Challenges in Design of Shallow Tunnel in Urban Areas Kumar Rakesh, Kacker Shreeja AF Consult India Pvt. Ltd., Noida, India Online published on 5 October, 2017. Abstract Construction of tunnels under urban area, which is highly populated, is a challenging task due to the shallow depth of construction, existing surface structures, complex geological conditions, ground water conditions and stringent displacement control criteria. The paper presents a parametric study of a shallow D-shaped tunnel of dimensions 7.6m x 7.6m, in an urban area. This tunnel passes through a complex stratigraphy in the presence of a water table, just 2m below the ground level. In this paper, a likely solution has been suggested for the efficient construction of this tunnel. The stress-deformation analysis of the tunnel has been carried out using Finite Element Programme PHASE2, as a continuum model using Mohr-Coulomb yield criteria. The stresses and deformations around the tunnel are estimated to check the stability of the tunnel. The five cases of the analyses are studied and presented in this paper for arriving at the optimal support system. The five cases analysed are: Case 1-Analysis without support system, without pipe roofing and without water table, Case 2-Analysis without support system, without pipe roofing but with water table, Case 3-Analysis without support system but with pipe roofing and water table, Case 4-Analysis with support system, pipe roofing and water table and Case 5-Analysis with support system, pipe roofing, water table and seismic loading for understanding the tunnel behaviour under various loading conditions. Based on this study, the optimised support system has been proposed for the tunnel. Top |