A method for directional grouting reinforcement of fractured surrounding rock around a tunnel

Abstract

This invention belongs to the field of grouting reinforcement technology for fractured surrounding rock, and discloses a directional grouting reinforcement method for fractured surrounding rock around a tunnel. This method aims to solve the problems of large grouting volume, long construction period and high cost caused by the existing grouting methods used for fractured surrounding rock in tunnels. The invention includes: (1) drilling holes into the fractured surrounding rock around the tunnel; (2) inserting grouting pipes into each hole, wherein at least three rows of grouting ports are provided along the length of the grouting pipe, and each row of grouting ports contains multiple grouting ports. The included angle between the two outermost rows of grouting ports on the grouting pipe is 100°-135°, and the grout sprayed from the two adjacent rows of grouting ports on two adjacent grouting pipes in the fractured surrounding rock around the tunnel can form an overlapping area; (3) injecting grout into the grouting pipe, and the grout sprayed from each grouting port of the grouting pipe into the gaps of the fractured surrounding rock to complete the grouting reinforcement of the fractured surrounding rock.

Description

Technical Field

[0001] This invention belongs to the technical field of grouting reinforcement technology for fractured surrounding rock, specifically relating to a directional grouting reinforcement method for fractured surrounding rock around a tunnel, used for grouting reinforcement of fractured surrounding rock around a tunnel. Background Technology

[0002] With the rapid development of society and economy, transportation construction has also advanced rapidly, and transportation routes inevitably pass through mountainous areas. Tunnels are widely used. For tunnel construction in fractured mountainous areas, it is usually necessary to perform indiscriminate grouting reinforcement on the surrounding fractured rock mass. For example, patent application number 201911224634.4 discloses a multi-layer grouting reinforcement method for soft and fractured surrounding rock in tunnels, including: First, after the tunnel is excavated, several U-shaped steel sheds are used for primary support to initially control the deformation of the surrounding rock. The spacing between the U-shaped steel sheds is 650mm, and the U-shaped steel sheds are interlocked by 5 tie rods; Second, after the U-shaped steel sheds are erected, a spraying operation is carried out within 5-10m of the lagging excavation face, spraying a 250mm thick sprayed layer on the tunnel surface, with a cycle of 2m, and the spraying sequence is from both sides. The process involves initial spraying, initial spraying of the roof, full-section re-spraying, and leveling. The third step, after the initial spraying is completed, involves setting up the grouting pump, high-pressure pipelines, and grouting pipes to begin shallow grouting reinforcement. Shallow grouting boreholes with a depth of 3m are drilled in the roof and both sides of the tunnel. Grouting pipes are inserted into these boreholes to perform shallow grouting of the soft, fractured surrounding rock. After the shallow 3m area of ​​surrounding rock is reinforced, the reinforced 3m surrounding rock, along with the U-shaped steel canopy and the shotcrete layer, forms the outer layer of the tunnel's load-bearing structure. The shallow grouting boreholes are arranged in a triangular pattern along the tunnel sides, with a spacing of 3m and a depth of 3m. The upper shallow grouting boreholes are 1m away from the roof. The shallow grouting boreholes are 0.2m deep and arranged horizontally; the lower shallow grouting boreholes are 0.4m from the bottom plate and arranged at a 45° angle with the roadway sidewalls; the shallow grouting boreholes on the roof are 0.3m from the centerline of the roadway and arranged vertically, with a grouting pressure of 1~2MPa and a final grouting pressure of 2MPa. The fourth step involves deep grouting reinforcement of the soft, fractured surrounding rock 3-5 days after the completion of the shallow grouting reinforcement work. The deep grouting holes are 8m deep and are constructed using grouting anchors with parameters of Φ22mm×9000mm. Through deep grouting, an inner layer of bearing capacity is formed within the soft, fractured surrounding rock at a depth of 6-9m. The deep grouting holes are evenly spaced along the roadway cross-section, with a spacing of 1... The grouting holes are laid out in sections of 0.5m apart and spaced 3m apart. The distance between the deep grouting holes near the bottom plate and the bottom plate of the roadway is 700mm. The angle between the deep grouting holes of the roadway shoulder and the vertical direction of the roadway is 45°. The deep grouting holes of the roof plate are drilled perpendicular to the roof plate of the roadway. The grouting pressure is 4~6MPa, and the final grouting pressure is 6MPa. In the fifth step, after the grouting reinforcement work of the shallow and deep parts of the soft and broken surrounding rock is completed, the outer layer bearing body and the inner layer bearing body are connected to each other by grouting anchor cables. The soft and broken rock mass with a thickness of 3m is between the inner layer bearing body and the outer layer bearing body.

