Microscopic Structures in Kaolin Subjected to Direct Shear

Abstract

Synopsis A clay with near perfect particle parallelism was prepared by consolidating a slurried kaolin in a large oedometer. Shear box samples trimmed at various angles to the compression direction revealed no significant difference in drained strength. Samples with original bedding normal and parallel to the shearing direction were interrupted at various displacements and thin sections prepared after impregnation with Carbowax. The sequence of microscopic shear structures shows that in both cases the features at peak strength result from simple shear conditions and that a continuous horizontal structure appears only towards the residual stage. Intermediate structures are interpreted in terms of the kinematic restraint imposed by the configuration of the box. Detailed examination of the development of kink-bands and compression textures lead to the notion of basal plane slip as the basic mechanism in shear induced structures. Une argile ayant une orientation preferentielle quasi-parfaite a ete preparee en...