CN107143338A - A kind of coal mine roadway driving and method for protecting support - Google Patents

Abstract

The invention discloses a tunneling and supporting method for an underground roadway in a coal mine, which is mainly aimed at solving problems such as that the surrounding rock of the roof is soft and broken and the roadway is difficult to form, which further affects the safety and speed of the tunneling, etc. The method of the present invention divides the excavation of the entire cut-out space into three stages: the first passage is formed by breaking the roof, the second passage is formed under the undercover, and the third passage is formed by expanding the side of the coal body to be mined. The present invention can well adapt to the roof The extremely soft and broken thick coal seam working face has the characteristics of a large cross-section cut-out roof, which is weak and broken, and effectively prevents the occurrence of roof fall accidents.

Description

A coal mine roadway excavation and support method

technical field

The invention relates to a coal mine roadway excavation and support method, which is suitable for excavation and support of large cross-section cutting holes in thick coal seam working faces with extremely soft and broken roofs.

Background technique

The degree of mechanization and the scope of application of coal mining in my country are gradually increasing, and the height and width of the cutout in the working face are increasing. Generally, the excavation method of tunnel expansion and secondary roadway formation is adopted. In the secondary expansion of the roadway, it is easy to cause the cutout and roof fall accidents. Especially in the cut eye of the thick coal seam working face with very soft and broken roof, roof fall accidents occur frequently. Therefore, it is of great economic and social significance to ensure the safety of excavation and the stability of the surrounding rock in thick coal seam working faces with extremely soft and broken roofs.

At present, the main method of tunneling in the excavation working face is the secondary tunneling method of tunnel expansion. eye, but still not completely eliminate the potential safety hazard of eye-cutting and roof fall. One of the main reasons is that because the width of the cut hole is often large, the width becomes the main controlling factor for the stability of the surrounding rock of the cut hole. The current secondary tunneling method of expanding the side of the guide tunnel only delays the time for the formation of the large width, and does not consider eliminating the large width. The deflection and buckling effect of the width cut hole, after the formation of the second side expansion cut hole, leads to the weak and broken coal and rock mass caving of the cut hole roof. Coal rock mass grouting reinforcement is one of the effective means to solve the roadway roof coal rock mass, but it has not been widely used due to the large amount of pre-grouting work, poor roof grouting effect, and high cost. To sum up, the existing hole-cutting tunneling methods show the following problems: 1) the existing hole-cutting tunneling technology can not achieve the purpose of preventing the roof from falling of the weak and broken coal and rock mass; 2) the existing hole-cutting pre-grouting Large technical engineering volume, large safety hazards, poor roof grouting effect, and high cost; 3) During the second side expansion process, the roof support is difficult, serious safety hazards, and the excavation speed of the cut hole is slow; 4) The cut hole roof cannot be eliminated Due to deflection effect and large-span buckling effect, there is always a hidden danger of roof fall.

Contents of the invention

The purpose of the present invention is to provide a coal mine roadway excavation and support method to overcome the problems in the prior art. The present invention can well adapt to the characteristics of the weak and broken roof of the thick coal seam working face with a large section cut hole that is extremely soft and broken. , Effectively prevent the occurrence of roof fall accidents.

To achieve the above object, the present invention adopts the following technical solutions:

A coal mine roadway excavation and support method, which divides the entire eye-cutting construction into three stages: breaking the roof to form the first passage, forming the second passage under the undercover, and expanding the side of the coal body to be mined to form the third passage. Specifically, it includes the following steps :

Step 1: Take the channel interface at a height H from the coal seam floor as the bottom foundation of the first channel, over-excavate part of the coal seam roof, and excavate to form the first channel, and support the first channel during the excavation process, where H is the second channel the height of;

Step 2: Carry out grouting reinforcement and strengthening support to the side of the roadway on the side of the coal body to be mined in the first passage;

Step 3: taking the coal seam floor as the bottom foundation, taking the passage interface as the top boundary to excavate the second passage, and supporting the two sides of the second passage;

Step 4: Expand the side of the coal body to be mined in the second channel, that is, excavate to form the third channel, and carry out joint support for the third channel, that is, form a cutting channel composed of the first channel, the second channel and the third channel. Eye.

