地震作用下混凝土重力坝破坏过程与破坏形态数值仿真
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摘要
在考虑混凝土材料细观非均匀性影响的基础上,探讨了在材料参数和地震动等不确定性因素影响下混凝土重力坝的破坏过程和破坏形态。通过对金安桥混凝土重力坝的180个样本的非线性数值模拟统计分析,得到了不同水平地震作用下的大坝损伤破坏情况,并提炼出4种典型的破坏形态。计算结果表明随着地震动的增大,大坝损伤总体上趋于严重,但也存在高地震动水平下轻微损伤的情况。典型的破坏形态除了坝头折断、坝踵开裂以外,还发现了下游面起裂、贯穿至上游的情况,且随着地震峰值加速度的增大而越发明显。这对于全面了解重力坝地震损伤的薄弱环节,优化抗震措施提高大坝抗震能力是十分有意义的。
The damage process and failure modes of concrete gravity dams affected by uncertain material properties and ground motion input are studied by numerical simulation.Based on 180 samples of nonlinear time-history analysis of the Jin'anqiao RCC Gravity Dam with the influences of concrete heterogeneity taken into account,the damage states of the dam subjected to different levels of ground motion are obtained,from which four typical failure modes are generalized.The simulation results show that stronger ground motion leads to more severe damage.But uncertainty exists,which means that the dam may stand in a strong earthquake but fail in a moderate one.Due to the uncertainty of material properties.Concerning the failure modes,besides the damage at the dam neck and heel,as conventionally regarded as vulnerable to earthquakes,the upstream and downstream surfaces may also suffer from severe damage,resulting in cracks cutting through the dam.More occurrence of this failure mode is observed when the input acceleration amplitude intensifies.This research is expected to provide more insights into the weak links of the dam when subjected to earthquake shocks and thus leads to more efficient aseismic measurements.
The damage process and failure modes of concrete gravity dams affected by uncertain material properties and ground motion input are studied by numerical simulation.Based on 180 samples of nonlinear time-history analysis of the Jin'anqiao RCC Gravity Dam with the influences of concrete heterogeneity taken into account,the damage states of the dam subjected to different levels of ground motion are obtained,from which four typical failure modes are generalized.The simulation results show that stronger ground motion leads to more severe damage.But uncertainty exists,which means that the dam may stand in a strong earthquake but fail in a moderate one.Due to the uncertainty of material properties.Concerning the failure modes,besides the damage at the dam neck and heel,as conventionally regarded as vulnerable to earthquakes,the upstream and downstream surfaces may also suffer from severe damage,resulting in cracks cutting through the dam.More occurrence of this failure mode is observed when the input acceleration amplitude intensifies.This research is expected to provide more insights into the weak links of the dam when subjected to earthquake shocks and thus leads to more efficient aseismic measurements.
引文
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[3]邱战洪,张我华,任廷鸿.地震荷载作用下大坝系统的非线性动力损伤分析[J].水利学报,2005,36(5):629-636.
[4]Yazdchi M,Khalili N,Valliappan S.Non-linear seismic behavior of concrete gravity dams using coupled finiteelement-boundary element technique[J].International Journal for Numerical Methods in Engineering,1998,44(1):101-130.
[5]Wang Guanglun,Pekau O A,Zhang Chuhan,et al.Seismic fracture analysis of concrete gravity dams based onnonlinear fracture mechanics[J].Engineering Fracture Mechanics,2000,65(1):67-87.
[6]沈怀至,张楚汉,寇立夯.基于功能的混凝土重力坝地震破坏评价模型[J].清华大学学报(自然科学版),2007,47(12):2114-2118.
[7]Pekau O A,Cui Yuzhu.Failure analysis of fractured dams during earthquakes by DEM[J].Engineering Struc tures,2004,26(10):1483-1502.
[8]林皋,王建全,胡志强,等.坝基坝肩潜在滑动体的地震动态稳定[C]//首届全国水工抗震防灾学术会议论文集.南京:中国水力发电工程学会抗震防灾专业委员会,2006:9-17.
[9]Mehdi Ben Ftima,Pierre Léger.Seismic stability of cracked concrete dams using rigid block models[J].Comput ers and Structures,2006,84(28):1802-1814.
[10]Faouzi Ghrib,RenéTinawi.Nonlinear behavior of concrete dams using damage mechanics[J].Journal of Engi neering Mechanics,1995,121(4):513-527.
[11]张仲卿.碾压混凝土重力坝破坏机理研究[J].水力发电,1998(11):31-33.
[12]范书立,陈健云.碾压混凝土重力坝动力模型破坏试验研究[J].水力发电,2009,35(5):33-35.
[13]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.
[14]沈怀至.基于性能的混凝土坝-地基系统地震破损分析与风险评价[D].北京:清华大学,2007.
[15]Seismic Analysis and Design,Chapter5,Structural Analysis and Design of Nuclear Plant Facilities[S].ASCE,1980.
[16]唐春安,王述红,傅宇方.岩石破裂过程数值试验[M].北京:科学出版社,2003.
[17]钟红.高拱坝地震损伤开裂的大型数值模拟[D].大连:大连理工大学,2008.
[18]刘钧玉.裂纹内水压对重力坝断裂特性影响的研究[D].大连:大连理工大学,2008.
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