可液化场地下盾构扩挖地铁车站结构地震破坏机制振动台试验  

Shaking table experiments on seismic response of a shield-enlarge-dig type subway station structure in liquefiable ground

作　　者：安军海[1,2] 陶连金[1,2] 王焕杰[1,2] 李积栋[3] 

机构地区：[1]北京工业大学城市与工程安全减灾省部共建教育部重点实验室,北京100124 [2]北京城市交通协同创新中心,北京100124 [3]中国建筑工程总公司技术中心,北京101300

出　　处：《岩石力学与工程学报》2017年第8期2018-2030,共13页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(41572276;41272337);北京市教育委员会科技计划重点项目(KZ200910005009)~~

摘　　要：开展近远场水平地震动作用下可液化地层中盾构扩挖地铁车站结构振动台试验,分析模型地基土层的侧向变形、孔压比、加速度、宏观现象和动土压力以及结构的加速度、应变等物理量。研究结果表明,可液化模型地基在激振时经历先震密而后上浮的物理过程,震后有明显的喷砂冒水现象;地基土层侧向发生的是剪切型变形,其左摆与右摆过程中的峰值位移出现明显的不对称现象;小震时,模型地基中的加速度放大系数从下部到表层逐渐增大,中震及大震时,表现出先减小后增大的趋势;地震波沿模型地基向上传播的过程中,出现明显的高频滤波、低频放大的现象;可液化地基的孔压在地震作用下经历"急增长、慢消散"的变化过程;地下结构的存在对其周围地基孔隙水压力的增长(砂土液化)有明显的抑制作用。随着输入地震动强度的增加,动土压力明显增大,地下结构上、下方的土压力差值是结构发生液化上浮的内因,结构本身在强震过程中逐渐从弹性状态向弹塑性转化;液化场地条件下的结构侧方动土压力有随着埋置深度的增加而增加的趋势;可液化场地条件下盾构扩挖地铁车站结构的地震破坏机制是:中柱率先发生剪压破坏,而后是隧道开口部位与拱肩破坏,随后是侧墙与顶板的连接部位受拉破坏,最终形成机构而发生倒塌。A shaking table experiment was conducted on a shield-enlarge-dig type structure in liquefiable ground subjected to the near and far field earthquakes respectively. The lateral deformation, the pore pressure ratio, the earth pressure of soil foundation, the accelerations of soil and structure and the strains of structure of subway station were analyzed. The results showed that liquefiable foundation experienced two physical process in earthquake, the loose sand compacted firstly and then moved upwardly. There were phenomena of sand erupting and water oozing in large area after the high intensity earthquake. The shear deformation occurred in the lateral side of the soil and the peak displacements swing left and right asymmetrically. The acceleration amplification factor of soil foundation increased gradually from the bottom to the surface when the small earthquake（peak acceleration was 0.1 g and 0.2 g） was input while it showed an increasing trend when a moderate or strong earthquake was input from the shaking table. A notable phenomenon of high frequency filtering and low frequency amplification appeared in the process of seismic wave propagation from the bottom to the surface of soil. The pore water pressure experienced mainly two stages, the pore water pressure increased slowly at first, rose sharply then at the second stage. The existence of the underground structure has an inhibitory effect on the growth of the pore water pressure of foundation. The earth pressure increased and the structure itself in the elastic state entered into the plastic state gradually with the increase of input vibration intensity. The difference between the upper and lower ground pressures of the underground structure was the intrinsic factor that caused the model structure to generate an upward movement. The earthquake damage of the underground subway station of shield-enlarge-dig type in liquefiable ground experienced three stages： firstly, a shear failure occurred on the column and a damage on the opening position and spandre

关 键 词：隧道工程 可液化场地 振动台试验 震害机制 盾构法地铁车站 石膏模型 

分 类 号：U45[建筑科学—桥梁与隧道工程]