DEM simulation of two main influence factors on stress release in tunnel excavation in noncohesive granular material

摘要

DEM method was used to simulate three different shapes of tunnel and four kinds of cover depth of circular tunnel in noncohesive granular material. It is shown that stress release at different locations around a tunnel may vary substantially, which is inconsistent with the calculation assumption in engineering practice based on continuum mechanics that the stress release coefficient is the same at the excavation boundary. Stress release is much different in the three shapes of tunnel even with a similar initial stress distribution. Besides, the stress release in a deep tunnel is much lower than that in a shallow one. It is thought that stress release has a certain correlation with the mobilization of internal frictional resistance of soil.