LANDSLIDE PROBABILITY ANALYSIS IN HIGWALL AND LOWWALL LOM SLOPES DESIGN OF PT XYZ’S OPEN COAL MINING

• Main Author: Yonathan, Juan
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/56969
• Institution: Institut Teknologi Bandung

The problem of Slope stability analysis will be faced with the problem of uncertainty of the physical and mechanical properties of rock. Slope stability analysis simply uses the concept of the value of the factor of safety (FoS) by using a single value for each input parameter, while the probabilistic method offers a more systematic way to accommodate uncertainty conditions and provides another alternative to the approach to the value of the factor of safety, namely information on the probability of failure (PoF). The calculation of the probability of a landslide is carried out by first determining the distribution that is in accordance with the distribution of the data held. The distribution adjustment is done by testing the goodness of fit test using the Kolmogorov-Smirnov method and the Akaike Information Criterion test on the data that will be the input parameters in the modeling and simulation process, namely cohesion data, internal friction angle, and density. The result of processing the goodness of fit test is in the form of a distribution function which is then used as an input parameter in the Monte-Carlo simulation using Slide 6.0 software to calculate the probability of failure. Modeling and simulation are done by making a cross-sectional design for each known section, then the simulation is carried out to determine FoS and PoF. The assumptions used are the horizontal seismic loading factor of 0.05g and the groundwater level following the slope contours with Hu values of 0.6 and 0.8. Based on the slope stability analysis, it was found that the highwall section BB' and CC' slopes in Pit C and the lowwall section AA', BB', CC' and DD' slopes in Pit C were in an unsafe condition with a static FK value <1.3; dynamic FK<1.1; and PoF >5%. So it is necessary to reconstruct the geometry of the slopes to make the slopes in a safe condition. Geometry reconstruction carried out on highwall slopes is sloping the overall slope angle from 31° to 26°, while on lowwall slopes is cutting, widening the berm, and cutting the slope height at several levels that have the potential for landslides due to the presence of weak fields. After reconstructing the slope geometry, static FS; dynamic FS; PoF (Hu=0.6) values were obtained respectively, in section AA' highwall slope 2.25; 2,006; 0%, lowwall slope 2,218; 1,986; 0%. In section BB' the highwall slope is 2.816; 2,505; 0%, lowwall slope 2,553; 2,282; 0%. In the CC' section the highwall slope is 1.441; 1,273; 0%, lowwall slope 2,314; 2.06; 0%. In section DD' highwall slope 2,198; 1,945; 0%, lowwall slope 2.106; 1,903; 0%.