[0003] Existing tunnel grouting reinforcement methods involve grouting the entire fractured surrounding rock around the tunnel. This means that the grouting nozzles on the grouting pipe are evenly distributed around the grouting pipe, allowing the cement grout inside the pipe to be sprayed out along the circumference of the grouting pipe. In other words, the cement grout is sprayed out in a 360° direction to reinforce the fractured surrounding rock around the grouting pipe. This method not only results in a large grouting volume, long construction period, and high construction cost, but also leads to a decrease in the stability of tunnel excavation due to the extended construction period. Summary of the Invention

[0004] To address the problems of large grouting volume, long construction period, and high cost associated with existing grouting methods for fractured surrounding rock in tunnels, this invention provides a directional grouting reinforcement method for fractured surrounding rock around tunnels. This method can reduce the amount of grouting required for fractured surrounding rock, shorten the construction period, and reduce construction costs. More importantly, it shortens the time cycle for grouting reinforcement of fractured surrounding rock, thereby improving the stability and bearing capacity of the surrounding rock around the tunnel.

[0005] To solve the technical problem, the technical solution adopted by this invention is as follows:

[0006] A method for directional grouting reinforcement of fractured surrounding rock around a tunnel, characterized by comprising:

[0007] (1) Drill holes into the fractured surrounding rock around the tunnel;

[0008] (2) Insert a grouting pipe into each hole. The grouting pipe has at least three rows of grouting ports along its length. Each row of grouting ports contains multiple grouting ports. The angle between the two outermost rows of grouting ports on the grouting pipe is 100°-135°. The grout sprayed from the two adjacent rows of grouting ports on two adjacent grouting pipes in the fractured surrounding rock of the tunnel can form an overlapping area.

[0009] (3) Inject grout into the grouting pipe. The grout sprays out from each grouting port of the grouting pipe and enters the gaps in the fractured surrounding rock, thereby completing the grouting reinforcement of the fractured surrounding rock.

[0010] In some embodiments, the grouting pipe includes a middle row of grouting ports arranged along the quadrant points of the grouting pipe, and outer rows of grouting ports located on both sides of the middle row of grouting ports are symmetrically arranged along the middle row of grouting ports.

[0011] In some embodiments, the grouting pipe includes three rows of grouting ports, namely a middle row of grouting ports and two outer rows of grouting ports, with the two outer rows of grouting ports symmetrically arranged along the middle row of grouting ports.

[0012] In some embodiments, the grouting ports on the outer row of grouting ports and the grouting ports on the middle row of grouting ports are spaced apart from each other.

[0013] In some embodiments, each grouting pipe is evenly distributed in the fractured surrounding rock around the tunnel, and each row of grouting ports of each grouting pipe is arranged in a direction away from the center of the tunnel, and the middle row of grouting ports of each grouting pipe is arranged in the radial direction of the tunnel, so that the grout sprayed from each grouting port can form a closed grouting reinforcement zone in the fractured surrounding rock outside the tunnel.

