可液化土阻尼系数对地铁结构地震响应的影响

Influence of Rayleigh damping coefficient on seismic response of subway structure in liquefiable soil

针对Rayleigh阻尼系数的影响因素,分析了目标阻尼比和敏感频率范围选择对地下结构地震下的孔隙水压力、上浮量和结构内力的影响。结果表明,目标阻尼比影响地铁车站的变形形态,且其值越大,土体的超孔隙水压力发展越慢,地铁结构的上浮量和内力增量越小;上限敏感频率的影响存在着阈值,超过阈值,超孔隙水压力、地铁结构上浮量和内力增量的变化基本不受影响。综合分析表明,可液化土中地铁结构动力分析应结合场地和输入震动的特性,充分考虑Rayleigh阻尼的影响因素,合理地引入粘性阻尼。

Considering the influencing factors of the damping coefficient,the influence of the selection of the target damping ratio and the sensitive frequency range on the pore water pressure,the amount of buoyancy and the internal force of the underground structure under seismic loads is analyzed. The results show that the larger the target damping ratio,the slower the increase of the excess pore water pressure of the soil,and the smaller the floating and the internal force increment of subway structure. There is a threshold for the influence of the upper sensitive frequency.When the effect range exceeds the threshold,the excess pore water pressure,the floating and the internal force of the structure are basically unaffected.The analysis shows that the influence factors of Rayleigh damping should be fully considered and the damping coefficient should be determined reasonably in the analysis of liquefaction dynamic of subway structure.