Slope Stability Analysis of Alterated Dasit Rock on Ponorogo Pacitan Road Using Hoek-Brown Failure Criteria

Abstract

To mitigate landslide on rock slopes the information on adequate safety factors is needed. The strength of rock and soil is one of the important parameters on a slope stability analysis. This paper discussed the stability of the altered and dissected dacite rock. To make it easier to determine the Hoek-Brown failure criteria, the GSI rock mass classification is used. By using the Hoek-Brown failure criterion and supporting by the Rocsience software the analysis of safety factor of rockslide has been conducted. From field and laboratory observations of the rock masses that make up the slopes at the study site, a Geological Strength Index value of 25 was obtained. Base on GSI and some field condition can be obtained the Hoek-Brown parameter are γ = 2.6 t/m3, mi = 25, Disturbance Factor (D) = 1.0, mb = 0.118, s = 3.73e-6, 𝑎 = 0.531. The rock mass strength of the sample was brittle so that it can easily collapse. The purpose of this analysis is to do further study to overcome the problems that occur in most rocks, especially those related to transportation routes next to the slope.