Implementation of a New Strain Softening Constitutive Model in the Material Point Method for the Simulation of Retrogressive Failure in Sensitive Clays

Sensitive clays experience significant strain-softening behavior, that is, when subjected to large strains. They disintegrate into a remolded liquid with diminutive shear strength. When a slope begins to fail, the remolded clay keeps moving away from its original position causing subsequent failures, resulting in catastrophic aftermath. The capability to reproduce realistic strain-softening characteristics in the constitutive soil model is necessary for more accurate numerical slope analyses in sensitive clays. This paper illustrates a simple yet practical constitutive model specially developed for simulating the strain-softening behavior of sensitive clays. The model is then implemented in Anura3D, an open-source software that uses the material point method to simulate large deformations. The model is tested using the failure of a previously occurred retrogressive failure in sensitive clay. Finally, the model's predictions have been compared with the actual post-failure run out of the landslide, and the results show that the model is reasonable and practical.