ABSTRACT
The ongoing planning, design and construction of civil, hydropower, and mining infrastructure has increasingly demanded the requirement for long and deep tunnels. Long and deep tunnels are associated with the risks of elevated stresses and overstressing, that in the extreme scenario, can include rockbursting events which have, and can, result in impacts to worker safety, equipment damage, construction progress and overall total project costs. In situ stresses are often significantly influenced by topography and regional geology and therefore simple assumptions for in situ stresses should not be adopted for planning and design. Long and deep tunnels fully warrant good quality in situ stress measurements as a fundamental planning and design requirement. A review of deep in situ stress measurements has been performed based on both historical and recent in situ stress measurements from a series of deep tunnel projects that highlights the importance to rather consider the ratio of the maximum in situ stress to the minimum in situ stress, and not average stresses, for planning and design.
