Bearing Capacity of Strip Footing Over Rectangular Tunnel in Soft Clay

Abstract

AbstractThis research work examines the bearing capacity of strip footing over rectangular tunnel in soft clay. The bearing capacity under undrained condition is being obtained for a various conjunctions of B/D, H/D, cuo/γD and m where D, B and H are height, width and soil cover depth of the tunnel, respectively, cuo is the undrained shear strength of the soil at the ground surface, γ is the unit weight of the soil and m is a dimensionless parameter which depicts the linear variation of undrained shear strength of soil with depth. The analysis is being performed using lower bound limit analysis, finite elements and nonlinear programming. The present results indicate that normalized bearing pressure decreases with a decrease in normalized vertical distance between tunnel and footing and it becomes constant at a critical normalized distance or say critical cover depth of the tunnel. The values of the critical depth depends upon the size of underlying tunnel and m. In case the tunnel is placed above this critical depth, the bearing capacity of footing varies with size and cover depth of tunnel and also on non-homogeneity of undrained clay.KeywordsFootingBearing capacityTunnelLimit analysisNonlinear programming