SLOPE STABILITY ANALYSIS OF LOWWALL PT XYZ’S OPEN PIT COAL MINE IN SOUTH KALIMANTAN

• Main Author: Zein, Ali
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/61802
• Institution: Institut Teknologi Bandung

Slope stability analysis is an activity that needs to be done in order to assess the stability condition and behavior of a slope. One of the stability analysis methods, called the deterministic method that uses the Factor of Safety (FoS) will consider one input parameter as the exact value of the entire parameter so that it faces the problem of uncertainty from the physical and mechanical properties of the rock. Another method, called the probabilistic stability analysis method, offers more systematic way to accommodate uncertainty conditions and provides another alternative to the Factor of Safety value approach uses the Probability of Failure (PoF). The calculation Probability of Failure is set by determining the distribution that suitable with the distribution of the data by testing the goodness of fit test using the Kolmogorov-Smirnov method and the Akaike Information Criterion (AIC) test on the data that will be used for parameters input in the modeling and simulation process, such as cohesion, internal friction angle, and bulk weight data. The results of the goodness of fit test processing in the form of a distribution function is used as input parameters in the Monte-Carlo simulation using Slide 6.0 software to calculate the Probability of Failure. Stability analysis is set by modeling the lowwall cross-section in each existing section, then simulating it to determine the FoS and PoF values for the slope model. The assumptions used are 0.05g horizontal seismic loading factor and the ground water level following the slope contours with hu values of 0.6, 0.8, 1.0 to determine the effect of water conditions on slope stability. The minimum criteria for FoS and PoF of the slope refer to the Decree of the Minister of Energy and Mineral Resources No. 1827 K/30/MEM/2018 that static FoS ?1.3; Dynamic FoS ? 1.1; and PoF ? 5%. From the results of the FK and PK calculations, it is concluded that the slopes in the actual conditions in July 2021 are safe at hu 0.6 and 0.8, but not safe at hu 1.0, then in the yearly 2021 plan design it is safe at hu 0.6 but not safe at hu 0.8 and 1.0, while the design Life of Mine (LOM) plans are not safe at hu 0.6, 0.8, and 1.0. The results of the unsafe stability analysis at hu 0.6, which is the LOM plan design is given a redesign recommendation on the overall slope from 27o to 25o and it is need to adjust the width of the berm on the slip plane which is categorized as unsafe in additions of 17.5m - 50.5m.