Fundamentals of rock joint deformation

A review of techniques, advances and outstanding issues in numerical modelling for rock mechanics and rock engineering

Discrete element methods are numerical procedures for simulating the complete behaviour of systems of discrete, interacting bodies. Three important aspects of discrete element programs are examined: (1) the representation of contacts; (2) the representation of solid material; and (3) the scheme used to detect and revise the set of contacts. A proposal is made to define what constitutes a discrete element program, and four classes of such programs are described: the distinct element method, modal methods, discontinuous deformation analysis and the momentum‐exchange method. Several applications and examples are presented, and a list is given of suggestions for future developments.

Numerical modelling of discontinua

This paper discusses the issues involved in the development of combined finite/discrete element methods; both from a fundamental theoretical viewpoint and some related algorithmic considerations essential for the efficient numerical solution of large scale industrial problems. The finite element representation of the solid region is combined with progressive fracturing, which leads to the formation of discrete elements, which may be composed of one or more deformable finite elements. The applicability of the approach is demonstrated by the solution of a range of examples relevant to various industrial sections.

A combined finite‐discrete element method in transient dynamics of fracturing solids

Numerical methods in rock mechanics

The representation of discontinuities in analysis of blocky rock is discussed. A linkage type element is developed for addition of rock joint stiffness to the structural stiffness matrix describing the behavior of a system of rock blocks and joints. Several basic problems of jointed rock are studied. These examples demonstrate the marked influence joints may have on the stress distribution, displacements, and failure pattern of an underground opening or other structures in jointed rock. A new classification of joints is introduced, based on the application of the joint element to finite element analysis of structures in jointed rock. Normal stiffness, tangential stiffness, and shear strength are used as parameters in the classification system. The methods discussed in this paper allow a jointed rock mass to be treated as a system of blocks and links. Just as analysis of a reinforced concrete building requires detailed knowledge of the behavior of concrete alone and steel alone, the joint stiffness approach calls for and uses detailed description of the behavior of rock blocks and rock joints independently.

A Model for the Mechanics of Jointed Rock

VASILESCU SUGGESTS THAT ROCK MECHANICS IS A NATURAL SCIENCE, ALTHOUGH THE AUTHOR IN THE CONTEXT OF THE PROBLEM BEING DISCUSSED, CONSIDERS THAT ROCK MECHANICS IS A BRANCH OF ENGINEERING, AND MATHEMATICALLY BASED METHODS OF DESCRIBING ROCK BEHAVIOR ARE NOT ONLY APPROPRIATE, BUT EXTREMELY POWERFUL. IN THE DESIGN OF EXCAVATIONS IN JOINT ROCK, ROCK MECHANICS IS VERY USEFUL. TERZAGHI OFTEN EXPRESSED THE VIEW THAT GEOLOGICAL UNCERTAINTIES LIMITED THE RELIABILITY OF ANALYSES IN WHICH A PARTICULAR JOINT WAS ASSUMED TO OCCUR AT A GIVEN LOCATION. THE MATHEMATICAL MODEL ENABLES THE EXTREME CASES TO BE STUDIED THROUGH PARAMETER STUDIES AND STATISTICAL METHODS. REPORTS ISSUED: A MODEL FOR THE MECHANICS OF JOINTED ROCK, RICHARD E. GOODMAN, ROBERT L. TAYLOR, TOR L. BREKKE, ASCE PROC. PAPER 5937, MAY 1968.

Tor L. Brekke

Papers

A Model for the Mechanics of Jointed Rock

Closure on a model for the mechanics of jointed rock