A combined support device and method for impact ground pressure top

Abstract

The present invention relates to a combined support device and method for impact ground pressure top wall, comprising an anchor net support, a first steel support (2) + a flexible intelligent impact-resistant material (3) + a second steel support (4) and a top wall impact-resistant device (7), so as to realize three-level combined support. The method comprises the following steps: S1: installing the anchor net support; S2: installing the secondary support consisting of the first steel support (2), the flexible intelligent impact-resistant material (3) and the second steel support (4); S3: installing the top wall impact-resistant device (7), wherein the position of the device is fixed by a sleeve expansion joint (8), a pressure sensor (9), a spring body (15) and a base (11) are provided at the bottom of the device, and a chain rod (14), a piston (12) and a steel gasket (10) are provided at the bottom of the two walls, so that the pressure from the top is transmitted to the two walls through the chain rod, the piston and the steel gasket. The method can buffer and release pressure layer by layer, absorb the released energy, effectively prevent and control excessive impact, ensure the safe construction of the tunnel, and has a wide range of application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of mine safety, and in particular relates to a rock burst top combined support device and method. Background Art

[0002] Rock burst is a mining dynamic phenomenon, which is usually defined as the violent release of deformation energy stored in coal and rock masses around mine shafts and mining areas, accompanied by sudden, rapid and violent destruction of coal and rock masses. Simply put, it is the sudden destruction of coal and rock masses. Rock burst is one of the main types of disasters that threaten coal mine production safety. It not only causes severe damage to coal and rock masses in the working space, but may also cause secondary disasters such as abnormal gas outburst, gas explosion, coal dust explosion, and roof collapse. With the mining of coal mines, its center of gravity gradually shifts to the deeper parts. Under the influence of high ground stress, high ground temperature and high karst water pressure, the frequency and intensity of coal and rock dynamic disasters such as rock burst have increased significantly, and the number of mines with rock burst has increased significantly. As of 2021, there were a total of 138 mines with rock burst in coal mines across the country.

[0003] Existing tunnel support methods include shed-type supports, stone supports, anchor supports, shotcrete supports, and advanced hydraulic supports. Shed-type supports are difficult to construct and expensive. The steel sheds bear heavy loads and can sometimes be crushed, making withdrawal difficult and impacting normal mining. They also have poor rock burst prevention capabilities. Stone supports are more effective in preventing large-scale watering or localized water inrush in chemically corrosive, water-bearing surrounding rock sections where treatment is ineffective. However, they offer insufficient support integrity for rock bursts and lack rock burst prevention capabilities. Anchor supports offer significant advantages in preventing roadway damage from rock bursts. Anchor supports are flexible and move with the overall displacement of the surrounding rock. Their support is less affected by impact forces and maintains its support function even after impact. However, anchor supports alone cannot meet rock burst prevention requirements. Shotcrete supports ensure a tight bond between the concrete and the surrounding rock, forming a rock arch around the tunnel wall and fully utilizing the surrounding rock's supporting function. However, they are not well-suited for preemptive rock burst prevention. Advanced hydraulic supports are a type of advanced support. These supports have high operating resistance and relatively high support strength. However, when subjected to large impact loads, the hydraulic supports are prone to significant deformation. Furthermore, existing anti-impact advanced support technology and its complete equipment are not yet mature. Existing conventional support methods and theories cannot effectively address rock burst issues.

[0004] Patent ZL201510148933.X discloses a method for preventing rock burst in all-coal tunnels. This method uses four measures: conventional support consisting of wire mesh, steel belts and anchor rods; anti-rock burst support consisting of two layers of steel plates and energy-absorbing boxes fixed between the two layers of steel plates; surrounding rock modification by drilling and grouting in the tunnel roof and both sides; and blasting to relieve pressure at the tunnel bottom corners. This method forms a "point-line-surface-body" three-dimensional distributed energy-absorbing and anti-rock burst system. Anchor rods, anchor cables and steel beams are integrated into the support. When the impact is too large or the local pressure is too large, structural damage can easily lead to overall failure; Patent ZL201910671449.3 discloses a strong impact ground pressure tunnel support method, which adopts a three-level combined support method of anchor net, U-shaped shed, and energy-absorbing anti-impact support. The combined support is a simple yielding support, which mainly yields to excessive pressure. This yielding is limited to excessive roof pressure. The combined support relies too much on the anti-impact support described therein and fails to achieve true combined support.

