MEASUREMENT OF IN-SITU ROCK STRESSES BY OVERCORING

The article reviews methods to determine the state of stress in rock masses which have been extensively researched and developed. Two methods of stress measurement which have met with some success in commercial application are stress relief by overcoring and hydraulic fracturing. The former method, for which apparatus and test procedures are described, is widely used and is readily available to engineers for site evaluation studies and rock mechanics programmes related to the design of underground structures. (TRRL)