Slope Instability Evaluation Using Geophysical Methods of Gua Musang-Cameron Highland Highway

Abstract

Slope failure is a complex phenomenon that may trigger the
occurrence of slope failure due to several factors. The internal
structures and mechanical properties of subsurface are
important parameters to investigate as a pre-requisite analysis.
Four parallel survey lines of 2-D resistivity and two lines of
seismic refraction were designed in order to achieve the
objectives. The model shows the resistivity values covered of 1-
4000 Ωm with investigation depth of 20 m. Highly weathered
zones were identified at values of 400-450 Ωm while saturated
zones with values of <100 Ωm. The high resistivity regions with
values of 1500-2500 Ωm indicates the weathered granite for this
area. The 2-D seismic refraction model shows velocity values
ranging between 200-2800 m/s and depth coverage about 30 m.
The result interpreted as 3 layer cases with 1st layer, 2nd layer,
and 3rd layer identified at velocity of 400-600 m/s, 800-1400 m/s
and >2000 m/s respectively. The low resistivity and velocity
indicate as highly fractured/crack zones which able to decreases
the shear strength of the slope soils and increases the hydraulic
conductivity of the soils. The saturated zone and infiltration with
the existence of boulders indicates the factor for the occurrence
of slope failure.