Experimental and numerical assessment of surface settlement and stress distribution due to construction of double arched tunnels in layered soils

Abstract To increase the transportation efficiency of modern cities through sustainable developments, double-arched tunnels constructed in soil and rocks are usually used to save space as underground passages to transport goods and passengers. Estimating ground response in terms of stresses generated in earth material and supporting structures is important for preliminary hazard estimation of existing infrastructure due to the construction of double-arched twin tunnels. Assessment of surface settlement during and after these constructions is crucial for the project’s success. The present study investigates the surface settlement response due to the construction of double-arched tunnels through small-scale physical modeling at different stages of excavation. Extensive numerical modeling has also been carried out to investigate the surface settlement and stresses in the surrounding soil medium. The accuracy of the numerical model has been benchmarked, comparing the numerical model results with the physical modeling and testing. Moreover, this study focuses on the investigation of surface settlement and stress in the full-scale metro model. In layered soil profiles, the condition in which soil with a higher value of bulk unit weight (γ) and cohesion (c) present up to the invert level of the tunnel shows maximum settlement and stresses. The results of the present study are useful for surface settlement estimation for the same or similar twin tunnel projects.