Abstract
When tunnels are excavated in squeezing rock masses, the surrounding rock masses of tunnels sometimes exhibit large deformations to break tunnel supports. This paper presents an analytical method to predict the deformational behavior and evaluate the development of plastic zone, which be considered as the main cause of squeezing phenomenon.The method is based on the assumptions that the ground around tunnel behaves as an elastoplastic dilatant material and exhibits strain-softening behavior.With regard to the support design of squeezing rock tunnels, a method for estimating the optimum support pressure is proposed.Finally, the proposed standard judgment is applied to an actual tunnel to proof its validity.
