Technical measures to realize rapid tunneling in t

2022-10-22
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Technical measures for realizing rapid tunneling in outburst dangerous coal seams

1 overview of working face

1222 (3) the smooth tunneling length is about 2400m, divided into East and West sections, each section is about 1200m. During the tunneling process, it is driven with the top, and the support form is mainly anchor beam support. The coal seam in this face generally presents a monoclinal structure with an average thickness of 3.6m. There are local faults developed during tunneling. The dip angle of the coal seam is 3 ° ~5 °, with an average of 4 °. The hydrogeological conditions are simple, and there is dripping water on the roof of some roadways. It is estimated that the gas emission from coal seam excavation is 3~6m3/min. 1222 (3) two 28kw local fans are used in the East and West sections of Yunshun Ф 800mm glue air duct supplies air to the head-on at the same time, and is equipped with two standby local fans of the same capacity, with the head-on air volume of about 570m3/min. The roadway adopts comprehensive mechanized tunneling. In fact, these two experiments are completed by universal experimental machine

the roadway is located in the coal seam below -600m, and there is a prominent risk of coating coal seams at different positions on the coating production line. In order to ensure safety and strengthen outburst prevention management, the system of "operation card in outburst area" has been implemented, combined with prevention and control measures. Through on-site investigation and reasonable application of measures, safety is ensured and the purpose of rapid excavation is achieved

2 prevention and control measures for coal and gas outburst

before 1222 (3) smooth driving, improve the local ventilation system in advance, prepare prevention and control measures for outburst, and Ф The laying scheme of 159mm gas drainage pipeline shall be prepared on site in advance for coal and gas outburst prediction and efficiency inspection Ф 42mm fried dough twist drill pipe, including coal electric drill and comprehensive protection facilities. Prepare the drilling rig and its supporting facilities for construction outburst elimination drilling on site in advance. And improve the laying of gas sensors and cables, and formulate safety measures during the failure period when the safety monitoring equipment fails

2.1 measures to prevent and control outbursts

2.1.1 during normal tunneling

(1) the implementation of 5m implementation measures and safety barriers in front of the work. Before the operation of 1222 (3), according to the provisions of Article 69 of the detailed rules for the prevention and control of coal and gas outburst, when implementing the measures for the first time, the normal construction of outburst prevention measures can be carried out only after a 5m safety barrier for the implementation measures is formed in front of the work to ensure the safety of the implementation measures. Therefore, according to the actual situation of the site, the combination of head-on shallow drilling and deep hole beside the roadway is adopted for gas drainage. When the drainage time is greater than 8h, continuous efficiency inspection shall be carried out immediately. When the amount of drilling cuttings and the initial speed of gas emission do not exceed the limit, footage is allowed, and a 2m efficiency inspection lead distance must be reserved for each footage

(2) implementation of measures to prevent and control coal and gas outburst. During normal tunneling, the leading domestic industrial cluster of high-performance fiber and composite materials around Hangzhou Bay will be built head-on, the "operation card of outburst area" will be hung, and the outburst elimination measures of deep and shallow drilling combined with gas drainage will be constructed. As the roadway is driven along the roof of the coal seam, click the "operation" button on the main interface of the control software to expand the scope of the roadway bottom and surrounding contour lines by 2.0m, and the deep hole pumping is expanded by 6.0m. A total of 16 boreholes are constructed for each cycle of head-on shallow drilling, with each group having a depth of 30m. The deep holes beside the roadway are constructed in a group of bilateral drilling yards constructed every 50m, with a total of 2 boreholes for each group × Four boreholes with a depth of 65m

after the construction of head-on shallow boreholes and roadway side deep boreholes, the boreholes shall be sealed immediately, and the sealing length shall not be less than 6m. The sealed boreholes shall be immediately combined and pumped. The deep hole beside the roadway shall be continuously pumped; After all the construction of head-on shallow drilling is completed, the pumping time is more than 8h. After continuous effectiveness inspection, the indicators are normal. A total of 25m footage is allowed, and a 5m measure distance is reserved to enter the next cycle of head-on pumping drilling construction. At the same time, in order to ensure that the negative pressure of head-on pumping is not less than 13kpa, only the first group of head-on drill field drilling and head-on shallow drilling are pumped. The drilling yard without pumping shall be immediately filled with coal gangue in plastic bags

in order to improve the drainage effect, keep the drainage pipeline unblocked, drain as much gas as possible, and improve the tunneling speed of the heading face, considering that the artificial water drain has a long drainage time interval, and the purpose of draining water at any time cannot be achieved. Therefore, an automatic water drainage device is specially installed on the pumping and discharging pipeline, which can discharge water to the pipeline at any time, ensuring the smoothness of the pipeline. At the same time, a slag remover matching the site is installed on the extraction and discharge pipeline, and the slag remover is cleaned at any time to remove the sundries in the pipeline

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