穿越土-岩变化地层盾构隧道地震响应分析

When a tunnel passes through soil-rock strata, it is the key controlling link for the seismic design of the structure. In order to explore the aseismic safety of a shield tunnel passing through strata with varying stiffness, taking a shield tunnel project in Nanjing as the background, a 3D finite element model of shield tunnel-strata is established considering the characteristics of soil-rock varying strata. Then, the dynamic time history analysis method is adopted to study the seismic response law of the shield tunnel passing through soil-rock strata. The results show that the acceleration and displacement responses of strata and tunnel are significantly different in soil-rock interface section, soil section and rock section under the same buried depth condition; as for the seismic wave, the spectrum amplification effect of the tunnel and the strata in the soil-rock interface presents much more the spectrum characteristics in harder rock stratum; when the ground motion is input parallel to the tunnel axis, the peak values of internal force and deformation response in the shield tunnel structure occur at the soil-rock interface, the abrupt change of stratum stiffness leads to significant amplification of seismic response of the tunnel structure passing through the stratum, which should be specially paid attention to in the seismic design.