SIMULATING SOIL DEFORMATION USING A CRITICAL-STATE MODEL .2. SOIL COMPACTION BENEATH TIRES AND TRACKS

A critical-state finite element model was used to simulate compaction under single and dual tyres and tracks. The compaction involved deform ations at three different scales, from small tyres with a contact area of about 70 cm(2) (single tyre) supporting a load of about 50 kg, to large tyres of about 1.2 m(2) (dual tyres) supporting a load of about 4500 kg. The predictions were compared with measured values for severa l different quantities. These included: rut depths; vertical displacem ent and shear strain: vertical stresses; and, void ratios and precompr ession stress measured on sampled soil cores. In general, the predicti ons and measurements agreed reasonably well. However, the agreement be tween prediction and measurement depended on the precision of measurem ents, soil disturbance, and the volume of soil involved in a measureme nt relative to the volume of soil influenced by the tyre or track. Thi s study shows that the critical-state finite element model is useful, offering insight into the compaction process, the dependence of compac tion on soil strength and compressibility, and practical implications for soil management.