DESIGN, OPTIMIZATION AND COMPARISON OF SINGLE AND TWIN TUNNEL AT SANGA PASS

Abstract

Nepal, being a mountainous and landlocked country, the construction of road tunnels is feasible for the context of Nepal. Due to the increasing traffic flow in the Araniko Highway, construction of tunnel is required for the accommodation of the traffic flow and to avoid steep and vulnerable areas with respect to stability of slopes at Sanga Pass. Considering these requirements and facts, and the matter of our interest, we undertook the project on “DESIGN, OPTIMIZATION AND COMPARISON OF SINGLE AND TWIN TUNNEL AT SANGA PASS”. The main aim of this project is to study and design the roadway through the tunnel. The report focuses on the design criteria of the road tunnel, determination of the alignment for tunnel based on geological conditions, cross-section and length of the tunnel, support system design and analysis, and comparison of different parameters (stress, displacement) between twin and single tunnel. Existing empirical relations was used and numerical modelling was done for estimation of stresses generated and support system to be applied. A detailed numerical study was carried out in 2D finite element analysis to design the tunnel in such region. Detailed analysis showed the deformation as well as displacement of tunnel. Support system to be applied in the tunnel was determined using empirical as well as numerical modelling. Support was optimized using 2D finite element numerical modelling.