地震荷载作用下重力坝坝踵裂缝内水压分布研究
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摘要
在地震荷载作用下,重力坝内水下裂缝突然闭合时会产生较大的附加水压力,从而可能引起裂缝失稳,对大坝抗震不利。基于大型有限元软件建立数值分析模型,人为在坝踵设置初始张开宽度为0.001 m的楔形裂缝,以分析在地震作用下不同长度、不同方向的裂缝内部的最大水压分布规律。其中,库水及缝内水体采用势流体单元,库水与坝体、坝基间采用流固单元。研究结果表明,随着裂缝长度的增长,裂缝内最大水压不断增加,最大可达到初始静水压的8.13倍;而随着裂缝角度的增大,裂缝内最大水压先增大后减小;裂缝长度越长,裂缝内最大水压随着角度变化越明显。
Large additional water pressure can be caused by the fast closing of the cracks in gravity dams under earthquake loads,which may induce crack instability that is unfavorable to dam safety.A numerical analysis model for gravity dam is established using finite element software.On the assumption that the cracks is a wedge-shaped fracture with 0.001m initial width at dam heel,internal pressure distributions laws are studied considering different crack lengths and angles.Reservoir water and water in crack are simulated by potential flow element,and fluid-solid element is adopted to simulate coupling effect between water and dam body,dam foundation.The results show that the maximum water-pressure increases with increasing in length,which can reach 8.13 times of initial hydrostatic pressure.However,with the increase of crack angle,the maximum water-pressure increases first and then decreases.Meanwhile,the longer the cracks are,the more obvious the maximum water-pressure changes with angle.
Large additional water pressure can be caused by the fast closing of the cracks in gravity dams under earthquake loads,which may induce crack instability that is unfavorable to dam safety.A numerical analysis model for gravity dam is established using finite element software.On the assumption that the cracks is a wedge-shaped fracture with 0.001m initial width at dam heel,internal pressure distributions laws are studied considering different crack lengths and angles.Reservoir water and water in crack are simulated by potential flow element,and fluid-solid element is adopted to simulate coupling effect between water and dam body,dam foundation.The results show that the maximum water-pressure increases with increasing in length,which can reach 8.13 times of initial hydrostatic pressure.However,with the increase of crack angle,the maximum water-pressure increases first and then decreases.Meanwhile,the longer the cracks are,the more obvious the maximum water-pressure changes with angle.
引文
[1]陈厚群.水工混凝土结构抗震研究进展的回顾和展望[J].中国水利水电科学研究院学报,2008,6(4):245-257.
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[9]SL203-97水工建筑物抗震设计规范[S].
[2]贾金生,李新宇,郑璀莹.特高重力坝高压水劈裂影响的初步研究[J].水利学报,2006,37(12):1509-1515.
[3]Lohrasbi A R,Attarnejad R.Crack Growth in Concrete Gravity DamsBased on Discrete Crack Method[J].Journal of Engineering and Ap-plied Sciences,2008,1(4):318-323.
[4]Slowik V,Saouma VE.Water pressure in propagating concrete cracks[J].Journal of Structural Engineering,2000,126(2):235-242.
[5]郑志芳,李宗利,孙丽丽.动力荷载作用下裂缝水力劈裂效应研究[J].水利水运工程学报,2010,(2):45-50.
[6]Tinwai R,Guizani L.Formulation of hydrodynamic pressure in cracksdue to earthquakes in concrete dams[J].Earthquake Engineering andStructural Dynamics,1994,23:699-715.
[7]Javanmardi F,Leger P,Tinawi R.Seismic Water Pressure in CrackedConcrete Gravity Dams:Experimental Study and Theoretical Modeling[J].Journal of Structural Engineering,2005,131(1):139-150.
[8]吕宏兴,裴国霞,杨玲霞.水力学[M].北京:中国农业出版社,2002.
[9]SL203-97水工建筑物抗震设计规范[S].
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