[0014] In some embodiments, the grouting pipe includes an inner pipe and an outer pipe. The inner pipe is sleeved inside the outer pipe and forms a cavity. The inner pipe has a discharge port. The outer pipe has a strip-shaped hole along its length, corresponding to the discharge port of the inner pipe. A sliding block is installed inside the cavity. The side of the sliding block facing the inner pipe has an arc-shaped cavity. The side of the sliding block facing the outer pipe has a grouting port communicating with the arc-shaped cavity. The position of the grouting port corresponds to the position of the strip-shaped hole. A telescopic plate for closing the arc-shaped cavity is connected to the side of the sliding block facing the inner pipe. A part of the telescopic plate connected to the discharge port is installed in the middle. A short feed tube extends into an arc-shaped cavity at one end. An elastic compression block is provided between the sliding block and the outer tube. A locking pin is provided on the side of the sliding block facing the inner tube. Several locking holes are provided on the inner tube that can engage with the locking pin. Under the action of the elastic compression block, the sliding block can compress the locking pin into the pin hole. A first spring and a second spring are respectively connected to both sides of the sliding block along the length of the inner tube. A fixing plate is installed on the inner wall of the outer tube or the outer wall of the inner tube. One end of the first spring and the second spring are fixedly connected to the sliding block, and the other end of the first spring and the second spring are fixed to the fixing plate.

[0015] In some embodiments, the sliding block is provided with elastic compression blocks at both ends facing the outer tube, and locking pins are provided at both ends facing the inner tube. The inner wall of the outer tube is provided with a sliding groove that is compatible with the elastic compression blocks.

[0016] In some embodiments, the tension applied to the slider by the first spring and the second spring is different.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The directional grouting reinforcement method for fractured surrounding rock of the present invention, compared with the existing technology of grouting reinforcement of fractured surrounding rock using grouting pipes, forms a closed grouting reinforcement zone within the fractured surrounding rock because the included angle between the outer grouting ports on the grouting pipe is 100°-135°, and the grout sprayed from the outer grouting ports on adjacent grouting pipes can form an overlapping zone. This effectively reinforces the fractured surrounding rock through grouting. In contrast, the existing technology allows grouting from the grouting ports on the grouting pipe to spray out along the 360° direction of the grouting pipe, thus requiring grouting reinforcement of both the fractured surrounding rock near and away from the tunnel, resulting in a large grouting volume and long grouting time. This invention performs grouting reinforcement only towards the fractured surrounding rock away from the tunnel from each grouting port. Grouting is not performed on the fractured surrounding rock near the tunnel side of the grouting pipe, thus significantly reducing the amount of grout required, shortening the grouting time, and lowering construction costs. More importantly, the shortened grouting reinforcement time allows for rapid grouting reinforcement of the fractured surrounding rock, thereby improving its stability and safety. In contrast, existing technologies, which use full grouting (i.e., grouting reinforcement is performed on both the fractured surrounding rock near and away from the tunnel), result in long grouting reinforcement times, preventing rapid grouting reinforcement of the fractured surrounding rock and significantly reducing its stability and safety. In this application, the fractured surrounding rock far from the tunnel side of the grouting pipe has been reinforced by grouting to form a grouting reinforcement zone. Furthermore, the inner side of the grouting reinforcement zone is not a complete ring, but rather serrated. This not only forms a closed grouting reinforcement zone, but also further reduces the amount of grouting and shortens the grouting time, thereby achieving the goal of reducing construction costs and improving construction efficiency.

[0019] When the grouting pipe of the present invention is in operation, when the high-pressure grout enters the inner tube of the grouting pipe, the high-pressure grout enters the arc-shaped cavity of the sliding block through the outlet. When the grouting port is not blocked by the broken surrounding rock, it means that the grout can be smoothly sprayed out at that position, allowing the sprayed grout to enter the gaps in the broken surrounding rock to form a spray zone, and the grouting pipe sprays normally. When the grouting port is blocked and completely blocked by the broken surrounding rock, the pressure at that position will increase, gradually driving the entire sliding block to squeeze the elastic compression block until the locking pin and locking hole at the lower end of the sliding block separate. After the sliding block loses the locking effect between the locking pin and the locking hole, it swings back and forth under the action of the first spring and the second spring to change position, thereby finding a position that will not be blocked by the broken surrounding rock. Furthermore, due to the effect of the arc-shaped cavity of the sliding block, when the sliding block swings under the action of the first spring and the second spring, the grout sprayed from the outlet of the inner tube will impact the arc-shaped cavity of the sliding block until the sliding block is grouting smoothly. Therefore, since the position of the grouting port on the sliding block of the present invention can be automatically adjusted, it can find a position that will not be blocked by the broken surrounding rock and smoothly perform grouting, thereby improving the quality of grouting and improving the stability and bearing capacity of the broken surrounding rock.

