3D Numerical simulation of adit excavation influence on the main tunnel

This paper investigates an adit excavation influence on the development of the strain at the main tunnel by 3D numerical simulation. For this purpose, a parametric study was conducted through categorizing different rocks and tunnel depths into five squeezing potential groups, and considering four adit intersection angles. According to the results, a formulation is introduced to predict the maximum extra strain of the main tunnel in terms of the tunnel squeezing potential and the intersection angle. The results show that for extreme and very severe squeezing problem (in which the uniaxial rock mass strength to the in-situ stress field ratio is less than 0.20), it is necessary to pay a specific attention to the adit construction process such as the excavation method and the intersection angle meanwhile, for the other cases, these factors are not case, and insignificant treatment can be sufficient

Keywords:

Adit Tunnels , Numerical modelling , Rocks mechanics , squeezing rock