覆盖层地基上250m级土石坝抗震分析
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摘要
以某250 m级高心墙堆石坝为例,运用三维非线性静动力有限元方法,模拟大坝的施工、蓄水过程,计算分析了坝体及坝基在场地谱人工地震波作用下的动力反应,验算了心墙及反滤料的动强度,采用Seed建议的安全系数法验算了坝基砂层发生液化的可能性.分析结果表明,坝顶部位的心墙及反滤层均存在动强度不足的问题,处理好材料密度、动强度及心墙拱效应的关系是解决该问题的关键.建议挖除坝基覆盖砂层,防止砂层液化,确保大坝安全.
The 3D nonlinear static and dynamic FEM was used for simulating the construction and water impounding processes of a 250 m high core wall earth-rock dam.The dynamic response of the dam body and foundation under the action of artificial seismic waves was analyzed.Furthermore,the dynamic strength of the corewall and filter material was calculated,and the possibility of sand layer liquefaction of dam foundation was verified by Seed's safety coefficient method. The result shows that the dynamic strength is insufficient in some parts of core-wall and filter material,and the rational adjustment of the relationship among the density of materials and the dynamic strength and arch effect of the corewall is the key to solve the above problem.It is suggested that the overburden sand layer should be removed to prevent the sand layer liquefaction and to ensure the safety of the dam.
The 3D nonlinear static and dynamic FEM was used for simulating the construction and water impounding processes of a 250 m high core wall earth-rock dam.The dynamic response of the dam body and foundation under the action of artificial seismic waves was analyzed.Furthermore,the dynamic strength of the corewall and filter material was calculated,and the possibility of sand layer liquefaction of dam foundation was verified by Seed's safety coefficient method. The result shows that the dynamic strength is insufficient in some parts of core-wall and filter material,and the rational adjustment of the relationship among the density of materials and the dynamic strength and arch effect of the corewall is the key to solve the above problem.It is suggested that the overburden sand layer should be removed to prevent the sand layer liquefaction and to ensure the safety of the dam.
引文
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[5]SEED H B.Soil liquefaction and cyclic mobility evaluation for level ground during earthquakes[J].Geotechnical Engineering Division,ASCE,1979,105(2):201-255.
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[2]顾淦臣,束一鸣,沈长松.土石坝工程经验与创新[M].北京:中国电力出版社,2004:6-29.
[3]孙明权,沈长松.水工建筑物[M].北京:中央广播电视大学出版社,2001:111-155
[4]周建,白冰,徐建平.土动力学理论与计算[M].北京:中国建筑工业出版社,2001:22-30.
[5]SEED H B.Soil liquefaction and cyclic mobility evaluation for level ground during earthquakes[J].Geotechnical Engineering Division,ASCE,1979,105(2):201-255.
[6]SEED H B,IDRISS I M.Ground motions soil liquefaction during earthquakes[M].Berkeley AC:Earthquake Engineering Research Institute,1982.
[7]YOUD L,IDRISS I M.Workshop on evaluation of liquefaction resistance of soils[C]//Proceeding of the National Center for EarthquakeEngineering Research.Salt Lake City:Utah,1997.
[8]沈凤生,潘恕,甘宪章.小浪底土石坝三维地震反应分析[J].人民黄河,1995(6):35-39.
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