Layered grouting anchor cable capable of conveniently determining grouting opportunity

Abstract

According to the layered grouting anchor cable capable of conveniently determining the grouting opportunity, an anchor cable rod body comprises an anchor tail section, a first-stage grouting section, a second-stage grouting section and an anchoring section, the anchor tail section and the first-stage grouting section are separated through a hole sealing plug and a tray, and the first-stage grouting section and the second-stage grouting section are separated through a shallow base point anchor fluke structure; the second-stage grouting section and the anchoring section are separated through a deep base point anchor fluke structure, a grouting guide pipe is arranged on the first-stage grouting section along the outer portion of the anchor cable rod body, a first steel wire rope is arranged in the grouting guide pipe in a penetrating mode, and the two ends of the first steel wire rope are connected with a shallow base point cat claw and a shallow base point displacement measuring instrument respectively. A second steel wire rope is arranged in the grouting core pipe in a penetrating mode, and the two ends of the second steel wire rope are connected with the deep base point cat claw structure and the deep base point displacement measuring instrument respectively. The anchor cable has the double functions of grouting and anchoring, the grouting opportunity of each grouting section can be determined through the two independent displacement monitoring devices, and effective control over weak surrounding rock of a mining roadway can be achieved.

Description

Technical Field

[0001] The invention relates to a layered grouting anchor cable which is convenient for determining the grouting time and a method for progressively reinforcing tunnel surrounding rock, belonging to the field of soft rock tunnel support in coal mines. Background Art

[0002] The support of mining roadways in complex environments such as strong mining disturbance and weak surrounding rock has always been a difficult problem in the control of surrounding rock in coal mine roadways. There are obvious time and space effects in the entire life cycle of mining roadways. The surrounding rock of the roadway is affected by the superposition of the residual support pressure of the section coal pillar and the advance support pressure of the working face of the working face, and there are significant differences in different areas of the roadway. During the mining process of the working face, the advance support pressure with a nonlinear spatial distribution curve moves forward with the advancement of the working face. The mining surrounding rock is subject to the superposition of the lateral support pressure and the support pressure of the front movement, showing significant time effects and spatial asymmetry. The highly developed primary cracks in the surrounding rock of the roadway in the coal-bearing strata make its bearing capacity and failure mode highly sensitive to changes in the stress environment. Considering the post-peak strain softening characteristics of the weak surrounding rock of the roadway, the time and space effects of the stress environment cause the surrounding rock of the roadway to continue to deteriorate from shallow to deep, the strength decays, and the plastic zone range expands to the depth, resulting in progressive instability and failure. The deterioration of surrounding rock due to the spatiotemporal effect of tunnel stress dominated by mining stress also has spatiotemporal distribution characteristics. The surrounding rock control method should take into account the adverse effects brought by this effect.

[0003] Since the evolution of the stress field of the tunnel surrounding rock has a time and space effect, the stress drives the crack zone of the tunnel surrounding rock to expand from the shallow to the deep, resulting in the gradual large deformation and instability of the tunnel surrounding rock, which has become a technical problem in controlling the surrounding rock of this type of tunnel. The main solution is that the control method needs to match the development process and expansion depth of the surrounding rock plastic zone, and gradually reinforce the tunnel surrounding rock in layers. It is difficult for the existing technologies to meet the above solutions. For example, the deep and shallow grouting reinforcement method cannot effectively grasp the timing of deep and shallow hole grouting, and the tunnel surrounding rock is drilled many times, which causes great damage to the surrounding rock strength. Although the traditional anchor bolt or hollow grouting anchor cable has the dual functions of anchoring and grouting, and has the dual benefits of anchoring and grouting, the grouting construction is constructed at the same time as the end anchor, and there is only one grouting section, which cannot match the timeliness and spatial effects of the deterioration of the surrounding rock of the mining tunnel. When the grouting and the end anchoring are not constructed at the same time, the grasp of the grouting timing is only based on experience and cannot be accurately determined. Summary of the invention

[0004] In view of the problems existing in the prior art and to adapt to the law of progressive deterioration and instability of surrounding rock of mining tunnels, the present invention provides a layered grouting anchor cable capable of determining the timing of grouting and a method for progressively reinforcing the surrounding rock of a tunnel.

[0005] The technical solution of the present invention is: A hierarchical grouting anchor cable which is convenient for determining the timing of grouting, comprises an anchor cable rod body, wherein the anchor cable rod body is sequentially divided into an anchor tail section, a primary grouting section, a secondary grouting section and an anchoring section along the length direction, the anchor cable rod body comprises a grouting core tube, a plurality of strands of steel strands are wrapped and wound around the outer periphery of the grouting core tube, the grouting core tube is a solid structure within the anchoring section range, and is a hollow structure outside the anchoring section, the grouting core tube comprises a plurality of enlarged ends within the secondary grouting section range, grouting holes are arranged on the enlarged ends, and the steel strands around the enlarged ends form a cage-type grouting outlet; the anchor tail section is separated from the primary grouting section by a sealing plug and a tray, and the primary grouting section is separated from the secondary grouting section by a shallow base point anchor claw structure, The secondary grouting section is separated from the anchoring section by a deep base point anchor claw structure, and the sealing plug, tray, and anchor claw structure are all sleeved on the anchor cable rod body; a grouting conduit is arranged along the outside of the anchor cable rod body in the primary grouting section, the grouting conduit passes through the sealing plug and the tray, a first steel wire rope is passed through the grouting conduit, one end of the first steel wire rope is connected to the shallow base point cat claw structure, and the other end of the first steel wire rope is connected to the shallow base point displacement measuring instrument; a second steel wire rope is passed through the grouting core tube, one end of the second steel wire rope is connected to the deep base point cat claw structure, and the other end of the second steel wire rope is connected to the deep base point displacement measuring instrument, and the shallow base point displacement measuring instrument and the deep base point displacement measuring instrument are both located outside the tray.

[0006] Furthermore, the structures of the shallow base point anchor claw structure and the deep base point anchor claw structure are the same, the anchor claw structure includes a cylinder, the cylinder is sleeved on the anchor cable rod body, and a plurality of U-shaped metal springs are fixedly connected to the outer wall of the cylinder at uniform intervals around the circumference, the inner arm of the U-shaped metal spring is fixedly connected to the cylinder, and a steel sheet is fixedly connected to the outer arm of each U-shaped metal spring, the upper end of the steel sheet is rotatably connected to the upper edge of the cylinder, the lower end of the steel sheet is pointed, and an elastic film is sleeved on the outside of the plurality of steel sheets, and in a natural state, the U-shaped metal spring pushes the steel sheet outward at a certain angle, and the plurality of steel sheets push the elastic film outward into a cone shape.

