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Abstract The mechanical behaviors of transverse evacuating passage for river-crossing double-line shield tunnels are analyzed with a three-dimensional explicit finite-difference program. Considering the interaction of surrounding rock，water pressure and tunnel lining，the calculating model was constructed based on the case of the shallowest overburden depth and the largest water pressure. Using this calculating model，the change rules of structure stress due to different passage widths and different differential settlements between two main tunnels are analyzed. The analytical results show that the stress concentration of intersecting interface between the passage and the main tunnels is obvious，which is influenced by passage width slightly. Passage width influences stress of the middle part of passage significantly，displaying linear relationship. The differential settlement has negative effects on the structural behaviors，and the stress of intersection interface is influenced by differential settlement severely. When differential settlement reaches to 10.3 mm，the stress of intersection interface becomes the largest one for the whole structure，and the interfaces become the weakest areas in both structure stress and waterproof functions. When differential settlement further increases，the stress of intersection interfaces increases in exponential form，which shows great divergent trend. The analytical conclusion provides an important mechanical demonstration for the scheme decision of the planed Nanjing Yangtze River double-line shield tunnels.
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Received: 23 April 2006
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