Further, the over-excavation part of the coal seam roof in step 1 specifically includes: excavating the false roof and the weak direct roof existing above the coal seam, so as to stabilize the direct roof as the roof of the first channel.

Further, the support for the first channel in step 1 is specifically: the joint support technology of anchor rods, anchor cables, metal mesh and steel belts is adopted for the roof of the first channel as a whole; The combined support technology of anchor cables, metal mesh and reinforced ladder beams, in which the anchor cables closely follow the excavation and head-on construction.

Further, the grouting material in step 2 is super-polymeric concrete, and the reinforced support method is to add anchor cables for reinforced support.

Further, in step 3, anchor mesh support is carried out on the two sides of the second channel, wherein the side walls of the coal body to be mined are supported by recoverable anchor rods.

Further, before the combined support of the third channel in step 4, the roof of the third channel is reinforced by grouting, and the side and bottom of the third channel are reinforced and supported by anchor cables.

Further, in step 4, the side of the coal body to be mined in the third channel is jointly supported by anchor rods and double-resistance nets, and the roof of the third channel is jointly supported by anchor rods, anchor cables, metal mesh and steel belts , wherein the anchor cable follows the head-on construction of the excavation.

Compared with the prior art, the present invention has the following beneficial technical effects:

The invention adopts a new roadway excavation and support method aiming at the characteristics of poor self-stability, poor bearing capacity and large span of the large-section cut-out roof of the thick coal seam working face with extremely soft and broken roof. This method can greatly reduce the deflection effect and buckling effect of the unstable long-span roof, and fundamentally improve the stress state of the roof; In the process of mining, the working face needs multiple cycles to gradually lower the process, and the support problem of the different elevations between the ends of the two roadways and the working face does not leave the bottom coal triangle area, which improves the coal recovery rate; Advanced pre-grouting technology, each process of this technology has little interaction with each other, multiple processes can be operated in parallel, and the construction speed is fast and safe and reliable. The invention is reasonable in design, safe and reliable, fast in construction speed and broad in application prospect, and can greatly improve the safety level and technical and economic benefits of large-section cutouts in thick coal seam working faces with extremely soft and broken roofs.

Furthermore, using chemical grout to reinforce the roof of the third channel on the side can significantly improve the grouting effect, enhance the overall stability of the broken coal strata, and provide a forming foundation and safety guarantee for the installation space of the mining equipment in the working face, which has significant reinforcement Effect: On the basis of the anchor net support of the roof of the third channel, it is reinforced with anchor cables, and at the same time, there is also an anchor cable reinforcement support on one side, the overall reinforcement effect is good, and the strength of the surrounding rock is high.

Description of drawings

Fig. 1 is a sectional view of the first channel support;

Fig. 2 is the schematic diagram of grouting bolt structure;

Figure 3 is a schematic diagram of the equipment layout of the grouting system;

Fig. 4 is a flow chart of the grouting construction process;

Fig. 5 is a sectional view of the second channel support;

Fig. 6 is a structural schematic diagram of a spin anchor;

Figure 7 is a sectional view of the third channel support;

In the figure: 1—first channel; 2—second channel; 3—third channel; 4—channel interface; 5—coal seam floor; 6—coal seam roof; 7—rebar anchor rod; 8—anchor cable; 9 — grouting anchor; 10—conical end; 11—grouting anchor body; 12—grouting hole; 13—retaining ring; 14—A group of materials; 15—B group of materials; 16—grouting pump; 17—high-pressure rubber tube; 18—injection gun; 19—sealer; 20—recoverable anchor rod; 21—squeezing and screwing in the cone head; 22—spinning anchor rod body; ; 25—disc-shaped tray; 26—surrounding rock surface; 27—glass fiber reinforced plastic bolt.

