A construction method for tunneling in broken coal and rock mass

Abstract

The present invention relates to the technical field of coal mine mining, and specifically to a construction method for driving in broken coal and rock mass. In order to solve the problems of complex process and high cost existing in the existing construction method for driving in broken coal and rock mass, the present invention provides a new construction method for driving in broken coal and rock mass, which includes the following steps: 1) Divide the part below the roof of the roadway section in the broken coal and rock mass section into the lower part of the roadway section and the upper part of the roadway section; 2) Gradually excavate the lower part of the roadway section from the roadway floor upwards until the upper part of the roadway section collapses by itself to form a natural balance arch and the crown of the natural balance arch is located at the position of the roof of the roadway section in the broken coal and rock mass section; 3) Vertically and permanently support the crown of the natural balance arch; 4) Excavate and permanently support the shoulders on both sides of the natural balance arch; 5) Support the rib sides on both sides of the roadway. The present invention breaks the conventional thinking and uses the stable load-bearing property of the arch body to hold the broken coal and rock mass, preventing the overlying broken coal and rock mass from leaking and collapsing.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mining, in particular to the technical field of tunneling in broken coal and rock masses, and specifically to a tunneling construction method for broken coal and rock masses. Background Art

[0002] When tunneling roadways through broken coal and rock masses such as faults, subsidence columns, igneous rock intrusion areas, soft coal and rock layers, stratified coal and rock layers, joint fissure developed areas, and fracture zones, after excavation along the designed roadway roof line, the overlying broken coal and rock masses become unstable and naturally leak and collapse to form a caving height area, that is, the phenomenon of roof leakage at the heading face occurs. The roof leakage at the heading face after tunneling not only seriously threatens the safety of operating personnel, but also the roof leakage generally occurs above the roof. Before the permanent support of the roof of this section of the tunneling roadway (the permanent support is to anchor and support the roof of the tunneling roadway with bolts and cables), it is necessary to fill the roof leakage part, and the process is complex and extremely dangerous.

[0003] To control the phenomenon of roof leakage at the heading face, the method of pre-injecting polymer materials for reinforcement of broken coal and rock masses in advance before excavation is often used. By this reinforcement method, the existing conditions and mechanical states of the roof of the broken coal and rock masses are changed, and the phenomenon of roof leakage after excavation is effectively prevented. However, this method is an independent process before excavation, which requires professional equipment, materials and personnel, and the process is complex and costly, affecting the advance rate level and efficiency improvement. Summary of the Invention

[0004] In order to solve the problems that the existing tunneling construction method for controlling roof leakage at the heading face of broken coal and rock masses is complex in process and high in cost, the present invention provides a new tunneling construction method for broken coal and rock masses.

[0005] The present invention is realized by adopting the following technical solutions:

[0006] A construction method for tunneling in broken coal and rock mass, comprising the following steps: 1) Divide the part below the roof of the roadway section in the broken coal and rock mass section into upper and lower parts, namely the lower part of the roadway section and the upper part of the roadway section; 2) Gradually excavate the lower part of the roadway section from the roadway floor upwards until the upper part of the roadway section collapses by itself to form a natural balance arch, and the crown of the natural balance arch (the crown is the highest part in the middle of the cross-section of the natural balance arch) is located at the roof position of the roadway section in the broken coal and rock mass section; 3) Carry out vertical permanent support on the crown of the natural balance arch (vertical permanent support is the conventional permanent support well-known to those skilled in the art, and it is named vertical permanent support here to distinguish it from the inclined pull permanent support); 4) Repeat in sequence the steps of inclined pull permanent support, brushing and expanding (brushing and expanding can also be called excavation, that is, using a cleaning tool to remove the local coal and rock mass) to the position flush with the roadway roof and carrying out vertical permanent support on the brushed and expanded position from the position close to the crown to the roadway side on both shoulders of the natural balance arch (the repeated sequence here is to repeat the steps of inclined pull permanent support, brushing and expanding to the position flush with the roadway roof and carrying out vertical permanent support on the brushed and expanded position after the steps of inclined pull permanent support, brushing and expanding to the position flush with the roadway roof and carrying out vertical permanent support on the brushed and expanded position), until the roadway section contour is formed (forming the roadway section contour is well-known to those skilled in the art. The roadway section contour is a rectangular section rather than an arched section. The roof of the rectangular section is an approximately horizontal plate, so forming the roadway section contour is to make the upper arch of the natural balance arch become approximately horizontal); 5) Carry out rib support on the ribs on both sides of the roadway.

