Analysis of Shear Zones of Landslides by the Numerical Simulation of Monitored Surficial Displacement Vectors-Case Study of the Landslide at Gunung Pass, Malaysia

摘要

Planning and designing countermeasures for a specific landslide require geotechnical and geological investigations of the landslide area. In particular, assessment of the extent of unstable zones and/or sliding surfaces of the landslide is essential for designing countermeasures. While borehole logging is the effective way to identify the sliding surface and shear zones, installation of the drilling systems can be prohibiting, depending on the accessibility and budgetary conditions. Past research, on the other hand, suggests that the surficial displacements may be utilized to estimate the shear zones. This paper presents the predictive analysis of the subsurface shear zone of the landslide along the highway passing the north mountain range of Malaysia. A marked failure occurred in 2003, followed by gradual continuous movements that have been monitored by 17 reflective prisms and the two total stations. No bore logging has been performed, and therefore, sliding surfaces are not well known. For the purpose of estimating the depth profile of the sliding surface, directions and magnitudes of the displacement vectors have been examined and subsequently numerical analysis of the displacement vectors was performed. The monitored displacements were reproduced by stepwise strength reduction, which yielded a band of cumulative shear failure zone that may represent the potential sliding surface.