Stress determination by back-analysis of excavation-induced stress changes — a case study
- 171 Downloads
An Underground Research Laboratory (URL) has been constructed by Atomic Energy of Canada Limited (AECL) to study various aspects of disposing of nuclear fuel waste in the Canadian Shield. In order to ensure good quality and long life of the construction, one important factor to be considered is the in situ stress field. As part of the research program, stress changes have been measured during the advance of a tunnel to monitor the stress response to excavation. It is desirable to estimate the state of in situ stress from these stress change measurements and to compare the results with overcoring data. This paper describes the application of a recently developed stress change fitting technique for stress determination. The basic principle and the fitting procedure are briefly summarized and the back-analysis process for the data collected at the URL is presented in detail. A boundary element model was used to predict the stress changes as required by the fitting approach. This new method of in situ stress determination was successfully applied in this case. The back-analyzed stresses agree very well with those determined from overcoring tests. The quality of individual measurements was assessed and the required minimum number of measurements for a conclusive data interpretation is evaluated.
KeywordsExcavation Boundary Element Nuclear Fuel Stress Change Change Measurement
Unable to display preview. Download preview PDF.
- Crough, S. L., Starfield, A. M. (1983): Boundary Element Method in Solid Mechanics. George Allen & Unwin, London.Google Scholar
- Lang, P. A., Kuzyk, G. W., Babulic, P. J., Bilinsky, D. M., Everitt, R. A., Spinney, M. H., Kozak, E. T., Davison, C. C. (in prep.): Room 209 Instrument Array: Measured Response to Excavation. Atomic Energy of Canada Ltd. Report AECL 9566-3.Google Scholar
- Lang, P. A. (1989): Room 209 Excavation Response Test in the Underground Research Laboratory. NEA Workshop on Excavation Response in Geological Repositories Radioactive Waste, Winnipeg (1988), Canada. Published by Nuclear Energy Agency, OECD, Paris, 295–329.Google Scholar
- Martin, C. D. (1989): Failure Observations and In Situ Stress Domains at the Underground Research Laboratory. Conference on Rock Mechanics and Rock Physics at Great Depth, Pau, France,2, 719–726.Google Scholar
- Wiles, T. D., Curran, J. H. (1982): Use of the 3 D Displacement Discontinuity Element for Modelling. 4th International Conference on Numerical Methods in Geomechanics, Edmonton, Alberta, Canada.1, 103–109.Google Scholar
- Zou, D., Kaiser, P. K. (1990): Determination of in situ Stresses from Excavation-induced Stress Changes. Rock Mech. and Rock Eng.23, 167–184.Google Scholar