Geotechnical investigation of landslide near Sairang Village in Aizawl district, Mizoram, India

Abstract

The investigated landslide area is about 5.4 km north of Sairang village on Aizawl-Silchar road (NH-54). The length, breadth and height of slide are 110 m, 20 m and 70 m respectively. The dominant rock types exposed in the study area are sandstone, siltstone and shales and their admixtures in various proportions. The main factors for the instability of this area stems from the intersection of two sets of joints dividing the rock beds into varying dimensions and the presence of bedding shears and clay pockets/beds with swelling and shrinkage properties, decrease in the shear strength of overburden and bed rocks during rainy season due to water saturation and erosion of shaly layer by scouring action and a high hill slope. Remedial measures such as; lined catch water drains and chute for channeling surface water flow along the hill slope; lining of side drain to prevent toe erosion and also to prevent water percolation through debris. Sealing/filling of ground fractures/cracks with clayey material; breast and retaining structures to prevent toe erosion are suggested.