Discrete element modelling of thermal penetration test with heating and cooling

Abstract

A three-dimensional discrete element method (DEM) is employed to simulate thermal penetration tests with heating and cooling. This study investigates the mechanical behavior of soil particles during penetration, and examines the effects of temperature boundary condition, overburden load, and heating duration on the heat transfer mechanisms of the probe-soil system. Simulation results of penetration indicate that larger overburden load causes an increase in tip resistance (qc), sleeve friction (fs), and the isotropy of particles, whereas less influence is found on the distributions of penetration-induced displacement. Despite of the negligible effects of various temperature boundary conditions, the thermal responses of DEM model show that both the peak temperature of the probe heating module and the cooling rate of soil increase with the overburden load, while the probe insulation section shows a decreasing trend. The heat concentrates around the vicinity of the cone tip and probe shaft, and the high temperature area gradually expands with longer heating duration. Additionally, thermo-coupling analysis illustrates that the heat transfer process has a milder effect on the mechanical properties of granular soils. The numerical results are then validated against laboratory model chamber tests under comparable conditions, showing acceptable agreements.