Investigation of Factor of Safety in Squeezing Ground
This paper calculates factor of safety based not only on strength reduction, but also on increasing in-situ stress. It is shown that using strength reduction only, over estimates factor of safety for problems at depth where confining stress is a significant issue. Factor of safety is calculated for a tunnel in squeezing ground. Tunnel convergence and radius of plastic zone are used as the stability indicators. Furthermore, the application of factoring stress and strength in conservative design of support system is investigated.