井巷岩塞爆破事故分析

Analysis of Water Pit Blasting Accident in Mine Rock Roadway

对一起井巷岩塞爆破中空气冲击波和有毒气体的危害作用进行了讨论，提出了在井巷特殊爆破中应该注意的安全问题。

In order to drain mine water, a temporary mine roadway in the -94 m Level in a mine was excavated to be connected with the shaft bottom to a water pit. The temporary roadway has a cross section of 5.2 m2 and a length of 2.5 m. And the water pit was in middle fine sand rocks. There were four drill holes each with a diameter of 325 mm and a depth of 6.88 m. The bottom of the pit has a depth of 2.2 m to the floor of the -94 m Level. Each drill hole was loaded with a gun cartridge and the cartridge was made of a steel tube with diameter of 273 mm x 5 mm and a length of 1.5 m. The each cartridge was loaded with 72 kg TNT and 3 kg emulsion explosives. After each cartridge loaded in the blasting hole, sand with a depth of 4 m were filled in each blasting hole. After the four blasting holes blasted in a same time, the water pit was formed a channel with cross section of 2 m x 2 m. This blasting result caused two accidents. One was that the blasting impact waves into the mine shaft caused the mine shaft cover open, almost the nails in the wooden plates were drawn out and some wooden plates were broken due to bending. Second was a content of toxic gas over limit. 288 kg TNT and 12 kg emulsion explosives for the four hole blasting have produced 73152 x 103 mg CO gas. After 75 min. ventilation with a 28 kW local fan, coal miners at the shaft bottom by the hoister were still poisoned and suffocated. Therefore the type of explosives was not properly selected. The quantity of the explosives were over loaded and the ventilation time was not sufficient.