Design Analysis in Rock Mechanics

Abstract

A preface gives the author an opportunity to explain his work: what the objective is, what level of understanding is assumed, why some material is included and some not, and so forth. Like most experienced practitioners and teachers of rock mechanics, I find that there is a lack of suitable textbooks for undergraduate courses and consequently I rely on personal notes and handouts. There are a number of reference books available that cover rock mechanics in varying degrees of depth and breadth, but most are best suited for supporting graduate study. None have a satisfactory array of worked out example problems, a selection of problems for homework assignment at the end of each chapter and a key containing detailed solutions as is customary in undergraduate textbooks. There is an opinion that rock mechanics is better left for advanced study, so any undergraduate course should be preparation for graduate study and should therefore emphasize the more scientific features of rock mechanics. My view is that there are important, practical engineering problems in rock mechanics that should and can be addressed at the undergraduate level. An important example is rock slope stability. Hence, the title of this book is Design Analysis in Rock Mechanics. Emphasis is on application to practical problems. Although intended primarily for undergraduate study, first year graduate students, whose introduction to rock mechanics was one of engineering science, may find application to engineering design of some interest. Of course, not all issues in rock mechanics can be addressed in a single book. The rich and varied area of numerical methods and computational rock mechanics must necessarily be left out. In any event, computer code usage should be learned only after a firm grasp of fundamentals is in hand. Numerical analyses provide much helpful guidance toward the solution of complex problems in rock mechanics, but becoming adept at keystrokes and program execution is no substitute for thoughtful analysis based on fundamental principles. This book builds on mechanics of materials, a course that is required of almost all engineers. Familiarity with the concepts of stress, strain, and elastic stress–strain relations for axially loaded members, for torsion of circular bars and for beams is assumed. Torsion is not often encountered in rock mechanics design, but axial load and beam bending find important parallels with pillars in underground excavations and roof spans in stratified ground. These problems are essentially one-dimensional and may be handled analytically and quantitatively with help from a calculator. The concept of stress concentration about a hole is also introduced in the first course in mechanics of materials. Application here, for example, is to circular mine shafts and rectangular tunnels. These two-dimensional problems (plane strain) require the ability to