In engineering, when layered rock formed by hard rock wrapping soft rock, the soft rock layer often causes engineering problems like fault sliding or uneven settlement. In this study, considering the layer spacing, thickness and inclination angle of two soft rock interlayers, 47 numerical models of layered rock samples through the discrete element method were established to study the influence of soft rock interlayer on the mechanics of the layered rock samples. The results shows that the ultimate strain and compression strength of layered rock sample mainly influenced by inclination angle and soft layer's thickness; under a critical value of inclination angle, the two mechanic parameters change little with the change of soft layer's thickness and layer spacing between two soft layers.


In engineering, layered rock is often hard rock wrapped with soft rock. As an inhomogeneous material, layered rock mass is consisting of discontinuous intact rock blocks separated by structures such as joints, bedding planes, and cracks. According to the International Society of Rock Mechanics (ISRM, 1990, 1993), soft rock refers to a category of rock for its uniaxial compressive strength ranges from 0.5MPa to 25MPa, and its uniaxial compressive strength is much lower than that of the hard rock. The existing of soft rock interlayer often causes engineering problem including fault sliding or non-uniform settlement, for its weak mechanical behavior (He, 2002). Soft rock (Hu, Xu, Wang and Xing, 2013) and hard rock (Zhao and Yue, 2009) are very common in the ocean, especially in the seabed mining. The influence of rock property change has to be considered.

Since the last century, researchers conducted investigation on the mechanics of layered rock mass through various methods. Salamon (1968) analytically studied the elastic moduli of a stratified rock mass. Taliercio and Landrian (1988) analytically employed homogenization technique to establish model which enabled the description with fair accuracy of the ultimate behaviour of layered rocks submitted to triaxial tests, varying both the orientation of the principal stresses to the layers and the confining pressure. Adhikary and Dyskin (1998) present a finite element smeared joint model to study the behaviour of an excavation in a layered rock mass, based on the Cosserat theory. These researches were mainly conducted by analytical method.

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