A transform-search technique for determination of frequency dependent dynamic properties of earth materials

This paper proposes a transform-search technique to evaluate the frequency dependent dynamic properties of earth materials. The earth materials are assumed to be homogeneous, isotropic and visco-elastic with frequency dependent Young's modulus E(ω)) and visco-damping coefficient η(ω)). A transfer function which characterizes the relation between the response impulse at fixed boundary and loading impulse at another free boundary is obtained by using Laplace Transform. In conjunction with the above transfer function, with the measured impulses at both boundaries provided from the shock tests, the frequency dependent dynamic properties are evaluated inversely through a search technique developed in this paper. Finally, an example is given to evaluate these properties in a soil material. Results are satisfactory.