EVALUATION OF LIQUEFACTION POTENTIAL FOR AN EARTH DAM SITE

Abstract

Liquefaction is a.major problem in the earthquake prone regions. This can be hazardous if occurs in a dam foundation. The proposed Polvaram der, in the State of Andhra Pradesh has its foundation mainly of and deposit. The problem for investi-gation of likely liquefaction at the site during earthaugke was referred to the Department of Earthquake Engineering. Twenty boreholes were carried out at the site in which SPT counts were obtained at 84 location by the site engineers. The data regard to the other soil properties viz, sieve analysis, density and shear parameter of the soil were also sent to the,Department. Analytical studies based on empirical approaches given by i) Seed and Idriss (1980), ii) Chinese Building Code (1976), 'iii) Seed et,al. (1983) and iv) Japanese State-of-.Art (1986) have been carried out, All these appro ches use the values of SPT results directly or indirectly. The Seed and Idriss Approach showed that there could be liqufaction at 6-locations out of 82 where SPT values have been obtained. The Chinese Building Code approach which is applicable upto a depth of 15 m showed that the liquefaction is likely only at 2 out of 64 locations considered. The Seed et al (1983) approach has indicated that there could be ' liquefaction only at 7 out of 82 locations. The Japanese State-.f-Art (1986) apor.oach pointed out that the liquefaction could only occur at 1 out of 82 locations.