地震荷载作用下坝及其岩基的脆性动力损伤分析
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摘要
将损伤、渗流及孔隙率演化等相互耦合的有效应力概念引入Mohr-Coulomb破坏准则,对岩石类的脆性材料建立了一种动力损伤破坏的模型,并应用该模型对地震荷载作用下的坝和岩基的破坏过程进行了脆性动力损伤分析。这种方法从连续损伤力学的观点研究了岩体结构在动力荷载作用下脆性损伤-破坏的突变机理。结果表明,损伤会在坝与岩基的上游坡的结合处由于应力集中而明显地增长。在硬岩基上的坝内,损伤发展比软岩基上灵敏。
In this paper,a brittle damage-failure mechanism for rock structures subject to earthquake loading is adopted for analysis of dynamic responses of damaged concrete gravity dams and rock foundation. The concept of the modified net effective stress which involves the coupling affects among damage,pore pressure and porosity evolution in cracked rock mass and concrete is introduced into the modified Mohr-Coulomb failure criterion in order to express the brittle dynamic damage growth and propagation phenomenon. The developed brittle dynamic damage model is based on the localization of damaged failure in brittle materials. Therefore,the brittle dynamic damage process is considered as the process of local fractures in material without plastic deformations. The dissipations of energy during the dynamic process consist of dissipations of the local damage development,the local changes of seepage flow velocity and the local evolution of porosity within the networks of crack-damaged porosity only; no energy is dissipated with the everlasting deformation. The numerical results of the brittle dynamic damage analysis for the concrete dam and the rock foundation show that the significant damage growth starts in the upstream side at the corner between the dam and rock foundation where a high stress concentration area exists. Damage growth is found to be more susceptible in the softer rock foundation than that in the intact rock foundation.
In this paper,a brittle damage-failure mechanism for rock structures subject to earthquake loading is adopted for analysis of dynamic responses of damaged concrete gravity dams and rock foundation. The concept of the modified net effective stress which involves the coupling affects among damage,pore pressure and porosity evolution in cracked rock mass and concrete is introduced into the modified Mohr-Coulomb failure criterion in order to express the brittle dynamic damage growth and propagation phenomenon. The developed brittle dynamic damage model is based on the localization of damaged failure in brittle materials. Therefore,the brittle dynamic damage process is considered as the process of local fractures in material without plastic deformations. The dissipations of energy during the dynamic process consist of dissipations of the local damage development,the local changes of seepage flow velocity and the local evolution of porosity within the networks of crack-damaged porosity only; no energy is dissipated with the everlasting deformation. The numerical results of the brittle dynamic damage analysis for the concrete dam and the rock foundation show that the significant damage growth starts in the upstream side at the corner between the dam and rock foundation where a high stress concentration area exists. Damage growth is found to be more susceptible in the softer rock foundation than that in the intact rock foundation.
引文
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2黄茂松,钱建固,吴世明.土坝动力应变局部化与渐进破坏的自适应有限元分析[J].岩土工程学报,2001,20(3):306～310
3李术才,朱维申.复杂应力状态下断续节理岩体断裂损伤机理研究及其应用[J].岩石力学与工程学报,1999,18(2):142～146
4高文学,刘运通,杨军.脆性岩石冲击损伤模型研究[J].岩石力学与工程学报,2000,19(2):153～156
5HudsonJA.岩石力学原理[J].岩石力学与工程学报,1989,8(3):252～268
6李九红,杨菊生.岩体损伤-弹塑性非线性有限元分析[J].岩石力学与工程学报,2000,19(6):707～711
7任伟中,白世伟.平面应力条件下闭合断续节理岩体力学特性实验研究[J].实验力学,1999,14(4):520～527
8赵吉东,尹健民,周维垣等.节理岩体断裂损伤模型在三峡坝基岩体力学参数模拟和预测中的应用[J].岩石力学与工程学报,2002,21(2):176～179
9张我华,金荑.各向异性损伤力学中的弹塑性分析[J].固体力学学报,2000,21(1):89～94
10ZhangWohua,Va ll iappan S.Analysiso frando manisotro picdamag em echa nicsproblemsofrockmass,p artI-probabilisticsimulation, partII-stitisticalestimation[ J].J.RockMechanicsandRockEngineering,1990,23(1):91～112;23(3):241～259
11ValliappanS,Zhan gWohua, MurtiV.F in iteelementa nalysi sofanisot ropicdamagemechanicsproblems[J].Eng.Frac.Mech.,1990,35(6):1061～1076
12ZhangWohua ,Valli appanS.Co ntinuu mda magemechanicstheoryandapplication,partI-theory,partII-applications[J].Int.J.DamageMecha.,1998,7:250～297
13张我华,金荑,陈云敏.损伤材料的动力响应特性[J].振动工程学报,2000,13(2):211～224
14尤明庆,华安增.岩石试样破坏过程的能量分析[J].岩石力学与工程学报,2002,21(6):778～781
15张我华.煤/瓦斯突出过程中煤介质局部化破坏的损伤机理[J].岩土工程学报,1999,21(6):731～736
16Va lliappanS ,Z hangWoh ua. Numerical mo del ling ofmethanegasmi gration indrycoalseam[ J].Int.J.forNum.andAnaly.Meth.inGeomechanics,1996,20:57 1～593
17RichardeG.IntroductiontoRockMechanics[M].台北:儒林图书有限公司,1 98 4
18Vall iappan S,Zh angWohua.Roleofgasenergyduri ngcoaloutbursts[J].Int.J.Num.Meth.inEngng.,1999,44:875～895
19Yazdc hM,Va lli appanS, ZhangW ohua.Acon ti nuummodelfo rdynami cdamageevolutionofanisotropi cbrittlematerials[J].Int.J.Num.Meth.inEngng.,1996,39:1555～1583
20 Kaw amotoT,Ich ikawaY,Ky oy aT.Deformatio nand frac tur ingbeh aviourofd iscontinuousrock massand damagemechanicstheory[J].Int.J.forNum.andAnaly.Meth.Geomechanics,1988,12(2): 1～30
21Chongb inZ ,Vallia ppanS.Tr an sientinf initeelementfor seepage problemsininfi nitemedia[J].Int.J.forNum.andAnaly.Meth.inGeomechanics,1993,17:324～341
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