Liquefaction Studies for Seismic Microzonation of Delhi Region

Abstract

During earthquake, soil can fail due to liquefaction with devastating effect such as land sliding, lateral spreading, or large ground settlement. The phenomenon of liquefaction of soil had been observed for many years, but was brought to the attention of engineers after Niigata 1964, and Alaska earthquakes 1964. Historic large earthquakes throughout the world explain that the liquefaction related ground failure commonly causes extensive structural and lifeline damage in urban areas. Delineating areas that are susceptible to liquefaction hazards is important for evaluating and reducing the risk from liquefaction through appropriate mitigation. Because liquefaction generally occurs in areas underlain by low density, saturated granular sediments, the liquefaction susceptibility can be mapped using specific, well established geologic and geotechnical criteria. Damages caused by liquefaction of saturated soil revealed that after liquefaction the ground failed, sand boiling occurred and the structure subsided unevenly causing tilting, cracking or even collapse. Since Delhi falls in the area with high seismic probability, there is a great need for the assessment of liquefaction potential. An attempt has been made to map the liquefaction hazard using the shear wave velocity database measured from Multichannel Analysis of Surface wave method.