[0007] Basic principle: In the traditional construction method for broken coal and rock mass, after the broken coal and rock mass is excavated along the roof line of the roadway section, the upper roof naturally caved in to form a balanced and stable arch-like structure, namely the natural balance arch structure. After the formation of this natural balance arch structure, it has two properties. One is the stable load-bearing capacity of the arch body: the arch body has a supporting ability, can bear the overlying rock mass, and prevent the upper rock mass from further caving in. The other is the self-collapsing property inside the arch: the broken coal and rock mass inside the arch naturally collapses to form an internal space. Due to the self-collapsing property, roof leakage occurs, and the effect of the second property is often considered negative, that is, after the roof leaks, the leaking part of the roof needs to be filled, and the leaking part is prone to safety accidents. However, the present invention breaks through the traditional thinking, makes full use of the above two properties of the natural balance arch structure, and cleverly moves the excavation position of the roof downward and changes the arch top of the natural arch structure formed after excavation and leakage into the roof position of the roadway section, so that the space formed after the broken coal and rock mass inside the arch naturally collapses becomes a part of the roadway section, and at the same time, the arch body stably supports the roof of the roadway. Simply put, the natural balance arch formed after the roof leaks after excavation along the roof line of the roadway section is moved downward to below the roof inside the roadway section, turning the negative effect of the natural balance arch into a positive effect. It can not only effectively support the roof of the roadway by using the stable load-bearing capacity of the arch body, prevent the roof above the roadway section from leaking, and play a temporary support role, but also make the upper rock mass of the roadway section naturally collapse, replacing the excavation of the upper rock mass of the roadway section, saving time and effort and achieving twice the result with half the effort. To achieve all this, only need to first excavate the lower part of the roadway section to make the upper part of the roadway section naturally collapse to form a natural balance arch structure.

[0008] The beneficial effects produced by the present invention are as follows: (1) Creatively apply and expand the natural balance arch theory, study and utilize the two properties of the natural balance arch - stable load-bearing capacity and self-collapsing property, and apply them to the tunneling construction of broken coal and rock mass. In the tunneling of a roadway with conventional thinking, the natural collapse of the broken coal and rock mass to form a natural balance arch occurs above the roof of the roadway section, causing roof leakage above the roof, and its effect is often negative, and its formation is often forced and imposed. However, everything has two sides. The present invention breaks through the conventional thinking and only by excavating the lower part of the roadway section, actively creates a natural balance arch above the upper part of the roadway section and below the roof of the roadway section. By using the stable load-bearing capacity of the arch body, it supports and holds the broken coal and rock mass overlying the roof of the roadway, preventing the overlying broken coal and rock mass from leaking; by using the self-collapsing property inside the arch to replace the excavation of the upper rock mass of the roadway section, changing the forced and imposed occurrence to active and positive creation, and changing the negative and passive effect to a positive and beneficial effect, achieving safety, speed and high efficiency, greatly expanding the application scope of the natural balance arch theory and injecting new applications into the natural balance arch theory.

[0009] (2) It overcomes the disadvantages that the broken coal and rock mass at the heading face is prone to caving and leakage, and the commonly used ultra-high pre-injected polymer material reinforcement method has multiple processes, long time, high cost, low efficiency, etc. It integrates construction and control, controls during construction, and constructs during control, solves the problem of caving and leakage at the heading face of the broken coal and rock mass, and achieves a win-win situation for safety and benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the basic principle of the natural balance arch;

[0011] Figure 2 It is a schematic diagram of the basic principle of the construction method in the present invention

[0012] Figure 3 It is a roadway cross-section contour diagram formed by using the tunneling construction method of the present invention;

[0013] Figure 4 It is a process diagram of the permanent support for the shoulder of the arch in step 4) of the present invention.

