning hole 1041. The anchor bolt cluster end tie rod 102 passes through the central positioning hole 1041, and the anchor bolt cluster end 103 passes through the corresponding peripheral positioning holes 1042. The anchor bolt cluster end 103 is fixed to the anchor bolt cluster end limiter 104 at the position where it passes through the peripheral positioning holes 1042.

[0031] The front end of the anchor bolt cluster end tie rod 102 passes through the central positioning hole 1041, and the rear end extends into the axial channel of the anchor bolt body 101 and protrudes from the rear end of the anchor bolt body 101. The anchor bolt cluster end tie rod 102 includes a tie rod body 1022 and a pressing part 1021 in the shape of an inverted frustum disposed at the front end of the tie rod body 1022. The pressing part 1021 is located on the front side of the space enclosed by the anchor bolt cluster end 103. The orthographic projection of the pressing part 1021 on a reference plane perpendicular to the axial direction of the anchor bolt body 101 at least partially coincides with the orthographic projection of the metal reinforcing collar 1032 on the same reference plane.

[0032] The front outer side of the anchor rod body 101 is also provided with a limiting part 105 that can be locked at the front opening of the anchor rod hole after the anchor rod body 101 is inserted into the anchor rod hole. The limiting part 105 includes a tension support limiter 1051, a tension support 1052, and an elastic element 1053. The tension support limiter 1051 is located on the front outer side of the anchor rod body 101 and is used to limit the opening angle of the tension support 1052. On the anchor rod body 101 located at the rear end of the tension support limiter 1051, six grooves 1054 are evenly opened along its circumference. The tension support 1052 is hinged in the groove 1054, and an elastic element 1053 is provided between the tension support 1052 and the bottom of the groove 1054. The elastic element 1053 is a wave-shaped elastic pad with a wavy bend. In its natural state, it has a certain height and can push the tension support 1052 outward, so that the tension support 1052 remains open in its natural state.

[0033] Reference Figure 6 , Figure 10 The structure of the peripheral anchor bolt assembly 12 differs from that of the central anchor bolt assembly 11 in the following ways: First, the peripheral anchor bolt assembly 12 has three anchor bolt cluster ends 103. When the anchor bolt cluster end pull rod 102 is pulled backward, the middle anchor bolt cluster end 103 bends towards the central anchor bolt assembly 11, and the two anchor bolt cluster ends 103 on both sides bend towards the adjacent peripheral anchor bolt assembly 12. The peripheral anchor bolt assembly 12 has a boss 1023 on the rear side of the compression part 1021, which faces one of the aforementioned anchor bolt cluster ends 103 on both sides. Second, a positioning steel bar 121 is provided between the anchor bolt cluster end limiter 104 of the peripheral anchor bolt assembly 12 and the front end of the anchor bolt body 101 to prevent the anchor bolt cluster end limiter 104 from deflecting or shifting when subjected to force.

[0034] Reference Figure 7 , Figure 8 During operation, the tie rod body 1022 of the central anchor bolt assembly 11 is pulled backward first. The pressing part 1021 presses the metal reinforcing collar 1032. Under the reaction force provided by the limiting part 105, the anchor bolt cluster end 103 of the central anchor bolt assembly 11 bends radially outward toward the corresponding peripheral anchor bolt assembly 12, up to 90°, in a petal-like distribution, and bends to the axial end position defined by the anchor bolt cluster end limiter 104 of the central anchor bolt assembly 11. Due to the constraint of the anchor bolt cluster end limiter 104, the anchor bolt cluster end 103 bends radially outward rather than deflecting arbitrarily.