[0020] In existing technologies, when the grouting port is blocked by fractured surrounding rock, the amount of grout injected from that port is significantly less than that from other normally injected grouting ports, resulting in uneven grout distribution and a decrease in the bearing capacity of the grout-reinforced zone. The grouting port position of the grouting pipe in this invention can be automatically adjusted, ensuring that all grouting ports can inject grout normally (with comparable injection volumes), greatly improving the uniformity of grout injection and achieving the goal of improving the stability and bearing capacity of the fractured surrounding rock.

[0021] In summary, this invention not only reduces the amount of grouting and shortens the grouting cycle, thereby reducing construction costs, but also automatically adjusts the position of the grouting ports, ensuring that each port can spray grout normally, thus improving the uniformity of grouting and enhancing the stability and bearing capacity of the fractured surrounding rock. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a grouting reinforcement zone formed by grouting pipes in existing tunnel technology for fractured surrounding rock.

[0023] Figure 2 This is a schematic diagram of a grouting pipe of the present invention during grouting;

[0024] Figure 3 This is a schematic diagram showing the completion of grouting in each of the grouting pipes of the present invention.

[0025] Figure 4This is a schematic diagram showing the grouting reinforcement zone formed after grouting is completed in each of the grouting pipes according to the present invention.

[0026] Figure 5 This is a schematic diagram showing the distribution of the middle row of grouting ports and the outer row of grouting ports on the grouting pipe of the present invention;

[0027] Figure 6 This is a schematic diagram showing the distribution of the two outermost rows of grouting ports on the grouting pipe of the present invention, forming an included angle.

[0028] Figure 7 This is a partial cross-sectional view of an embodiment of the grouting pipe of the present invention.

[0029] Figure 8 This is a partial cross-sectional view of another embodiment of the grouting pipe of the present invention.

[0030] The markings in the diagram are: 1. Broken surrounding rock, 2. Tunnel, 3. Grouting pipe, 31. Grouting port, 32. Middle row grouting port, 33. Outer row grouting port, 34. Inner pipe, 35. Outer pipe, 36. Cavity, 37. Discharge port, 38. Strip hole, 39. Sliding block, 310. Arc-shaped cavity, 311. Telescopic plate, 312. Feed short pipe, 313. Elastic extrusion block, 314. Locking pin, 315. Locking hole, 316. First spring, 317. Second spring, 318. Fixing plate, 319. Slide groove, 320. Arc-shaped cylinder, 4. Grouting reinforcement zone, 41. Spraying zone, 42. Overlapping zone. Detailed Implementation

[0031] The present invention will be further described below with reference to embodiments. These embodiments are merely some, not all, of the embodiments of the present invention. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the protection scope of the present invention.

[0032] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention in conjunction with the specific circumstances.

[0033] Combined with appendix Figure 1 In existing technologies, when using grouting pipes to reinforce the fractured surrounding rock of a tunnel, the grouting ports on the pipes are evenly distributed along the circumference of the pipe, resulting in grouting of all the fractured surrounding rock around the pipe (often referred to as indiscriminate grouting). This method leads to a large grouting reinforcement zone 4, requiring a high volume of grout and taking a longer time, resulting in high construction costs. More importantly, it increases the time the fractured surrounding rock is not reinforced by grouting, increasing the risk of instability.

