武都碾压混凝土重力坝抗震分析与安全评价

Seismic Analysis and Safety Evaluation of Wudu RCC Gravity Dam

武都水库是四川省江油市境内的涪江干流上的大(1)型水利工程。汶川8级地震中,武都水库工程紧邻震中区附近,并正处于施工高峰期,大地震对武都水库工程已建和在建的40多个项目均有不同程度的损坏。分别采用水工建筑物抗震设计规范给定的地震动参数值和地震后复核确定的地震动参数值,对武都大坝进行抗震分析与安全性评价。计算表明,当设计设防加速度256cm/s2时,按规范规定的悬臂梁法进行抗震计算时,均满足现行抗震规范的要求。按平面有限元计算时局部拉应力超出规范的允许值,建议挡水坝段下游坝面折坡附近以及溢流坝段在导墙与边墩交接处附近提高混凝土的强度等级。鉴于坝踵、坝址部位局部范围内仍有较大水平的拉应力,建议自建基面的一定高度内应确保混凝土的浇筑质量,以确保大坝的抗震强度安全。

Wudu water diversion project is a large scale backbone hydraulic project in north-western Sichuan.In the course of construction,Wenchuan Earthquake caused damage to different degrees to over 40 structures completed or under construction.Seismic analysis and safety evaluation was carried out by using ground motion parameters given by re-evaluation.Results indicated that these typical dam blocks can meet the seismic design requirements when subject to action with fortification acceleration 2.56 m/s2 if the one-dimensional cantilever method suggested by the Chinese standards is adopted,while plane finite element method showed that limits of tensile stress may be exceeded in some local areas.These cases show that these areas,especially the dam crest,are the weakest points in seismic action and special attention should be paid to them during design.So it is suggested to increase the strength grade of concrete adjacent to the changing point of the downstream surface in slope as well as the juncture of the guiding wall and side wall of the overflow section.