1 - Analysis and Design in Rock Mechanics – The General Context

Abstract

This chapter discusses the way in which analysis and design in rock engineering have evolved. It discusses special characteristics of rock engineering design and design methodology. Design of structures in or on a rock mass poses a very different and far more complex set of challenges, as can be illustrated by considering a typical problem of support design for a tunnel in rock. The rock formations cannot be perpendicular or parallel to the axis of the proposed tunnel. The chapter explains the way by which study of relatively simple homogeneous continuum solutions can provide useful guidance for practical excavation support systems. Many applications of elasticity and plasticity theory, in other branches of engineering, are traditionally concerned with ductile materials and/or essentially tensile loading situations where, when failure of the material occurs, the failure surfaces separate and no longer interact. The fact that a rock mass is usually loaded in compression, both gravitationally and technically, has important consequences in that the failure surfaces generally continue to interact and can continue to sustain stresses at some level and dissipate energy by relative movement between the failure surfaces in compression, after the peak load is exceeded.