[0007] Furthermore, one end of the first steel wire rope is connected to the cylinder of the shallow base point cat's claw structure, and one end of the second steel wire rope is connected to the cylinder of the deep base point cat's claw structure.

[0008] Furthermore, the number of the steel sheets is three, and they are evenly distributed around the circumference of the cylinder at an interval of 120 degrees.

[0009] Furthermore, the structures of the shallow base point displacement measuring instrument and the deep base point displacement measuring instrument are the same. The displacement measuring instrument includes a calibrated tube, a baffle, a spring, and a rope buckle. The calibrated tube includes a measuring part and a fixed part. The fixed part is detachably connected to the entrance of the grouting guide tube or the grouting core tube. Scales and through seams are arranged on the tube body of the measuring part in the length direction. The baffle and the spring are arranged in the tube body of the measuring part. The spring is located between the fixed part and the baffle, and the spring and the rope buckle are respectively located on both sides of the baffle; after the steel wire rope passes through the entrance of the grouting guide tube or the grouting core tube, it passes through the fixed part, the spring, the baffle, and the rope buckle of the calibrated tube in turn. The steel wire rope finally passes through the measuring part of the calibrated tube. The steel wire rope on the spring side of the baffle is in a tensioned state. The baffle can drive the steel wire rope to move axially in the calibrated tube to compress the spring or restore the spring to a natural state.

[0010] Furthermore, a retaining ring is sleeved on the tube body of the measuring part, and the retaining ring and the retaining plate are fixedly connected through a round rod, and the round rod passes through the through slit on the graduated tube, and the retaining ring and the retaining plate can move synchronously along the length direction of the graduated tube.

[0011] A method for progressive reinforcement of tunnel surrounding rock, using the above-mentioned layered grouting anchor cable, comprises the following steps: Step 1: anchoring of anchor cable segments: anchor cable anchor holes are drilled along the surrounding rock of the tunnel to the designed depth, and resin anchor capsules are pushed to the bottom of the anchor holes. The cylinder in the deep base anchor claw structure is inserted from the top of the grouting anchor cable to the enlarged end of the cage-type grouting outlet. The second steel wire rope connected to the bottom of the deep base anchor claw is inserted into the grouting core tube from the grouting outlet and out of the core tube of the anchor tail section. The excess length of the steel wire rope is reserved for future use. The rod body of the grouting anchor cable of this layer is pushed into the bottom of the anchor hole together with the inserted anchor claw, and the rod body of the anchor cable is rotated at the same time to make the anchor cable stir the anchor capsule to complete the anchoring of the anchor section at the end of the grouting anchor cable. Step 2, install the displacement measuring instrument: push the deep base point anchor claw that was previously pushed into the anchor hole together with the anchor cable further into the depth to the front end of the anchor section along the anchor cable rod body, so that it serves as the anchor claw base point of the medium-deep surrounding rock; then penetrate the shallow base point anchor claw structure into the anchor cable rod body and send it to the top of the first-level grouting section, the first steel wire rope at the bottom of the shallow base point anchor claw penetrates into the grouting conduit on the sealing plug, and the sealing plug is penetrated into the anchor tail section, and the anchor hole opening is sealed with the sealing plug; then install the tray and lock at the anchor tail section, pass the grouting conduit through the tray, and apply preload to the design value; tension the steel wire rope that passes through the grouting core tube and the grouting conduit, and respectively pass it into the scale tubes of the shallow base point displacement measuring instrument and the deep base point displacement measuring instrument, first fix the fixed parts of the scale tube to the grouting core tube and the grouting conduit respectively, push the gear ring down, compress the bottom spring until the edge of the gear ring is at the zero scale line, tighten the rope buckle, and tie up the excess steel wire rope; Step 3, grouting of the first grouting section: observe the deformation reading of the shallow base point displacement measuring instrument. When the warning displacement value is reached, pull the excess wire rope outside the scale tube baffle until the first wire rope is separated from the shallow base point anchor claw cylinder. Due to the downward pull of the wire rope, the cylinder moves downward, the steel sheet on the anchor claw opens, and the elastic film is stretched into an umbrella shape, covering the gap between the anchor cable rod body and the surrounding rock, forming a grouting plug to prevent the grouting slurry from flowing into the second grouting section; then prepare the grouting liquid, and inject the grouting liquid into the anchor hole and its surroundings where the first grouting section is located along the grouting conduit. When slurry flows out from the surface of the surrounding rock, stop grouting and seal the grouting conduit; Step 4, grouting of the secondary grouting section: observe the deformation reading of the deep foundation displacement measuring instrument. When the warning displacement value is reached, follow the operation similar to step 3. First, pull the second steel wire rope to separate it from the deep foundation anchor claw cylinder. The elastic film is stretched to form a grouting plug. The grouting liquid is injected along the grouting core tube at the lower end of the anchor cable. The slurry flows out from the cage outlet into the anchor hole and its surroundings where the secondary grouting section is located, completing the grouting construction of the secondary grouting section.

[0012] Beneficial effect: The layered grouting anchor provided by the present invention has the dual functions of grouting and anchoring. Two independent primary grouting sections and secondary grouting sections are arranged in the free section of the anchor. The grouting timing of each grouting section can be determined by means of two built-in rock internal displacement monitoring devices. A progressive reinforcement method similar to "drip irrigation" is adopted to efficiently match the timeliness and spatial effects of the deterioration of the surrounding rock of the mining tunnel, and effective control of the weak surrounding rock of the mining tunnel can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the front view of the layered grouting anchor cable in Example 1.

[0014] Figure 2 for Figure 1 AA cross-section of the mid-layer grouting anchor anchor section.

[0015] Figure 3 for Figure 1 BB cross-section of the secondary grouting section of the mid-layer grouting anchor cable.

[0016] Figure 4 for Figure 1 Cross-section diagram of the first-level grouting section CC of the mid-layer grouting anchor cable.

[0017] Figure 5 This is a schematic diagram of the core tube and grouting hole of the secondary grouting section of the layered grouting anchor cable in Example 1.

[0018] Figure 6 This is a partial enlarged schematic diagram of the cage-type grouting outlet of the secondary grouting section of the layered grouting anchor cable in Example 1.

[0019] Figure 7This is a partial enlarged view of the anchor tail structure of the layered grouting anchor cable in Example 1.

[0020] Figure 8 Schematic diagram of the connection between the steel sheet and the U-shaped spring in the anchor claw structure.

[0021] Fig. 9 Schematic diagram of the plastic cylinder structure in the anchor claw structure.

[0022] Fig.10 Schematic diagram of the rubber elastic film in the anchor claw structure.

[0023] Fig.11 Schematic diagram of the main components and mechanical connections of the anchor claw structure.