[0014] In the figure: 1 - roof, 2 - roadway side, 3 - lower part of the roadway cross-section, 4 - upper part of the roadway cross-section, 5 - floor, 6 - natural balance arch, 61 - arch crown, 62 - arch shoulder, 7 - inclined permanent support, 8 - vertical permanent support. DETAILED DESCRIPTION OF THE INVENTION

[0015] As Figure 2 、 3 、shown in FIG. 4, a tunneling construction method for broken coal and rock mass includes the following steps: 1) Divide the part below the roof 1 of the roadway cross-section in the broken coal and rock mass section into upper and lower parts, namely the lower part 3 and the upper part 4 of the roadway cross-section; 2) Gradually excavate the lower part 3 of the roadway cross-section from the floor 5 of the roadway upwards until the upper part 4 of the roadway cross-section collapses by itself to form a natural balance arch 6, and the arch crown 61 of the natural balance arch 6 is located at the position of the roof 1 of the roadway cross-section in the broken coal and rock mass section; 3) Carry out vertical permanent support 8 for the arch crown 61 of the natural balance arch 6; 4) Repeat the steps of carrying out inclined permanent support 7 (the function of the inclined permanent support 7 is to prevent local collapse during the next expansion and brushing) in sequence from the position close to the arch crown 61 to the direction of the roadway side 2 for the shoulders 62 on both sides of the natural balance arch 6, expanding and brushing to the position flush with the roadway roof and carrying out vertical permanent support 8 for the expanded and brushed position until the roadway cross-section contour is formed; 5) Carry out rib support for the roadway sides 2 on both sides of the roadway.

[0016] Basic principle: In the traditional construction method of broken coal and rock mass, after the broken coal and rock mass is excavated along the roof line of the tunnel section, the upper roof naturally rises to form a balanced and stable arch-like structure, that is, a natural balanced arch structure. After the formation of this natural balanced arch structure, it has two properties. One is the stable bearing capacity of the arch body: the arch body has the supporting capacity to bear the overlying rock mass and prevent the upper rock mass from continuing to rise; the other is the self-collapse property within the arch: the broken coal and rock mass inside the arch naturally collapses to form an internal space. Since the self-collapse property causes roof leakage, the effect of the second property is often considered to be negative, that is, after the roof leaks, the leaking part of the roof needs to be filled and filling the leaking part is prone to cause safety accidents, such as Figure 1 As shown. The present invention breaks through traditional thinking and makes full use of the above two properties of the natural balance arch structure. It cleverly moves the position of the excavation top plate downward and turns the arch top of the natural arch structure formed by leakage after excavation into the top plate position of the tunnel section, so that the space after the broken coal rock in the arch naturally collapses becomes a part of the tunnel section, and at the same time, the arch stably supports the tunnel roof. In simple terms, the natural balance arch formed by the leakage of the top plate after excavation along the top plate line of the tunnel section is moved down to below the top plate in the tunnel section, turning the negative effect of the natural balance arch into a positive effect. It can not only use the stable bearing capacity of the arch to effectively support the tunnel roof and prevent leakage from the upper part of the tunnel section roof, playing a temporary support role, but also make the upper part of the tunnel section rock collapse naturally, instead of excavating the upper part of the tunnel section rock, saving time and effort to achieve twice the result with half the effort. To achieve all this, it is only necessary to first excavate the lower part of the tunnel section and let the upper part of the tunnel section collapse naturally to form a natural balance arch structure. Figure 2 shown.

[0017] During specific implementation, the brushing should be expanded gradually in a small area, and the width of each expansion (it is well known to people in this field that the direction of the expansion width here is consistent with the direction of the lane width) should not exceed 1m to further prevent local collapse during expansion.

[0018] In this specific implementation, the inclined permanent support 7 is an inclined anchor support with an angle of 55° to 75° upward. When expanding, a long-handled tool is used to poke, pry, plan, or open with a pneumatic pick or a planer head of a tunneling machine is used to lightly sweep to achieve expansion.

[0019] The following example is taken from the Tongfa Dongzhouyao Mine under Jinneng Holding Coal Group. The geological conditions of the mine are complex, with frequent faults, collapse columns, igneous rock intrusions, and broken zones. For a period of time, leakage often occurred during excavation. In recent years, the construction control technology of natural balance arch 6 supporting method for breaking leakage has been used to significantly reduce leakage, effectively ensuring safe production. The following example is taken from C5#5206 Lane to illustrate the application of this technology.

