拱坝地震破坏的模型试验与数值模拟
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摘要
从模型试验和数值模拟两方面研究拱坝在地震作用下的破坏情况。在振动台上进行了高拱坝的动力模型试验,研究空库情况下整体坝的破坏过程和破坏形态。试验中采用仿真混凝土,模拟部分地基和山体。由设计加速度反应谱生成地震加速度时程,在顺河向逐级加载输入。为与模型试验互相验证,文中模拟相似的条件,对拱坝的原型进行非线性有限元分析。在宏观均质假定的基础上考虑混凝土细观分布的非均匀性,得出的破坏过程和破坏形态与模型试验结果一致。证明了模型试验设计和本文数值模型的有效性。研究表明,顶拱中部附近是拱坝抗震设防的关键部位,地震作用下易发生开裂,极端情况下坝块可能脱落,随后其两侧的混凝土相继脱落导致破坏区域扩大,应对该区域进行深入的抗震分析并采取合理的抗震措施。
The failure mode of the Dagangshan arch dam under earthquakes was experimentally studied by a shaking table test and a nonlinear FEM simulation.In the test,simulation concrete was employed to model the dam material,foundation rock and topographic features,and a sequence of streamwise seismic loading of the design acceleration spectrum was generated and gradually added to the dam.Assumption of macroscopic homogeneity is adopted,but mesoscopic inhomogeneity of the concrete material was introduced.The FEM simulation conditions,except for a prototype dam,are the same as the model test.The test results are similar to the FEM analysis,which shows the validity of both methods.It is discovered that under strong earthquakes the region around the cantilever top is vulnerable,and that cracks maybe initiate there,extend further,and even result in the fell-off of concrete blocks.Thus,special seismic measures for this region are suggested.
The failure mode of the Dagangshan arch dam under earthquakes was experimentally studied by a shaking table test and a nonlinear FEM simulation.In the test,simulation concrete was employed to model the dam material,foundation rock and topographic features,and a sequence of streamwise seismic loading of the design acceleration spectrum was generated and gradually added to the dam.Assumption of macroscopic homogeneity is adopted,but mesoscopic inhomogeneity of the concrete material was introduced.The FEM simulation conditions,except for a prototype dam,are the same as the model test.The test results are similar to the FEM analysis,which shows the validity of both methods.It is discovered that under strong earthquakes the region around the cantilever top is vulnerable,and that cracks maybe initiate there,extend further,and even result in the fell-off of concrete blocks.Thus,special seismic measures for this region are suggested.
引文
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[2]朱伯芳.1999年台湾921集集大地震中的水利水电工程[J].水力发电学报,2003,(1):21～33.Zhu Bofang.Damages to hydranlic structures caused by 921 Earthquake of Taiwan in 1999[J].Journal of Hydroelectric Engineering,2003,(1):21～33.(in Chinese)
[3]周晶,林皋,王承伦.双曲拱坝的地震破坏模型试验[J].大连理工大学学报,1992,32(2):218～223.Zhou Jing,Lin Gao,Wang Chenglun.Seismic rupture model test of double curvature arch dam[J].1992,32(2):218～223.(inChinese)
[4]王海波,李德玉,陈厚群.拱坝振动台动力破坏试验研究[J].土木工程学报,2006,39(7):109～118.Wang Haibo,Li Deyu,Chen Houqun.Experimental study on the dynamic failure of arch dmns using a shaking table[J].Journal ofCivil Engineering,2006,39(7):109～118.(in Chinese)
[5]Ghanaat Y.Seismic performance and damage criteria for concrete dams[A].Proc.3rd U.S.-Japan Workshop on Advanced Researchon Earthquake Engineering for Dams[C].California:Sam Diego,2002,22～23.
[6]Wang G L,Pekau O A,Zhang C H,Wang S M.Seismic fracture analysis of concrete gravity dams based on nonlinear fracturemechanics[J].Engineering Fracture Mechanics,2000,65(1):67～87.
[7]Valliappan S,Yazdchi M,Khalili N.Seismic analysis of arch dams——a continuum damage mechanics appmach[J].InternationalJournal of Numerical Methods in Engineering,1999,45:1695～1724.
[8]中国水利水电科学研究院.DL5073-2000水工建筑物抗震设计规范[S].北京:中国电力出版利,2001.IWHR.DL5073-2000 Specifications for seismic design of hydraulic structures[S].Beijing:China Electric Power Press,2001.(inChinese)
[9]唐春安,朱万成.混凝土损伤与断裂-数值试验[M].北京:科学出版社,2003.Tang Chun-an,Zhu Wancheng.Damage and fracture of concrete:numerical test[M].Beijing:Science Press,2003.(in Chinese)
[10]钟红,林皋,李红军.单向恒定侧压下混凝土抗压特性数值模拟[A].隧道、地下工程及岩石破碎理论与应用论文集[C].大连:大连理工大学出版社,2007:320～325.Zhong Hong,Lin Gao,Li Hongjun.Numerical simulation of concrete under compressive loading with constant lateral compression[A].Theory and application of tunneling,underground engineering and rock fragmentation[C].Dalian:Dalian University Press,2007:320～325.(in Chinese)
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