Shear wave velocity estimation of pilani soil using ultrasonics

Abstract

In order to evaluate dynamic response of soils, shear wave velocity of soils is widely used. This is small-strain parameter. These dynamic responses are seismic site response, machine foundation vibration and liquefaction potential of soil at site. Geologic aging of soil, its stress history, density, in-situ void ratio and effective confining stress are important parameters affecting shear wave velocity. Its correlation with SPT N value is available in literature. Involved technique of obtaining shear wave velocity of soil is complicated. There should be simple alternative of estimating it. In present study, ultrasonic P wave propagation at five different silty clay contents for Pilani region soil has been used for this purpose. SPTNvalue for these silty contents have been determined based on correlation equations available in literature. Based on these SPT N values, shear wave velocity for same silty clay contents have been determined for Pilani region soil. Variation of P wave velocity and shear wave velocity with silty clay content can be used as calibration curve. P wave velocity through 300micron sieved soil of same region can be determined. Its estimated value of shear wave velocity can be obtained from the calibration curve. For some sites in the region, additional sieving through 150micron sieve will also be required. This technique of estimating shear wave velocity is much simple for a specific region soil.