[0034] Combined with appendix Figure 2 -Appendix Figure 7 The present invention provides a method for directional grouting reinforcement of fractured surrounding rock around a tunnel, comprising:

[0035] (1) Drilling holes into the broken surrounding rock 1 around the tunnel 2; wherein the method of drilling is existing technology, the depth of drilling should meet the design requirements, and those skilled in the art can understand it, for example, using a rotary drilling rig to drill holes in the broken surrounding rock, which will not be elaborated here.

[0036] (2) Insert a grouting pipe 3 into each hole. The grouting pipe 3 has at least three rows of grouting ports along its length. Each row of grouting ports contains multiple grouting ports 31. The angle between the two outermost rows of grouting ports on the grouting pipe 3 is 100°-135°. The grout sprayed from the two adjacent rows of grouting ports on the two adjacent grouting pipes 3 in the fractured surrounding rock of the tunnel can form an overlapping area 42. When a hole is completed, the grouting pipe 3 should be inserted immediately to fill the hole.

[0037] (3) Grout is injected into the grouting pipe 3. The grout is sprayed from each grouting port of the grouting pipe into the cracks of the fractured surrounding rock, thereby completing the grouting reinforcement of the fractured surrounding rock 1 and forming the grouting reinforcement zone 4. When all the grouting pipes 3 are inserted into the grouting holes, the grouting pipes are connected to the grouting pump (or other grouting equipment such as grouting gun) through pipes for grouting. During the grouting process, the grouting pressure should be controlled. The grouting pressure will not be the same in different geological structures, so it is necessary to strictly follow the set grouting pressure. The grout sprayed from each grouting pipe can form a fan-shaped spray zone 41, and there is an overlap zone 42 between adjacent grouting pipes.

[0038] The directional grouting reinforcement method for fractured surrounding rock of the present invention, compared with the existing technology of grouting reinforcement of fractured surrounding rock using grouting pipes, forms a closed grouting reinforcement zone within the fractured surrounding rock because the included angle between the outer grouting ports on the grouting pipe is 100°-135°, and the grout sprayed from the outer grouting ports on adjacent grouting pipes can form an overlapping zone. This effectively reinforces the fractured surrounding rock through grouting. In contrast, the existing technology allows grouting from the grouting ports on the grouting pipe to spray out along the 360° direction of the grouting pipe, thus requiring grouting reinforcement of both the fractured surrounding rock near and away from the tunnel, resulting in a large grouting volume and long grouting time. This invention performs grouting reinforcement only towards the fractured surrounding rock away from the tunnel from each grouting port. Grouting is not performed on the fractured surrounding rock near the tunnel side of the grouting pipe, thus significantly reducing the amount of grout required, shortening the grouting time, and lowering construction costs. More importantly, the shortened grouting reinforcement time allows for rapid grouting reinforcement of the fractured surrounding rock, thereby improving its stability and safety. In contrast, existing technologies, which use full grouting (i.e., grouting reinforcement is performed on both the fractured surrounding rock near and away from the tunnel), result in long grouting reinforcement times, preventing rapid grouting reinforcement of the fractured surrounding rock and significantly reducing its stability and safety. In this application, the fractured surrounding rock far from the tunnel side of the grouting pipe has been reinforced by grouting to form a grouting reinforcement zone. Furthermore, the inner side of the grouting reinforcement zone is not a complete ring, but rather serrated. This not only forms a closed grouting reinforcement zone, but also further reduces the amount of grouting and shortens the grouting time, thereby achieving the goal of reducing construction costs and improving construction efficiency.

[0039] Combined with appendix Figure 1 and attached Figure 4Under the same conditions (including but not limited to tunnel size and the same geological strata), the area of ​​the grouting reinforcement zone 4 of the present invention is significantly smaller than that of the grouting reinforcement zone in the prior art. Therefore, compared with the prior art, the present invention can reduce the amount of grouting and shorten the grouting time, thereby reducing construction costs. At the same time, due to the reduction in grouting time, the time without grouting reinforcement of fractured surrounding rock can be reduced, thus reducing the risk of instability of fractured surrounding rock.

