EVALUATION OF SHEAR MODULUS OF SOILS USING GEOPMETHODS"HYSICAL

Abstract

The evaluation of Shear Modulus of soils is a very important factor in Geotechnical Earthquake Engineering under dynamic loading. In the present study Electrical Resistivity Tests, Standard Penetration Tests, Cross borehole Tests and Spectral Analysis of Surface Waves (SASW) Tests were performed at the same site in front of Soil Dynamic Laboratory in the Earthquake Engineering Department of University of Roorkee. The Cross borehole method is one of the most popular and reliable seismic methods as in this the seismic properties of the underlying materials between any two depths of a test site can be accurately determined and the variation of shear wave velocity and Dynamic Shear Modulus with depth can be obtained. Hence this test was used as a standard reference for comparing the data from the other tests. An attempt has been made to replace the Cross borehole test which is costly and time consuming by any of the other three methods by comparing the results so obtained. Analysing the results, it is observed that out of the two surface in-situ tests, the SASW test give results which are in reasonable agreement with those of the Cross borehole test. Empirical methods, Ohta and Goto (1978) and Mitra (1995) give fairly good results when compared to Cross borehole results at depths greater than 5metres. 111