小浪底土石坝抗震设计

The Seismic Design of Earth and Rockfill Dam of Xiaolangdi Project

小浪底土石坝高１５４ｍ，为斜心墙坝，库容１２６．５×１０８ｍ３，坝基覆盖层为夹有砂层的砂卵石，厚一般为３０～４０ｍ，最深达８０ｍ左右，用混凝土防渗墙作坝基渗流控制，并作内铺盖连接斜心墙和围堰斜墙，以便和水库淤积连接作为第二道渗流控制防线，场地基本烈度为Ⅶ度，设防烈度为Ⅷ度，显然，坝基和坝体的抗震问题是该工程的重要问题之一。小浪底大坝坑震设计研究的主要内容有：河床覆盖层与各种坝料的静力和动力参数的试验研究；用经验法、剪应力对比法和有限元动力分析法判别河床覆盖层和坝体反滤层在地震动力作用下，是否会引起孔隙水压力升高，直至高于上覆荷载而产生液化，坝体防渗土料产生大的变形和裂缝，以及堆石体产生大的变形等；研究采用抗震性较好的材料和结构，使坝基和坝体不易产生液化和破坏。

The maximum height of XLD(as abbreviation of Xiaolangdi Project)earth rockfill dam with a sloping impervious core is 154m,creating a reservoir capacity of 126 5×10 8m 3.The dam is founded on alluvial sandy gravels with sand lenses.The seepage of dam foundation is controlled by concrete cutoff and the connection of sloping core,inner blanket,and sloping cofferdam sloping diaphragm.Reservior deposition is designed as a secondary line of seepage prevention.Basic seismic intensity in XLD region is Ⅶ degree,and design intensity of Ⅷ is used.Obviously,the seismic design of the dam foundation and dam body is one of the important subjects.The major contents of seismic design for XLD dam include:test and study of static and dynamic coefficients of riverbed overburden and various dam fill materials by experimentation;shear stress determination by static and dynamic finite element analysis;possibility of liquefaction of the riverbed overburen and dam filter,because of the higher seismic pore pressue.Materials and stuctures with better aseismic function are compared.