带有参数不确定性的重力坝地震响应的直接数值模拟
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摘要
采用蒙特卡罗法对考虑参数不确定性的重力坝地震响应进行研究,参数不确定性主要考虑了材料的弹性模量、混凝土材料的抗拉强度、抗压强度和碾压混凝土重力坝建基面和层面的摩擦系数和凝聚力等,地震荷载按反应谱法进行计算,主要考虑了地震系数的不确定性,利用大型商业软件MARC计算快捷、处理方便的优点,对拟建的龙滩碾压混凝土重力坝(高196.5米)进行了上千次随机数值计算,根据概率论和数理统计原理给出了在95%置信度下重力坝关键部位的位移、应力响应,并给出其响应分布的直方图,所得结果还与确定性的时程响应的结果进行了比较,同时还给出了关键部位开裂概率。最后对该重力坝沿建基面和典型层面的整体抗滑稳定可靠度进行分析研究。结果表明在上游坝踵处、下游坝颈和高程341米之间的下游侧在8度地震作用下会出现开裂破坏,大坝沿高程341米层面和建基面的整体抗滑稳定可靠度最低。
The seismic response of gravity dam with the parameter uncertainty is studied by using the Monte Carlo method.Parameter uncertainties of the elastic modulus,tensile strength and compressive strength of concrete,as well as the friction factor and cohesion of the surface between a dam body and the concrete base near the foundation and the bedding surface of the dam are considered.The earthquake loads are calculated by using response spectrum method,and the uncertainty of the earthquake dynamic parameter is considered as the major factors in the calculations.Over 1,000 times random sampling calculations are made on a 196.5m-high Longtan roller compacted concrete gravity dam,which will be constructed,taking use of the software MARC whose calculating velocity is very fast and fore-and post-processing quite convenient.According to the principle of probability and statistics theory,the displacement and stress response of key parts of the gravity dam are gained under the confidence level of 95%,and their sample histograms are given.Finally,the possible failure mode and reliability of the gravity dam are analyzed,and the results indicate that cracking occurs in the upstream base and the downstream neck under the action of 8° earthquake.
The seismic response of gravity dam with the parameter uncertainty is studied by using the Monte Carlo method.Parameter uncertainties of the elastic modulus,tensile strength and compressive strength of concrete,as well as the friction factor and cohesion of the surface between a dam body and the concrete base near the foundation and the bedding surface of the dam are considered.The earthquake loads are calculated by using response spectrum method,and the uncertainty of the earthquake dynamic parameter is considered as the major factors in the calculations.Over 1,000 times random sampling calculations are made on a 196.5m-high Longtan roller compacted concrete gravity dam,which will be constructed,taking use of the software MARC whose calculating velocity is very fast and fore-and post-processing quite convenient.According to the principle of probability and statistics theory,the displacement and stress response of key parts of the gravity dam are gained under the confidence level of 95%,and their sample histograms are given.Finally,the possible failure mode and reliability of the gravity dam are analyzed,and the results indicate that cracking occurs in the upstream base and the downstream neck under the action of 8° earthquake.
引文
[1]张湘伟.结构分析中的概率方法[M].北京:科学出版社,2000,170-184
[2]沈风生,吴世伟.求解结构可靠度的蒙特卡罗法及其改进[A].吴世伟,等著,结构安全度与可靠度分析论文集[C].南京:河海大学出版社,1987.43-51.
[3]PraluaterH J,Schu¨eller G I.On advanced Monte Carlo S imu lation procedures in stochastic structural dynam ics[J].International Journal ofNon-linearM echan ics,1997,32(4):735-744.
[4]贺才兴,童品苗,王纪林等编.概率论与数理统计[M].北京:科学出版社,2001.199-201.
[5]DL 5073-1997,水工建筑物抗震设计规范[S].
[2]沈风生,吴世伟.求解结构可靠度的蒙特卡罗法及其改进[A].吴世伟,等著,结构安全度与可靠度分析论文集[C].南京:河海大学出版社,1987.43-51.
[3]PraluaterH J,Schu¨eller G I.On advanced Monte Carlo S imu lation procedures in stochastic structural dynam ics[J].International Journal ofNon-linearM echan ics,1997,32(4):735-744.
[4]贺才兴,童品苗,王纪林等编.概率论与数理统计[M].北京:科学出版社,2001.199-201.
[5]DL 5073-1997,水工建筑物抗震设计规范[S].
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