[0024] Fig.12 Schematic diagram of the displacement measuring instrument.

[0025] Fig.13 for Fig.12 Schematic diagram of the cross-section of the medium displacement measuring instrument DD.

[0026] Fig.14 This is a schematic diagram of the connection between the baffle and the baffle ring in the displacement measuring instrument.

[0027] Fig.15 This is a schematic diagram of the connection between the rope buckle and wire rope in the displacement measuring instrument.

[0028] Fig.16 It is a schematic diagram of the anchoring section of the layered grouting anchor cable in the method for progressively reinforcing surrounding rock of the present invention.

[0029] Fig.17 It is a schematic diagram of the process of measuring the displacement of a shallow base point by a displacement measuring instrument in the progressive surrounding rock reinforcement method of the present invention.

[0030] Fig.18 It is a schematic diagram of the process of the anchor claw structure being expanded to form a grout stop plug in the method for progressively reinforcing surrounding rock of the present invention.

[0031] Fig.19 It is a schematic diagram of grouting in the first-level grouting section in the method for progressively reinforcing surrounding rock of the present invention.

[0032] Fig. 20 It is a schematic diagram of the process of measuring the displacement of the deep base point by the displacement measuring instrument in the progressive reinforcement surrounding rock method of the present invention.

[0033] Fig.21 It is a schematic diagram of grouting in the secondary grouting section in the method for progressively reinforcing surrounding rock of the present invention.

[0034] Fig. 22 This is a schematic diagram of the anchor cable in Example 2.

[0035] Fig.23 This is a schematic diagram of the anchor cable in Example 3.

[0036] Fig.24 This is a schematic diagram of the radial cross-section of the three-stage grouting anchor cable in Example 4.

[0037] Markings in the figure: 0—anchor tail section, 1—first-level grouting section, 2—second-level grouting section, 3—anchoring section, 4—shallow base displacement measuring instrument, 5—grouting conduit, 6—grouting hole, 7—shallow base anchor claw, 8—deep base anchor claw, 9—anchor rod body, 10—deep base displacement measuring instrument, 11—tray, 12—lock, 13—hole sealing plug, 14—grouting core tube, 15—core tube expansion end, 16—tray slit, 17—U-shaped spring clip, 18—anchor claw steel sheet, 1 9—wire ring, 20—plastic cylinder, 21—wire rope, 22—compression spring, 23—rope buckle, 24—gradient tube, 25—blocking ring, 26—blocking plate, 27—round rod, 28—surrounding rock, 29—resin anchor, 30—anchor hole, 31—grouting slurry, 32—surrounding rock crack, 33—elastic film, 34—middle base point anchor claw, 35—middle base point displacement measuring instrument, 36—cage type slurry outlet, 141—steel strand, 142—sub-pipe. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0039] Example 1 The present example provides a hierarchical grouting anchor cable capable of determining the timing of grouting, comprising a primary grouting section 1, a secondary grouting section 2, an anchoring section 3, an anchor tail structure tray 11 and a lock 12, a shallow base point anchor claw 7, a deep base point anchor claw 8, a grouting conduit 5, a shallow base point displacement measuring instrument 4, a deep base point displacement measuring instrument 10, a grouting core tube 14, a measuring steel wire rope 21 (including a first steel wire rope and a second steel wire rope), etc.

[0040] The main structure of the layered grouting anchor cable that can determine the timing of grouting is as follows: Figures 1 to 7 As shown. The anchor tail section 0, the first grouting section 1, the second grouting section 2, and the anchoring section 3 are different length ranges of a full-length hollow grouting anchor cable rod 9, which are divided from bottom to top in sequence due to different functions. The anchor tail section of the grouting anchor cable includes an anchor cable tray 11, a lock 12, and an exposed anchor cable rod 9. The anchoring section 3 is the part where the resin anchoring agent 29 is stirred at the end of the anchor cable during construction and is anchored to the surrounding rock 28 to stabilize the rock mass. The anchor tail section is separated from the first grouting section 1 by a conical sealing plug 13, and the first grouting section 1 and the second grouting section 2, and the second grouting section 2 and the anchoring section 3 are separated along the rod body by shallow base point anchor claws 7 and deep base point anchor claws 8, respectively.

[0041] The sealing plug 13 is made of flexible silicone material and is a tapered cylinder. The inner diameter matches the diameter and cross-sectional shape of the anchor rod body, and the maximum outer diameter is slightly larger than the anchor hole 30 of the anchor cable, so that it can penetrate into the anchor rod body 9 and seal the grouting slurry 31 in the drilled hole. The sealing plug 13 penetrates into the anchor rod body 9 and is arranged in the anchor hole 30 near the hole mouth to prevent the grouting slurry of the primary grouting section 1 from overflowing. The "L-shaped" primary grouting conduit 5 is longitudinally penetrated into the cylindrical wall thickness of the sealing plug 13, and the two are firmly glued and fixed. The other end of the primary grouting conduit 5 passes through the slit 16 in the center of the anchor tray 11 and is exposed to the outside of the tray 11. The anchor cable tray 11 is made of high-strength steel plate with a circular hole in the center. The anchor cable rod body 9 is inserted through the central circular hole and is arranged outside the opening of the anchor hole 30. It can support the sealing plug and cover the anchor hole. During installation, it is fixed by the anchor cable lock 12 on the back side, which can apply anchor cable prestress to the surrounding rock surface or transmit support resistance.

[0042] The primary grouting section 1 is located at the front end of the grouting anchor cable structure and penetrates the shallow part of the anchor support surrounding rock. The head and tail are separated by the hole plug 13 and the shallow base anchor claw 7 respectively. The space between the anchor cable rod body 9 and the wall of the surrounding rock anchor hole 30 can be regarded as a closed space, which is connected to the outside of the hole through the "L-shaped" primary grouting conduit 5.

[0043] The secondary grouting section 2 is located in the middle of the anchor cable structure and runs through the middle and deep part of the anchor support surrounding rock 28. The head and tail are separated by the anchor claw structure, and this section is a cage-type hollow grouting anchor cable structure. The central grouting core tube 14 of the anchor cable structure forms a plurality of shuttle-shaped core tube enlarged ends 15 with enlarged radius within the scope of the secondary grouting section 2, and two transversely opposite slurry outlet holes 6 are arranged in the middle of the shuttle-shaped enlarged end. When the steel strands outside the core tube 14 are wound around the shuttle-shaped core tube slurry outlet holes with enlarged radius, a cage-type slurry outlet 36 is formed to facilitate smooth slurry outlet. The core tube 14 is connected to the core tube inside the anchor tail rod body and ends at the anchoring section 3. The space between the rod body and the wall of the anchor hole 30 within the scope of the secondary grouting section 2 can be regarded as a closed space, and is connected to the outside through the grouting core tube 14.