detailed description

Below in conjunction with accompanying drawing, the present invention is described in further detail:

Referring to Fig. 1 to Fig. 7, a coal mine underground roadway excavation and support method according to the present invention is mainly to solve the problem that the surrounding rock of the roof is soft and broken, and the roadway is difficult to form, which in turn affects the tunneling problems such as security and speed. The method of the present invention divides the excavation of the entire cut-out space into three stages: breaking the roof to form the first passage 1, forming the second passage 2 undercover, and expanding the side of the coal body to be mined to form the third passage 3, which includes the following steps:

Step 1: take the channel interface 4 at a certain distance from the coal seam floor 5 (a certain distance refers to the height of the second channel 2) as the bottom foundation of the first channel 1, over-excavate part of the coal seam roof 6, break the false roof, and excavate to form the first channel 1. Passage 1 is to excavate the false roof and weak direct roof existing above the coal seam, and use the direct roof with better stability as the roof of the first passage 1. During the excavation process, the first passage 1 shall be supported in time, and the roof shall be anchored Combined support technology of rod + anchor cable + metal mesh + steel belt, the two sides adopt the combined support technology of anchor rod + anchor cable + metal mesh + steel ladder beam, and the joint support is implemented in steps, in which the anchor cable closely follows the head of the excavation construction;

Step 2: Carry out grouting reinforcement and reinforced support to the side of the roadway on the side of the advancing direction of the working face of the first passage 1. The grouting material is superpolymer concrete, and the superpolymer concrete is composed of group A material 14 and group B material 15. Group A material 14 and B group material 15 both use inorganic materials as aggregates and a variety of resins as bonding materials. They have the characteristics of both inorganic and organic polymer materials, with good adhesion, high early strength, adjustable curing time, For the advantages of high safety performance and low cost, please refer to the patent CNCN201110207625.1 for details. The reinforced support method is to add anchor cables 8 to strengthen the support; the chemical grouting adopts the method of combining theoretical calculation and numerical simulation to preliminarily determine the grouting value. Various parameters, including depth of grouting hole, grouting pressure, grouting diffusion radius, grouting time, row spacing between grouting holes, grouting sequence and single hole grouting amount of grouting anchor, etc., and then according to the site engineering Feedback analysis of practical effects can optimize various grouting parameters;

Step 3: Take the coal seam floor 5 as the bottom foundation, and take the passage interface 4 as the top boundary to excavate the second passage 2, and carry out anchor mesh support for the two sides in time, and select the recoverable anchor rod 10 for the side of the coal body to be mined support;

Step 4: Expand the side of the coal body to be mined in the second channel 2, that is, excavate to form the third channel 3, and on the basis of grouting and strengthening the roof of the third channel 3, anchor cables to it from the side and below Reinforce the support, and then carry out combined support for the third channel 3 in time, in which the side of the coal body to be mined is supported by bolts + double-resistant nets, and the roof is supported by bolts + anchor cables + metal mesh + steel belts The anchor cable is closely followed by the head-on construction of the excavation. The second channel 2 and the third channel 3 together constitute the space for the installation of the cutting hole mining equipment. Three channels are composed of 3.

The present invention preferentially excavates the first channel 1 to provide conditions for the grouting of the extremely weak and broken surrounding rock on the roof of the mining equipment installation space of the working face. Grouting the side of the above-mentioned extremely weak and broken surrounding rock ensures the safety of the grouting project space on the one hand. On the other hand, it is better to strengthen the surrounding rock by grouting directly in the space under the weak surrounding rock.

The diameter of the grouting anchor rod 9 adopted during grouting is Φ20mm～Φ25mm. The determination of the drilling depth is to use numerical simulation to determine the range of the plastic zone of the surrounding rock after the formation of the first channel 1 as a reference basis for determining the depth of the grouting hole. The determination of grouting time is to obtain the grout penetration range map and pore pressure diffusion cloud map of the working face with the grouting time through numerical simulation. The grouting time is suitable when the grouting diffusion speed is very slow and tends to be stable. The grouting sequence is from bottom to top, that is, the side foot is injected first, and then the middle and top side are injected, and the grouting method of skipping holes at intervals is adopted.

