Stability of strip footings above concrete-lined soft ground tunnels: Fid-Bau Portal

Stability of strip footings above concrete-lined soft ground tunnels

Jao, M. / Wang, M.C.

There are cases that footings are underlain by shallow tunnels. The presence of underground tunnels may adversely affect the stability of the overlying footings. Presently, there is no widely accepted analysis or design methodology available to ensure the stability of such footing-soft ground tunnel systems. As a step toward the development of such a methodology, this study was undertaken to investigate the effect of underground tunnel on the bearing capacity of strip footings. In this study, a two-dimensional plane-strain elasto-plastic finite element computer program was used for analysis. Using this computer program, the stability of strip footings was analyzed for a wide range of soil type and tunnel conditions, including tunnel size, tunnel location, and lining thickness. Based on the results of analysis, the mechanistic behavior of the footing-tunnel system was evaluated. Furthermore, bearing capacity equations for strip footings above concrete-lined soft ground tunnels were formulated. The developed equations are shown to be capable of predicting the bearing capacity of footings located above concrete-lined tunnels reasonably well.