Nam Ngum5水电站分缝重力拱坝地震响应分析
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摘要
针对老挝在建的Nam Ngum5水电站重力拱坝,利用基于ABAQUS平台的非线性指数型动接触模型和混凝土塑性损伤本构模型,研究了该重力拱坝在地震荷载作用下横缝的张开、闭合和滑移的非线性动力特性以及坝体的动力响应.计算结果表明:横缝张开使得大坝的坝踵主拉应力大幅增加至3.0MPa;考虑诱导短缝时,坝体整体性下降,刚度减弱,坝顶顺河向动位移响应有一定幅度的提高,同时横缝的开度也有所增加,但诱导短缝对坝体应力的影响较小;大坝能承受的最大峰值加速度为0.40g,大坝可能的破坏模式为从横缝底端与岸坡交界面处起裂,损伤部位逐渐向坝踵以及左岸坝肩、右岸坝肩延伸.
The exponential nonlinear dynamic contact model and the concrete damage plasticity model based on the ABAQUS platform were employed to study the nonlinear dynamic characteristics of contraction joints,i.e.,opening,closing and sliding,and dynamic responses,of the gravity arch dam of the Nam Ngum5 Hydropower Station in Laos during earthquakes. The results indicate that the principal tensile stress of the dam heel increases greatly,up to 3.0 MPa,owing to the opening of the contraction joints. Because of the induced joints,the dam integrity further decreases and it becomes less stiff,and the dynamic displacement of the dam crest along the river shows a certain increase. Simultaneously,the opening of the contraction joints increases. The induced joints have little influence on the dam stress. The dam can bear a peak acceleration of 0.40 g,and the possible failure mode is the development of cracks on the interface between the bottom of contraction joints and the slope,and then extension of damage to the dam heel and the dam abutments.
The exponential nonlinear dynamic contact model and the concrete damage plasticity model based on the ABAQUS platform were employed to study the nonlinear dynamic characteristics of contraction joints,i.e.,opening,closing and sliding,and dynamic responses,of the gravity arch dam of the Nam Ngum5 Hydropower Station in Laos during earthquakes. The results indicate that the principal tensile stress of the dam heel increases greatly,up to 3.0 MPa,owing to the opening of the contraction joints. Because of the induced joints,the dam integrity further decreases and it becomes less stiff,and the dynamic displacement of the dam crest along the river shows a certain increase. Simultaneously,the opening of the contraction joints increases. The induced joints have little influence on the dam stress. The dam can bear a peak acceleration of 0.40 g,and the possible failure mode is the development of cracks on the interface between the bottom of contraction joints and the slope,and then extension of damage to the dam heel and the dam abutments.
引文
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[2]蔡新,郭兴文,王德信,等.拱坝整体非线性稳定分析[J].河海大学学报:自然科学版,1999,27(2):74-80.(CAI Xin,GUO Xing-wen,WANGDe-xin,et al.Nonlinear stability analysis of arch dams[J].Journal of Hohai University:Natural Sciences,1999,27(2):74-80.(in Chinese))
[3]赵光恒,杜成斌.分缝拱坝的地震响应分析[J].河海大学学报,1994,22(5):1-8.(ZHAO Guang-heng,DUCheng-bin.Seismic response analysis of jointed arch dams[J].Journal of Hohai University,1994,22(5):1-8.(in Chinese))
[4]GOODMAN R E,TAYLOR R L,BREKKE T L.A model for the mechanics of jointd rock[J].Journal of the Soil Mechanics and Foundations,1968,94(3):660-677.
[5]杜成斌,任青文.用于接触面模拟的三维非线性接触单元[J].东南大学学报:自然科学版,2001,31(4):92-96.(DUCheng-bin,RENQing-wen.Anewthree-dimensional nonlinear interface element for modelingjoints[J].Journal of Southeast University:Natural Science Edition,2001,31(4):92-96.(in Chinese))
[6]赵兰浩,李同春,牛志伟,等.有横缝高拱坝非线性地震响应动接触模型[J].水力发电学报,2007,26(4):91-95.(ZHAOLan-hao,LI Tong-chun,NIUZhi-wei,et al.The dynamic contact model of nonlinear seismic response of high arch dams with contractionjoints[J].Journal of Hydroelectric Engineering,2007,26(4):91-95.(in Chinese))
[7]石建军,孙冰,周元德,等.不同横缝接触与库水模型对拱坝动力反应的影响[J].水力发电学报,2005,24(3):34-38.(SHI Jian-jun,SUNBing,ZHOUYuan-de.Effects of contraction joint contact and reservoir models on dynamic response of arch dams[J].Journal of Hydroelectric Engineering,2005,24(3):34-38.(in Chinese))
[8]龙渝川,周元德,张楚汉.基于两类横缝接触模型的拱坝非线性动力响应研究[J].水利学报,2005,36(9):1094-1099.(LONG Yu-chuan,ZHOUYuan-de,ZHANG Chu-han.Acomparison study of nonlinear dynamic responses of arch dams based on two types of contractionjoint models[J].Journal of Hydrolic Engineering,2005,36(9):1094-1099.(in Chinese))
[9]DL5073—2000水工建筑物抗震设计规范[S].
[10]DL5077—1997水工建筑物荷载设计规范[S].
[11]LUBLINERJ,OLIVERJ,OLLERRS,et al.Aplastic-damage model for concrete[J].International Journal of Solids and Structures,1989,25(3):229-326.
[12]LEEJ,FENVES G L.Plastic-damage model for cyclic loading of concrete structures[J].Journal of Engineering Mechanics,1998,124(8):892-900.
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