The stability of the roof during the secondary roadway forming of the cut-out and widening of the working face is the key factor affecting the construction speed of the cut-out and ensuring the safety of the roadway. The present invention decomposes the cutting hole space of the working face into three passages for excavation in stages, and provides space for the roof coal and rock layer grouting project through the excavation of the first passage 1. At the same time, the anchor cables of the construction side are strengthened and supported, which further enhances its stability. When the technical level of workers, construction organization and other conditions permit, the second passage 2 can be constructed at an appropriate distance behind the first passage 1; if the equipment and tools allow, the second passage 2 and the third passage 3 can also be constructed at the same time.

The operation process of the present invention is described in detail below in conjunction with embodiment:

A coal mine roadway excavation and support method according to the present invention divides the entire eye-cutting construction into three stages: breaking the roof to form the first passage 1, forming the second passage 2 under the undercover, and forming the third passage 3 by expanding the side, including the steps :

Step 1. Starting from any end where the two lanes are connected to the cut hole of the working face, taking the channel interface 4 at a certain distance from the coal seam floor 5 as the bottom foundation of the first channel 1, over-excavating part of the coal seam roof 6, and removing the false roof. The first passage 1 is excavated by a roadheader or blasting, and the first passage 1 is a roadway connecting the air return lane and the air inlet lane.

Step 2. In order to ensure the stability of the surrounding rock of the first channel 1, the roof is supported by bolts + anchor cables + metal mesh + steel belts, in which the anchor cables are arranged alternately with the anchor bolts, and the anchor cables are closely followed by the head-on construction. The length of threaded steel anchor rod 7 is 2.4m, and the distance between rows is 900×800mm; the anchor cable 8 is made of seven prestressed steel strands, the specification is Φ17.8×6000mm, the distance between rows is 1400×1600mm, and the anchor rod is matched with 300 ×300×10mm drum-shaped pallet, anchor cable with steel belt and padded 400×400×12mm flat pallet.

The two gangs are supported by anchor rods + metal + reinforced ladder beams + anchor cables. In order to avoid the impact on the roof support of the third channel 3 in the later stage, the anchor cables and the anchor rods are arranged on the same section, and the anchor cables lag behind the excavation head by 30m construction. The row spacing between the anchor rods is 800×800mm, the row spacing between the anchor cables is 1600×1600mm, the distance between the anchor bolts of the support foot and the bottom plate is not more than 300mm, lagging behind the first channel 1 excavation and facing the side support of the first channel 1 working face at a certain distance Carry out reinforcement support with 8 anchor cables, the spacing between rows is 1600×1600mm, and the parameters of the pallet are the same as the roof support. The cross-sectional view of the support is shown in Figure 1. The pre-tightening torque of threaded steel bolts in coal seams and rock formations is not less than 200N m and 250N m, and the pre-tightening force of anchor cables is not less than 8T, and the pre-tightening force (moment) of anchor rods and cables should be pre-tightened twice after 7 days of construction. Tighten to eliminate the rebound effect of preload (moment).

Step 3: Grouting the side roadway side of the working face of the first passage 1. Grouting parameters should be preliminarily determined based on theoretical calculations and numerical simulations, and further optimized based on on-site implementation results. The main parameters include grouting pressure, grout diffusion radius, grouting time, row spacing between grouting holes, and grouting sequence.

