ABSTRACT
Numerous shallow slope failures took place in residual soils derived from sedimentary rock formation of Uttaradit province, Northern Thailand in 2005, due to prolonged and intense rainfall. Shear behaviour as well as water retention behaviour of this material has thus been investigated in details in order to investigate the slope failure mechanism. Fully saturated Consolidated-Drained (CD) as well as suction-monitored direct shear tests have been performed on undisturbed samples collected from depths of 0.3–1 m. A miniature tensiometer has been used for suction measurement during these tests. In addition, influence of number of drying/wetting cycles on saturated shear strength is investigated. The results from a simple infinite slope analysis suggest that the major slope destabilization mechanism is a combination of material degradation and pore water pressure increase.
