Study On Stress Distribution And Activation Law In Mining Influence

The predication and prevention of fault activation in coal mine has always been important subject of safe mining production in china. Fault activation mainly manifested as variation of field of stress and displacement of fault. For fault variation laws of stress and displacemen in work face advancing process, in this paper, according to the fault of 2375 work face in Huopu coal mine, theoretical analysis and numerical simulation are used to study the variation of stress distribution of fault and fault activation law. The main conclusions are as follows:According to the support pressure distribution of mining floor, and considering the weight of floor strata, a mechanical model of mining floor fault activation is established, and the analytic expression of normal stress and shear stress of fault plane can be obtained ultimately. Meanwhile, analysing the influence of the buried depth of coal seam H, the working face advancing distance L, in front of the working face supporting pressure coefficient K1, fault dip θ and goaf compaction coefficient α on fault normal stress to shear stress. Analysing influence of main impact factor on shear stress and normal stress of fault, find enter some deep, it’s shear stress tend to zero, but normal stress tend to weight of overburden rock. Work face advancing distance has largest impact on stress of fault, and then the fault dip.Using numerical simulation software FLAC3 D simulation with positive(negative) typical faults of mine working face by the hanging wall and foot wall respectively to the fault plane to promote four kinds of schemes, according to the analysis, the foot wall excavation of normal fault is more likely to make fault activation than hanging side.Using Fish language embedded in the FLAC3 D exports the results data— each excavation step distance results of the foot wall of excavation and inverse excavation in the hanging wall of the fault, and processing and mapping. Analysing the variation characteristics of the normal stress, shear stress, horizontal displacement, vertical displacement and the support pressure of the bottom plate of rock closed to the fault zone in mining panel, especially before and after fault activation.According to change law of stress and displacement of rock closed to fault zones at mining panel in mining influence, proposed the criterion of fault activation analysis by numerical simulation, it is considered that fault will be activated when the area between the shear stress and the displacement curve of the adjacent excavation step is increasing rapidly, or the obvious change of the stress and displacement curve.Huopu coal mine 2375 work face is used, safe distance between F2 fault and 2375 work face is 25 meter are obtained by theoritical analysis and numerical simulation. According to the in-situ data in 2375 work face, when work face advancing to the distance between work face and F2 fault is 23 meter, F2 fault has apprently actition phenomenon, basically fitted to theoritical analysis and numerical simulation, veriated the effectivity of fault criteria in this paper.