Numerical study on rock failure around a tunnel destressed by a conceptualized notched technique

Abstract

A destressing method for reducing the strainburst risk in burst-prone grounds is suggested. In this method, the rock is destressed by cutting notches at the excavation boundary. First, the concept of the proposed method is described both analytically and numerically. Then, the method is applied to a tunneling problem. Several numerical models are built to study the destressing process and the failure mechanism around a circular tunnel. Results show that when the notch is added to the model, the rock at the tunnel wall is destressed, and the stress concentration zones shift to a farther distance away from the wall. Also, the analysis of the failure zone around the tunnel and the velocity of the failed elements show that the failure in the notched tunnel is less violent compared to that in the tunnel without the notch. Finally, a parametric study is conducted to investigate the influences of the notch dimensions on the stress distribution, deformation, and failures around the tunnel.

Keywords

• Strainburst
• Destressing
• Deep excavation
• Notched tunnel
• Rock violent failure