Liquefaction potential of sand deposits in Sri Lanka

Abstract

After 2004 tsunami, the frequency of earthquake occurrence near Sri Lanka has increased significantly. On the other hand. it should be noted that most of the important structures in Sri Lanka are founded on sandy soils along the coastal line. During a strong earthquake. there is a high risk that these sand deposits may liquefy causing significant damage to the structures founded on sandy soils. Standard Penetration Test (SPT) and Cone Penetration Test (CPT) are widely used for the site specific evaluation of liquefaction potential of sandy soils. In this paper, results of SPT-based liquefaction potential evaluation are presented. Mere. 46 hare holes front Colombo and east- coast were analyzed, and the liquefaction potential was evaluated by means of a factor of safety against different earthquake magnitudes, front the analysis results, liquefiable areas and its depths were identified. It was observed from the analysis of 46 boreholes, that 3-12 m depths from ground surface are liquefiable in Colombo area during a 6.5 magnitude earthquake, while on average 4-10 m depths are liquefiable in Batticaloa. Mutur and Ampara areas in the east coast.