Numerical Simulation Of Rock Fracture Based On The Key Strata Theory

To keep the Chinese economy increasing steadily and rapidly, the strong demand for coal is necessity. However, the geological conditions for coal mining are more complicated than before, the roof accidents such as support crushing in stope with thick and strong roof are often happened. Therefore, the rock pressure character and rock strata movement became the urgent and significant problems needed to be solved in mining engineering. This paper, based on the behavior law of mine pressure and hard roof control, with multi-research methods, such as the theoretical analysis and the computer numerical simulation, mainly to research the rupture regularity of thick and hard roof in longwall mining face, characteristics of surrounding rocks, the deformation mechanism of the overburden strata and the distribution of the fault fracture, which providing theoretical basis for settling down the problem of rock pressure control and developing a technical approach. The main innovative results for this dissertation are shown as follows:Firstly, the new rock pressure model of thick and strong roof is established in RFPA, UDEC and ANSYS based on the analysis of classical rock pressure models and the distribution characteristics of mining-induced stress with thick and strong roof, and the mechanical analysis of breakage process of thick and strong roof is carried out as well;Secondly, the breakage process of thick and strong roof is simulated by RFPA and UDEC. As mining, the soft strata over the thick and hard strata were changed as the rupture of the thick and hard roof. The thick and hard roof and overlying strata were coordinated subsidence. The thick and hard roof plays a key role in controlling the displacement and deformation of overhead strata. So controlling the caving interval is the key to controlling roof weighting in working face of thick and hard roof;Thirdly, the fracture configurations of thick and strong roof are simulated firstly by finite element numerical method; according to the surrounding rock conditions of stope with thick and strong roof, the breakage process of thick and strong roof is systematically studied, and the general law of the changes of mining-induced stress with thick and strong roof with the working face advances distance are obtained.