随机地震作用下含减震层隧道结构动力响应研究

Dynamic response study of tunnels with seismic isolation layers under random earthquake excitations

采用改进的谱表示法生成随机地震动,建立设置不同减震层的隧道模型进行动力响应分析,比较典型地震动与随机地震动下隧道倾斜角与直径变形率2个变形指标的变化情况.然后建立变形指标的概率密度演化模型,比较不同工况下减震层对隧道倾斜角概率密度演化过程的影响;选取结构倾斜角限值作为评价标准,并结合累积分布函数曲线分析减震层对隧道抗震可靠性的影响.结果表明:减震层不会改变随机地震动下隧道变形指标的变化趋势,但会降低整体的均值,减震层厚度不变时,弹性模量越大隧道倾斜角降低越多,最多降低7.393%;减震层可以使隧道在随机地震下的变形响应更稳定集中,且厚度不变时,弹性模量越大效果越明显;减震层可以提高隧道在随机地震下的结构可靠度,减震层厚度不变时,弹性模量越大可靠度提升越多,最多提升6.236%.

An updated spectral representation method was utilized to generate random ground motions,and tunnel models incorporating various seismic isolation layers were established for dynamic response analysis.The variations in two deformation indicators,the inclination angle and the diameter deformation rate of the tunnel,under typical seismic motion were compared with those under random seismic motion.By developing a probability density evolution model for the deformation indices,the impact of isolation layers on the probability density evolution process of the tunnel inclination angle was evaluated under various conditions.Structural inclination angle limits were selected as evaluation criteria,and cumulative distribution function curves were employed to assess the influence of different seismic isolation layers on the seismic reliability of the tunnel.The findings indicate that seismic isolation layers do not alter the overall trend of the deformation indices under random ground motion,while they significantly reduce the overall mean values.For a given thickness of the isolation layers,the reduction in the inclination angle becomes more pronounced as the elastic modulus increases,achieving a maximum reduction of 7.393%.Furthermore,seismic isolation layers make the deformation response of tunnels more stable and concentrated under random seismic conditions.With a constant thickness of the isolation layers,the effect becomes more pronounced as the elastic modulus increases.Additionally,the presence of isolation layers improves the structural reliability of tunnels subjected to random seismic motion.When the thickness of the isolation layers keeps constant,the improvement in reliability increases with the increase of elastic modulus values,reaching up to 6.236%.