[0035] Pulling the tie rod body 1022 of the peripheral anchor bolt assembly 12 causes the three anchor bolt cluster ends 103 of the peripheral anchor bolt assembly 12 to bend radially outwards. The middle anchor bolt cluster end 103 bends towards the central anchor bolt assembly 11, while the two anchor bolt cluster ends 103 on both sides bend towards the adjacent peripheral anchor bolt assembly 12, forming a petal-like distribution. Because a boss 1023 is provided on the rear side of the compression part 1021 of the peripheral anchor bolt assembly 12, the radial bend of the anchor bolt cluster end 103 corresponding to the boss 1023 is axially offset from the radial bends of the other two anchor bolt cluster ends 103, avoiding interference.

[0036] The anchor bolt cluster end limiters 104 of the central anchor bolt assembly 11 and the peripheral anchor bolt assembly 12 are set at the same position in the axial direction. When the anchor bolt cluster end pull rod 102 is pulled, the boss 1023 abuts against the anchor bolt cluster end limiter 104 in advance, which shortens the backward stroke of the anchor bolt cluster end pull rod 102 of the peripheral anchor bolt assembly 12. Except for the anchor bolt cluster end 103 corresponding to the rear side of the boss 1023, the radial bends of the other two anchor bolt cluster end 103s in the peripheral anchor bolt assembly 12 are relatively rearward in the axial direction, and are offset from the anchor bolt cluster end 103 of the central anchor bolt assembly 11 in the axial direction to avoid interference.

[0037] Finally, the anchor cluster end 103 of the central anchor bolt assembly 11 and the anchor cluster end 103 of the peripheral anchor bolt assembly 12 overlap on the orthographic projection portion of the reference plane perpendicular to the axial direction of the anchor bolt body 101, and are spaced apart axially to form an integral load-bearing skeleton. The two anchor cluster end 103s between adjacent peripheral anchor bolt assemblies 12 overlap on the orthographic projection portion of the reference plane perpendicular to the axial direction of the anchor bolt body 101, and are spaced apart axially.

[0038] Reference Figure 4 , Figure 9 The rear ends of the central anchor bolt assembly 11 and the peripheral anchor bolt assembly 12 pass through the inner ring pad 13, the anchor bolt group pad 14, and the outer ring pad 15 in sequence, and are then locked and fixed by nuts to complete the construction of a group of anchor bolts 1.

[0039] Reference Figure 3As a second embodiment of the present invention, the difference from the first embodiment lies in the structure of the protective component 2. In this embodiment, the protective component 2 is a grid frame 22. The grid frame 22 includes a plurality of first partitions 2201 arranged in a ring along the longitudinal direction of the tunnel. A second partition group is arranged between two adjacent first partitions 2201. The second partition group includes a plurality of second partitions 2202 distributed circumferentially. Each second partition 2202 is perpendicular to the first partition 2201. The second partitions 2202 in two adjacent second partition groups are staggered. A plurality of circumferential grooves for installing the first partitions 2201 are opened in the surrounding rock along the longitudinal direction of the tunnel. A plurality of longitudinal grooves for installing the second partitions 2202 are opened between two adjacent circumferential grooves. The first partitions 2201 and the second partitions 2202 are both made of aluminum foam and their outer surfaces are coated with a polyurea layer.

[0040] Based on the above structure, the present invention also proposes a construction method for a blast-resistant and wave-damping tunnel anchorage structure, which specifically includes the following steps: S1. First, based on the physical and mechanical properties of the engineering rock mass and the support requirements, determine the length of the individual anchor rod 101 in a group of anchor rods 1. Since the excavation of tunnels and underground caverns is mostly carried out by blasting, even under the same geological conditions, different blasting design schemes and construction may cause different ranges of loosening of the surrounding rock. Therefore, the determination of the length of the individual anchor rod 101 must be carried out by on-site experiments.

[0041] The thickness of the loosened zone of the surrounding rock is determined by on-site acoustic wave velocity testing, and the radius R of the plastic zone is obtained. Then, the length of the anchor rod 101 can be calculated according to the following formula: L = R + L0 + L1 + L2, where R is the radius of the plastic zone, L0 is the anchoring length extending into the intact rock mass, L0≥0.5m in hard rock, L0≥1.0m in soft rock or high ground stress, L1 is the length of the anchor rod cluster end 103, L1≥0.3m; L2 is the exposed length of the pad, that is, the length of the rear end of the anchor rod 101 extending out of the outer side of the outer ring pad 15, used for installing the nut, L2 is taken as 0.15m.

