Liquefaction Potential of Roorkee Region Using Field and Laboratory Tests

Abstract

Before taking up the ground improvement of a site, assessment of liquefaction potential of a region is very important. This also helps in seismic microzonation of the area. It can be rationally performed if the data of site (using either field tests or laboratory tests) are available. The aim of the present study is to evaluate liquefaction potential of Roorkee (India) region. For this purpose the liquefaction resistance of the soil, within the radius of 30 km of Roorkee, was evaluated using two different approaches. First is the field approach based on standard penetration test (SPT) N-Value and second is the laboratory approach employing mean grain size distribution (D 50). Investigation was carried out at five different locations by conducting SPT tests and collecting soil samples at regular interval. The cyclic shear stress due to earthquake loading was examined using simplified method as well as using ground response analysis. The factor of safety against liquefaction was evaluated at different depths for all the sites using both field and laboratory data. It was found that the factor of safety against the liquefaction using field approach is marginally greater than that using the laboratory approach for all the sites. Also the factor of safety using ground response analysis is significantly smaller than that using simplified method. Thus it was concluded that use of simplified method may not be adequate.