[0005] To sum up, the existing anti-bumping support is difficult to meet the anti-bumping requirements with a single support, and there is less advanced support. When the impact load is large, the hydraulic support is prone to produce relatively large deformation. In addition, the existing anti-bumping advanced support technology and its complete set of equipment are still not very mature. Summary of the Invention

[0006] The purpose of the present invention is to provide a rock burst top combined support device and method, which can buffer and release pressure layer by layer.

[0007] The objectives of the present invention can be achieved through the following technical solutions: a combined support device for top and side impact of rock burst, the combined support device comprising a primary support, a secondary support and a tertiary support; the primary support is an anchor net support, which is arranged on the top plate and the two sides of the roadway; the secondary support is installed between two rows of anchor rods in the anchor net support; the tertiary support is a top and side impact resistance device, which is installed on the top plate and the two sides of the roadway of the secondary support to achieve a three-level combined support;

[0008] The top side impact resistant device includes a steel column, a sleeve expansion joint, a connecting steel, a spring body, a pressure sensor, a base, a chain rod, a piston and a steel gasket; wherein, the sleeve expansion joint is located on the upper part of the steel column and is connected to the steel column by bolts, the connecting steel at the lower part of the steel column is fixedly connected to the spring body below, the spring body is fixedly connected to the pressure sensor, and the pressure sensor is fixedly connected to the base; the two sides of the connecting steel are connected to the piston rod in the piston through a chain rod, and the piston is tightly installed on the steel gasket on the side.

[0009] Furthermore, the sleeve expander in the top side impact resistance device is used to fix the position of the device. The chain rod, piston and steel gasket installed at the bottom of the two sides of the device transfer the pressure from the top to the steel gasket through the chain rod and piston rod and then to the two sides; since the two sides are also impacted and squeezed by the surrounding rock pressure, the top side impact resistance device also relieves the pressure on the sides to a certain extent, preventing the two sides from deforming too much and causing bottom bulging.

[0010] Furthermore, the spring body, pressure sensor and base installed at the bottom of the top impact resistance device can prevent the device from being suddenly damaged due to excessive top impact pressure.

[0011] Furthermore, the connection mode between the connecting steel and the chain rod is hinged; the connection mode between the chain rod and the piston rod is hinged.

[0012] Furthermore, the anchor mesh support includes hollow grouting anchor rods, anchor cables and steel mesh; wherein, the spacing of the hollow grouting anchor rods is 1.5-2m, and the spacing of the anchor cables is 1.5-2m.

[0013] Furthermore, the secondary support consists of a first steel support, a flexible intelligent impact-resistant material and a second steel support; wherein, the spacing between the first steel support and the second steel support is 1.5m; the flexible intelligent impact-resistant material includes FIAM flexible intelligent impact-resistant material or ESA energy-absorbing filler (non-Newtonian fluid material); the flexible intelligent impact-resistant material has excellent impact resistance and buffering performance, and is soft and elastic under normal conditions. Once subjected to a strong impact, the material quickly hardens to withstand the external impact force. When the external force disappears, the material will return to its original soft state; under tunnel impact, the first steel support, the flexible intelligent impact-resistant material and the second steel support are combined to realize secondary support to ensure the stability of the tunnel.

