Prediction of settlement trough induced by tunneling in cohesive ground

Abstract

Surface settlements of soil due to tunneling are caused by stress relief and subsidence due to movement of support by excavation. There are significant discrepancies between empirical solutions to predict surface settlement trough because of different interpretations and database collection by different authors. In this paper, the shape of settlement trough caused by tunneling in cohesive ground is investigated by different approaches, namely analytical solutions, empirical solutions, and numerical solutions by the finite element method. The width of settlement trough was obtained by the finite element method through establishing the change in the slope of the computed settlement profile. The finite element elastic-plastic analysis gives better predictions than the linear elastic model with satisfactory estimate for the displacement magnitude and slightly overestimated width of the surface settlement trough. The finite element method overpredicted the settlement trough width i compared with the results of Peck for soft and stiff clay, but there is an excellent agreement with Rankin’s estimation. The results show that there is a good agreement between the complex variable analysis for Z/D = 1.5, while using Z/D = 2 and 3, the curve diverges in the region faraway from the center of the tunnel.