Stochastic response of underground structures

Abstract

This investigation uses a linear elastic finite-element method to analyse the stochastic dynamic response of the Bolu tunnel in Turkey when subjected to spatially varying earthquake ground motion. The research conducts a parametric study to discover the critical magnitude of earthquake ground motion that causes tensile cracking in the reinforced concrete tunnel lining. The Drucker-Prager yield criterion determines the forces that cause cracking of reinforced elements of three cross-sections of the tunnel system subjected to spatially varying seismic ground motion. The study applies spatially varying ground-motion models, wave passage, incoherence and site response as well as the uniform ground-motion model to three cross-sections of the tunnel-soil deposit interaction system. The purpose is to determine the stochastic seismic behaviour of the tunnel. Of particular emphasis is the importance of the site response effect that arises from the difference in the local soil conditions at the different support points of the tunnel-soil deposit interaction system. The results of the analyses demonstrate that the number of cracked elements increases as the amplitude of earthquake ground motion increases. In addition, the means of the maximum values obtained from the spatially varying ground-motion case are compared with those of specialised earthquake ground-motion models. The result is proof that variations in local soil conditions have important effects on the stochastic response of tunnels.