[0042] For a circular tunnel with a cross-sectional diameter of 10m and Class III surrounding rock, when the loosening range of the surrounding rock is determined to be 1.1m using the on-site acoustic wave testing method, according to the formula, R is 1.1m, L0 is 1.55m, L1 is 0.3m, L2 is 0.15m, and the total length of the anchor rod 101 can be taken as 3.0m. To increase the pull-out resistance, the anchor rod 101 is selected with a diameter of φ32mm and a wall thickness of 6mm.

[0043] S2. Based on the equilibrium calculation of the surrounding rock's stable plastic zone, and taking into account the synergistic effect of group anchor bolt 1, the distribution design of group anchor bolt 1 is carried out with the basic principle of preventing local collapse arches. The maximum spacing S between groups of anchor bolt 1 is... max ≤0.5L＇ L ＇ The effective anchorage length of the anchor rod 101 excluding exposed sections; the spacing of the group anchor rods 1 can be selected as 1.5m, and the row spacing is selected according to 1.5×sin60°=1.3m. At this time, each group of anchor rods 1 will be able to uniformly bear the surrounding rock stress, forming an optimal support structure system. According to the maximum row spacing of the group anchor rods 1, several groups of anchor rods 1 are arranged along the longitudinal and circumferential directions of the tunnel, so that adjacent groups of anchor rods 1 form an anchorage support system covering the entire tunnel cross section. Figure 1 The direction of arrow AB in the middle is the circumferential direction of the tunnel, and the direction of arrow CD is the longitudinal direction of the tunnel.

[0044] S3. After determining the number and distribution design of the group anchor bolts 1, drill the anchor bolt holes (the anchor bolt holes include the drilled section and the enlarged section at the bottom of the hole). First, drill the center anchor bolt hole. The initial section drilling length is R + L0, and the minimum drilling diameter is selected as φ45, φ48, or φ52mm (in this embodiment, φ76mm is selected for easy enlargement later). The enlarged section drilling length is L1 + L2, and the minimum enlarged diameter is 0.3m (0.4m in this embodiment). After drilling to the designed depth, through multi-stage enlargement, a front enlarged cavity of a cylinder with a diameter of 400mm and a height of 400mm is finally formed. Then, drill the peripheral anchor bolt holes. The specifications of the anchor bolt body 101 of the peripheral anchor bolt assembly 12 are the same as those of the center anchor bolt assembly 11. In this embodiment, a φ50mm drill bit is used for drilling, and the drilling length is the same. Each peripheral anchor bolt hole intersects and connects with the front enlarged cavity of the center anchor bolt hole.

[0045] S4. After drilling is completed, the central anchor bolt assembly 11 is installed into the central anchor bolt hole. During installation, the tension support 1052 is radially compressed by the hole wall, compressing the wave-shaped elastic gasket and retracting into the groove 1054, thus closing the hole. When the tension support 1052, along with the anchor bolt body 101, passes the front end opening of the central anchor bolt hole (i.e., the junction of the drilling section and the reaming section) and enters the front reaming cavity, the radial constraint of the hole wall on the tension support 1052 disappears. The wave-shaped elastic gasket rebounds and resets under its own elastic force, pushing the tension support 1052 radially outward, causing it to open. The opened tension support 1052 is locked at the front end opening of the central anchor bolt hole, and its maximum rotation angle is limited to 90° by the tension support limiter 1051. At this time, the tension support 1052 locked at the front end opening serves as a fixed fulcrum, providing a reaction force for the pulling of the anchor bolt cluster end tie rod 102. Then pull the anchor bolt cluster end pull rod 102, and the extrusion part 1021 extrudes the anchor bolt cluster end 103, so that the anchor bolt cluster end 103 is bent in the front end expansion cavity to form a 90° angle with the anchor bolt body 101, and is distributed in a petal shape.

