Probabilistic Of Slope Failure Grasberg Open Pit Mining PT Freeport Indonesia

Abstract

The stability of a slope in mining activities is highly influenced by geology, especially the
nature of rocks and geological structures. Slope stability analysis will be faced with several
problems in the uncertainty of rock properties and rock mass. Slope stability analysis using
probabilistic methods offers a more systematic way of treating conditions of uncertainty and
provides other alternatives to the value factor approach to security regarding information on
the probability of a slope failure.Grasberg Open Mine rock type classification based on
geotechnical parameters or Geotechnical Rock Code (GTRCK) classifies rocks based on
rock type, rock mechanical properties, hydrothermal alteration type, clay content and Rock
Quality Designation (RQD) to 46 types of GTRCK. The GTRCK type which has a low rock
mass strength value is a change in intrusive rock minerals and a low RQD value such as a
lot of clay material is exposed in the Northeast and Southwest of the Grasberg Open Pit
Mine.The overall slope probabilistic modeling of the Grasberg mine uses a cross section of
220o (northwest) with the effect of a 0.02g seismic factor which is the maximum criterion
according to the probability of slope failure received with the average FK 1.13 and PK 0%.