煤-页岩结构面剪切力学特性试验研究

Shear bearing capacity of coal-rock interface has a major impact on the stability and damage type of coal pillar. Friction properties and normal deformation characteristics of native coal-shale interface were studied by conducting direct shear tests. The ratio of shear stress to normal stress- shear displacement curve of coal-shale interface in the first shear process is non-monotonic, so that a composite function and hyperbolic function were used to fit the curve segments of before and after the peak point, respectively, assuming the regressed curve to have gone through the peak point. A very high correlation coefficient was obtained for curve segments before the peak point, and that for the curve segments after the peak point was still acceptable. Besides, p4, a regression parameter, can be used to judge the influence of failure process of interface on the failure type of coal pillar. Complete failure of coal-shale interface occurs in the post-peak curve because normal deformation before the peak point is very small in the shear process, and both shear dilatancy and shrinkage phenomena occur during the sliding friction process. These conclusions have contribution to the understanding of mechanical properties of coal-rock interface.