重力坝层间抗滑稳定体系的动力可靠度分析方法
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摘要
受明显的层状结构影响,加之材料参数和动荷载的双重随机性,动力条件下碾压混凝土重力坝的层间抗滑稳定可靠度问题值得关注。考虑地震波频谱特性、峰值加速度、坝体材料参数的随机性,统计概化出地震作用下坝体的潜在滑动失效路径;在特定地震动作用下,基于随机有限元分析结果,采用刚体极限状态判断准则和响应面法构建失效路径的动力抗滑稳定功能函数,进而求得其抗滑稳定可靠指标;接着考虑不同失效路径的相关性,用Ditlevsen窄界限公式估算体系的可靠度;最后,考虑地震动荷载的随机性,采用基于全概率公式的数值拟合积分方法求解大坝抗滑稳定体系的动力可靠度。研究结果表明,动力条件下,当水平地震系数大于0.2时,重力坝层间抗滑体系可靠度不再由建基面失效路径决定,而是由下游折坡处层面的失效路径决定。该方法数学意义明确,实用性强。
Due to the randomness of dynamic loads and structural parameters,dynamic reliability of stability between layers of RCC gravity dam deserves the attention.Considering the randomness of spectrum characteristics and peak acceleration of seismic waves as well as material parameters of the dam,potential sliding paths of the dam subjected to earthquake can be identified by generalized statistics;based on stochastic finite element method(SFEM) results,the limit state function of dynamic sliding is built according to rigid limit state criteria and response surface method(RSM) under a certain seismic loading;the reliability index is got as well;then,considering the relativity between different failure paths,the reliability index of the system can be estimated by Ditlevsen narrow-bound method.Finally,the randomness of seismic load is taken into account,the numerical integration method based on complete probability formula is used to get the dynamic system reliability.The results indicate that the system reliability between layers of gravity dam no longer depends on the failure path of the foundation plane,but is closely related to the failure paths at the downstream fold slope when the horizontal earthquake coefficient is greater than 0.2.This method is mathematically clear and practical.
Due to the randomness of dynamic loads and structural parameters,dynamic reliability of stability between layers of RCC gravity dam deserves the attention.Considering the randomness of spectrum characteristics and peak acceleration of seismic waves as well as material parameters of the dam,potential sliding paths of the dam subjected to earthquake can be identified by generalized statistics;based on stochastic finite element method(SFEM) results,the limit state function of dynamic sliding is built according to rigid limit state criteria and response surface method(RSM) under a certain seismic loading;the reliability index is got as well;then,considering the relativity between different failure paths,the reliability index of the system can be estimated by Ditlevsen narrow-bound method.Finally,the randomness of seismic load is taken into account,the numerical integration method based on complete probability formula is used to get the dynamic system reliability.The results indicate that the system reliability between layers of gravity dam no longer depends on the failure path of the foundation plane,but is closely related to the failure paths at the downstream fold slope when the horizontal earthquake coefficient is greater than 0.2.This method is mathematically clear and practical.
引文
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[9]颜立新,康红普,高谦.基于响应面函数的可靠度分析及其应用[J].岩土力学,2001,22(3):327-333.YAN Li-xin,KANG Hong-pu,GAO Qian.Reliability analysis based on response surface function and its application to a chamber[J].Rock and Soil Mechanics,2001,22(3):327-333.
[10]DITLEVSEN O.Narrow reliability bounds for structural system[J].Structural Mechanics,1979,7(4):453-472.
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[13]方修君,金峰,王进廷.基于扩展有限元法的Koyna重力坝地震开裂过程模拟[J].清华大学学报(自然科学版),2008,48(12):2065-2069.FANG Xiu-jun,JIN Feng,WANG Jin-ting.Seismic fracture simulation of the Koyna gravity dam using an extended finite element method[J].Journal of Tsinghua University(Science and Technology),2008,48(12):2065-2069.
[14]MECANN W.Seismic hazard map for Puerto Rico 1994[R].Puerto Rico:Seismic Safety Commission Puerto Rico,1994.