[0040] In some embodiments, the grouting pipe 3 includes a middle row of grouting ports 32 arranged along the quadrant points of the grouting pipe, and outer rows of grouting ports 33 located on both sides of the middle row of grouting ports 32 are symmetrically arranged along the middle row of grouting ports. In specific implementations, one row of outer rows of grouting ports is arranged on each side of the grouting pipe 3, or two rows of outer rows of grouting ports are arranged on each side of the grouting pipe.

[0041] Preferably, in some embodiments, the grouting pipe 3 includes three rows of grouting ports, namely a middle row of grouting ports 32 and two rows of outer rows of grouting ports 33, with the two rows of outer rows of grouting ports 33 symmetrically arranged along the middle row of grouting ports 32.

[0042] In some embodiments, the grouting ports 31 on the outer row of grouting ports 33 and the grouting ports 31 on the middle row of grouting ports 32 are spaced apart from each other.

[0043] In some embodiments, each grouting pipe 3 is evenly distributed in the fractured surrounding rock 1 around the tunnel 2, and each row of grouting ports of each grouting pipe 3 is arranged in a direction away from the center of the tunnel 2, and the middle row of grouting ports 32 of each grouting pipe 3 is arranged in the radial direction of the tunnel 2, so that the grout sprayed from each grouting port 31 can form a closed grouting reinforcement zone 4 in the fractured surrounding rock 1 around the tunnel 2.

[0044] In some embodiments, the grouting pipe 3 includes an inner pipe 34 and an outer pipe 35. The inner pipe 34 is sleeved inside the outer pipe 35 and forms a cavity 36. The inner pipe 34 has a discharge port 37. The outer pipe 36 has a strip-shaped hole 38 arranged along the length of the outer pipe 35, corresponding to the position of the discharge port 37 of the inner pipe 34. A sliding block 39 is installed in the cavity 36. The side of the sliding block 39 facing the inner pipe 34 has an arc-shaped cavity 310. The side of the sliding block 39 facing the outer pipe 35 has a grouting port 31 that communicates with the arc-shaped cavity 310. The position of the grouting port 31 corresponds to the position of the strip-shaped hole 38. A telescopic plate 311 for closing the arc-shaped cavity 310 is connected to the side of the sliding block 39 facing the inner pipe 34. A short feed pipe 3 connected to the discharge port 37 is installed in the middle of the telescopic plate 311. 12. The other end of the feed short pipe 312 extends into the arc-shaped cavity 310; an elastic extrusion block 313 is provided between the sliding block 3 and the outer pipe 35; a locking pin 314 is provided on the side of the sliding block 39 facing the inner pipe 34; the inner pipe 34 has several locking holes 315 that can engage with the locking pin 314; the sliding block 39 can press the locking pin 314 into the pin hole 315 under the action of the elastic extrusion block 313; a first spring 316 and a second spring 317 are respectively connected to both sides of the sliding block 39 along the length direction of the inner pipe 34; a fixing plate 318 is installed on the inner wall of the outer pipe 35 or the outer wall of the inner pipe 34; one end of the first spring 316 and the second spring 317 is fixedly connected to the sliding block 39; and the other end of the first spring 316 and the second spring 317 is fixed on the fixing plate 317. Since the outer and inner tubes are cylindrical, the telescopic plate 311 and sliding block 39 of this invention are installed in an arc shape between the outer and inner tubes. During assembly, the sliding block, elastic compression block, telescopic plate, first spring, second spring, and fixing plate are first installed on the inner tube, and then the outer tube is fitted on. After the outer tube is fitted, it can be fixed to the inner tube using bolts or other connection methods.

[0045] Preferably, the inner tube has a pointed tip to facilitate insertion into the borehole.

