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Zhao J.-H.,Xian University of Science and Technology | Lai X.-P.,Xian University of Science and Technology | Lai X.-P.,Key Laboratory of Western Mines and Hazard Prevention
Journal of Coal Science and Engineering | Year: 2011

For mining extra-steep-thick coal seam, the sublevel top coal caving is a high efficient method in practical engineering. However, major challenges associated with mining high-section top-coal-caving (HSTCC) are related to the resulting high ground stresses. Inevitability, using the high-section sublevel top coal caving for extra-steep-thick coal seam, the large scale of mined-out area appears. If the prefracture blasting and hydraulic fracture techniques are utilized, the top coal damage and cracks will develop, and the mining complexity will increase, such as seam inclination, continuity, mechanical characteristics of roof and susceptibility of top coal, etc. First, the field conditions of B 1+2 seam were investigated at the +588 level of the Weihuliang Underground Mine of China. Subsequently, according to caving mechanism of strata response obtained from several special models including physical simulation tests and numerical simulation models, the prefracture process including blasting and injecting water were analyzed. Then, the prefracture blasting technique was successfully applied to the caving of 52 m-sublevel seam. Finally, the effects were verified by advanced detecting instruments, and the results show these methods and measurements are feasible and valid. © The Editorial Office of Journal of Coal Science and Engineering (China) and Springer-Verlag Berlin Heidelberg 2011. Source


Qiu H.F.,Shaanxi University of Science and Technology | Qiu H.F.,Key Laboratory of Western Mines and Hazard Prevention | Lai X.P.,Shaanxi University of Science and Technology | Lai X.P.,Key Laboratory of Western Mines and Hazard Prevention | And 2 more authors.
Transit Development in Rock Mechanics-Recognition, Thinking and Innovation - Proceedings of the 3rd ISRM Young Scholars Symposium on Rock Mechanics, 2014 | Year: 2015

Taking the project in China as background, established a physical model experimental platform to simulate the cavity construction using the similar theory. The influence of interlayer to the cavity construction was studied. It was found: when the interlayer exists, the flow field becomes more complex; and the brine distribution besides the interlayer will be changed. Thus the dissolution of salt rock besides the interlayer was affected which results the triangle insoluble inclination appearing on the top of the interlayer, making the cave building inefficient and being not conducive to the cave shape control. It is the key to make the interlayer reasonable collapse in cavity construction. © 2015 Taylor & Francis Group, London. Source


Lai X.-P.,Xian University of Science and Technology | Lai X.-P.,Key Laboratory of Western Mines and Hazard Prevention | Wu Y.-P.,Xian University of Science and Technology | Wu Y.-P.,Key Laboratory of Western Mines and Hazard Prevention | And 8 more authors.
Meitan Xuebao/Journal of the China Coal Society | Year: 2010

Aimed at quantitatively prediction the process of rock-mass localized deformation regularity and their relating indicators of Nindong coal region in broken rock-mass induced historical seismicity and rich water environment, and comprehensive analyzed geophysical characteristics, loading framework and its mechanical performance, invalid indicators of rock-mass deformation and their quantitative discrimination methods, structure and flaw and characterization of simulative material, etc., the largest scale 3D physical simulative assembly was constructed with integrated real-time monitoring system of multi-acoustics-optics-electricity-indicators, and experiment was undertaken with the constant and variable static-dynamical loading model. The acoustic emission(AE) characteristics and their regularity relating to rock-mass localized fracture were acquired, and distributing characteristics of radial and tangential stress in excavation disturbance were statistically and comparatively discriminated. The results obviously indicate that the durable damage and deformation may bring potentially after the crack and deformation of complex rockmass undergo oscillatory and quietness. Even, the characteristics will be found upon localized destabilization of composite coal and rockmass. Source


Cui F.,Xian University of Science and Technology | Cui F.,Key Laboratory of Western Mines and Hazard Prevention | Lai X.P.,Xian University of Science and Technology | Lai X.P.,Key Laboratory of Western Mines and Hazard Prevention | And 2 more authors.
Rock Mechanics: Achievements and Ambitions - Proceedings of the 2nd ISRM International Young Scholars' Symposium on Rock Mechanics | Year: 2012

Low recovery is a problem existing in top coal caving mining of steep and thick coal seams. Pre-blasting in top-coal for weakening the coal seam is proposed to solve this prblem. Based on the background of pre-blasting working face in Jiangou coal mine, the numerical analysis model of long holes pre-blasting was established. By numerical analysis with nonlinear program LS-DYNA, the parameters of blasting for presplit coal, stress-strain state in the pre-blasting influenced zone were studied. The purpose of the study was for keeping stability of the surrounding roadways while effective weakening in the top coal. The results showed that thickness of the retaining top coal above the support frane was 3.0 to 4.0 meters, the horizontal distance between final position for pre-explosion hole and roadway was not less than 4 meters, the vertical distance between explosive bottom for pre-explosion hole and the top of roadway was not less than 4 meters, the row spacing for pre-explosion hole was 4.0 meters. Pre-blasting with these parameters got effective weakening results with the roadways in stable conditions. © 2012 Taylor & Francis Group. Source


Lai X.-P.,Xian University of Science and Technology | Lai X.-P.,Key Laboratory of Western Mines and Hazard Prevention | Zheng J.-W.,Xian University of Science and Technology | Zheng J.-W.,Key Laboratory of Western Mines and Hazard Prevention | And 5 more authors.
Meitan Xuebao/Journal of the China Coal Society | Year: 2015

With coal excavation, the surrounding rock of roadway in a fault broken zone might induce a dynamic hazard in a coal mine. The determination of internal critical destabilization range plays an important part in supporting parameter optimization and safe excavation. Disturbed zone of roadway at 1193 working face in Tunbao coal district was investigated in this study. In order to control the stability of rock-mass in fault broken zone, engineering geology investigation, theoretical analysis and site monitoring were used to study the range of internal critical destabilization in fault influenced broken zone. It shows that the range could be 2.30 m combined with hybrid consideration including statistical analysis of cracks and internal cracks propagation of surrounding rock with various depths. Different support loadings were given based on different destabilization ranges between roof side and coal seam side. The optimized design of roadway achieved good results in safety and efficient mining. ©, 2015, China Coal Society. All right reserved. Source

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