碧口心墙堆石坝抗震复核分析
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摘要
经历"5.12"汶川大地震后,碧口心墙堆石坝出现不同程度的震损现象。根据汶川地震自由场峰值加速度随断层距的衰减关系,利用距坝址较近的文县地震台站(062WIX)实测记录,推求碧口水电站坝址岩基输入加速度时程。通过类比相关工程室内大型动三轴试验资料,结合筑坝材料的工程特性,确定大坝填料的动力模型参数。基于三维动力有限元分析TSDA程序,计算得到的大坝震后永久变形、心墙动孔隙水压力与实测资料较为接近;大坝的绝对加速度反应不大,最大放大倍数仅为2.36倍,坝基防渗墙的动力反应也较小。由于坝址区位于汶川地震发震断层的上盘,虽然地震持续时间较长,但地震波的高频分量发育,大坝的动力反应小于依据《水工建筑物抗震设计规范》设计反应谱合成规范波的对应值。研究结果表明,采用现代重型振动碾压技术填筑的碧口心墙堆石坝具有良好的抗震性能,现阶段土石坝抗震计算理论与方法基本合理。
Some damage phenomena appear in Bikou earth core dam after "5.12" Wenchuan earthquake.With the bedrock motions at Wenxian seismic station(062WIX),the input acceleration time-history is obtained from the relationship of free-field peak ground acceleration(PGA) and fault distance in Wenchuan earthquake.The dynamic parameters of dam soils are determined by comparing with the information of large-scaled laboratory triaxial experiments of other projects based on their physical and mechanical characteristics.Based on TSDA program for three-dimensional finite element dynamic analysis,the permanent deformation and the pore water pressure of core dam are close to the recorded data;the maximum acceleration along the dam axis is scaled up in amplitude only by a factor of 2.36 at the dam crest,and the dynamic response of cut-off walls is also weak.Because Bikou dam is located on the hanging wall of fault,and high-frequency componet of the bedrock motions had developed,although the earthquake lasted much longer,the dynamic response is weaker than that under the standard seismic waves synthesized by design response spectrum according to "Specifications for seismic design of hydraulic structures".From the results of seismic review,it could be found that the core dam built by the modern technology of heavy vibration has good seismic behavior;and the current seismic theories and methods for earth dam are basically feasible.
Some damage phenomena appear in Bikou earth core dam after "5.12" Wenchuan earthquake.With the bedrock motions at Wenxian seismic station(062WIX),the input acceleration time-history is obtained from the relationship of free-field peak ground acceleration(PGA) and fault distance in Wenchuan earthquake.The dynamic parameters of dam soils are determined by comparing with the information of large-scaled laboratory triaxial experiments of other projects based on their physical and mechanical characteristics.Based on TSDA program for three-dimensional finite element dynamic analysis,the permanent deformation and the pore water pressure of core dam are close to the recorded data;the maximum acceleration along the dam axis is scaled up in amplitude only by a factor of 2.36 at the dam crest,and the dynamic response of cut-off walls is also weak.Because Bikou dam is located on the hanging wall of fault,and high-frequency componet of the bedrock motions had developed,although the earthquake lasted much longer,the dynamic response is weaker than that under the standard seismic waves synthesized by design response spectrum according to "Specifications for seismic design of hydraulic structures".From the results of seismic review,it could be found that the core dam built by the modern technology of heavy vibration has good seismic behavior;and the current seismic theories and methods for earth dam are basically feasible.
