Finite Difference Time Domain Simulations of Dynamic Response of Thin Multilayer Soil in Continuous Compaction Control

Abstract

For about 50 years, Continuous Compaction Control (CCC) has been somewhat applied in earthworks by using a roller integrated measurement during compaction process. In recent years, many researchers have developed a theoretical background of roller/soil interaction coupled to experimental verification. Basically theoretical parts of these research works have been performed using spring-dashpot dynamic models. By means of solutions of single degree of freedom equations in real time engineers are able to estimate the soil degree of compaction via reaction soil force. A major goal in this field of applied research is to find out if the desirable material density, the roller-integrated stiffness-measurement, and the in-situ elastic parameters of compacted materials could have a consistent relation. Regarding this, many previous studies were focused on earth fills with significant height. Due to this, the equipment measurement involved only one material. This work presents the results of numerical simulations using the Finite-Differences Time Domain method, in order to depict the response of thin multilayer systems when CCC is used. Numerical simulations are performed by using different height lifts. Toward to validate the models, synthetic time-stress diagrams are confronted with field measurement data reported in literature showing good agreement. Results show the dependency of vertical acceleration of drum-soil contact surface on the thick and the stiffness of the layers, and that the higher elastic moduli of the layered-system the lower acceleration of the roller when vibration forces still allow for continuous contact of drum and soil interface.