[0014] Furthermore, the top plate and the side of the inner surface of the first steel support and the outer surface of the second steel support are installed with strain gauges;

[0015] Furthermore, the sleeve telescope includes an upper plate, a lower plate, a bolt and a telescopic steel column; the distance between the upper plate and the lower plate is controlled by rotating the bolt, thereby controlling the telescopic length of the telescopic steel column and fixing the position of the top impact resistance device.

[0016] A second object of the present invention is to provide a rock burst top support method, using the rock burst top support device, the method comprising the following steps:

[0017] Step S1: excavate the rock burst tunnel, remove dangerous rocks, perform initial concrete spraying, drill holes at equal intervals on the sidewalls, install hollow grouting anchor rods, connect the grouting equipment for grouting, install pads and nuts after grouting, and then hang the steel mesh; after the hollow grouting anchor rods are installed, drill holes at equal intervals on the top plate of the same section of the hollow grouting anchor rods and at the bottom of both sides, fix anchor cables in the holes, and install anchor pads and anchors at the ends to achieve primary support;

[0018] Step S2: Installing the first steel support and the second steel support in the middle of the two rows of hollow grouting anchors, filling the space between the first and second steel supports with flexible intelligent impact-resistant material, and installing strain gauges on the inner surface of the first steel support and the outer surface of the second steel support to achieve secondary support;

[0019] Step S3: Installing top impact resistant devices on the secondary support at intervals, fixing the position of the top impact resistant devices by using a sleeve expansion joint, and observing the pressure of the top impact resistant devices by using a pressure sensor at the bottom of the device, thereby achieving the third level of support;

[0020] Step S4: While the tunnel is being excavated, the support installation is adjusted according to the geological conditions and the observed strain of the strain gauge and the pressure of the pressure sensor; when the strain of the strain gauge is too large, the support is reinforced according to the location; when the pressure of the pressure sensor is too large, the number of top impact resistance devices is increased or the support is reinforced to ensure the safety of the tunnel construction.

[0021] Furthermore, in step S1, the thickness of the initial sprayed concrete is 4-6 cm. After the initial spraying is completed, measurement and layout are performed to determine the position of the construction hole.

[0022] Furthermore, in step S1, the drilling direction is perpendicular to the rock surface, wherein the top anchor hole is drilled by an anchor drill rig, and the side wall of the side is drilled by an air-leg rock drill; the drilling depth and angle are checked after drilling; the length of the hollow grouting anchor inserted into the hole is ≥ 95% of its own length.

[0023] Furthermore, in step S1, the grouting pressure is 0.3-0.6 MPa, and the cement: sand: water ratio in the slurry is 1:1:0.45. Grouting is stopped after slurry comes out of the exhaust port; the steel mesh is firmly connected to the hollow grouting anchor rod, and the gap between the steel mesh and the sprayed surface is 20-30 mm.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] The present invention adopts anchor net support, first steel support + flexible intelligent impact-resistant material + second steel support and top impact-resistant device support to realize three-level joint support. The method can buffer and release pressure layer by layer, absorb the released energy, effectively prevent and control impact, ensure the safety of tunnel construction, have important practical significance and significant social benefits, and have broad application prospects; among them, the hollow grouting anchor moves with the overall displacement of the surrounding rock, the anchor support effect is less affected by the impact power, can actively absorb the energy released by the surrounding rock due to the impact, the anchor cable can ensure long-term stability, and can still maintain its support effect after the impact; the steel support can resist and buffer external force impact Pressure, once subjected to rapid and strong impact, the flexible intelligent impact-resistant material between the first steel support and the second steel support plays an energy-absorbing and protective role, quickly hardens to withstand the external impact force, and performs secondary pressure relief; the top wall anti-impact device, once a strong impact ground pressure occurs, the first and second level supports cannot effectively protect, the strong impact force may cause the first and second level support structures to be destroyed, at this time the top wall anti-impact device can effectively prevent impact, and transfer the excessive roof pressure to the two sides through the top wall anti-impact device. In addition, it can also relieve the surrounding rock pressure on the two sides, realize three-level support, and release pressure layer by layer. No matter what kind of impact, the tunnel structure can be guaranteed to be stable and the construction safety can be guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the hollow grouting anchor rod of the present invention;

