Abstract
A guide for the logging of borehole core for rock engineering purposes is proposed.
General acceptance of such a guide ensures that core logs will generally contain meaningful descriptions of the rock mass parameters most significant in rock engineering problems. The use of defined terms and format ensures that any reader of the log will have an appreciation of the original appearance of the core, and in particular those aspects important to rock engineering.
The proposed guide takes due cognizance of existing accepted systems of soil and rock mass description or classification and attempts to remain compatible with these wherever feasible.
Only those parameters which are commonly of interest in rock engineering are described. Qualitative descriptions depending only on visual inspection and simple mechanical field tests are used. Primary core descriptions include descriptions of colour, weathering, fabric, discontinuity surface spacing, hardness, rock name and stratigraphic horizon. This is followed, where required, by a description of the discontinuity surfaces including their type, separation, fracture filling (presence or absence), roughness and orientation. If significant, an additional description of the nature of the fracture filling including moisture, colour, consistency or hardness, soil or rock type and origin is added. The significance of each of these parameters with respect to engineering behaviour is discussed and standard descriptive terms defined.
Other information commonly recorded on the borehole log, such as drilling method and size, core recovery, RQD, fracture frequency and standard tests are reviewed and techniques of presentation are suggested.
Recommendations are made for the handling and storage of rock cores. Some useful techniques for the logging of core are discussed.
