Safety precautions for gas tunnel construction

(1) Gas control plans and safety technical measures must be formulated for gas tunnel construction.

(2) The positive step method should be used for excavation, the arch should be excavated once and formed, and the surrounding rock should be sealed with concrete in time to reduce gas overflow. Excavation uses smooth blasting to reduce local gas accumulation caused by uneven rock surfaces.

(3) Drilling and blasting excavation should insist on drilling more holes, less charge, shorter footage, fast anchor injection, strong support, frequent inspection, and use advanced grouting anchor double-liquid grouting to reinforce and Block cracks in rock mass and reduce or prevent gas overflow.

(4) Drilling and charging: Use a coal electric drill to drill the hole. When the hole depth is less than 60 centimeters, no explosives can be charged; when the hole depth is 60-100 centimeters, the sealing mud should not be less than half the hole depth; When the hole depth is 1-2.5 meters, the sealing mud should be no less than 50 centimeters; when the hole depth is greater than 2.5 meters, the sealing mud should be no less than 1 meter.

(5) Detonation: ① Electric detonation must be used; ② The detonation busbar must use single-circuit copper core insulated wire; ③ The initiator must be 20 meters away from the entrance of the cave, and the power must be cut off in the cave when blasting; ④ The same series connection The detonators in the network must be from the same manufacturer, the same batch number, and the same brand; ⑤ The duration of the last section of the detonator must not exceed 130 milliseconds.

(6) Detonators and explosives: Special coal mine detonators and coal mine special explosives that have obtained a production license must be used. Adding salt to explosives can reduce the force and prevent sparks.