[0046] S5. Insert the peripheral anchor bolt assemblies 12 into their respective peripheral anchor bolt holes, so that the limiting part 105 of the peripheral anchor bolt assembly 12 passes over the front end opening of the corresponding peripheral anchor bolt hole and is locked at the front end opening. Pull the anchor bolt cluster connection end pull rod 102 of the peripheral anchor bolt assembly 12, so that the three anchor bolt cluster connection ends 103 of the peripheral anchor bolt assembly 12 bend radially outward in the front end enlarged cavity. The middle anchor bolt cluster connection end 103 bends towards the central anchor bolt assembly 11, and the two anchor bolt cluster connection ends 103 on both sides bend towards the adjacent peripheral anchor bolt assembly 12, arranged in a petal shape. Since the peripheral anchor bolt assembly 12 has a boss 1023 on the rear side of the extrusion part 1021, the radial bend of the anchor bolt cluster connection end 103 corresponding to the boss 1023 is axially offset from the radial bends of the other two anchor bolt cluster connection ends 103, avoiding interference.

[0047] The anchor bolt cluster end limiters 104 of the central anchor bolt assembly 11 and the peripheral anchor bolt assembly 12 are positioned at the same axial position. When the anchor bolt cluster end pull rod 102 is pulled, the boss 1023 abuts against the anchor bolt cluster end limiter 104 in advance, causing the backward stroke of the anchor bolt cluster end pull rod 102 of the peripheral anchor bolt assembly 12 to be shortened. Among the three anchor bolt cluster ends 103 of the peripheral anchor bolt assembly 12, except for the anchor bolt cluster end 103 corresponding to the boss 1023, the radial bends of the other two anchor bolt cluster ends 103 are relatively rearward in the axial direction, offset from the anchor bolt cluster end 103 of the central anchor bolt assembly 11 in the axial direction, to avoid interference. Finally, the orthographic projections of each anchor bolt cluster end 103 on the reference plane perpendicular to the axial direction of the anchor bolt body 101 overlap and are spaced apart in the axial direction, forming an integral force-bearing skeleton.

[0048] S6. Grouting is performed on the anchor rods 101 of the central anchor bolt assembly 11 and the peripheral anchor bolt assembly 12 into the central anchor bolt hole, the peripheral anchor bolt hole and the front end enlarged cavity, respectively.

[0049] S7. After grouting is completed, seal the openings of the central anchor bolt hole and each peripheral anchor bolt hole respectively. Pass the rear ends of the central anchor bolt assembly 11 and the peripheral anchor bolt assembly 12 through the inner ring pad 13, the anchor bolt assembly pad 14 and the outer ring pad 15 in sequence, and then tighten them with nuts.

[0050] S8. After the group anchor bolt 1 is installed, install the protective component 2 around the group anchor bolt 1. If the protective component 2 is a protective cylinder 21, use a large-diameter cylinder drill with a wall thickness of 30mm and a diameter of 600mm, with the axis of the central anchor bolt assembly 11 as the drilling direction, and drill to a depth of 1m to form an annular mounting groove to accommodate the protective cylinder 21. During the drilling process, the drilling rig must be kept stable to ensure that the drilling direction is consistent with the axis of the group anchor bolt 1 and to avoid deviation. The diameter of the cylinder drill is more than twice the diameter of the circumscribed circle of the cross-section of the group anchor bolt 1. Embed and fix the protective cylinder 21 in the annular mounting groove. The protective cylinder 21 is prefabricated by the manufacturer, and its material is foamed aluminum. The thickness of the protective cylinder 21 is 22mm, and the thickness of the polyurea spray layer on the outer surface is 6mm. During installation, align the protective cylinder 21 with the annular mounting groove, slowly insert it, and fix it.

