摘要：Surface drilling was performed at the Luling coal Mine,in Huaibei,to shorten the period required for gas *** experimental study was designed to reduce the cost of gas control by efficiently draining gas from the upper protected *** structural arraignment and technical principles of pressure relief via surface drilling are *** from the trial showed that gas drained from the surface system over a period of 10 *** total amount of collected gas was 248.4 million m^*** gas draining occurred in three stages：a growth period;a period of maximum gas production;and an attenuation *** period of maximum gas production lasted for 4 *** this time the methane concentration ranged from 60%to 90%and the average draining rate was 10.6 m^3/*** with other methods of draining it was possible to drain 70.6%of the gas from middle coal seam *** amount of residual gas dropped to 5.2 m^3/ton,and the pressure of the residual gas fell to 0.53 MPa, thereby eliminating the outburst danger in the middle coal seam *** factors affecting pressure relief gas draining by surface drilling were analysed.

摘要：Based on the blasting theory and stress wave theory, stemming mechanism and movement of stemmed material in rock blasting were analyzed and the calculation expression of stemming lengths was deduced. The blasting experiment with different stemming lengths was carried out and the results show that the theoretical stemming length, which is 0.73 ~ 0.8 time of burden, is in the range of the experiential length, which is O. 63 - O. 88 time of burden. The blasting results of field experiments with theoretical stemming length are satisfactory, which shows the theoretical derivation and analysis are correct and reliable. The results will supply rock blasting with the theoretical gist of parameters design.