MAPPING OF SOIL LIQUEFACTION POTENTIAL SUSCEPTIBILITY FOR URBAN AREAS

Abstract

Urban areas lying in the alluvial soil generally pose to threat of liquefaction even for moderate magnitude earthquakes. Liquefaction is the measure of vulnerability of saturated sediment to compact during earthquake shaking and thus generate pore water pressures sufficient to cause possible ground instability or failure. The buildings which are constructed over the liquefiable soil are more vulnerable during seismic shaking for a potential earthquake. The Chennai city of India is one of the most densely populated cities in the world, which consist of densely constructed high rise buildings in many parts. The city is under moderate seismic zone as classified by Bureau of Indian Standard where one can expected maximum magnitude of 6,9. The major part of the city covered by the Recent Alluvial soil with shallow water table, which is more vulnerable during earthquake shaking and quiet enough to trigger liquefaction. In this regard a study carried out to understand the liquefaction susceptibility of soil in the city using geotechnical parameters. Also the study reveals spatially 60% of the area is prone to liquefaction. Vladikavkaz city of Russia is also one of the most densely populated in the North Caucasus. Despite on the absence of historical data on liquefaction on this territory, there are soil conditions in new regions with a possible liquefaction behavior during strong earthquakes. Especially taking into account of Vladikavkaz seismic fault potential of Mmax=7,1. In cooperation with Indian colleagues liquefaction susceptibility assessment method was adopted and applied for Vladikavkaz city. Seismic refraction survey is wide used in Russia rather than SPT and calculations were made on the basis size of shear velocity Vs. As a result 20% of the territory of Vladikavkaz city is liquefiable. The present study can be an eye opening for urban planners and decision makers and emergency responders for future developmental planning activity within the city.