[0051] If the protective component 2 is a grid tube frame 22, a chain grooving machine with a chain width of 30mm and a grooving depth of 1m is used to groove the tunnel perpendicular to the surrounding rock surface. Circumferential grooves are opened along the tunnel longitudinal direction at the centerline between adjacent rows of anchor bolt groups 1, and longitudinal grooves are opened along the tunnel circumferential direction at the centerline between adjacent rows of anchor bolt groups 1. The longitudinal grooves and circumferential grooves intersect to form a grid structure. Ensure that the direction of the grid structure is perpendicular to the tunnel surface and that the groove walls are flat. Then, the grid tube frame 22 is placed inside the grid structure and fixed. The grid tube frame 22 is prefabricated by the manufacturer. Its first partition 2201 and second partition 2202 are both made of aluminum foam material, and their outer surface is coated with a polyurea layer with a thickness of 6mm.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the design and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A tunnel anchoring structure for blast resistance and wave suppression, characterized in that: The system includes a group of anchor bolts (1) and protective components (2). The group of anchor bolts (1) includes a central anchor bolt assembly (11) and several peripheral anchor bolt assemblies (12) arranged around the outside of the central anchor bolt assembly (11). The protective components (2) are embedded in the surrounding rock around the group of anchor bolts (1). The group of anchor bolts (1) includes a central anchor bolt assembly (11) and six peripheral anchor bolt assemblies (12) evenly distributed around the outside of the central anchor bolt assembly (11). Both the central anchor bolt assembly (11) and the peripheral anchor bolt assemblies (12) include an anchor bolt body (101), an anchor bolt cluster end tie rod (102), multiple anchor bolt cluster ends (103), and an anchor bolt cluster end limiter (104). The anchor bolt body (101) is... One end of the anchor bolt hole used to drill into the surrounding rock is defined as the front end, and the other end is defined as the rear end. The front end face of the anchor bolt body (101) of the central anchor bolt assembly (11) is connected to six anchor bolt cluster ends (103) evenly distributed in the circumferential direction. An anchor bolt cluster end limiter (104) is set on the anchor bolt cluster end (103). The front end of the anchor bolt cluster end pull rod (102) passes through the anchor bolt cluster end limiter (104), and its rear end extends into the axial channel of the anchor bolt body (101) and extends out from the rear end of the anchor bolt body (101). The front end of the anchor bolt cluster end pull rod (102) is provided with a compression part (1021), and the compression part (1021) is located in the area enclosed by the anchor bolt cluster ends (103). The front side of the space; the front side of the anchor rod body (101) is also provided with a limiting part (105) that can be locked at the front opening of the anchor hole after the anchor rod body (101) is inserted into the anchor hole; when the anchor rod cluster end pull rod (102) is pulled back, the squeezing part (1021) squeezes the anchor rod cluster end (103), and under the reaction force provided by the limiting part (105), the anchor rod cluster end (103) of the central anchor rod assembly (11) bends toward the corresponding peripheral anchor rod assembly (12), and among the three anchor rod cluster ends (103) of the peripheral anchor rod assembly (12), the middle anchor rod cluster end (103) bends toward the central anchor rod assembly (11), and the two anchor rod cluster ends (103) on both sides bend toward the central anchor rod assembly (11). 3) The peripheral anchor bolt assemblies (12) are bent toward the adjacent sides respectively. The extrusion part (1021) of the peripheral anchor bolt assembly (12) is provided with a boss (1023) on the rear side. The boss (1023) is facing one of the anchor bolt cluster ends (103) located on both sides. The anchor bolt cluster ends (103) of the central anchor bolt assembly (11) and the peripheral anchor bolt assembly (12) overlap on the orthographic projection portion on the reference plane perpendicular to the axial direction of the anchor bolt body (101) and are spaced apart axially. The two anchor bolt cluster ends (103) between adjacent peripheral anchor bolt assemblies (12) overlap on the orthographic projection portion on the reference plane perpendicular to the axial direction of the anchor bolt body (101) and are spaced apart axially to form an overall load-bearing skeleton.

