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Li T.,University of Science and Technology Beijing | Wang W.,University of Science and Technology Beijing | He Z.-L.,China Pingmei Shenma Group | Kou J.-X.,China Pingmei Shenma Group | And 3 more authors.
Meitan Xuebao/Journal of the China Coal Society | Year: 2014

To explore the mechanism of unusual quake behavior in dip roadway during mining long distance coal seam group, on the basis of high-precision micro-seismic monitoring data and field investigation, the anthors analyzed the reasons of mining-induced quake by MapRAS which was used to analysis and forecast the laws of rockmass breaking, and the dynamic response laws of roadway surrounding rock was analyzed by distinct element method UDEC. The following conclusions were gotten. Frequent mine earthquakes in industrial square protective coal pillar and non-mining area of F-2 dip roadway are the results that key roof stratum movements act on strong shear stress zones of edge coal pillar during working face mining and the effects are directly proportional to the mining depth and inversely proportional to mining influence distance. The quake behavior often occurred in F-2 dip roadway which is non-mining direct influent area and the unusual phenomena are related to the physical and mechanical properties of F group coal, composite pressure arch springing dynamic loading and unloading effects during mining the three groups of working face and the effect distance of mine earthquake dynamic source. The authors proposed the surrounding rock of roadway quake behavior hazard level criterion and index according to the quake magnitude, quake behavior level and rock mass particle vibration velocity from numerical experimentation and the criterion basically conforms to the facts. The authors got images by inversion using micro-quake frequency and Fourier cycle method which sensitively reflect the periodic breakage laws of roof key stratum and the correlation of rock dynamic response in adjacent sections. Simulation test by UDEC reveals the effect laws of working face mining on the surrounding rock of F-2 dip roadway.

Cao M.,Yima Coal Industry Group | Cao M.,Henan Polytechnic University | Wang M.,Henan Polytechnic University | Gu X.-H.,Zhong Ping Energy Chemical Group | And 3 more authors.
Huaxue Gongcheng/Chemical Engineering (China) | Year: 2010

The CO2 gasification reactivity of Yima coal chars was investigated by pressurized thermo gravimetric analyzer. The results show that the gasification reactivity and rate increase with elevating temperature, which accords with the preliminary studies under atmospheric condition. Elevated pressure is beneficial to gasification reactivity, and the influence of temperature is stronger than that of pressure. The reaction rate is fast at initial stage and then declined. Kinetic parameters were discussed. The relationship between reaction rate and temperature is consistent with Arrhenius law. Reaction order decreases when temperature increases, and the relationship is close to linear. The activation energy of coal char is about 60.02 kJ/mol.

Li T.,University of Science and Technology Beijing | Wang J.,University of Science and Technology Beijing | Liu J.,Yima Coal Industry Group
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2014

In Laohutai coal mine, it occurred that normal fault was activated and varied into thrust fault movement, and strong mining earthquake energy release was produced during deep mining. The mechanical mechanism was explored by using microseismic monitoring and focal mechanism solutions, combining field investigation, in-situ stress measurement and three-dimensional numerical experiments. Analysis and conclusions: coal mining resulted in activation of faults, and the action mode of mining stress led the mode of fault movement. changing the fracture mechanisms of original fault;deep normal fault was mined in hanging wall after crossing fault in footwall, and the change of the direction of normal fault motion was caused by mining induced concentrated stress, forcing thrust motion, accompanied by the releasing of strong mining earthquake energy, and barriers and asperities can be sheared, also it may initiate second main-earthquake;the details about preventing normal fault catastrophe should be dynamically determined, according to the mode of action of stress during mining;by equipping with high-precision microseismic equipment, tracing analysis on spatial distribution of rock rupture sources and failure mechanism, the tendency of mining induced fault activation and variation can be caught out ahead of time, so that precaution will be taken promptly. ©, 2014, Academia Sinica. All right reserved.

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