Modelling of fall-cone tests with strain-rate effects

Abstract

Material Point Method (MPM) is a numerical method, which is well suited for large displacement simulations. Large displacements problems are relatively common in geotechnics, including post-failure behaviour of landslides as well as a wide range of problems involving penetration into the soil body. One of those problems is the fall-cone test, commonly used to establish the undrained shear strength and the sensitivity of saturated fine grained soils. This paper shows a Generalized Interpolation Material Point Method (GIMP) simulation replicating published free-fall cone experiment performed on a kaolin clay. In the fall-cone tests, the penetration characteristics of the cone, such as velocity and total penetration depth depend on the soil properties. Those properties are affected greatly by the strain-rate which must be accounted for in a numerical simulation. Hence, the simulations shown uses a Mohr-Coulomb / Tresca material extended with strain-rate effects. The presented numerical simulations are compared with the published fall-cone experiment in which displacement and force were measured. The comparison indicates that Generalized Interpolation Material Point Method and Mohr-Coulomb / Tresca model extended with strain-rate effects are able to replicate the fall-cone penetration test very well.