紫坪铺大坝是世界上第一个遭受强震的百米以上面板堆石坝,在"5.12"汶川地震中有明显的局部损伤。采用有限元数据平滑方法,对大坝位移监测数据进行处理,得到了坝体典型剖面的永久应变。分析了大坝在地震中沉降和堆石料剪胀变形发生的部位和原因,表明坝体最大震陷率发生在2/3坝高附近;大坝发生剪胀的范围为坝顶区域和从坝顶往下25~30 m的上下游坝坡附近;永久剪应变过大是造成面板水平施工缝错台的直接原因。
Zipingpu Concrete-Faced Rockfill Dam,which was subjected to significant local damage during "5.12" Wenchuan Earthquake,which is the first concrete-faced rockfill dam of more than one hundred meters in height encountering strong earthquake in the world.Based on the finite element data smoothing method,the permanent strain at a typical cross-section of the dam is obtained by processing the monitored displacement data.The positions of the dam settlement and rockfill dilatancy and the causes are analyzed according to the section permanent strain.The results show that the maximum settlement ratio of the dam approximately occurs at 2/3 of the dam height.The dilatancy occurs from the dam crest to 25~30 m in the upstream and downstream slope.The excessive permanent shear strain during the earthquake is the immediate cause for dislocation of the horizontal construction joints in the face slabs.