Hazard analysis of Li-shan landslide in Taiwan

Abstract

In this study, a method coupling limit equilibrium analysis, Monte Carlo analysis and Geography Information System (GIS) was implemented to evaluate landslide hazard, with consideration of spatial uncertainties. With the GIS, the three-dimensional surface topography, underground geomaterial distribution and groundwater level were processed for slope stability analysis. In addition, mechanical properties of the geomaterials were considered as random variables instead of single values; slope sections and groundwater levels were also randomly adopted. Through a Monte Carlo sampling process, a distribution of safety factor and probability of failure were determined. This approach was applied to hazard assessment of the Li-shan landslide in Central Taiwan. Through a series of analyses, the hazards of sliding bodies of the Li-shan landslide were estimated and ranked. It shows the influence of ground water level is significant, which reveals the importance of ground water control and monitoring. The results show the safety of the northeast and southeast areas of the landslide have been significantly improved since the ground water levels have been lowered by the drainage system. Spatially, the hazard moderately dissipates from center area in the post-remediation phase.