A Velocity Field for Some Passive Earth Pressure Problems

Abstract

Synopsis A simple velocity field is developed for the passive earth pressure problem of the displacement of a rough plane wall into a mass of dry sand. Three modes of wall displacement are considered: wall rotation about the top, wall rotation about the toe and wall translation. The validity of the velocity field for the three cases is discussed. The pattern of the velocity field and the velocity boundary conditions enables predictions to be made of the strain fields associated with the three modes of wall movement and these predictions are compared with experimental observations. The velocity field also predicts the location and sequence of the rupture surfaces that occur in dense sand and leads to an understanding of the differences in the experimentally observed strain fields and wall stress distributions. This Paper follows on from an earlier paper (James and Bransby, 1970) in which the boundary stresses and the predicted principal stress directions in the mass were compared with measured boundary stresses and with measured strain increment directions. The present Paper makes direct comparison between predicted and measured strains for different modes of wall movement. Un simple champ de vitesse est créé pour le problème de la pression passive du sol dans le déplacement d'une paroi brute, dans une masse de sable sec. Trois modes de déplacement de paroi sont considérés: la rotation de la paroi sur la partie supérieure, la rotation du mur sur le pied et la translation. La validité du champ de vitesse dans les trois cas est discutée. Le modèle offert par le champ de vitesse et par les conditions de la zone limite de vitesse permet de faire des prédictions des champs de déformation dans les trois modes de mouvement de paroi et ces prédictions sont comparées à des observations expérimentales. Le champ de vitesse prédit également la position et la série des surfaces de rupture qui se produisent dans un sable dense et qui aboutissent à une compréhension des différences dans les champs déformation et dans les distributions de contrainte dans la paroi. Cet Exposé suit un article antérieur (James et Bransby, 1970) dans lequel les contraintes de zone limite et les directions prédites des contraintes principales dans la masse étaient comparées avec des contraintes mesurées de zones limites et avec des mesures des directions d'accroissement de déformation. Le présent Exposé fait une comparaison directe entre les déformations prédites et mesurées pour différents modes de mouvement de paroi.

Discrete simulations of shear zone patterning in sand in earth pressure problems of a retaining wall

“…Within the first approach, assuming the material yielding behind the wall according to the Mohr-Coulomb law, one can obtain mathematically closed solutions of pressure distribution for simple boundary conditions (Caquot and Kerisel, 1948;Negre, 1959). In the case of complex boundary and load conditions, numerical solutions using a characteristics method for stress and velocity fields can be obtained (Sokolovski, 1965;Roscoe, 1970;James and Bransby, 1971;Szczepiń ski, 1974;Bransby and Milligan, 1975;Houlsby and Wroth, 1982;Milligan, 1983). Within a simpler kinematic approach, based on the force equilibrium, different failure mechanisms consisting of slip surfaces are assumed.…”

Investigation of Parameters Influencing Reverse Fault Rupture Propagation to the Ground Surface

“…This suggests that the nature of failure planes in sand are controlled by the rate of volume change, meaning the stress characteristics of a sand mass are less important. Similar results were reported by Roscoe (1970), Bransby and James (1970), James and Bransby (1971), and Wroth and Basset (1965). This is pertinent because rate of volume change is described by the angle of dilation which is related to the velocity characteristics of a material.…”

Effect of stress level on the bearing capacity factor, N γ , by the ZEL method

“…James and Bransby (1971) used them for prediction of strains and deformations behind a model Kumar and Khatri, 2008) retaining wall. Habibagahi and Ghahramani (1979) and Ghahramani and Clemence (1980) calculated the soil pressures by considering the force-equilibrium of soil elements between the zero extension lines.…”