Experimental and Theoretical Investigations of a Passive Earth Pressure Problem

Abstract

Synopsis The Paper presents data from the experimental investigation of the passive failure of an initially vertical, rough, plane wall which is rotated about its toe into a mass of dry sand with an unloaded horizontal surface. The sand is constrained to deform in plane strain. Measurements are made of the distribution of the normal and shear stresses on the wall while strain fields are determined from observations by an X-ray technique of the positions of lead shot buried in the sand mass. The form of the rupture surface mechanism in dense sand is determined. The strain data are used to investigate the φ= constant assumption of the Sokolovski (1965) method and Sokolovski solutions are compared with the experimental data for two cases. There is marked agreement between the predicted principal compressive stress directions and the observed principal compressive strain increment directions. Cet Exposé présente des données provenant de recherches expérimentales portant sur la rupture de butée d'un mur plan, rugueux, vertical au départ auquel on imprime un mouvement de rotation autour de son pied dans une masse de sable sec à surface horizontale ne supportant pas de charge. Le sable est contraint de se déformer selon une déformation en plan. On prend des mesures de la répartition des contraintes normales et de cisaillement subies par le mur tandis que des champs de déformation sont filig;xés à partir d'observations au moyen d'une technique à rayons X des positions de billes de plomb enterées dans la masse de sable. On établit le genre du mécanisme de la surface de rupture. On utilise les données relatives à la déformation pour examiner la supposition portant sur la constante φ de la méthode de Sokolovski (1965) et l'on compare des solutions de Sokolovski aux données expérimentales relativement à deux cas. Il se présente un accord notable entre les directions des contraintes de compression principales prévues et les directions des accroissements de déformation de compression principales observées.

Nonuniformities imposed by simple shear apparatus

“…In the rectangular apparatus the horizontal rupture surface coincides with the imposed zero-extension direction of the apparatus and the postulate of Roscoe (1970) and James and Bransby (1970) would be applicable. The orientation of the inclined rupture surface in the circular apparatus was shown to be reasonably predicted (Budhu 1979), using internal strain measurements, by eq.…”

The variation of Nγ with footing roughness using the method of characteristics

“…On account of the symmetry, the computations were performed only for the plastic domain on the right side of the vertical axis of symmetry. The procedure for applying the method of characteristics is described in detail by Sokolovski [11,; the method is also explained by Larkin [12], James and Bransby [25] [28]. The numerical procedure is, therefore, not repeated in this paper.…”

Performance of an elastoplastic model

“…In relation to the passive earth pressure problem, deformation patterns and failure surfaces developed in experiments were observed earlier by James and Bransby (1970). In their experiments, rupture surfaces (Fig.…”