The grouting anchor rod 9 is installed on the side of the coal body to be mined in the first channel 1 . The exposed length of the grouting anchor rod 9 is 100mm, and the hole is drilled to the design depth with a Φ26 drill bit, and the hole depth is 2.2m. Put the grouting anchor rod 9 into the borehole, then put into the hollow annular cement roll along the anchor rod diameter or block with gauze soaked in cement slurry. The grouting material is Bolein, which is a two-liquid modified polyurethane grouting material, which is composed of two liquid components, Group A material 14 and Group B material 15, and the weight ratio is 1:1 during construction. mix. Grouting from bottom to top in the same section, i.e. injecting the foot of the side first, then the center of the side, and finally the top of the side; different sections are grouped and spaced for grouting, and each 8 rows is a group, that is, first, 1, 3, 5, 7 singles Row grouting, and then 2, 4, 6, 8 double row grouting, alternately. The grouting pressure is not greater than 3Mpa. The grouting time for a single hole is 10-13 minutes. In order to ensure that the grouting can fill the cracks tightly, in principle, it should be injected until the grouting is not obvious. After the grouting is completed, add a pallet to the exposed end of the grouting anchor rod, and pre-tighten it with nuts, and the pre-tightening torque is not less than 150N·m.

The structural diagram of the grouting anchor 9 is shown in FIG. 2 . The front end of the grouting anchor rod 9 is a conical end 10, the length K is 200mm, and it is firmly welded. The grouting anchor body 11 is arranged with Φ8mm grout holes 12, the hole distance d=200mm, arranged in a five-flower shape, the outer diameter of the rod is D=22mm, the wall thickness is 3mm, there is no grout hole in the rear end of the rod body L=500mm, and the screw thread Segment S=100mm, the high 5mm of retaining ring 13. If the surrounding rock is so broken that the hole cannot be drilled, a self-drilling grouting bolt can be used. The schematic diagram of the equipment layout of the grouting system is shown in Figure 3.

The flow chart of the grouting construction process is shown in Figure 4. Drill holes → install grouting bolt 9 → install hole sealer 19 → connect injection gun 18 and grouting pump 16 with high-pressure rubber pipe 17 → connect the two pipes to group A material 14 and group B material 15 → open Grouting pump 16 → meet the grouting requirements → close the grouting pump 16 → disassemble the injection gun 18 .

Before using the grouting pump in each grouting class, check whether the equipment is working properly, including grouting pipelines, pressure gauges, etc., by pumping and draining clean water.

Step 4, excavate the second channel 2. Use roadheader or gun excavation to excavate the first channel 1 undercover to the coal seam floor 5 to form the second channel 2, and support the two sides with anchor rods + metal mesh + steel ladder beams, and the distance between rows is 800×800mm , the side of the coal body to be mined is supported with a retrievable prestressed bolt 20, and the retrievable bolt 20 is a spiral retrievable bolt, which is provided by the screw 23 and the fastener on the spin bolt body 22. The friction and preload force support the surrounding rock. The remaining parameters are the same as the requirements of the first channel 1, and the support section is shown in Figure 5.

The structural schematic diagram of the recoverable anchor 20 , that is, the recoverable prestressed anchor is shown in FIG. 6 . The front end of the recoverable bolt 20 is an extruded screw-in cone head 21, the length N=50mm, the diameter of the spin bolt body 22 is 20mm, and the spin bolt body 22 is covered with spiral threads 23, and the distance between the spiral bolts M is 30～ 40mm, the screw height is 4~7mm. The rear end exerts a torque on the pre-tightening nut 24 to make the dish-shaped tray 25 close to the surface 26 of the surrounding rock, so as to exert a pre-tightening force on the recoverable bolt 20 . The anchor rod is an integrated anchor rod for drilling and anchoring, that is, no anchoring agent is used, and the pre-tightening force and anchoring force are realized by relying on the characteristics of fast initial deformation of the weak surrounding rock and the similar diameter of the drilled hole to the nominal diameter of the rod body.

Step five, excavate the third passage 3. The side of the coal body to be mined in the second channel 2 is expanded to form the third channel 3 by means of a roadheader or blasting, and the roof is supported by bolts + anchor cables + metal mesh + steel belts, and the roof bolts and anchors are combined. The cables are arranged in the same section, and are staggered from the section where the first channel 1 side support anchor rod and cables are located by half a row distance, that is, 400mm, and the anchor cables are closely followed by the head-on construction of the excavation. The spacing between the three anchor cables on the roof is 1500×1600mm, and the other parameters are the same as the roof support requirements of the first channel 1.

