A tunneling technology for machine tunnel under coal roof with large inclination angle

Abstract

The present invention belongs to the field of coal mining technology, especially a machine tunnel high-angle coal roof excavation process, which solves the problems of large coal seam angle, soft coal seam, difficult roof management, large-angle uphill excavation, difficult end face protection, and high gas control risk in the existing medium-thick coal seam mining and placing technology. The machine tunnel high-angle coal roof excavation process includes the following steps: S1, step method construction; S2. Medium-deep hole grouting anchor rod; S3. Water injection; S4. Anchor cable beam + locking leg anchor rod; S5. Flat-top 29U steel shed; S6. Process transformation. The 837 machine tunnel high-angle coal roof excavation proposed by the present invention adopts the "step + follow-up drilling and anchoring flat" excavation construction technology. During the period of crossing the fault and the structural zone, the medium-deep hole advance grouting reinforcement plan is strictly implemented, and the stub cycle stepping construction is carried out, which effectively controls the roof and greatly improves the safety factor.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining, and in particular to a tunneling process under a coal roof with a large inclination angle in a machine lane. Background Art

[0002] The comprehensive top-coal caving mining method in thick coal seams has low cost, large production capacity and high efficiency. It is one of the important technical methods for intensive, safe and efficient mining in coal mines. In recent years, the comprehensive top-coal caving mining technology has developed rapidly, the supporting equipment of the "three machines" has been upgraded, and the production capacity has been greatly improved. Therefore, accelerating the production preparation progress of the comprehensive top-coal caving working face and maintaining the balance of mining and excavation are the keys to achieving sustainable development of mine production.

[0003] The design engineering volume of 837 machine tunnel is 385m, of which 360m has been constructed, of which the excavation length under the steeply inclined coal roof is 210m. The tunnel section specifications are: 4.8m wide, 3.3m high, the average uphill construction angle of the tunnel is 22°, and the maximum construction slope is 38°. In the existing technology, the excavation process under the steeply inclined coal roof of 837 machine tunnel has the following defects:

[0004] (1) The coal seam is at a large angle and is soft, making roof management difficult

[0005] The 837 machine tunnel has an average uphill slope of 22°. During tunnel construction, the coal seam was lifted due to the geological structure, resulting in uphill excavation under the large-angle coal roof in most sections. The 8 coal in this area is soft, with a loose coefficient of only 0.22. During excavation, there is a risk of roof collapse.

[0006] (2) Difficulty in end face protection during uphill excavation at a large inclination angle

[0007] The excavation area of ​​837 machine tunnel reaches 18.5m 2 There is a risk of collapse of large sections going up the mountain.

[0008] (3) Roof management is difficult and gas control risks are high

[0009] 8 coal is a protruding coal seam with a gas content of 5.1m3 / t. Inadequate roof control has the direct consequence of large-scale coal falling, which in turn leads to gas outbursts, posing a high risk for safe construction. In 2019, the 837 machine tunnel was affected by the structure during construction, and two gas over-limit accidents caused by end face extraction occurred. In the "8.22" gas over-limit accident, the maximum gas concentration reached 1.08%. Based on the above statement, the present invention proposes a machine tunnel high-angle coal roof excavation process. Summary of the invention

[0010] The purpose of the present invention is to solve the problems of large coal seam angle, soft coal seam, difficult roof management, large-angle uphill excavation, difficult end face protection, and high gas control risk in the existing medium-thick coal seam mining and release technology, and to propose a large-angle coal roof excavation process for a machine lane.

[0011] A tunneling process under a coal roof with a large inclination angle in a machine lane comprises the following steps:

[0012] S1. Step method construction

[0013] According to the characteristics of large-angle uphill construction, the "step method" is adopted to reduce the construction height of the headway. The height of the first step is controlled at 1.5m-1.8m, and the second and third steps increase the height of the roadway in turn. The number of steps is adjusted appropriately according to the slope of the roadway, generally not less than 3 steps, and the construction is carried out in a circular step.

