The effect of soil layers stiffness on the stress pattern in the presence of water transmission tunnels with concrete lining

In this paper, by using numerical method of half-plane boundary element which was previously proposed by the authors for single layer soil was applied for modeling embedded lined water transmission tunnels in the layered-soil medium. In the use of this method, only the boundary of lining and interfaces were required to be discretized. In addition to present the formulation of the mentioned method and verify the results in comparison of the literature, the behavior of a pressure tunnel embedded in two-layer soil was studied. In this regard, the effect of soil layers properties including Poisson ratio and elasticity modulus was investigated to obtain the stress distribution on the ground surface as well as around the tunnel. The results showed that half-plane boundary element method was a simple approach with high accuracy for modeling lined tunnel embedded in the layered soils. Use of this method was recommended for analyzing underground structures and presenting stress patterns in order to correct the existing codes.