Micro-mechanical behaviors of rock masses with structure planes can provide information regarding precursory characteristics of macro-fracture of strata and rock bursts. Hence, numerical simulation with uniaxial compression test is conducted using Realistic Failure Process Analysis (RFPA). Then, mechanical properties and progressive failure processes for rock masses with different dip angle structure planes are studied, and the macroscopic fractures, mechanical responses, and acoustic emission (AE) responses of rock masses are analyzed. Moreover, the strength weakening and interface slipping effects with different dip angle structure planes are revealed. The results show that rocks with different dip angle structure planes show significant strength and interface slipping effects. A small dip angle structure plane has little influence on the rock strength and interface slipping, which mainly manifests as failure in rock interiors. For medium dip angle structure plane, the rock strength decreases obviously, and interface slipping is notable along the structure plane. The effects caused by the weak plane are more prominent with rising dip angles. Compared to rocks with small dip angle structure planes, those with medium dip angle structure planes are more easily broken. However, the total energy released and total AE counts are smaller, indicating less serious bursting liability from rock failure.
Rock burst is a common mine disaster often accompanied with casualties and property damage. An effective and accurate method for predicting rock burst is necessary. This paper proposed a method for predicting rock burst on the basis of energy theory. Firstly, according to the laws of energy distribution in the front of coalface, the energy judgment coefficient Q is proposed, the energy is not released to the outside when Q<0, it means that the rock burst will not occurs, the energy is released to the outside when Q>0, it means that the rock burst may occur, the greater Q value is, the more energy is released to the outside when rock burst occurs. Secondly, based on the geological structure of erosion zone, the influence of the uniaxial compressive strength and pre-peak energy with the different of the height ratio, lithology, and dip angle are analyzed, it concluded that uniaxial compressive strength and pre-peak energy at the bottom of the erosion zone slope are greater and the uniaxial compressive strength and pre-peak energy at the edge of the erosion zone slope are smaller. Finally, taking the Xiaoyun Coal Mine as the engineering background, the energy judgment coefficient Q for predicting rock burst is applied. The results of the field observation are consistent with the results of the energy judgment coefficient Q. It indicates that this method can better predict the location and intensity of rock burst and provide a novel idea for preventing the occurrence of rock burst.
The irregular distribution of stress in rock mass is a decisive factor for the origin of rock bursts. Besides, a sound knowledge of stress distribution is very important in the excavation of mine workings. Stress state is affected both by natural stress, including the gravitational, tectonic, hydraulic and residual stress and the stress induced by mining operations. Natural stress fields are defined by their geological structure and rock properties. It is important in mining practice to understand that there is a close relationship between recent and residual tectonic stress, as defined by tectonic evolution and tectonic structure. Since 1994, a large number of horizontal stress measurements have been carried out at a depth of 600 m to 800 m under the surface. The application of the results obtained from the measurements of stress and their comparison with the results of structural analysis and their generalization for the Karviná subbasin can be an important contribution to optimize the timespace designs of the mining activity., Petr Waclawik, Jiří Ptáček and Radomír Grygar., and Obsahuje bibliografii