Modeling dynamic responses of a cross-river road shield tunnel under stochastic vehicle loads

Vehicle-induced dynamic loads are far more complex than those induced by trains because of their stochastic nature. In this study, we developed the stochastic dynamic vehicle load model and addressed a series of loading scenarios for a large road shield tunnel across the Yangtze River of China. The range analysis results show that, given the three factors influencing the dynamic responses of the tunnel, the pavement roughness plays a more important role than the vehicle type and running speed. The finite element model analysis shows that stress concentration occurs around the corbels fixed to the tunnel haunches; the stress amplitude of the soil responses, ranked in the descending order, is at the tunnel sides, under the tunnel bottom and above the tunnel, respectively. Under the stochastic vehicle loads, the amplitudes of the displacement of the road shield tunnel and the maximal settlement of the surrounding soils are basically one-tenth of those of the subway tunnel; the surrounding soil stress amplitude of the road shield tunnel is about one-third of that of the subway shield tunnel; while the structural stress amplitude of the road shield tunnel, focused around the corbels, are about 4 times of that of the subway shield tunnel. Those insights can be referred by the practitioners, especially those of the cross-river combined road-and-subway shield tunnels.