Numerical Modelling of Dynamic Compaction of Soils

Dynamic compaction is a process for densifying soils by repeatedly dropping a large tamper from a crane, and this process can be applied to densify a wide range of soils in place to depths greater than ten metres. This procedure has proved to be useful in reducing the potential for settlements associated with wetting of unsaturated soils. Although field experience and experimental tests indicate that compaction efficiency is related to the soil moisture content, the compaction process makes it difficult to install some measurement instruments below the impact areas to study different aspects of the response of unsaturated soils, such as suction and degree of saturation changes. Therefore, numerical modelling could be a more cost-effective way to gain a better understanding of the dynamic response of unsaturated soils and ultimately to improve the efficiency of dynamic compaction on unsaturated soils with different water contents. Due to the numerical difficulties caused by the complexity of constitutive models of unsaturated soils and the dynamic response of a three-phase system, the numerical simulation of dynamic compaction of soils is necessarily limited. In this paper, a finite element model has been developed with an advanced constitutive model implemented, and the generalised-α method has been applied to solve the global equations of motion.