The paper presents the influence of varying immediate roof thickness on the lower strong roof strata movement and failure pattern in longwall coal mining with large mining height. The investigation is based on 58 geol...The paper presents the influence of varying immediate roof thickness on the lower strong roof strata movement and failure pattern in longwall coal mining with large mining height. The investigation is based on 58 geological drill holes and hydraulic shield pressure measurements around the longwall Panel 42105 of the Buertai Mine in Inner Mongolia Autonomous Region, China. The longwall Panel 42105 is characterized by relatively soft immediate roof strata of varying thickness superposed by strong strata,herein defined as lower strong roof. A voussoir beam model is adopted to interpret the structural movement of the lower strong roof strata and shield pressure measurements. It is shown that when the immediate roof is relatively thick, the broken overlying lower strong roof tends to form a stable voussoir beam with previously broken layer, thus not exerting high pressure on the hydraulic shield and working face. When the immediate roof is relatively thin, the broken overlying lower strong roof tends to behave as a cantilever beam, thus exerting higher pressure on the hydraulic shield and working face. Comparison of model predictions with measured time-weighted average shield pressure(TWAP) shows good agreement.展开更多
Aiming at the limitation of the traditional method for determination of protection region, combined with the actual situation of a mine, a new method for determination of protection region was put forward （including ...Aiming at the limitation of the traditional method for determination of protection region, combined with the actual situation of a mine, a new method for determination of protection region was put forward （including the protection of working face layout and development direction）, that is, gas flow observation analysis on the spot and gas content contrast method. The protection region was determined by gas flow observation analysis, gas content contrast, and computer numerical simulation combined with engineering practice. In the process of gas content test, the fixed sampling method ＂big hole drill reaming, small orifice drill rod connected with core tube＂ was employed. The results show that the determined protection region is in accordance with the actual site situation. The fixed sampling method ensures the accuracy of gas measurement of gas content.展开更多
基金the fund supported by the National Natural Science Foundation of China(Grant No.U1261207)
文摘The paper presents the influence of varying immediate roof thickness on the lower strong roof strata movement and failure pattern in longwall coal mining with large mining height. The investigation is based on 58 geological drill holes and hydraulic shield pressure measurements around the longwall Panel 42105 of the Buertai Mine in Inner Mongolia Autonomous Region, China. The longwall Panel 42105 is characterized by relatively soft immediate roof strata of varying thickness superposed by strong strata,herein defined as lower strong roof. A voussoir beam model is adopted to interpret the structural movement of the lower strong roof strata and shield pressure measurements. It is shown that when the immediate roof is relatively thick, the broken overlying lower strong roof tends to form a stable voussoir beam with previously broken layer, thus not exerting high pressure on the hydraulic shield and working face. When the immediate roof is relatively thin, the broken overlying lower strong roof tends to behave as a cantilever beam, thus exerting higher pressure on the hydraulic shield and working face. Comparison of model predictions with measured time-weighted average shield pressure(TWAP) shows good agreement.
文摘Aiming at the limitation of the traditional method for determination of protection region, combined with the actual situation of a mine, a new method for determination of protection region was put forward （including the protection of working face layout and development direction）, that is, gas flow observation analysis on the spot and gas content contrast method. The protection region was determined by gas flow observation analysis, gas content contrast, and computer numerical simulation combined with engineering practice. In the process of gas content test, the fixed sampling method ＂big hole drill reaming, small orifice drill rod connected with core tube＂ was employed. The results show that the determined protection region is in accordance with the actual site situation. The fixed sampling method ensures the accuracy of gas measurement of gas content.
