Despite the significance of in situ stresses in geotechnical engineering, they are often not well defined due to (1) insufficient reliable stress data, which can be due to a lack of measurements and/or the uncertainties/errors associated with the measurement methods employed, and (2) natural variability in the in situ stresses due to the anisotropic and heterogeneous nature of the geology. This is especially true in the Coast Range Mountains of western British Columbia in Canada, where a number of tunnels have been planned for the coming years. This paper aims to provide guidance for the determination of in situ stress conditions in this complex environment through an assessment of the applicability of existing in situ stress methods and a review of previous project experience. The geological history of the area is presented to provide insight into the broad tectonic domain and allows general conclusions to be drawn regarding the state of stress in the region.

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