The side of the coal body to be mined is supported by anchor rods + double-resistant nets. The anchor rods are made of glass fiber reinforced plastic anchor rods 27, and the glass fiber reinforced plastic pallets are made of pallets with a spherical shell thickness and height of 7mm and 18mm respectively. The support section is shown in Figure 7.

Step 6. Check the reinforcement effect of the grouting project. You can use the method of drilling and peeking at the roof rock layer of the third channel 3 to observe the filling of the cracks in the roof rock layer; optimize and analyze the support parameters, mainly through the roof rock layer. Monitor the separation layer, check the overall stability of the roof, and adjust support parameters.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention. Any simple modification and equivalent structural changes made to the above embodiments according to the technical essence of the present invention belong to the present invention. within the scope of protection of the technical solution.

Claims (7)

1. A coal mine roadway excavation and support method, characterized in that the whole cutting construction is divided into breaking the roof to form the first passage (1), forming the second passage (2) under the undercover and expanding the side to the side of the coal body to be mined Form the three stages of the third channel (3), specifically including the following steps: Step 1: Taking the passage interface (4) at a height H from the coal seam floor (5) as the bottom surface foundation of the first passage (1), over-excavating part of the coal seam roof (6), and excavating to form the first passage (1), the excavation process The first channel (1) is supported in the center, wherein H is the height of the second channel (2); Step 2: Carry out grouting reinforcement and strengthening support to the side of the roadway on the side of the coal body to be mined in the first passage (1); Step 3: taking the coal seam floor (5) as the bottom surface foundation, taking the channel interface (4) as the top surface boundary to excavate the second channel (2), and supporting the two sides of the second channel (2); Step 4: Expand the side of the coal body to be mined in the second channel (2), that is, excavate to form the third channel (3), and carry out joint support for the third channel (3), that is, form the first channel (1 ), the cut eye formed by the second channel (2) and the third channel (3). 2. A coal mine roadway excavation and support method according to claim 1, characterized in that the over-excavation part of the coal seam roof (6) in step 1 is specifically: excavating the false roof and the weak direct roof existing above the coal seam , with a stable direct top as the top plate of the first channel (1). 3. A coal mine roadway excavation and support method according to claim 1, characterized in that, in step 1, supporting the first channel (1) is specifically: generally adopting anchors for the roof of the first channel (1) Combined support technology of rods, anchor cables, metal mesh and steel belts; the combined support technology of anchor rods, anchor cables, metal mesh and steel ladder beams is generally used for the two sides of the first passage (1), in which the anchor cables closely follow the head-on construction. 4. A kind of coal mine roadway excavation and support method according to claim 1, it is characterized in that, in step 2, the grouting material is super-polymeric concrete, and the reinforced support mode is to add anchor cables (8) for reinforced support . 5. A kind of coal mine roadway excavation and support method according to claim 1, it is characterized in that, in step 3, carry out anchor mesh support to the two sides of the second channel (2), wherein the side sides of the coal body to be mined adopt Recovery bolt (20) supports. 6. A kind of coal mine roadway excavation and support method according to claim 1, is characterized in that, before carrying out joint support to the 3rd channel (3) in step 4, first carries out to the roof of the 3rd channel (3) Grouting is reinforced, and the side and bottom of the third channel (3) are reinforced with anchor cables. 7. A kind of coal mine roadway excavation and support method according to claim 1, is characterized in that, in the step 4, adopt bolt and double resistance net to carry out joint support to the side of the coal body to be mined in the third passage (3) For protection, the roof of the third channel (3) is jointly supported by anchor rods, anchor cables, metal mesh and steel belts, wherein the anchor cables are closely followed by the head-on construction.