[0046] In some embodiments, the sliding block 39 is provided with elastic compression blocks 313 at both ends facing the outer tube 35, and locking pins 315 at both ends facing the inner tube 34. The inner wall of the outer tube 35 is provided with a sliding groove 319 that is compatible with the elastic compression block 313. Thus, the elastic compression block can provide a preload to the sliding block, and at the same time, the elastic compression block can slide in the sliding groove 319 of the outer tube.

[0047] In some embodiments, the first spring 316 and the second spring 317 apply different tensions to the sliding block 39, so that when the locking pin of the sliding block 39 disengages from the lock hole, it can wobble under the action of the first spring and the second spring.

[0048] The pre-tightening force applied to the sliding block by the elastic extrusion block 313 can be adapted to the set grouting pressure. That is, when the grout pressure in the arc cavity is less than or equal to a certain value, the elastic extrusion block 313 can always lock the sliding block in the locking pin. When the grout pressure in the arc cavity 310 is greater than a certain value, the elastic extrusion block 313 can be squeezed, causing the entire sliding block to move towards the outer pipe.

[0049] In order to improve the mobility of the telescopic plate 311, the side of the telescopic plate 311 closest to the inner tube does not contact the inner tube. That is, the telescopic plate is installed inside the arc-shaped cavity 311, so that the telescopic plate 311 will not contact the inner tube during the movement and ensures that the telescopic plate has room to move.

[0050] Preferably, in order to prevent the injected slurry from hindering the movement of the corrugated pipe, an arc-shaped cylinder is also installed inside the arc-shaped cavity 310. The arc-shaped cylinder and the feed short pipe are connected to each other through a pipe, so that the slurry can impact the arc-shaped cylinder while avoiding contact between the corrugated plate and the slurry.

[0051] When the grouting pipe of the present invention is in operation, when the high-pressure grout enters the inner tube of the grouting pipe, the high-pressure grout enters the arc-shaped cavity of the sliding block through the outlet. When the grouting port is not blocked by the broken surrounding rock, it means that the grout can be smoothly sprayed out at that position, allowing the sprayed grout to enter the gaps in the broken surrounding rock to form a spray zone, and the grouting pipe sprays normally. When the grouting port is blocked and completely blocked by the broken surrounding rock, the pressure at that position will increase, gradually driving the entire sliding block to squeeze the elastic compression block until the locking pin and locking hole at the lower end of the sliding block separate. After the sliding block loses the locking effect between the locking pin and the locking hole, it swings back and forth under the action of the first spring and the second spring to change position, thereby finding a position that will not be blocked by the broken surrounding rock. Furthermore, due to the effect of the arc-shaped cavity of the sliding block, when the sliding block swings under the action of the first spring and the second spring, the grout sprayed from the outlet of the inner tube will impact the arc-shaped cavity of the sliding block until the sliding block is grouting smoothly. Therefore, since the position of the grouting port on the sliding block of the present invention can be automatically adjusted, it can find a position that will not be blocked by the broken surrounding rock and smoothly perform grouting, thereby improving the quality of grouting and improving the stability and bearing capacity of the broken surrounding rock.

[0052] In existing technologies, when the grouting port is blocked by fractured surrounding rock, the amount of grout injected from that port is significantly less than that from other normally injected grouting ports, resulting in uneven grout distribution and a decrease in the bearing capacity of the grout-reinforced zone. The grouting port position of the grouting pipe in this invention can be automatically adjusted, ensuring that all grouting ports can inject grout normally (with comparable injection volumes), greatly improving the uniformity of grout injection and achieving the goal of improving the stability and bearing capacity of the fractured surrounding rock.

[0053] In summary, this invention not only reduces the amount of grouting and shortens the grouting cycle, thereby reducing construction costs, but also automatically adjusts the position of the grouting ports, ensuring that each port can spray grout normally, thus improving the uniformity of grouting and enhancing the stability and bearing capacity of the fractured surrounding rock.

