Abstract. As the depth of tunnels and underground construction increases, instability occurs in the form of rock bursting or spalling because of the induced stresses.Spall ing may appear as a strong compressi ve stress causing crack growth behind the excavated surface and buckling of the thin rock slabs. In this paper, we describe how to reduce the rock spalling failure to increase the underground safety and the tunnel stability. Thus, a parametric study is implemented using 2-D Elasto plastic finite clements stress analysis software to investigate the parameters that can minimize the extent and depth of the failure zone. The critical section of Pahang Selangor Raw Water Transfer Tunnel under high overburden is analyzed. The effect of the shotcrete lining thickness, tunnel size and the removal of fallouts or scaled v-notch on the failure zone depth is investigated. The results demonstrate that the shotcrete lining thickness has less influence on the failure depth, while a small tunnel diameter minimizes the failure depth. ln addition, the stability of the tunnel improves by removing the loose rock mass.
Evaluation of TBM tunnel with respect to stability agains spalling_Prof Madya Dr. Mohd Ashraf Mohd Ismail