[0027] Figure 2 Schematic diagram of the sleeve retractor of the present invention;

[0028] Figure 3 This is a schematic diagram of the secondary support of the present invention;

[0029] Figure 4 This is a schematic diagram of the installation of the combined support for the roadway according to the present invention;

[0030] The markings in the figure are: 1: hollow grouting anchor rod; 2: first steel support; 3: flexible intelligent impact-resistant material; 4: second steel support; 5: anchor cable; 6: strain gauge; 7: top impact-resistant device; 8: sleeve expansion joint; 9: pressure sensor; 10: steel gasket; 11: base; 12: piston; 13: piston rod; 14: chain rod; 15: spring body; 16: connecting steel; 1.1: plastic anchor head; 1.2: hollow anchor rod body; 1.3: grouting plug; 1.4: pad; 1.5: nut; 8.1: upper plate; 8.2: lower plate; 8.3: bolt; 8.4: telescopic steel column. DETAILED DESCRIPTION

[0031] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, those skilled in the art will be able to make several changes and improvements without departing from the scope of the present invention, all of which fall within the scope of protection of the present invention.

[0032] The materials and equipment used in the following examples are all commercially available.

[0033] Example 1

[0034] See also Figure 4 The anti-impact combined support system of the present invention includes anchor net support, secondary support consisting of first steel support 2, flexible intelligent impact-resistant material 3 and second steel support 4, and top impact-resistant device 7, to achieve three-level combined support. It includes the following steps:

[0035] Step S1: Installation of primary support anchor net support

[0036] Excavate the rock burst tunnel, remove dangerous rocks, and perform initial spraying. The thickness of the initial sprayed concrete is controlled at 4-6cm. Drill holes at equal intervals on the side of the tunnel, with the drilling direction perpendicular to the rock surface. Install hollow grouting anchor rods 1. The spacing of the hollow grouting anchor rods 1 is 1.5m, which can be adjusted according to the specific engineering geological conditions and is generally not more than 2m. Figure 1 The installation consists of a plastic anchor head 1.1, a hollow anchor rod body 1.2, a grouting plug 1.3, a backing plate 1.4, and a nut 1.5. During installation, insert the hollow grouting anchor rod 1 into the hole at the specified angle and depth. The hole depth is set to 4m, and the anchor rod insertion length is ≥ 95% of its own length. A grouting plug 1.3 is installed to ensure the hollow portion is unobstructed, and a vent hole is reserved. The grouting equipment is connected to inject mortar. After grouting is completed, the backing plate 1.4 and nut 1.5 are installed after the re-spraying of concrete. A steel mesh is installed, using φ8 steel bars. The overlap length of the steel bars must not be less than 35 times the steel bar diameter. The mesh is firmly connected to the anchor rod, and the gap between the mesh and the sprayed surface is controlled between 20-30mm. The hollow grouting anchor 1 absorbs the energy released by the surrounding rock due to impact, ensuring long-term stability. After installation, holes are drilled at equal intervals in the top plate and at the bottom of both sides of the same section. The top anchor hole is drilled using an anchor drill rig, while the side walls are drilled using an air-leg rock drill. The hole depth is set to 10m. Anchor cables 5 are fixed in the holes, with anchor pads and anchors installed at the ends. The spacing of the anchor cables 5 is 1.5m, which can be adjusted according to the specific geological conditions of the project, but generally does not exceed 2m.