2. The blast-resistant and wave-damping tunnel anchoring structure according to claim 1, characterized in that: The protective component (2) is a protective cylinder (21). The protective cylinder (21) is made of aluminum foam and its outer surface is coated with a polyurea layer. The protective cylinder (21) is embedded in the annular installation groove of the surrounding rock and surrounds the outside of the group of anchor bolts (1).

3. The blast-resistant and wave-damping tunnel anchoring structure according to claim 1, characterized in that: The protective component (2) is a grid frame (22). The grid frame (22) includes a plurality of first partitions (2201) arranged in a ring along the longitudinal direction of the tunnel. A second partition group is arranged between two adjacent first partitions (2201). The second partition group includes a plurality of second partitions (2202) distributed in the circumferential direction. Each second partition (2202) is perpendicular to the first partition (2201). The second partitions (2202) in two adjacent second partition groups are staggered. A plurality of circumferential grooves for installing the first partitions (2201) are opened in the surrounding rock along the longitudinal direction of the tunnel. A plurality of longitudinal grooves for installing the second partitions (2202) are opened between two adjacent circumferential grooves. The first partitions (2201) and the second partitions (2202) are made of aluminum foam and their outer surfaces are coated with a polyurea layer.

4. The blast-resistant and wave-damping tunnel anchoring structure according to claim 1, characterized in that: The anchor bolt cluster end limiter (104) is provided with a central positioning hole (1041) and a number of peripheral positioning holes (1042) evenly distributed around the central positioning hole (1041). The anchor bolt cluster end tie rod (102) passes through the central positioning hole (1041), and the anchor bolt cluster end (103) passes through the corresponding peripheral positioning holes (1042). The anchor bolt cluster end (103) is fixedly connected to the anchor bolt cluster end limiter (104) at the position where it passes through the peripheral positioning hole (1042).

5. The blast-resistant and wave-damping tunnel anchoring structure according to claim 1, characterized in that: A positioning steel bar (121) is provided between the anchor cluster end limiter (104) of the peripheral anchor assembly (12) and the front end of the anchor rod body (101).

6. The blast-resistant and wave-damping tunnel anchoring structure according to claim 1, characterized in that: The anchor bolt cluster end (103) includes a plain round steel bar (1031). On the plain round steel bar (1031) located at the front end of the anchor bolt cluster end limiter (104), a plurality of metal reinforcing collars (1032) are arranged at intervals along its length direction. The rear end of the plain round steel bar (1031) is connected to the front end face of the anchor bolt body (101).

7. The blast-resistant and wave-damping tunnel anchoring structure according to claim 6, characterized in that: The anchor bolt cluster end tie rod (102) includes a tie rod body (1022) and an extrusion part (1021) in the shape of an inverted frustum disposed at the front end of the tie rod body (1022). The orthographic projection of the extrusion part (1021) on a reference plane perpendicular to the axial direction of the anchor bolt body (101) at least partially coincides with the orthographic projection of the metal reinforcing collar (1032) on the reference plane.

8. The blast-resistant and wave-damping tunnel anchoring structure according to claim 1, characterized in that: The limiting part (105) includes a tension support limiter (1051), a tension support (1052), and an elastic element (1053). The tension support limiter (1051) is disposed on the outer side of the front end of the anchor rod body (101) to limit the opening angle of the tension support (1052). Multiple grooves (1054) are evenly provided circumferentially on the anchor rod body (101) at the rear end of the tension support limiter (1051). A tension support (1052) is hinged in the groove (1054). An elastic element (1053) is also provided between the tension support (1052) and the bottom of the groove (1054). The tension support (1052) opens radially under the action of the elastic element (1053) and is locked at the front end of the anchor bolt hole to limit the displacement of the anchor bolt body (101) in the rear direction and provide a reaction force for pulling the anchor bolt cluster end pull rod (102).

