ABSTRACT
The trend in tunnel design in Australia is to specify a 100 year design life for permanent support. Often that support is provided by rock bolts and shotcrete. Experience with concrete in compression extends back to Roman times but experience with the longevity of elements in tension is limited. For example, the British Standard BS8081 (Code of Practice for Ground Anchorages) has been available to guide the design of permanent rock bolts since the early 1990s.
