State parameter predictions based on cone penetration test simulated with MPM: an application to tailing deposits

The ‘state parameter’, which compares the current void ratio with the critical state void ratio, plays a crucial role in quantifying sandy soil behaviour. In situ methods, such as cone penetration tests (CPTs), can quantify the mechanical state of sand. However, establishing a direct relationship between cone resistance and the state parameter requires a complex back-analysis of the processes occurring in the soil during the test. Currently, a cavity expansion solution is being used to relate the state parameter to the cone resistance, necessitating the use of a calibrated scaling equation. In this study, 600 material point method CPT simulations are performed – which employ the critical state NorSand model – to derive a direct predictive equation for estimating the state parameter from CPTs. This eliminates the need for a scaling equation. The predictive equation computes cone resistance as a function of the NorSand parameters and the state parameter of the soil. The accuracy of this predictive equation is subsequently evaluated by comparing the results against the chamber test data of tailings deposits, showing promising performance.