[0044] The anchoring section 3 is located at the end of the anchor cable structure. During the anchor cable construction process, the rod body within the anchoring section 3 stirs the resin anchor 29 so that it is firmly bonded to the hole wall surrounding rock, mobilizes the deep stable rock mass, provides prestress, and "roots" the anchor structure.

[0045] The shallow base anchor claw 7 and the deep base anchor claw 8 have the same structure, and their structural components are as follows: Figures 8 to 11. The anchor claw structure is composed of a plastic cylinder 20, a steel sheet 18, a U-shaped metal spring sheet 17, an elastic film 33 and a measuring wire rope 21. The inner diameter of the plastic cylinder 20 is larger than the maximum diameter of the anchor cable rod body 9, so that it can penetrate the anchor cable rod body 9. Three notches are set along the cross section of the top of the plastic cylinder, and the cross section of the notch crosses the wire ring 19. The three notches are evenly set on the circumference of the plastic cylinder 20, and the center angles are 120 degrees. The width of the anchor claw steel sheet 18 is about 8mm, and it has a certain rigidity, so that it is not easy to bend. A protrusion is set at the bottom of the plane at one end of the steel sheet, and a small hole is set on it, which is respectively inserted into the wire ring 19 at the top of the cylinder, so that the steel sheet 18 can rotate along the node. The other end of the steel sheet 18 is cut into a triangular pointed claw, the middle of the steel sheet 18 is glued to one side of the U-shaped metal spring sheet 17, and the other side of the U-shaped metal spring sheet 17 is firmly glued to the outer wall surface of the cylinder 20. The U-shaped metal spring piece 17 has elasticity and large deformation capacity, which can make the three steel sheets 18 open to a certain angle around the cylinder 20, so that the tip of the anchor claw can be embedded in the rock mass of the hole wall and deform with the radial deformation of the surrounding rock. The outer surface of the three steel sheets 18 is tightly attached to the elastic film 33, forming an "umbrella" shape. The steel wire rope 21 is buried in the thickness of the plastic cylinder 20. This connection method can prevent the steel wire rope 21 from loosening with the anchor claw under the action of a small external force, and keep the steel wire rope in a tensioned state. Under the pulling action of a large external force, the steel wire rope 21 can be completely separated from the anchor claw plastic cylinder 20.

[0046] The shallow base point displacement measuring instrument 4 and the deep base point displacement measuring instrument 10 have the same structure. Figures 12 to 15 As shown. The structure consists of a graduated tube 24, a baffle 26, a compression spring 22, a rope buckle 23, etc. The graduated tube 24 can be divided into two parts, front and back. The tube body is made of plastic and can be a transparent material tube, which is convenient for observing the position of the baffle inside. The front half of the graduated tube 24 is used for measurement, called the measuring part, which occupies 3 / 4 of the length of the tube body, and the back half is used for fixing, called the fixing part, which occupies 1 / 4 of the length of the tube body. The two parts have the same diameter. The graduated tube can be an integrated structure or a split structure. If it is a split structure, it can be tightened by rotating the inner thread of the tube. The measuring part of the graduated tube 24 is a hollow tube, and the tube body is provided with a through seam of about 5mm wide, and the outer surface of the tube body along the length direction of the through seam is provided with a scale number of 0~20cm. A spring 22 is provided in the measuring part of the graduated tube 24, and the length in the natural state exceeds the scale number. One end of the spring 22 is pressed against the solid boss at the bottom of the measuring part of the graduated tube 24, and the other end of the spring 22 is pressed against the baffle 26. The fixed part of the graduated tube 24 is a hollow round tube or a solid round rod. The outer diameter of the grouting tube can be inserted into the graduated tube or the solid round rod of the graduated tube can be inserted into the grouting tube. The specific method can be determined according to the construction situation.

[0047] The center of the baffle 26 is a plastic circular sheet, the diameter of which is slightly smaller than the inner diameter of the graduated tube, so that it can move in the graduated tube 24. The circular sheet fixes a metal round rod 27, which passes through the center of the circular sheet, and the rod body of the round rod 27 is located in the plane of the circular sheet. The cross-sectional diameter of the round rod 27 is slightly smaller than the width of the through-slit on the graduated tube 24, and the length of the round rod 27 is greater than the outer diameter of the graduated tube. The two ends of the round rod 27 are inserted into the small holes opened at the two ends of the semicircular retaining ring 25, and are fixed. The baffle 26, the round rod 27 and the retaining ring 25 are kept in the same plane, and the plane relationship state remains unchanged during movement. During use, the circular baffle 26 is inserted into the cross-section of the graduated tube, and the two ends of the round rod 27 are exposed from the through-slit of the graduated tube, and the inner diameter of the retaining ring 25 is close to the outer wall of the graduated tube 24.

[0048] Through holes are provided at the center of the graduated tube 24 and the center of the baffle 26, and the hole diameter is about 1.1-1.2 mm, which is slightly larger than the diameter of the wire rope, for passing the wire rope 21 therethrough.

[0049] During the installation of the displacement measuring instrument, the other end of the steel wire rope 21 connected to the anchor claw is passed through the grouting core tube 14 or the first-level grouting conduit 5, and then passed out from one end of the core tube 14 at the tail of the anchor cable or from the grouting conduit 5 exposed on the tray. The steel wire rope passing through the grouting pipe is passed through the central small hole of the scale tube 24 and the through hole in the center of the baffle 26 again, and finally passed through the rope buckle 23. The fixed part of the scale tube 24 is stably inserted into the grouting pipe 14 or the grouting conduit 5, the outermost edge 21 of the steel wire rope is tightened, and the baffle 26 is pushed down to press the spring 22 until the annular edge of the baffle ring 25 is at the zero scale line, and the screw on the rope buckle 23 is tightened to limit the movement of the baffle 26. The steel wire rope connecting the shallow base point displacement measuring instrument and the shallow base point anchor claw is the first steel wire rope, and the steel wire rope connecting the deep base point displacement measuring instrument and the deep base point anchor claw is the second steel wire rope.

[0050] The present invention provides a layered grouting anchor cable working principle and a progressive reinforcement method for tunnel surrounding rock that can determine the timing of grouting. The construction steps can be found in Figures 16 to 21 shown.

