Simple Numerical Model to Simulate Penetration Testing in Unsaturated Soils

Abstract

Abstract. Cone penetration test in unsaturated sand is modelled numerically using Finite Element Method. Simple elastic-perfectly plastic Mohr-Coulomb constitutive model is modified with an apparent cohesion to incorporate the effect of suction on cone resistance. The Arbitrary Lagrangian-Eulerian (ALE) remeshing algorithm is also implemented to avoid mesh distortion problem due to the large deformation in the soil around the cone tip. The simulated models indicate that the cone resistance was increased consistently under higher suction or lower degree of saturation. Sensitivity analysis investigating the effect of input soil parameters on the cone tip resistance shows that unsaturated soil condition can be adequately modelled by incorporating the apparent cohesion concept. However, updating the soil stiffness by including a suction-dependent effective stress formula in Mohr-Coulomb material model does not influence the cone resistance significantly.

Elastoplastic Model and Three-Dimensional Method for Unsaturated Soils

“…Loading collapse yield curve (LC) is the most important part of BBM model; it is originally the expression of isotropic yield stress and suction derived when plastic bulk strain of unsaturated soils reached the same under different suction conditions; however, it also reflected the yield stress of unsaturated soil increase with an increase in suction. Later, on the basis of adhering to the advantages of Alonso model, a large number of models [9][10][11][12][13][14][15] were proposed to explain the mechanical behaviour of unsaturated soils. Kohgo et al [9] formulated effective stress equations using shear strength of soil on the wet side of the critical state line and proposed an elastoplastic model taking into account two suction effects, i.e., the critical suction and the effective suction.…”

“…Shamsabadi [13] investigated that partially water saturated condition in soils may change the cone penetration resistance comparing with that of dry or saturated conditions by using numerical finite element modeling and experimental centrifuge testing. Jarast et al [14] modelled numerically on cone penetration test in unsaturated sand using Finite Element Method. Simple elastic perfectly plastic Mohr-Coulomb constitutive model is modified with an apparent cohesion to incorporate the effect of suction on cone resistance.…”