Simplified Numerical Modeling Strategies of Deep Vibratory Compaction

Abstract

Abstract. In this paper different simplified approaches for numerical simulation of deep vibratory compaction are presented. In the first approach, modal analysis yields the mode shapes and natural frequencies of a planar soil model, with the objective of reducing the degrees of freedom of the soil continuum in a subsequent response history analysis considering only the most dominate modes. Based on the maximum elastic strain energy per mode criterion, the most dominant modes excited by a rotating force are identified, revealing that the most dominant natural frequencies are clustered around multiples of the excitation frequency. It is also shown that 1.4 % of the modes contribute to 80 % of the total strain energy. The second study addresses modeling of vibro-soil interaction, approximating the soil as three-dimensional planar circular section and the vibratory as rigid cylinder rotating in the hole at the soil center. To the surfaces of the two bodies potentially in contact, a contact formulation is assigned. The outcomes of the numerical simulations on this finite element model serve as input for system identification of the soil parameters varying with time due to the compaction process. The underlying lumped parameter model is composed of two discrete spring-dashpot systems and a lumped mass subjected to a rotating force. The contact force can be reasonably identified, however, the utilized mapping algorithm for identification of the time varying soil parameter needs further investigation.