[0037] Step S2: Installation of secondary support

[0038] The first steel support 2 and the second steel support 4 are fixed in the middle of the two rows of hollow grouting anchor rods 1, and the space between the first steel support 2 and the second steel support 4 is filled with flexible intelligent impact-resistant material 3. Strain gauges 6 are installed on the inner surface of the first steel support 2 and the outer surface of the second steel support 4, and the installation positions are respectively on the top plate and the two sides; the flexible intelligent impact-resistant material 3 has excellent impact resistance and buffering performance, and forms a steel support structure with the first steel support 2 and the second steel support 4, which can bear pressure and realize secondary support. The spacing between the first steel support 2 and the second steel support 4 is 1.5m. The schematic diagram of the secondary support is shown in FIG. Figure 3 .

[0039] Step S3: Installation of the three-level support top impact resistance device

[0040] The top impact resistance device 7 is installed at intervals on the secondary support. The lower part of the device is provided with a spring body 15, a pressure sensor 9 and a base 11. The position of the top impact resistance device 7 is fixed by a sleeve expansion joint 8. The structural diagram of the sleeve expansion joint 8 is shown in FIG. Figure 2 The distance between the upper plate 8.1 and the lower plate 8.2 is controlled by rotating the bolt 8.3, and the telescopic length of the telescopic steel column 8.4 is controlled to fix the position of the top anti-impact device 7. The pressure of the top anti-impact device 7 is observed by observing the pressure sensor 9. The bottom of the two sides of the top anti-impact device 7 is equipped with a chain rod 14, a piston 12 and a steel gasket 10. The pressure from the top is transmitted to the steel gasket 10 through the chain rod 14 and the piston 12, and then to the two sides. In addition, it can also relieve the pressure of the surrounding rocks on the two sides, realizing three-level support. By releasing pressure layer by layer, the stability of the tunnel structure is guaranteed, and the construction safety is guaranteed.

[0041] Among them, installing the top impact resistance device 7 on the secondary support at intervals can be understood as installing the top impact resistance device 7 on the 2N+1th secondary support, where the value range of N in 2N+1 is 0, 1, 2, ... When N=0, the top impact resistance device 7 is installed on the first secondary support; when N=1, the top impact resistance device 7 is installed on the third secondary support; when N=2, the top impact resistance device 7 is installed on the fifth secondary support, and so on.

[0042] The installation order of the top side anti-impact device 7 is the bottom first, then the two sides, and then the top; specifically, first install the fixed base 11, install the fixed pressure sensor 9 on the base 11, and then install the spring body 15 on the pressure sensor 9. The spring body 15 is fixed to the connecting steel 16, and then install the piston 12 on the two sides of the tunnel. The piston 12 is tightly against the steel gasket 10 installed on the side. The piston 12 and the piston rod 13 are connected to the middle connecting steel 16 through the chain rod 14, and the connection method is hinged. Finally, the upper steel column structure is installed, and the initial installation position is fixed by the sleeve retractor 8.

[0043] Step S4: While the tunnel is being excavated, the support installation is adjusted according to the geological conditions and the observed strain of the strain gauge 6 and the pressure of the pressure sensor 9; when the strain of the strain gauge is too large, the support is reinforced according to the location; when the pressure of the pressure sensor is too large, the number of top impact resistance devices is increased or the support is reinforced to ensure the safety of the tunnel construction.

[0044] When rock burst occurs, the elastic deformation can be released instantaneously. The present invention can buffer and release pressure layer by layer, absorb the released energy, and transmit excessive roof pressure to the two sides through the device, thereby alleviating the rock burst pressure on the two sides, effectively preventing and controlling the impact, and ensuring the safety of tunnel construction.