引文
[1]中国水电工程顾问集团西北勘测设计研究院.白龙江碧口水电站工程“5.12”汶川地震震损调查及初步分析报告[R].西安:中国水电工程顾问集团西北勘测设计研究院,2008.(HydroChina Xibei Engineering Corporation.Damage investigation and preliminary analysis report of Bikou station on Bailong River during“5.12”Wenchuan earthquake[R].Xi′an:HydroChina Xibei Engineering Corporation,2008.(in Chinese))
[2]周建平,杨泽艳,范俊喜,等.汶川地震灾区大中型水电工程震损调查及主要成果[J].水力发电,2009,35(5):1-6.(ZHOU Jianping,YANG Zeyan,FAN Junxi,et al.Seismic damage investigation on large and medium sized hydropower projects in Wenchuan earthquake area[J].Water Power,2009,35(5):1-6.(in Chinese))
[3]林鹏,王仁坤,李庆斌,等.汶川8.0级地震对典型高坝结构安全的影响分析[J].岩石力学与工程学报,2009,28(6):1 261-1 268.(LIN Peng,WANG Renkun,LI Qingbin,et al.Effect analysis of structural safety of typical large dams in Wenchuan 8.0 earthquake[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(6):1 261-1 268.(in Chinese))
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[8]朱晟,周建波.粗粒筑坝材料的动力变形特性[J].岩土力学,2010,31(5):1 375-1 380.(ZHU Sheng,ZHOU Jianbo.Deformation behaviour of coarse grained materials under cyclic loading[J].Rock and Soil Mechanics,2010,31(5):1 375-1 380.(in Chinese))
[9]LEE K L,CHAN K.Number of equivalent significant cycles in strong motion earthquakes[C]//Proceedings of International Conference on Microzonation for Safer Construction Research and Application.[S.l.]:[s.n.],1972:609-627.
[2]周建平,杨泽艳,范俊喜,等.汶川地震灾区大中型水电工程震损调查及主要成果[J].水力发电,2009,35(5):1-6.(ZHOU Jianping,YANG Zeyan,FAN Junxi,et al.Seismic damage investigation on large and medium sized hydropower projects in Wenchuan earthquake area[J].Water Power,2009,35(5):1-6.(in Chinese))
[3]林鹏,王仁坤,李庆斌,等.汶川8.0级地震对典型高坝结构安全的影响分析[J].岩石力学与工程学报,2009,28(6):1 261-1 268.(LIN Peng,WANG Renkun,LI Qingbin,et al.Effect analysis of structural safety of typical large dams in Wenchuan 8.0 earthquake[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(6):1 261-1 268.(in Chinese))
[4]顾淦臣.土石坝地震工程[M].南京:河海大学出版社,1989.(GU Ganchen.Earthquake engineering for earth-rock dams[M].Nanjing:Hohai University Press,1989.(in Chinese))
[5]NEWMARK N M.Effects of earthquakes on dams and embankments[J].Geotechnique,1965,15(2):139-160.
[6]于海英,王栋,杨永强,等.汶川8.0级地震强震动加速度记录的初步分析[J].地震工程与工程振动,2009,29(1):1-13.(YU Haiying,WANG Dong,YANG Yongqiang,et al.The preliminary analysis of strong ground motion records from the Ms 8.0 Wenchuan earthquake[J].Journal of Earthquake Engineering and Engineering Vibration,2009,29(1):1-13.(in Chinese))
[7]潘如意.碧口心墙堆石坝震害复核分析[硕士学位论文][D].南京:河海大学,2009.(PAN Ruyi.Analysis of the recheck of the earthquake damage of Bikou core rockfill dam[M.S.Thesis][D].Nanjing:Hohai University,2009.(in Chinese))
[8]朱晟,周建波.粗粒筑坝材料的动力变形特性[J].岩土力学,2010,31(5):1 375-1 380.(ZHU Sheng,ZHOU Jianbo.Deformation behaviour of coarse grained materials under cyclic loading[J].Rock and Soil Mechanics,2010,31(5):1 375-1 380.(in Chinese))
[9]LEE K L,CHAN K.Number of equivalent significant cycles in strong motion earthquakes[C]//Proceedings of International Conference on Microzonation for Safer Construction Research and Application.[S.l.]:[s.n.],1972:609-627.
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