[2]赵会香,张思俊,张广键.龙滩水电站碾压混凝土高重力坝可靠度研究[J].水力发电,1999,(2):200-203.ZHAO Hui-xiang,ZHANG Si-jun,ZHANG Guang-jian.Study on reliability of high RCC gravity dam of Longtanhydropower station[J].Water Power,1999,(2):200-203.
[3]张社荣,李振富,郭怀志.重力坝抗震可靠度分析[J].天津大学学报,1991,(增刊2):137-141.ZHANG She-rong,LI Zhen-fu,GUO Huai-zhi.Earthquake resistant reliability analysis of gravity dam[J].Journal of Tianjin University,1991,(Supp.2):137-141.
[4]胡强,刘宁,李锦辉.一种新的可靠度计算方法及其在工程中的应用[J].岩土力学,2004,25(4):632-636.HU Qiang,LIU Ning,LI Jin-hui.A new method of structural reliability analysis and its application[J].Rock and Soil Mechanics,2004,25(4):632-636.
[5]陈颖,王东升,朱长春.随机结构在随机载荷下的动力可靠度分析[J].工程力学,2006,23(10):82-85.CHEN Ying,WANG Dong-sheng,ZHU Chang-chun.Dynamic reliability analysis of stochastic structures subjected to random loads[J].Engineering Mechanics,2006,23(10):82-85.
[6]范书立,陈健云,范武强,等.地震作用下碾压混凝土重力坝的可靠度分析[J].岩石力学与工程学报,2008,27(3):564-571.FAN Shu-li,CHEN Jian-yun,FAN Wu-qiang,et al.Reliability analysis of roller compacted concrete gravity dams subjected to earthquake[J].Chinese Journal of Rock Mechanics and Engineering,2008,3(3):564-571.
[7]徐强,陈建云,李静,等.非平稳地震动过程中混凝土重力坝受拉失效路径可靠度分析[J].工程力学,2011,28(3):123-128.XU Qiang,CHEN Jian-yun,LI Jing,et al.Concrete gravity dam reliability analysis on tension failure path under non-stationary ground motion processes[J].Engineering Mechanics,2011,28(3):123-128.
[8]徐强,陈建云,李静,等.基于贝叶斯理论的大坝体系可靠度计算方法[J].大连理工大学学报,2011,(1):84-89.XU Qiang,CHEN Jian-yun,LI Jing,et al.Calculation method for system reliability of dam based on Bayes theory[J].Journal of Dalian University of Technology,2011,(1):84-89.
[9]颜立新,康红普,高谦.基于响应面函数的可靠度分析及其应用[J].岩土力学,2001,22(3):327-333.YAN Li-xin,KANG Hong-pu,GAO Qian.Reliability analysis based on response surface function and its application to a chamber[J].Rock and Soil Mechanics,2001,22(3):327-333.
[10]DITLEVSEN O.Narrow reliability bounds for structural system[J].Structural Mechanics,1979,7(4):453-472.
[11]贾超,刘宁,陈进.地震作用下土坡可靠度风险分析[J].岩石力学与工程学报,2005,(04):703-707.JIA Chao,LIU Ning,CHEN Jin.Slope risk analysis under the earthquake effect[J].Chinese Journal of Rock Mechanics and Engineering,2005,(04):703-707.
[12]ABDELAZIZ Y,BENDAHANE K,BARAKA A.Extended finite element modeling[J].Basic Review and Programming Engineering,2011,3:713-718.
[13]方修君,金峰,王进廷.基于扩展有限元法的Koyna重力坝地震开裂过程模拟[J].清华大学学报(自然科学版),2008,48(12):2065-2069.FANG Xiu-jun,JIN Feng,WANG Jin-ting.Seismic fracture simulation of the Koyna gravity dam using an extended finite element method[J].Journal of Tsinghua University(Science and Technology),2008,48(12):2065-2069.
[14]MECANN W.Seismic hazard map for Puerto Rico 1994[R].Puerto Rico:Seismic Safety Commission Puerto Rico,1994.
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