[0051] The basic principle of the shallow base point displacement measuring instrument 4 and the deep base point displacement measuring instrument 10 is that the tensile stiffness of the anchor cable whose end is anchored in the stable rock formation is large, and its own axial deformation can be ignored, so it can be regarded as a fixed point. The graduation tube 24 is fixed on the grouting pipe 5 and the grouting core tube 14 on the anchor cable, and the graduation tube can be regarded as a fixed point. The tip of the anchor claw steel sheet 18 is embedded in the rock mass of the wall of the anchor hole 30, and is consistent with the radial deformation of the surrounding rock of the tunnel. When the surrounding rock at the anchor claw position undergoes radial deformation, it moves into the tunnel together with the anchor claw, and the tensioned wire rope 21 moves together, driving the compression spring 22 in the tail graduation tube 24 to extend outward, and the retaining ring 25 moves a certain number of scales along the scale line. Then, the surrounding rock deformation at the anchor claw base point is fed back to the graduation tube 24 fixed outside the surrounding rock, and the surrounding rock deformation at the base point can be obtained by changing the scale value on the outer edge of the retaining ring 25. For example, Fig.17 As shown, the outer edge scale of the retaining ring 25 is 10 cm, indicating that the radial displacement of the shallow base anchor claw 7 is 10 cm, and the grouting time of the first-level grouting section has been reached.

[0052] The shallow base point anchor claw 7 and the deep base point anchor claw 8 have both the base point embedding function and the grout stopper function. The three separate steel sheets 18 in the anchor claw structure are fixed by the U-shaped spring sheet 17. The sharp points of the steel sheets 18 are opened outwards and firmly embedded in the rock mass, serving as the anchor point of the displacement measuring instrument at the base point, and undergoing radial displacement with the rock mass. When the base point displacement reaches the warning displacement value for grouting, the rope buckle 23 outside the baffle 26 is loosened, the graduated tube 24 is pulled out from the grouting port, and the wire rope 21 is pulled hard. The wire rope 21 drives the anchor claw cylinder 20 to move downward, and the tip of the opened anchor claw steel sheet 18 is embedded in the rock mass and is stable. The top of the steel sheet 18 rotates around the inserted wire ring 19. Under the action of the U-shaped spring piece 17, the three steel sheets 18 are further opened in the cross section of the anchoring borehole, driving the elastic film 33 covering the upper surface of the steel sheet 18 to open, completely covering the cross-sectional gap between the anchor cable rod body and the borehole, forming a grouting plug. The principle of this transmission mechanism is similar to the principle of opening a multi-strand umbrella. The connection between the steel wire rope 21 and the anchor claw plastic cylinder 20 is a "defective connection", which can not only ensure that the steel wire rope 21 and the plastic cylinder 20 do not separate under a small external force, but also keep the steel wire rope 21 straight under the push of the compression spring 22 in the measuring instrument. Under a larger external force, the steel wire rope can pull the plastic cylinder until the rubber elastic film 33 is opened to form an "umbrella-shaped" stop plug, and then the steel wire rope 21 can be separated from the plastic cylinder 20 and pulled out for reuse. Fig.18 shown.

[0053] The layered grouting anchor cable and its progressive reinforcement method for tunnel surrounding rock are to install the above-mentioned layered grouting anchor cable structure in the tunnel surrounding rock anchor hole, and pull out the corresponding graduated tube 24 outside the grouting hole by the deformation information at the anchor claw base point fed back by the shallow base point displacement measuring instrument 4 inserted in each level of grouting hole, and pull the wire rope 21 hard to make the anchor claw open to form a grouting plug, and then use the grouting equipment to perform grouting construction on the grouting conduit hole 5. Under the same operation conditions, the grouting of the deep rock mass in the tunnel surrounding rock is completed. This method of reinforcing the tunnel surrounding rock is similar to the "drip irrigation" mode. In the time domain when the surrounding rock deteriorates and the cracks gradually expand from the shallow part to the deep part, the rock joints and fissures are gradually closed and repaired, and the fissure surrounding rock is condensed into a multi-segment grouting consolidation body through the cementation of the slurry, so as to improve the self-bearing capacity of the surrounding rock and ensure the stability of the surrounding rock.

[0054] The invention provides a method for progressively reinforcing tunnel surrounding rock by using layered grouting anchor cables. The method is summarized as follows: firstly, anchor holes are drilled in the tunnel surrounding rock, and then layered grouting anchor cables are installed in the anchor holes, and the heads of the anchor cables are anchored at the top of the heads of the holes; then, deformation of the surrounding rock is monitored, and when the reading of a shallow base point displacement measuring instrument reaches a warning displacement value, grouting is injected into the first-level grouting section hole and solidified; the deformation of the surrounding rock is continuously monitored, and when the reading of a deep base point displacement measuring instrument reaches a warning displacement value, grouting is injected into the second-level grouting section hole and solidified, thereby completing the progressive reinforcement of the tunnel surrounding rock.

[0055] The above method may specifically include the following steps: Step one, layered grouting anchor cable anchoring. The layered grouting anchor cable is an anchor cable anchoring cable with an additional grouting channel, while still retaining the basic function of high-strength anchor cable anchoring. First, according to the design parameters of the tunnel surrounding rock support, the anchor cable anchoring hole is drilled along the tunnel surrounding rock to the designed depth, and the resin anchor agent 29 capsule is pushed to the bottom of the anchor hole 30. The plastic cylinder 20 in the structure of the mid-deep base point anchor claw 8 is inserted from the top of the grouting anchor cable to the top of the enlarged end of the cage-type grouting outlet, and the wire rope 21 connected to the bottom of the anchor claw 8 is inserted through the grouting hole 6 and out of the core tube 14 at the tail of the anchor cable. The excess length of the wire rope 21 is bundled up for standby use. The layered grouting anchor cable rod body is pushed into the bottom of the hole together with the inserted mid-deep base point anchor claw 8, and the anchor drilling rig is used to rotate the rod body to stir the anchor cable with the anchor agent capsule to complete the anchoring of the anchor section 3 at the end of the grouting anchor cable.

[0056] Step 2, install the displacement meter. Use the PVC pipe to push the deep base anchor claw 8 that was previously pushed to the anchor hole 30 together with the anchor cable along the anchor cable rod body to the bottom of the anchor section 3, so that it serves as the anchor claw base point of the medium-deep surrounding rock. Then the shallow base anchor claw 7 structure is inserted into the anchor cable rod body, and pushed into the top of the first-level grouting section 1 by the PVC pipe. The steel wire rope 21 at the bottom is inserted into the L-shaped grouting conduit 5 on the sealing plug 13, and is inserted into the tail of the anchor cable together with the sealing plug 13 to block the opening of the anchor hole 30. Install the tray 11 and lock 12 at the tail of the anchor cable, and pass the bent end of the L-shaped grouting conduit 5 through the preset slit 16 on the center side of the tray 11, and apply the preload force to the design value. The first steel wire rope and the second steel wire rope that pass through the grouting core tube 14 and the grouting conduit 5 are tensioned respectively, and respectively inserted into the small hole in the center of the graduation tube 24, and pass out from one end of the baffle 26, and a rope buckle 23 is inserted into the tail. According to the form of the grouting hole, select the type of the fixed part of the tail of the scale tube 24, insert it into the grouting core tube 14 and the grouting conduit 5, and fix it. Then, push the gear ring 25 down, compress the bottom spring 22 until the edge of the gear ring 25 is at the zero scale line, tighten the rope buckle 23, fix the baffle 26 and the gear ring 25, and tie up the excess wire rope 21. At this time, the indication positions of the shallow base point displacement measuring instrument and the deep base point displacement measuring instrument are both at the zero scale.

