Abstract
The directional strength behavior of a kaolin clay subjected to different stress conditions was evaluated experimentally by use of data from miniature vane shear tests. Clay slurries with flocculated and dispersed intrinsic fabrics were consolidated in large-diameter slurry consolidometers under conditions of no lateral strain to different values of the major principal stress. Upon completion of predetermined stages of consolidation, vertically and horizontally oriented vanes were introduced into the consolidated clay blocks while they were still under their in-situ states of stress, and vane shear strength determinations were made. Similar vane tests were then conducted on unloaded clay blocks to assess the effects of unloading history and back-pressure on the directional strength characteristics. In general, in-situ strength was dependent on fabric and vane orientation, higher strengths being obtained for flocculated clays and horizontal vane orientations. Variations in the unloading history also caused changes in strength, and some of these changes were direction-dependent.
