A new initiative in Canadian rock mechanics research
P.K.Kaiser
Geomechanics Research Centre, Laurentian University, Sudbury, Ont., Canada
Department of Civil Engineering, University of Toronto, Toronto, Ont., Canada
Department of Mining Engineering, Queen’s University, Kingston, Ont., Canada
ABSTRACT: Rock mechanics research in Ontario, Canada, received a new impetus in 1987 through the creation of three research chairs in mine design (at Queen’s University), rock engineering (at the University of Toronto), and rock mechanics and ground control (at Laurentian University). In this manner, three teams involved in rock mechanics research were linked to enhance research productivity and technology transfer. This paper provides a brief overview and summary of the structure linking the three universities, and their current research projects.
In response to the recommendations contained in the 1986 report of the Provincial Inquiry into Ground Control and Emergency Preparedness (the Stevenson Commission), a number of initiatives were taken by the Ontario Provincial Government and the mining industry. Among these were the formation of a Mining Research Directorate (MRD), which is responsible for the coordination of mining industry sponsored research, and the creation of two Research Chairs, one at Laurentian University in the heart of Ontario’s largest mining centre (Chair for Rock Mechanics and Ground Control) and the other at Queen’s University (Chair for Mine Design). A third Industrial Research Chair was jointly sponsored by the Natural Sciences and Engineering Research Council (NSERC) and Placer Dome Mines. It is located at the University of Toronto.
A formal arrangement has been established in which the three universities cooperate on research and teaching on subjects related to their fields. The three chair holders are each cross-appointed to the other two universities. This permits graduate students to obtain full credit for courses taken at another participating university and provides the necessary structure for joint supervision of research by them.
In an effort to build on the different areas of expertise that the three professors and their colleagues at the respective universities bring to the field of rock engineering, each Chair is focussing its activities in complimentary areas. These can be summarized as follows:
• E. Hoek - Fundamental rock mechanics, failure criteria of rock and rock masses, and analytical, numerical and empirical studies on rock support.
• W. F. Bawden - Study on influence of rock support selection and performance upon mine design and consideration of the economic and mine planning implications of rock support.
• P. K. Kaiser - Monitoring of rock and rock support behaviour in selected field locations and interpretation of these observations in terms of support-interaction and rock mass failure mechanisms.
A more detailed description of the current activities at each institution is given below.
2. SUPPORT OF UNDERGROUND MINING EXCAVATIONS IN HARD ROCK - AN MRD PROJECT
The largest research project of the MRD was initiated in Spring 1989 on the development of design methods for underground mining excavations in hard rock. In this project, the MRD and the research groups at the three participating universities work closely with the mining industry and draw upon the experience of engineers and geologists within the mining companies sponsoring the project. An advisory board, made up of technical specialists, monitors the progress and provides advice on future research directions. The project extends over three years and involves about 50 man years of research. The annual budget of approximately $600,000, plus $200,000 of in-kind support for field work, has been provided by 12 sponsoring mining companies in Ontario and is administered through the MRD.
The final product of this research will be a handbook on the design of support for underground excavations. This book will contain guide-lines on the selection and design of support for a wide range of rock conditions and excavation configurations, discussions on the use of microcomputer programs provided with the handbook or obtainable from recommended sources and guidance on installation, quality control, economic and planning issues. As many as 40 graduate students will be exposed to and will participate in various aspects of this research program and it is anticipated that a significant number of these students will be available for employment by the mining industry.
While all aspects of support will be covered in the handbook, the research work will centre primarily around topics such as: numerical simulation of support/ground interaction, rock mass strength and deformation properties for design, failure modes and mechanisms, blast damage control, support of ground subjected to progressive failure, support of bursting ground, support of backfill and support by backfill, etc.
3. RESEARCH FOCUS AT UNIVERSITY OF TORONTO
The primary goal of this research team is to develop numerical and empirical tools for the design of support in underground excavations. This work includes research into the way in which geological data is collected and interpreted, particularly in relationship to its use in estimating rock mass properties. Work is also being carried out on the development and evaluation of a range of numerical tools for the analysis of excavation stability and support performance for both stress controlled and structurally controlled failures. A great deal of emphasis will be placed on the presentation of the results of this research in user-friendly programs and simple design techniques.
Estimation of Rock Mass Properties
Key components in any numerical model of excavation stability are the strength and deformation properties of the rock mass surrounding the opening. Both pre- and post-peak strength characteristics are important because of the significant changes which occur as failure propagates through the rock mass. Present methods for determining or estimating these rock mass properties are inadequate and a significant research effort is being directed towards improving the geological data interpretation process and the back-analysis of documented failures in order to develop more reliable techniques for estimating these properties.
It was originally planned that no new numerical models would be developed. Only existing commercial programs would be evaluated and used for structural data analysis, interpretation and analysis of laboratory and field measurements (stresses, displacements and progressive failure mechanisms), and the evaluation of support performance. This goal proved to be unrealistic and the research group has embarked upon the development of a suite of programs to carry out these tasks. All of these programs share a powerful but very user-friendly interactive graphics input/output interface and all are distributed as share-ware programs to the sponsoring companies and those interested in evaluating or using them. The following programs have been completed: DIPS, for structural geology data handling, and EXAMINE, a 2D elastic BEM program for stress and factor of safety analyses. Other programs are under development, e.g., STRENGTH, for statistical analysis of rock strength data, UNWEDGE, a 3D structural stability analysis code for.underground openings, and SUPPORT, a 2D hybrid FE (non-linear) - BE (linear) analysis code with support elements.
In support of the theoretical work, a number of field programs have been carried out or are planned. These range from short term observational studies on the installation and performance of rock bolts, cable bolts, mesh, lacing and shotcrete in various underground mining environments to longer term studies in which the performance of support during the extraction of a series of stopes will be carefully monitored and evaluated. These investigations are closely coordinated with those being carried out by the GRC at Laurentian University and at Queen’s University. It is hoped that this strong field component will ensure that the theoretical studies remain...
