Slope Stability Analysis to Evaluate Slope Failure in Northern Thailand by Standard Penetration Test

Abstract

Highway embankments constructed on high mountain areas usually have a problem of slope stability in the rainy season that can have a great impact on road users because it is often limited in terms of boundaries. The purpose of this study was to analyze the stability of slope by using the Standard Penetration Test (SPT). The SPT is an in-situ of soil testing that can be collected data while boring. N-Value from SPT gives shear strength parameters of soil that can analyze the factor of safety. A total of 30 samples were collected from slope failure locations along the highway in Northern Thailand that had boring data in the area or nearby distance between slope failure area and borehole, not more than 30 km. N-Value can compare the relationship with the effective friction angle of coarse grains (sand) or the cohesion of fine gains (clay). Friction angle and cohesion have analyzed the factor of safety under a critical period of rain and normal traffic volume. The factor of safety is between 0.108-1.471 and displayed the results of the analysis in "Factor of Safety Map in Northern Thailand".