[0057] Step three, grouting of the first-level grouting section conduit. The surrounding rock of the tunnel is disturbed by multiple mining stresses, and the deformation of the surrounding rock increases. Observe the deformation reading of the shallow hole displacement measuring instrument 7. After reaching the warning displacement value, loosen the rope buckle 23 to restore the spring 22 to its natural state, and pull the excess wire rope on the outer edge of the baffle 26 until the anchor claw plastic cylinder 20 is separated from the bottom wire rope 21. Due to the downward pull of the wire rope 21, the plastic cylinder 20 moves down, the steel sheet 18 on the anchor claw opens, and the rubber film 33 is opened in an umbrella shape, covering the gap between the anchor cable rod body 9 and the surrounding rock 28, forming a grouting plug to prevent the grouting slurry from flowing into the second-level grouting section 2. Then configure the cement-based grouting material, connect the grouting pipe on the grouting pump to the first-level grouting port 5, and use the pressure of the grouting pump to inject the grouting material into the first-level grouting section 1. After the slurry flows out of the surrounding rock surface, stop grouting and seal the grouting conduit 5. Since the first-level grouting section 1 is located in the shallow surrounding rock of the tunnel and in the early stage of progressive damage development of the tunnel, the density and aperture of the shallow surrounding rock cracks continue to develop. The slurry in the first-level grouting section penetrates into these cracks and diffuses to the surrounding areas, which can improve the strength and stiffness of the rock joints and cracks around the first-level grouting section, improve the self-bearing capacity of the surrounding rock mass, and reduce and delay the development of the fractured rock mass to a broken state.

[0058] Step 4: Grouting of the core pipe of the secondary grouting section. As the mining stress continues to disturb, the fracture zone continues to develop towards the high and deep rock mass. Observe the deformation reading of the medium-deep displacement measuring instrument 10. After the displacement at the measuring base point reaches the warning displacement value, the transformation of the medium-deep anchor claw structure to the stop plug is completed in accordance with the operation similar to step 3. At the same time, grouting construction is carried out on the secondary grouting section 2. As the grouting pressure gradually increases to the designed final pressure, for example, the final pressure of the medium-deep hole can be set to 2~4MPa according to the actual situation, and the grouting is terminated after a certain period of time, for example, 10 minutes.

[0059] The method of progressive reinforcement of tunnel surrounding rock is similar to the "drip irrigation" mode. In the time domain of surrounding rock deterioration and crack expansion, the rock joints and fissures are gradually sealed and repaired. Through the cementation of slurry, the fractured surrounding rock is condensed into multi-segment grouting consolidation bodies, which improves the self-bearing capacity of the surrounding rock and ensures the stability of the surrounding rock.

[0060] This example provides a layered grouting anchor cable that can determine the timing of grouting and a method for progressively reinforcing the surrounding rock of a tunnel, which is used to solve the problem of progressive instability and destruction of weak surrounding rock in a tunnel that is disturbed by multiple mining stresses. The grouting anchor cable structure includes a primary grouting section, a secondary grouting section, an anchoring section, an anchor tail structure tray and lock, an anchor claw, a grouting pipe, a graduated pipe, a steel wire, etc. The primary grouting section is grouted through a grouting pipe inserted from the anchor cable tray; the secondary grouting section is grouted by the hollow core tube of the anchor cable, and the grouting flows out from the cage-type grouting outlet within the scope of the secondary grouting section; the anchoring section is anchored by a resin anchoring agent in a normal manner according to the anchor cable anchoring method. The primary grouting section and the anchor tail tray are separated by a grouting plug inserted into the anchor cable rod body; the primary and secondary grouting sections, and the secondary grouting section and the anchoring section are separated by anchor claws with rubber films, which can separate the grouting sections of the anchor cable rod body from each other. The anchor claw structure consists of three open steel sheets arranged around the sleeve. One end of the steel sheet is inserted into the iron ring at the upper end of the sleeve. The middle part is fixedly connected to the outer wall of the sleeve through a U-shaped spring. The bottom of the sleeve is fixedly connected to the measuring wire. The tail wires of the anchor claws at two positions pass through the hollow core tube and the grouting tube respectively, and are connected to the graduated tube fixed to the grouting port on the outside of the tray. The end of the grouting anchor cable is normally anchored in the hard rock body using a resin anchoring agent. The anchor claw structure is installed at the ends of different grouting sections in turn, and the tray, lock and tension measuring wire are installed and connected to the graduated tube. The tail of the anchor cable can be regarded as a fixed point. The tip of the anchor claw steel sheet is embedded in the rock mass of the anchor hole wall and deforms synchronously with the surrounding rock of the tunnel. The deformation of the grouting section range can be read through the reading on the graduated tube, which can accurately grasp the timing of grouting. When the warning displacement value is reached, the graduated tube at the grouting port is pulled out, and the measuring wire is pulled hard until the wire is disengaged from the anchor claw sleeve, and the rubber film at the top of the anchor claw opens to form an umbrella-shaped grouting plug to separate each grouting section, and then the first and second grouting sections are grouting construction is carried out in sequence. Within the time domain range of the gradual deterioration of the tunnel surrounding rock from shallow to deep, the tunnel surrounding rock is gradually modified and reinforced at different levels of depth, providing an effective solution for the support of weak surrounding rock in the mining tunnel disturbed by mining stress. In actual engineering, the above-mentioned layered grouting anchor cable and the method of gradually reinforcing the tunnel surrounding rock can also be simplified, and the simplified anchor cable structure is shown in the following Examples 2 and 3.