9. A construction method for a blast-resistant tunnel anchorage structure as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. The thickness of the loosened zone of the surrounding rock is determined by on-site acoustic wave velocity test, and the radius R of the plastic zone is obtained. The length of a single anchor rod (101) is calculated according to the following formula: L = R + L0 + L1 + L2, where R is the radius of the plastic zone, L0 is the anchoring length extending into the complete rock mass, L0≥0.5m in hard rock, L0≥1.0m in soft rock or high ground stress, L1 is the length of the anchor rod cluster end (103), L1≥0.3m; L2 is the exposed length of the pad, that is, the length of the rear end of the anchor rod (101) extending out of the outer side of the outer ring pad (15), used for installing nuts, L2 is 0.15m; S2. Based on the balance calculation of the surrounding rock stability plastic zone, and taking into account the synergistic effect of the group anchors (1), the distribution design of the group anchors (1) is carried out with the basic principle of not causing local collapse arches. The maximum spacing between the group anchors (1) is S. max ≤0.5L ＇ L ＇ The effective anchorage length of the anchor rod body (101) without exposed sections; according to the maximum spacing between the group anchor rods (1), several groups of group anchor rods (1) are arranged along the longitudinal and circumferential directions of the tunnel to form an anchorage support system covering the entire tunnel section; S3. Drill a central anchor bolt hole in the surrounding rock. At the bottom of the central anchor bolt hole, expand the hole through multiple stages to form a cylindrical front-end expanded cavity. Then drill several peripheral anchor bolt holes to make the peripheral anchor bolt holes and the front-end expanded cavity connected. S4. Insert the central anchor bolt assembly (11) into the central anchor bolt hole, so that the limiting part (105) of the central anchor bolt assembly (11) passes through the front end opening of the central anchor bolt hole and stops at the front end opening. Pull the anchor bolt cluster end pull rod (102) backward, so that the anchor bolt cluster end (103) of the central anchor bolt assembly (11) is bent radially in the front end enlarged cavity. S5. Insert the peripheral anchor bolt assembly (12) into the corresponding peripheral anchor bolt hole, so that the limiting part (105) of the peripheral anchor bolt assembly (12) passes through the front end opening of the corresponding peripheral anchor bolt hole and is stuck at the front end opening. Pull the anchor bolt cluster end pull rod (102) of the peripheral anchor bolt assembly (12) respectively, so that the anchor bolt cluster end (103) of the peripheral anchor bolt assembly (12) is bent radially in the front end enlarged cavity. S6. Grouting is performed on the central anchor bolt assembly (11) and the peripheral anchor bolt assembly (12) through the anchor bolt body (101) to the central anchor bolt hole, the peripheral anchor bolt hole and the front end enlarged cavity respectively. S7. Seal the openings of the central anchor bolt hole and each peripheral anchor bolt hole respectively. Pass the rear ends of the central anchor bolt assembly (11) and the peripheral anchor bolt assembly (12) through the inner ring pad (13), the anchor bolt assembly pad (14), and the outer ring pad (15) in sequence and then lock them with nuts. S8. After the group anchor bolts (1) are installed, protective components (2) are installed on the periphery of the group anchor bolts (1). If the protective component (2) is a protective cylinder (21), the axis of the central anchor bolt assembly (11) is used as a reference. A cylinder drill is used to drill into the surrounding rock along the axis to form an annular installation groove. Then the protective cylinder (21) is embedded in the annular installation groove and fixed. If the protective component (2) is a grid cylinder frame (22), a chain grooving machine is used to groove in a direction perpendicular to the tunnel surrounding rock surface. When grooving, an annular groove is opened along the tunnel longitudinal direction at the center line position between two adjacent rows of group anchor bolts (1). A longitudinal groove is opened along the tunnel circumferential direction at the center line position between two adjacent columns of group anchor bolts (1). The longitudinal groove and the annular groove intersect to form a grid structure. Then the grid cylinder frame (22) is placed into the grid structure and fixed.

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