Claims

1. A method for directional grouting reinforcement of fractured surrounding rock around a tunnel, characterized in that, include: (1) Drill holes into the fractured surrounding rock around the tunnel; (2) Insert a grouting pipe into each hole. The grouting pipe has at least three rows of grouting ports along its length. Each row of grouting ports contains multiple grouting ports. The angle between the two outermost rows of grouting ports on the grouting pipe is 100°-135°. The grout sprayed from the two adjacent rows of grouting ports on two adjacent grouting pipes in the fractured surrounding rock of the tunnel can form an overlapping area. (3) Inject grout into the grouting pipe. The grout sprays out from each grouting port of the grouting pipe and enters the gaps in the fractured surrounding rock, thereby completing the grouting reinforcement of the fractured surrounding rock. The grouting pipe includes an inner pipe and an outer pipe. The inner pipe is fitted inside the outer pipe and forms a cavity. The inner pipe has a discharge port. The outer pipe has a strip-shaped hole along its length, corresponding to the discharge port of the inner pipe. A sliding block is installed inside the cavity. The side of the sliding block facing the inner pipe has an arc-shaped cavity. A grouting port communicating with the arc-shaped cavity is located on the side of the sliding block facing the outer pipe. The position of the grouting port corresponds to the position of the strip-shaped hole. A telescopic plate for closing the arc-shaped cavity is connected to the side of the sliding block facing the inner pipe. A feed inlet connected to the discharge port is installed in the middle of the telescopic plate. A short tube, with the other end of the feed short tube extending into an arc-shaped cavity; an elastic compression block is provided between the sliding block and the outer tube, and a locking pin is provided on the side of the sliding block facing the inner tube. The inner tube has several locking holes that can engage with the locking pin. Under the action of the elastic compression block, the sliding block can compress the locking pin into the pin hole. A first spring and a second spring are respectively connected to both sides of the sliding block along the length direction of the inner tube. A fixing plate is installed on the inner wall of the outer tube or the outer wall of the inner tube. One end of the first spring and the second spring are fixedly connected to the sliding block, and the other end of the first spring and the second spring are fixed to the fixing plate.

2. The method for directional grouting reinforcement of fractured surrounding rock around a tunnel according to claim 1, characterized in that, The grouting pipe includes a middle row of grouting ports arranged along the quadrant points of the grouting pipe, and outer rows of grouting ports located on both sides of the middle row of grouting ports are symmetrically arranged along the middle row of grouting ports.

3. The method for directional grouting reinforcement of fractured surrounding rock around a tunnel according to claim 2, characterized in that, The grouting pipe includes three rows of grouting ports, namely a middle row of grouting ports and two outer rows of grouting ports, with the two outer rows of grouting ports symmetrically arranged along the middle row of grouting ports.

4. The method for directional grouting reinforcement of fractured surrounding rock around a tunnel according to claim 2 or 3, characterized in that, The grouting ports on the outer row and the grouting ports on the middle row are spaced apart from each other.

5. The method for directional grouting reinforcement of fractured surrounding rock around a tunnel according to claim 2, characterized in that, Each grouting pipe is evenly distributed in the fractured surrounding rock around the tunnel, and the grouting ports of each grouting pipe are set in a direction away from the center of the tunnel, while the middle row of grouting ports of each grouting pipe is set in the radial direction of the tunnel. This allows the grout sprayed from each grouting port to form a closed grouting reinforcement zone in the fractured surrounding rock outside the tunnel.

6. The method for directional grouting reinforcement of fractured surrounding rock around a tunnel according to claim 1, characterized in that, Both ends of the sliding block facing the outer tube are equipped with elastic compression blocks, and both ends of the sliding block facing the inner tube are equipped with locking pins. The inner wall of the outer tube is provided with a sliding groove that matches the elastic compression block.

7. The method for directional grouting reinforcement of fractured surrounding rock around a tunnel according to claim 1, characterized in that, The first spring and the second spring exert different pulling forces on the sliding block.

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