Assessment of Small Strain Dynamic Soil Properties of Railway site Agartala, India by Bender Element Tests

Small strain dynamic properties of soil is the primary input parameter in seismic ground response analysis studies. This study examines the small strain shear modulus (Gs or Gmax) and damping ratio (ξ) using bender element tests on subsoil samples along with evaluation of liquefaction potential (Sandy soil) collected from a railway construction site at Agartala, India. The objective of this study is to develop a database and empirical relationship on dynamic properties of soil Agartala which may help to carry out site specific seismic hazard studies of Agartala city. In present study, both undisturbed and disturbed soil samples were collected from twelve boreholes near the study area which is mainly of soft marshy ground with localized deposits of peat layer. Similar type of soil is often found in various parts of Agartala basin and other regions of India. Experimental results indicate that Vs, Gmax and ξ vary within a wide range depending upon the type of soil and a closed form empirical equation are proposed to calculate Gmax for different types of soil which would be applicable for evaluating dynamic properties for similar nature soil available across various sites of India.