[0061] Example 2 like Fig. 22As shown, in this example, an anchor cable structure capable of monitoring the deformation of tunnel surrounding rock and grouting is provided, including an anchor cable rod body 9, wherein the anchor cable rod body 9 is composed of an anchor tail section 0, a grouting section 1, and an anchoring section 3 from bottom to top along the length direction, and the anchor cable rod body is wound by multiple strands of steel strands. Optionally, the anchor cable rod body also includes a core tube, and multiple strands of steel strands are wrapped and wound around the outer periphery of the core tube, and the core tube is a solid structure throughout the length of the anchor cable; the anchor tail section 0 is the exposed end of the anchor cable structure, and includes a lock 12 and a tray 11, which is installed outside the orifice of the anchor hole, and is connected to the grouting section 1 through a sealing hole. The sealing plug 13 is separated from the tray 11, and a middle base point anchor claw 34 is installed within the grouting section 1. The sealing plug 13, the tray 11, and the middle base point anchor claw 34 are all sleeved on the anchor cable rod body 9; a grouting conduit 5 is arranged along the outside of the anchor cable rod body in the first-level grouting section 1, and the grouting conduit 5 passes through the sealing plug 13 and the tray 11 downward in an L shape, and a steel wire rope is passed through the grouting conduit 5, the upper end of the steel wire rope is connected to the middle base point anchor claw 34 structure, and the lower end of the steel wire rope is connected to the middle base point displacement measuring instrument 35, and the middle base point displacement measuring instrument is located at the lower part of the tray and is connected to the entrance of the grouting conduit. The structure of the middle base point anchor claw 34 is compared with the structure of the shallow base point anchor claw 7 in Example 1, except that the elastic film 33 pasted on the steel sheet is removed, and the remaining structures are the same; the structure of the middle base point displacement measuring instrument 35 is the same as that of the shallow base point displacement measuring instrument 4 in Example 1, and will not be repeated; that is, the middle base point anchor claw 34 and the middle base point displacement measuring instrument 35 in this example are connected by a steel wire rope, and the movement of the middle base point anchor claw can be monitored by the middle base point displacement measuring instrument, and the movement of the anchor claw feeds back the deformation of the middle part of the surrounding rock of the tunnel.

[0062] The difference between the grouting anchor cable structure in this example and Example 1 is that there is no secondary grouting section, and the core tube is a solid structure throughout the entire length. There is no expansion end mechanism on the core tube, and grouting is only performed into the anchor hole through the grouting conduit. There is only one grouting section in this scheme, and the anchor claw structure no longer needs to assume the grouting function as a grouting plug. The anchor claw structure is appropriately simplified, and the elastic film 33 covering the outer surface of the three steel sheets 18 is removed, which does not affect the flow of slurry. The other structures are the same or similar to Example 1, which can simplify the manufacturing and use process of the anchor cable. The method of use is similar to that of Example 1 and will not be repeated. The advantage of the grouting anchor cable structure in this example over the traditional grouting anchor cable or grouting reinforcement surrounding rock method is that the deep displacement monitoring system of the surrounding rock is combined with the anchor structure. The internal deformation of the surrounding rock is fed back by the base point displacement measuring instrument, which can clarify the timing of grouting anchor cables. Compared with the surface displacement measurement results of the surrounding rock, the timing of grouting is more accurate, and it avoids repeated drilling of grouting holes or deep base point monitoring holes on the surrounding rock, reducing the damage caused by repeated drilling of surrounding rocks.

[0063] Example 3 like Fig.23As shown, in this example, a core tube grouting anchor cable structure is provided, including an anchor cable rod body 9, wherein the anchor cable rod body 9 is composed of an anchor tail section 0, a grouting section 2, and an anchoring section 3 from bottom to top along the length direction, wherein the anchor cable rod body 9 includes a grouting core tube, and a plurality of strands of steel wire are wrapped and wound around the outer periphery of the grouting core tube, wherein the grouting core tube is a solid structure within the anchoring section and a hollow structure outside the anchoring section, wherein the grouting core tube includes a plurality of enlarged ends within the grouting section, and slurry outlet holes are arranged on the enlarged ends, and the steel wire strands around the enlarged ends form a cage-type slurry outlet 36; the anchor tail section 0 is The exposed end of the anchor cable structure, including a lock 12 and a tray 11, is installed outside the anchor hole and is separated from the grouting section 2 by a sealing plug 13. A middle base point anchor claw 34 is arranged within the grouting section 2. The sealing plug, tray and anchor claw structure are all sleeved on the anchor cable rod body. A steel wire rope is passed through the grouting core tube. The upper end of the steel wire rope passes through the uppermost cage-type grouting outlet and is connected to the middle base point anchor claw. The lower end of the steel wire rope is connected to the middle base point displacement measuring instrument 35. The middle base point displacement measuring instrument is located at the outer lower part of the tray and is connected to the entrance of the grouting core tube. The structure of the middle base point anchor claw 34 is compared with the structure of the middle-depth base point anchor claw 8 in Example 1, except that the flexible film 33 pasted on the steel sheet is removed, and the remaining structures are the same; the structure of the middle base point displacement measuring instrument 35 is the same as that of the middle-depth base point displacement measuring instrument 10 in Example 1, and will not be repeated here; that is, the middle base point anchor claw 34 and the middle base point displacement measuring instrument 35 in this example are connected by a steel wire rope, and the movement of the middle base point anchor claw can be monitored by the middle base point displacement measuring instrument, and the movement of the anchor claw feeds back the deformation of the middle part of the surrounding rock of the tunnel.

[0064] The difference between the grouting anchor cable structure in this example and Example 1 is that there is no primary grouting section and L-shaped grouting conduit, and grouting is only performed within the range of the grouting section 2 of the anchor hole through the grouting core tube. There is also only one grouting section in this scheme, and the anchor claw structure no longer assumes the grouting function as a grouting plug. The anchor claw structure is appropriately simplified, and the elastic film 33 covering the outer surface of the three steel sheets 18 is removed. The other structures are the same or similar to those in Example 1, which can simplify the anchor cable use process. Its use method is similar to that in Example 1 and will not be repeated. The advantage of the grouting anchor cable structure in this example over the traditional grouting anchor cable or grouting reinforcement surrounding rock method is that the surrounding rock deep displacement monitoring system and the anchor structure are combined. The internal deformation of the surrounding rock is fed back by the base point displacement measuring instrument, which can clarify the grouting timing of the grouting anchor cable. Compared with the surface displacement measurement result of the surrounding rock, the grouting timing is determined more accurately, and repeated drilling of grouting holes or deep base point monitoring holes in the surrounding rock is avoided, reducing the damage caused by repeated drilling of the surrounding rock.

