[H-DS08] Landslides and related phenomena

[HDS08-P18] Determination of Strength Parameters for Weak Planes by Considering Rock Anisotropy

*Chung Ying Yu¹, Kuang Tsung Chang¹ (1.National Chung Hsing University)

Keywords:Weak planes, Coefficient of Anisotropy, Strength parameter, Rock layer

The rock layers on the hillsides in Taiwan are primarily composed of sedimentary rocks, such as sandstone and shale, as well as metamorphic rocks like slate and schist. Weak planes, joints, and bedding planes are commonly present, causing the rock mass to exhibit anisotropic behavior, which reduces rock strength and overall slope stability. However, in practice, due to the complexity of anisotropic models and the difficulty in determining rock mass parameters for weak planes, the anisotropic behavior of rock masses is often overlooked, and isotropic behavior is assumed in analyses. This can lead to an overestimation of slope safety factors and stability. This paper aims to establish a relationship chart between coefficient of anisotropy and strength parameters of the rock mass (cohesion and friction angle) and the strength parameters of weak planes (cohesion and friction angle). By using coefficient of anisotropy and rock mass strength parameters to predict weak plane parameters, this approach allows for considering the influence of both rock mass and weak plane parameters in numerical simulations.