Fast planar slides. A closed form thermo-hydro-mechanical solution

Abstract

Heat-induced eccess pore pressures on the failure surface of a planar slide have been calculated by solving the mass and heat balance equations on the shear band. The set of differential equations and the equation of motion of the slide have been solved in closed form for the case of incompressible fluid and incompressible soil skeleton. The solution describes the accelerated motion of the slide. It has been compared with the numerical solution when soil and water stiffness terms are not disregarded. A case study, based on a well-known translational slide (Cortes slide) has been solved. Numerical and analytical solutions are compared. Results of a sensitivity analysis indicate that the permeability of the shear band is the key parameter to control the onset of a rapid motion. For a band permeability above a threshold value, in the vicinity of 10−15m2 (10−8m/s), fast accelerated motions are very unlikely.