Basic Rock Mechanics and Testing

Abstract

The application of rock mechanics to solve engineering problems requires some knowledge of engineering geology and an appreciation of the difference between parameters measured in the laboratory and the design parameters used in field problems. This concept is particularly important in the practice of rock engineering because laboratory tests described in subsequent sections are performed on small specimens of intact rock. In contrast, the rock mass in the field is often dissected by variousdiscontinuities such as joints. Therefore, quantities of engineering importance measured in the laboratory, such as the elastic modulus and strength, can seldom be directly used in the field. However, the results of laboratory measurements do form an intrinsic component of the knowledge required for design. The parameters measured in the laboratory may serve as: (1) an index to correlate experience between different rock formations, (2) an index to represent the variation of material behavior over a proposed site, (3) upper bound values such as elastic modulus and strength, and (4) a component to which a “correction factor” may be applied to obtain the design value.