[0020] The 5206 roadway is the gateway of the fully mechanized top coal caving face, driven along the coal floor by mechanical excavation. It has a rectangular cross-section with a width of 5 m and a height of 3.8 m. The top coal thickness is 8 m - 9 m. Under normal conditions, the roof support is a single-point cable bolt with a steel bar mesh and a steel belt. From June 19, 2020 to June 25, 2020, during the excavation from mileage 659 m to 696 m, the top coal was difficult to retain due to the development of joint fissures and the influence of the fracture zone. Therefore, the excavation construction method of the present invention was adopted, including the following steps: 1) Divide the part below the roof 1 of the roadway cross-section in the broken coal and rock mass section into upper and lower parts, namely the lower part 3 and the upper part 4 of the roadway cross-section; 2) Gradually excavate the lower part 3 of the roadway cross-section from the roadway floor 5 upwards. When the lower part 3 of the roadway cross-section is excavated to a height of 2 m, the upper part 4 of the roadway cross-section collapses spontaneously to form a natural balance arch 6 with a height of 1.8 m, and the crown 61 of the natural balance arch 6 is located at the position of the roof 1 of the roadway cross-section in the broken coal and rock mass section; 3) Carry out vertical permanent support 8 for the crown 61 of the natural balance arch 6 (first support with a single-point bolt using a steel bar mesh, bolt specification φ22×2400 mm, 450×280×3 mm short W-shaped steel belt, small steel tray 150×150×10 mm, full-length anchorage, row and spacing are flexibly arranged according to the site conditions at 500 - 700 mm, pre-tightening torque 400 Nm, designed anchoring force 190 kN, and then drive a set of three-eye combined cable bolts at the top center, cable bolt specification φ21.8×8300 mm, 600×600×16 mm steel plate tray, pre-tightening force 290 kN, designed anchoring force 520 kN); 4) Repeat the steps of inclined pull permanent support 7 (drive inclined pull bolts obliquely upwards at 55° - 75° to prevent local collapse during the next enlargement), enlargement (using a pickaxe for enlargement) and vertical permanent support 8 for the positions after enlargement from the position close to the crown 61 to the direction of the roadway side 2 on both sides of the natural balance arch 6 until the roadway cross-section contour is formed; 5) Carry out rib support for the rib 2 on both sides of the roadway.

Claims

1. A construction method for tunneling in broken coal and rock mass Characterized in that It includes the following steps: 1) Divide the part below the roof (1) of the roadway section in the broken coal and rock mass section into upper and lower parts, namely the lower part (3) of the roadway section and the upper part (4) of the roadway section; 2) Gradually excavate the lower part (3) of the roadway section from the roadway floor (5) upwards until the upper part (4) of the roadway section collapses by itself to form a natural equilibrium arch (6), and the crown (61) of the natural equilibrium arch (6) is located at the position of the roof (1) of the roadway section in the broken coal and rock mass section; 3) Carry out vertical permanent support (8) on the crown (61) of the natural equilibrium arch (6); 4) Repeat the steps of carrying out inclined permanent support (7), brushing and expanding to the position flush with the roadway roof and carrying out vertical permanent support (8) on the expanded position in sequence from the position close to the crown (61) to the roadway side (2) direction at both shoulders (62) of the natural equilibrium arch (6) until the roadway section contour is formed; 5) Carry out rib support on the rib (2) on both sides of the roadway.

2. A construction method for tunneling in broken coal and rock mass according to claim 1 Characterized in that During brushing and expanding, it should be carried out in small ranges step by step.

3. A construction method for tunneling in broken coal and rock mass according to claim 2 Characterized in that The width of each brushing and expanding does not exceed 1 m.

4. A construction method for tunneling in broken coal and rock mass according to claim 3 Characterized in that The inclined permanent support (7) is to drive inclined pull bolts at an angle of 55° to 75° obliquely upwards for support.

5. A construction method for tunneling in broken coal and rock mass according to claim 4 Characterized in that During brushing and expanding, a long-handled tool is used to poke or pry or plane or use a pneumatic pick to cut or use the cutting head of a roadheader to gently sweep to achieve brushing and expanding.

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