[0014] S2. Medium and deep hole grouting anchor

[0015] When excavating under the coal roof, 16 holes are arranged in the front end face (11 holes are used to reinforce the front roof, and 5 holes in the middle are used to reinforce the end face to prevent collapse). The hole depth is 9.9 meters. Three 3.3-meter-long grouting anchor rods are connected by special joints, and then grouting reinforcement is carried out. After the grouting is completed, the advance is protected;

[0016] The present invention optimizes and adjusts the grouting parameters, proposes a skeleton idea for grouting in medium and deep holes, uses an electric grouting pump for grouting, connects multiple grouting heads at the same time, and performs network-based rapid grouting to improve grouting efficiency. At the same time, it simplifies the construction process and improves construction efficiency. The test has been conducted many times and the effect is good. The stop time for a single round of grouting is only 1 day, and the distance for covering the excavation construction is more than 7 meters.

[0017] S3. Water injection

[0018] Arrange 2-3 water injection holes on the head end face, inject water in advance to improve the plasticity of the coal seam, and use water injection and grouting as auxiliary;

[0019] S4. Anchor cable beam + locking leg anchor

[0020] Active support is adopted in time to reinforce the roof, and excavation is carried out under the coal roof with a large inclination. Three anchor beams are arranged in the middle top. The anchor cables are required to penetrate into the rock by no less than 2.0m. Locking leg anchors are arranged on both sides for reinforcement. The lag of the cable beams and the locking leg anchors is no more than 15m.

[0021] S5. Flat roof 29U steel shed

[0022] A flat-top 29U steel shed is used for support. At the same time, according to the deformation pressure of the tunnel, the arch curvature is appropriately increased to improve the tunnel support strength.

[0023] S6. Process Change

[0024] According to the characteristics of uphill excavation under the steeply inclined coal roof, the original construction procedure was adjusted to first carry out advance support of the roof, then temporary support of the end face, and finally permanent support of the roof, with the top of the roof being supported first.

[0025] The invention provides a tunneling technology under the coal roof with a large inclination angle in a machine lane, which has the following beneficial effects:

[0026] The 837 machine lane was excavated under the steeply inclined coal roof and the roof was effectively controlled by adopting the "step + follow-up drilling and anchoring" excavation construction technology. The main effects are as follows:

[0027] 1. The safety factor is greatly improved

[0028] In the past, when going uphill from the coal roof with a large dip angle, there were more or less accidents such as roof falling and gas exceeding the limit. Since the 837 machine tunnel was excavated with the above technology, related roof accidents have been eliminated. Especially during the period of crossing the fault and structural zone, the advanced grouting reinforcement plan for medium and deep holes was strictly implemented, and the construction was carried out in a cyclic manner, which effectively controlled the roof.

[0029] 2. Efficiency guarantee

[0030] Adhere to the concept of "managing the roof well is to ensure progress". If the roof is well controlled and there are no problems, the progress can be continuous and the succession is guaranteed.

[0031] 3. Promotion and reference significance

[0032] The optimization of roof management scheme for high-angle uphill excavation, especially high-angle uphill excavation under coal roof, and high-angle monorail crane transportation provide reference for safe excavation under similar conditions in other mining areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the step method construction in a machine tunnel under a large-angle coal roof excavation process proposed by the present invention.

[0034] Figure 2 This is a cross-sectional view of the arrangement of grouting anchor rods in the 837 machine tunnel in a machine tunnel high-angle coal roof excavation process proposed by the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further explained below in conjunction with specific embodiments.

[0036] Example

[0037] The present invention proposes a tunneling process under the coal roof with a large inclination angle in the machine lane. The head roof is managed and constructed by the "step + drilling, anchoring and leveling" method. The specific steps are as follows:

[0038] S1. Step method construction

[0039] According to the characteristics of the large-angle uphill construction, the "step method" is used to reduce the construction height of the headway. The height of the first step is controlled at 1.5m-1.8m, and the second and third steps increase the height of the roadway in turn. The number of steps is adjusted appropriately according to the slope of the roadway, generally not less than 3 steps, and the construction is carried out in a circular step.

