基于震害调查的土石坝震陷规律和关键影响因素分析

Analysis of earthquake subsidence and key influencing factors of earth-rock dam based on seismic damage investigation

基于国内外典型地震中155个土石坝地震震害调查样本数据,分析了土石坝震陷规律,并基于灰色关联度分析法对土石坝地震关键影响因素进行了研究。结果表明:震陷率上包线随地震动峰值加速度和震级的增大而增大,随震中距的增大而减小,近场范围内震陷率较大,震中距达到100~150 km时,震陷率已很小;土坝的震陷率上包线值最大,其次是心墙堆石坝,面板堆石坝最小;修建时间越早,震陷率上包线值越大,反映出施工设备和筑坝施工方式的演变所带来的大坝填筑质量的差异;地震动峰值加速度、震级、坝型、修建年份、震中距5项因素对震陷率的影响依次减小,但不存在绝对主导因素。依据震陷规律和关键影响因素分析结果,结合水工抗震规范对土石坝地震残余变形预测和控制进行了讨论,给出了土石坝抗震安全变形控制标准及设计原则,可为土石坝抗震设计、地震残余变形预测和控制提供指导。

Based on seismic damage survey data from 155 earth-rock dams in typical earthquakes worldwide,we analyzed the earthquake subsidence pattern of earth-rock dams and investigated key influencing factors using grey relational analysis.The results show that the upper envelope of earthquake subsidence rate increases with the increase of peak ground acceleration and earthquake magnitude,and decreases with the increase of epicenter distance.The subsidence rate is higher in the near-field range,and becomes minimal at an epicenter distance of 100–150 km.The maximum upper envelope value of earthquake subsidence rate is observed in filled earth dams,followed by core rockfill dams and face rockfill dams.The earlier the construction time,the higher the upper envelope value of earthquake subsidence rate,which reflects the differences in dam filling quality due to varying construction equipment and methods.The effects of peak acceleration,magnitude,dam type,construction year and epicenter distance on the subsidence rate decrease successively,with no single factor being absolute dominant.The prediction and control of seismic residual deformation of earth-rock dam are discussed according to the earthquake subsidence patterns and the analysis results of key influencing factors,in conjunction with the seismic code of hydraulic engineering.Control standards and design principles for seismic safety deformation of earth-rock dam are provided.