Investigation of hydraulic heave in excavations using the material point method

Owing to the total head difference between the inside and outside of an excavation, seepage occurs into the excavation. In cases where the head difference is large, the seepage velocities and resulting seepage forces can cause the catastrophic phenomenon of hydraulic heave inside the excavation, as well as overall basal instability. To investigate this phenomenon, the Material Point Method (MPM) has been employed in this study. MPM is a numerical procedure that accommodates large deformations and displacements of a continuum avoiding shortcomings of the classical Lagrangian finite element method. An in-house program, capable of modelling a biphasic medium as well as pure water in one model in the context of MPM was developed. Numerical results are presented and are compared to analytical predictions and the results of experimental investigations to verify the applicability of the modelling procedure.