Estimation of small-strain shear modulus of embankment soils before construction using bender elements in compaction test

Design of railway track and highways on embankments with compacted fills often needs the value of small-strain shear modulus of the fill soil to be known before construction. This paper presents a new method of determining the value of Gmax using bender elements within the mould of laboratory compaction test which is generally performed to decide specifications of field compaction before construction. This method is much easier to perform and simulates the field conditions closely. A design mould configuration is suggested after due consideration to near-field effect and rigid boundary effect during wave propagation in the compaction mould. This process of wave propagation is also simulated using 3-D finite element model in ABAQUS to study the effect of aspect ratio of mould for different values of Poisson’s ratio of compacted soil. Accordingly, the testing procedure is laid out for bender element test after compaction of soil in the mould and applying vertical load to simulate the overburden expected at different depths of embankments. Using the proposed test procedure, the value of Gmax has been measured at different overburden values for several soil samples. The collected Gmax data is used to look at overburden effect and how it can be applied in design.by Amit Prashant, Himanshu Kotak and Prajakta R. Jadha