拱坝-无限地基系统非线性地震超载分析
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摘要
汶川地震的经验表明,高拱坝可能遭受远超其设计烈度的强地震作用.研究拱坝的地震损伤破坏情况,探究其地震超载潜力,对于防止发生严重的地震灾变具有重要意义.在拱坝的动力分析中,采用宏观均质假定基础上考虑混凝土细观非均匀性影响的地震损伤破坏模型,以及基于阻尼溶剂抽取法的拱坝-地基动力相互作用模型以考虑无限地基辐射阻尼的影响,研究了拱坝在不同地震超载水平下的损伤破坏情况.结果表明,算例采用的拱坝在1倍和2倍设计地震动作用下损伤程度很轻;在3倍地震动作用下出现较多微裂纹,但并未聚集贯通形成宏观裂缝,从而保持了坝体的整体性和蓄水功能.由于在3倍设计地震动以内非线性程度都不严重,应力分布和坝顶加速度时程都表现出一致的趋势和形态.总的来说,该坝具有良好的地震超载能力.
As shown by the experience obtained from Wenchuan Earthquake,high arch dams are likely to experience ground motion much stronger than their design value.So it becomes extremely important for avoiding serious earthquake disasters to investigate the damage of arch dams subjected to earthquakes and examine their seismic overloading capacity.The damage of an arch dam subjected to earthquakes of different intensities is studied.The damage model for dynamic analysis of arch dams which incorporates the heterogeneity of concrete is employed.The radiation damping of unbounded media is also considered using the arch dam-foundation interaction model based on damping solvent extraction method.According to numerical simulation,the investigated dam only suffers negligible damage when subjected to design earthquake and twice the design earthquake.While for the case of three times the design earthquake,many microcracks occur,but are generally scattered and don′t form macrocracks,so the integrity and water-pounding function of the dam are retained.Since the degree of nonlinearity is not high within three times the design earthquake,the distribution of response of the dam is similar for different levels of earthquake intensity.In a word,this dam has remarkable seismic overloading capacity.
As shown by the experience obtained from Wenchuan Earthquake,high arch dams are likely to experience ground motion much stronger than their design value.So it becomes extremely important for avoiding serious earthquake disasters to investigate the damage of arch dams subjected to earthquakes and examine their seismic overloading capacity.The damage of an arch dam subjected to earthquakes of different intensities is studied.The damage model for dynamic analysis of arch dams which incorporates the heterogeneity of concrete is employed.The radiation damping of unbounded media is also considered using the arch dam-foundation interaction model based on damping solvent extraction method.According to numerical simulation,the investigated dam only suffers negligible damage when subjected to design earthquake and twice the design earthquake.While for the case of three times the design earthquake,many microcracks occur,but are generally scattered and don′t form macrocracks,so the integrity and water-pounding function of the dam are retained.Since the degree of nonlinearity is not high within three times the design earthquake,the distribution of response of the dam is similar for different levels of earthquake intensity.In a word,this dam has remarkable seismic overloading capacity.
引文
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[2]WOLF J P,SONG C.Finite-Element Modeling ofUnbounded Media[M].New York:John Wiley&Sons,1997
[3]李建波,陈健云,林皋.求解非均匀无限地基相互作用力的有限元时域阻尼抽取法[J].岩土工程学报,2004,26(2):264-267
[4]钟红,林皋,李建波.空间结构-地基动力相互作用数值分析的时域算法研究[J].大连理工大学学报,2007,47(1):78-84(ZHONG Hong,LIN Gao,LI Jian-bo.Numericalanalysis of soil-structure dynamic interaction for 3-Dproblems in time domain[J].Journal of DalianUniversity of Technology,2007,47(1):78-84)
[5]周元德.混凝土非线性断裂模型与高拱坝开裂分析研究[D].北京:清华大学,2004
[6]VALLIAPPAN S,YAZDCHI M,KHALILI N.Seismic analysis of arch dams—a continuum damagemechanics approach[J].International Journal ofNumerical Methods in Engineering,1999,45:1695-1724
[7]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
[8]马怀发,陈厚群,黎保琨.混凝土试件细观结构的数值模拟[J].水利学报,2004(10):29-37
[9]唐欣薇,张楚汉.基于改进随机骨料模型的混凝土细观断裂模拟[J].清华大学学报,2008,48(3):348-351
[10]钟红,林皋,李建波,等.高拱坝地震损伤破坏的数值模拟[J].水利学报,2008,39(7):848-853
[11]梁正召.三维条件下的岩石破裂过程分析及其数值试验方法研究[D].沈阳:东北大学,2005
[12]钟红,林皋,陈健云.一种用于有限元疏密过渡的新型十三节点单元[J].哈尔滨工业大学学报,2009,41(4):219-221
[13]钟红.高拱坝地震损伤破坏的大型数值模拟[D].大连:大连理工大学,2008
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