The Presence and Influence of Fissures in the Boulder Clays of West Central Scotland

The recent urban and rural developments in west central Scotland have involved the execution of much more widespread, and often deeper, excavations than previously undertaken in the boulder clays of the area. A number of failures in deep trenches and slope excavations have occurred, whose character appeared to be influenced by the presence of macrofabric features. A detailed field study has confirmed the presence of fissures and showed that they exhibit definite preferred orientation patterns. The influence of these fissure patterns on undrained shear strength and consolidation properties have been assessed using test specimens ranging from 76 to 254 mm diameter and correlations between observed laboratory anisotropic behavior and behavior in excavations have been suggested.