[0065] Example 4 Example 1 provides an anchor cable with a two-stage grouting structure. If more levels of grouting are desired, such as three-stage grouting, four-stage grouting or more, and corresponding displacement measuring instruments are required, the grouting core tube structure of the anchor cable needs to be improved. This example takes a three-stage grouting anchor cable as an example. The improved anchor cable radial cross section is as follows: Fig.24 As shown, the anchor cable rod body is composed of an anchor tail section, a primary grouting section, a secondary grouting section, a tertiary grouting section, and an anchoring section in sequence along the length direction. The anchor cable rod body includes a grouting core tube 14, and three sub-tubes 142 are arranged in the grouting core tube, namely a first sub-tube, a second sub-tube, and a third sub-tube. A plurality of steel strands 141 are wrapped around the outer periphery of the grouting core tube. Similar to Example 1, the grouting core tube is provided with an expanded end of an expansion portion similar to that in Example 1 in the primary grouting section, the secondary grouting section, and the tertiary grouting section. The steel strands corresponding to the expanded end are cage-type grouting outlets, and the first sub-tube is provided with a grouting hole at the expanded end of the expansion portion of the primary grouting section, the second sub-tube is provided with a grouting hole at the expanded end of the expansion portion of the secondary grouting section, and the third sub-tube is provided with a grouting hole at the expanded end of the expansion portion of the tertiary grouting section. A grouting hole is provided at the expanded end of the expansion part, and a first anchor claw is provided between the first grouting section and the second grouting section, a second anchor claw is provided between the second grouting section and the third grouting section, and a third anchor claw is provided between the third grouting section and the anchoring section. The three anchor claw structures are the same as the anchor claw structures in Example 1. The first steel wire rope connected to the cylinder on the first anchor claw passes through the first sub-tube and then passes through the anchor tail section to connect to the first displacement measuring instrument. The second steel wire rope connected to the cylinder on the second anchor claw passes through the second sub-tube and then passes through the anchor tail section to connect to the second displacement measuring instrument. The third steel wire rope connected to the cylinder on the third anchor claw passes through the third sub-tube and then passes through the anchor tail section to connect to the third displacement measuring instrument. The three displacement measuring instruments are all connected against the tail of the anchor tail section. The structures of the three displacement measuring instruments are the same as those in Example 1. In this way, the deformation of the surrounding rock at different depths can be monitored, and multi-stage and multi-level grouting can be implemented. The specific principles and methods are the same as in Example 1 and will not be repeated.

[0066] In this example, if the number of sub-tubes in the grouting core tube is 1, it degenerates to the state of Example 3, and the effect is the same as that of Example 3; if the number of sub-tubes in the grouting core tube is 2 (the first sub-tube and the second sub-tube), its functional effect is the same as the two-stage grouting effect in Example 1, and the first sub-tube replaces the function of the grouting conduit in Example 1.

Claims

1. A layered grouting anchor cable that facilitates determination of grouting timing, comprising an anchor cable rod body, characterized in that: The anchor cable rod body is composed of an anchor tail section, a primary grouting section, a secondary grouting section, and an anchoring section in sequence along the length direction. The anchor cable rod body includes a grouting core tube, and multiple strands of steel strands are wrapped and wound around the outer periphery of the grouting core tube. The grouting core tube is provided with a grouting outlet within the scope of the secondary grouting section. The anchor tail section is separated from the primary grouting section by a hole sealing plug and a tray, the primary grouting section is separated from the secondary grouting section by a shallow base point anchor claw structure, and the secondary grouting section is separated from the anchoring section by a deep base point anchor claw structure. The hole sealing plug, tray, and anchor claw structure are all sleeved on the anchor cable rod body. A grouting conduit is arranged along the outside of the anchor rod body in the first-level grouting section, the grouting conduit passes through the sealing plug and the tray, a first steel wire rope is passed through the grouting conduit, one end of the first steel wire rope is connected to the shallow base point cat's claw structure, and the other end of the first steel wire rope is connected to the shallow base point displacement measuring instrument; a second steel wire rope is passed through the grouting core tube, one end of the second steel wire rope is connected to the deep base point cat's claw structure, and the other end of the second steel wire rope is connected to the deep base point displacement measuring instrument, and the shallow base point displacement measuring instrument and the deep base point displacement measuring instrument are both located outside the tray.

2. A layered grouting anchor cable that facilitates determination of grouting timing according to claim 1, characterized in that: The structures of the shallow base point anchor claw structure and the deep base point anchor claw structure are the same. The anchor claw structure includes a cylinder, which is sleeved on the anchor cable rod body. A plurality of U-shaped metal springs are fixedly connected to the outer wall of the cylinder at uniform intervals around the circumference. The inner arm of the U-shaped metal spring is fixedly connected to the cylinder. A steel sheet is fixedly connected to the outer arm of each U-shaped metal spring. The upper end of the steel sheet is rotatably connected to the upper edge of the cylinder. The lower end of the steel sheet is pointed. An elastic film is sleeved on the outside of the plurality of steel sheets. In a natural state, the U-shaped metal spring pushes the steel sheet outward at a certain angle, and the plurality of steel sheets push the elastic film outward into a cone shape.

3. A layered grouting anchor cable that facilitates determination of grouting timing according to claim 2, characterized in that: One end of the first steel wire rope is connected to the cylinder of the shallow base point cat's claw structure, and one end of the second steel wire rope is connected to the cylinder of the deep base point cat's claw structure.

4. The layered grouting anchor cable for facilitating determination of grouting timing according to claim 2, characterized in that: The number of the steel sheets is three, and they are evenly distributed around the circumference of the cylinder at an interval of 120 degrees.

5. The layered grouting anchor cable for facilitating determination of grouting timing according to claim 1, characterized in that: The shallow base point displacement measuring instrument and the deep base point displacement measuring instrument have the same structure. The displacement measuring instrument includes a graduated tube, a baffle, a spring, and a rope buckle. The graduated tube includes a measuring part and a fixed part. The fixed part is detachably connected to the entrance of the grouting conduit or the grouting core tube. Graduations and through-slits are arranged on the tube body of the measuring part in the length direction. The baffle and the spring are arranged in the tube body of the measuring part. The spring is located between the fixed part and the baffle. The spring and the rope buckle are respectively located on both sides of the baffle. After passing through the entrance of the grouting conduit or the grouting core tube, the steel wire rope passes through the fixed part, the spring, the baffle, and the rope buckle of the graduated tube in sequence. The steel wire rope finally passes through the measuring part of the graduated tube. The steel wire rope on the spring side of the baffle is in a tensioned state. The baffle can drive the steel wire rope to move axially in the graduated tube to compress the spring or restore the spring to a natural state.

6. The layered grouting anchor cable for facilitating determination of grouting timing according to claim 5, characterized in that: A retaining ring is sleeved on the tube body of the measuring part, and the retaining ring and the retaining piece are fixedly connected through a round rod, which passes through the through slit on the graduated tube, and the retaining ring and the retaining piece can move synchronously along the length direction of the graduated tube.

7. The layered grouting anchor cable for facilitating determination of grouting timing according to claim 1, characterized in that: The grouting core tube comprises a plurality of enlarged ends within the scope of the secondary grouting section, grout outlet holes are arranged on the enlarged ends, and the steel strands on the periphery of the enlarged ends form a cage-type grout outlet.

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