[0045] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A rock burst top joint support method, characterized in that: A combined support device for impact ground pressure top wall is adopted, and the combined support device includes a primary support, a secondary support, and a tertiary support; the primary support is an anchor net support, which is arranged on the top plate and the two sides of the roadway; the secondary support is installed between two rows of anchor rods in the anchor net support; the tertiary support is a top wall anti-impact device (7), which is installed on the top plate and the two sides of the roadway of the secondary support, so as to realize a three-level combined support; the top wall anti-impact device (7) includes a steel column, a sleeve expansion joint (8), a connecting steel (16), a spring body (15), a pressure sensor (9), a base (11), a chain rod (14), a piston (12), and a steel gasket (10); The sleeve expansion joint (8) is located at the upper part of the steel column and is connected to the steel column by bolts. The connecting steel (16) at the lower part of the steel column is fixedly connected to the spring body (15) below. The spring body (15) is fixedly connected to the pressure sensor (9). The pressure sensor (9) is fixedly connected to the base (11). Both sides of the connecting steel (16) are connected to the piston rod (13) in the piston (12) through the chain rod (14). The piston (12) is tightly attached to the steel gasket (10) installed at the side. The anchor mesh support comprises hollow grouting anchor rods (1), anchor cables (5) and a steel mesh; wherein the spacing of the hollow grouting anchor rods (1) is 1.5-2 m, and the spacing of the anchor cables (5) is 1.5-2 m; The secondary support is composed of a first steel support (2), a flexible intelligent impact-resistant material (3), and a second steel support (4); the first steel support (2) and the second steel support (4) are both spaced 1.5 m apart; Strain gauges (6) are installed on the top plate and the side of the inner surface of the first steel support (2) and the outer surface of the second steel support (4); The rock burst top support combined method comprises the following steps: Step S1: excavate the rock burst tunnel, perform initial concrete spraying, drill holes at equal intervals on the sidewalls, install hollow grouting anchor rods (1) for grouting, hang steel mesh after grouting, and then drill holes at equal intervals on the top plate of the same section of the hollow grouting anchor rods (1) and at the bottom of both sides, and fix anchor cables (5) in the holes; Step S2: installing a first steel support (2) and a second steel support (4) in the middle of the two rows of anchor rods, filling the space between the first steel support (2) and the second steel support (4) with a flexible intelligent impact-resistant material (3), and installing strain gauges (6) on the inner surface of the first steel support (2) and the outer surface of the second steel support (4); Step S3: Installing the top impact resistant device (7) at intervals on the secondary support, fixing the position of the top impact resistant device (7) by means of a sleeve expansion joint (8), and observing the pressure of the top impact resistant device (7) by means of a pressure sensor (9) at the bottom of the device; Step S4: While the tunnel is being excavated, according to the geological conditions and the observed strain of the strain gauge (6) and the pressure of the pressure sensor (9), the support is reinforced according to the location, the number of top wall anti-impact devices is increased, or the support is reinforced to ensure the safety of the tunnel construction.

2. A rock burst top joint support method according to claim 1, characterized in that: The connection mode of the connecting steel (16) and the chain rod (14) is hinged; the connection mode of the chain rod (14) and the piston rod (13) is hinged.

3. The rock burst top joint support method according to claim 1, characterized in that: The telescopic sleeve (8) comprises an upper plate (8.1), a lower plate (8.2), a bolt (8.3), and a telescopic steel column (8.4); the distance between the upper plate (8.1) and the lower plate (8.2) is controlled by rotating the bolt (8.3), thereby controlling the telescopic length of the telescopic steel column (8.4) and fixing the position of the top impact resistance device (7).

4. The rock burst top support method according to claim 1, characterized in that: In step S1, the thickness of the initial sprayed concrete is 4-6 cm.

5. The rock burst top joint support method according to claim 1 is characterized in that: In step S1, the drilling direction is perpendicular to the rock surface, wherein the top anchor hole is drilled by an anchor drill, and the side wall of the side is drilled by an air leg rock drill; the length of the hollow grouting anchor (1) inserted into the hole is ≥ 95% of its own length.

6. The rock burst top support method according to claim 1, characterized in that: In step S1, the grouting pressure is 0.3-0.6 MPa, the cement: sand: water ratio in the slurry is 1:1:0.45, and the grouting is stopped after the slurry is discharged from the exhaust port; the steel mesh is firmly connected to the hollow grouting anchor rod (1), and the gap between the steel mesh and the sprayed surface is 20-30 mm.

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