Analysis of the Influence Mechanism of Small Fault Activation under the Influence of Mining at Deep Coal Faces

The influence mechanism of different geological parameters on the activation of small faults under mining in the deep coal face was investigated by numerical simulation. The study shows that (1) the degree of influence of six parameters including the fault lateral pressure coefficient λ, elastic modulus E, Poisson's ratio μ, cohesion c, internal friction angle φ, and fault inclination angle θ on the activation of small faults was ranked in order as θ > λ > φ > μ > E > c. (2) The lateral pressure coefficient λ of the fault zone rock mass, the internal friction angle φ, and the fault inclination angle θ had a great influence on the fault activation. The larger the λ of the fault zone rock mass was, the smaller the φ was, the larger the subsidence amount drop of the rock layers on both sides of the fault was, and the greater the severity of the fault activation was. The fault activation degree decreased first, then increased, and then decreased with the increase of θ. When θ was 15 and 60°, there was relatively severe fault activation. When θ was 75°, the fault was not easy to activate. (3) Poisson's ratio μ, elastic-modulus E, and cohesion c of the fault zone rock mass had little effect on the fault activation. The larger the E of the fault zone rock mass was, the larger the μ was, the smaller the c was, and the possibility of fault activation increased slightly. The research results can provide important theoretical support for the theoretical research on fault activation, on-site roof management, and mining schedule arrangement in the mining process of deep coal face.