Numerical Simulation Study on Seismic Instability of Fault with Different Roughness and Confining Pressures
The roughness of fault surface and biaxial confining pressure have important influence on the mechanical prop-erties of the fault during stick-slip period.In this paper,in order to analyze the influence law of the biaxial confining pressure and the fault surface roughness on the fault-induced mining seismicity,the dolomite around a fault in a deep mine was selected as the research object and biaxial compression numerical simulation was carry out for the surrounding rock specimen by estab-lishing a refined numerical model.The results show that with the increase of the fault surface roughness JRC value and the bi-axial confining pressure,the elastic modulus and elastic limit of the surrounding rock specimen increase;the axial peak stress increases and maintains the positive relationship with the variables;the shear dilation effect of the specimen is weakened;the number of stick-slip events in the surrounding rock specimen decreases;the average stress drop value and the stick-slip period increase,leading to the inhibition of fault activation.Once the fault has slipped,the released energy is in a high seismic level.The microscopic damage mechanism of the surrounding rock specimen is dominated by shear and supplemented by tensile,and the macroscopic performance is a mixed mode of tensile-shear failure.Inside the surrounding rock specimen,the hot spot distri-bution area of the magnitude of tensile contact force is parallel to the loading direction,and the hot spot distribution area of the magnitude of shear contact force corresponds to the hot spot distribution area of the shear cracks.With the increase of the fault surface roughness JRC value,the influence range of the fault stick-slip on the surrounding rocks shows a multi-regional local-ized and concentrated distribution.From the particles peak velocity distribution of the surrounding rock specimen,with the in-crease of the biaxial confining pressure,the influence range of the fault stick-slip on the surrounding rock is wider,and mainly concentrated in the upper and lower loading position.
fault-induced mining seismicitystick-slip eventfault surface roughnessconfining pressurestress dropstick-slip period
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