Prediction of tunnel behavior in time-dependent soft rock using displacement measurements of borehole

Two-dimensional theoretical solution using visco-elastic type constitutive model for the support design of a tunnel with time-dependent characteristics, which takes progression of the tunnel face into account, is derived. In order to predict the tunnel behavior with time-dependent characteristics and determine the mechanical-constants representing the time-dependent behavior, a method using the time-dependent displacement measurements of borehole wall is proposed, and a developed instrument to measure the displacement of a borehole drilled from tunnel face or sidewall is presented. A comparison between theoretical solution and field measurements shows the applicability of proposed method to the tunnel design.