[0040] S2. Medium and deep hole grouting anchor

[0041] In the existing technology, when digging under the coal roof, we insist on advanced support grouting to reinforce the roof. First, we use the mountain sealing spraying method to reinforce the two sheds in the front. In the early stage, we use a 3200 drilling rig to construct an advanced skeleton hole with a depth of 15m. The skeleton is mainly made of waste drill rods. After the skeleton construction is completed, grouting is performed to protect the progress. This process has obvious disadvantages, such as large grouting volume and long time consumption. Generally, 200 bags of cement are used for one round of grouting. After the grouting is completed, although the longest distance of the protected progress can reach 12 meters, the stop time is as long as 10 days.

[0042] The present invention optimizes and adjusts the grouting parameters, and proposes a medium-deep hole grouting skeleton idea. 16 holes are arranged in the front end face (11 holes reinforce the front top plate, and 5 holes in the middle reinforce the end face to prevent collapse). The hole depth is 9.9 meters. Three 3.3-meter-long grouting anchor rods are connected by special joints, and then grouting reinforcement is carried out. An electric grouting pump is used for grouting, and multiple grouting heads are connected at the same time. Network-type rapid grouting improves grouting efficiency. At the same time, the construction process is simplified and the construction efficiency is improved. The test has been carried out many times with good results. The stop time for a single round of grouting during excavation is only 1 day, and the distance for covering excavation construction is more than 7 meters.

[0043] S3. Water injection

[0044] Arrange 2-3 water injection holes on the head end face, inject water in advance to improve the plasticity of the coal seam, and use water injection and grouting as auxiliary.

[0045] S4. Anchor cable beam + locking leg anchor

[0046] Active support is adopted in time to reinforce the roof, and excavation is carried out under the coal roof with a large inclination. Three anchor beams are arranged in the middle top. The anchor cables are required to penetrate into the rock by no less than 2.0m. Locking leg anchors are arranged on both sides for reinforcement. The lag of the cable beams and the locking leg anchors is no more than 15m.

[0047] S5. Flat roof 29U steel shed

[0048] A flat-top 29U steel shed is used for support. At the same time, according to the deformation pressure of the tunnel, the arch curvature is appropriately increased to improve the tunnel support strength.

[0049] S6. Process Change

[0050] According to the characteristics of tunneling under the steeply inclined coal roof, the original construction process was adjusted to first carry out the advanced support of the roof, then the temporary support of the end face, and finally the permanent support of the roof, with the top pipe first and the side pipe first.

[0051] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A tunneling process under a coal roof with a large inclination angle in a machine lane, characterized in that: The following steps are involved: S1. Step method construction According to the characteristics of large-angle uphill construction, the "step method" is adopted to reduce the construction height of the headway. The height of the first step is controlled at 1.5m-1.8m, and the second and third steps increase the height of the roadway in turn. The number of steps is adjusted appropriately according to the slope of the roadway, and the construction is carried out in a circular step. S2. Medium and deep hole grouting anchor When excavating under the coal roof, 16 holes are arranged in the front end face, of which 11 holes are used to reinforce the front roof, and 5 holes in the middle are used to reinforce the end face to prevent collapse. The hole depth is 9.9 meters. Three 3.3-meter-long grouting anchor rods are connected by special joints, and then grouting reinforcement is carried out. After the grouting is completed, the advance is protected; S3. Water injection Arrange 2-3 water injection holes on the head end face, inject water in advance to improve the plasticity of the coal seam, and use water injection and grouting as auxiliary; S4. Anchor cable beam + locking leg anchor Active support is used to reinforce the roof in time. When driving under the coal roof with a large dip angle, three anchor beams are arranged in the middle roof. The anchors are required to penetrate into the rock by no less than 2.0m. Locking leg anchors are arranged on both sides for reinforcement. The lag of the cable beams and locking leg anchors is no more than 15m. S5. Flat roof 29U steel shed Adopt flat-top 29U steel shed support, and appropriately increase the arch curvature according to the deformation pressure of the tunnel to improve the tunnel support strength; S6. Process Change According to the characteristics of uphill excavation under the steeply inclined coal roof, the original construction procedure was adjusted to first carry out advance support of the roof, then temporary support of the end face, and finally permanent support of the roof, with the top of the roof being supported first.

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