强震荷载下裂缝岩体拉剪破坏机理
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摘要
崩塌是地震诱发的最严重次生地质灾害之一,但目前有关地震崩塌的力学机理还不清晰。为此,基于天然危岩体的宏观结构特征,从岩石断裂力学的角度入手,对比分析了不同震波模式下裂缝的失稳扩展条件,确立了拉剪破坏的危岩失稳机制;继而以能量法为手段,研究了震波能量在危岩体中的输入和耗散机制,解析拉剪条件下裂缝的扩展方向和危岩失稳机理,给出裂缝扩展的加速度临界值ac和扩展量的计算方法;最后,通过具体算例验证了模型的合理性;结果显示,震时危岩体的失稳是裂缝在拉剪震波作用下沿震波入射垂直方向间断扩展累积的结果。
As one of the most serious hazards in an earthquake,the collapse is very hard to control largely because the failure mechanism of rock slope is not clearly addressed.Here from the view of Fracture Mechanics and based on the structural characters of natural dangerous rock,the propagation condition of cracks under different seismic waves was analyzed contrastively,and it is found that the tension-shear failure of cracks is the main mode of collapse in an earthquake.Then the energy method was taken as a main way to study the crack propagation direction and rock failure mechanism.The paper proposed approaches to calculate the crack growth amount and critical seismic acceleration,which result in crack failure.Finally,an example was given to validate the theory.The result shows the failure of dangerous rock in earthquake is mainly caused by the discontinuous propagation and continuous accumulation of cracks under tension-shear action of seismic action and along the vertical direction of seismic force.
As one of the most serious hazards in an earthquake,the collapse is very hard to control largely because the failure mechanism of rock slope is not clearly addressed.Here from the view of Fracture Mechanics and based on the structural characters of natural dangerous rock,the propagation condition of cracks under different seismic waves was analyzed contrastively,and it is found that the tension-shear failure of cracks is the main mode of collapse in an earthquake.Then the energy method was taken as a main way to study the crack propagation direction and rock failure mechanism.The paper proposed approaches to calculate the crack growth amount and critical seismic acceleration,which result in crack failure.Finally,an example was given to validate the theory.The result shows the failure of dangerous rock in earthquake is mainly caused by the discontinuous propagation and continuous accumulation of cracks under tension-shear action of seismic action and along the vertical direction of seismic force.
引文
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[2]Ambraseys N,Srbulov M.Earthquake induceddisplacements of slopes[J].Soil Dynamics andEarthquake Engineering,1995,14(1):59―71.
[3]杨庆华,姚令侃,任自铭,等.地震作用下松散体斜坡崩塌动力学特性离心模型试验研究[J].岩石力学与工程学报,2008,27(2):368―374.Yang Qinghua,Yao Lingkan,Ren Ziming,et al.Centrifugal model test on dynamical characteristics oflandslips of loose slope under seismic loading[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(2):368―374.(in Chinese)
[4]Kobayashi Y,Harp E L,Kagawa T.Simulation ofrock-falls triggered by earthquakes[J].Rock Mechanicsand Rock Engineering,1990,23(1):1―20.
[5]董志高,吴继敏,王文远,等.地震作用崩塌堆积体边坡稳定性分析[J].水利水电科技进展,2006,26(5):37―40.Dong Zhigao,Wu Jimin,Wang Wenyuan,et al.Stabilityanalysis of avalanche deposit slopes under earthquakeaction[J].Advances in Science and Technology of WaterResources,2006,26(5):37–40.(in Chinese)
[6]丁彦惠,王庆余,孙进忠,等.地震崩滑预测方法及其工程应用研究[J].工程地质学报,2000,8(4):475―480.Ding Yanhui,Wang Qingyu,Sun Jinzhong,et al.Research on the method for prediction ofearthquake-induced landslides and its application toengineering projects[J].Journal of Engineering Geology,2000,8(4):475―480.(in Chinese)
[7]李杰,李国强.地震工程学导论[M].北京:建筑工业出版社,1992.Li Jie,Li Guoqiang.Introduction of earthquakeengineering[M].Beijing:China Architecture&BuildingPress,1992.(in Chinese)
[8]中国航空研究院.应力强度因子手册[M].北京:科学出版社,1993.Chinese Aeronautical Establishment(CAE).Handbookof stress intensity factors[M].Beijng:Science Press,1993.(in Chinese)
[9]中国科学院水利部成都山地所.都江堰拉法基水泥有限公司矿山上山公路地震损毁边坡及路基修复整治工程工程地质勘察报告[R].成都:中国科学院成都山地灾害与环境研究所,2008.Institute of Mountain Hazards and Environment,ChineseAcademy of Science.Geological prospecting report inthe damage road treating project of lafarge Dujiangyancement Co.,Ltd.[R].Chengdu:Institute of MountainHazards and Environment,Chinese Academy of Science,2008.(in Chinese)
[10]Morishita K,Ochiai S,Okuda H,et al.Fracturetoughness of a crystalline silicon carbide fiber[J].Journal of the American Ceramic Society,2006,89(8):2571―2576.
[11]Li Liyun,Xu Fengguang,Xie Heping,Wei Ning.Fracture study on mode I-III crack of rock[C]//International Conference on Fracture and DamageMechanics.Switzerland:Trans Tech Publications,2006:1217―1220.
[12]Radaj D,Zhang S.On the relations between notch stressand crack stress intensity in plane shear and mixed modeloading[J].Engineering Fracture Mechanics,1993,44(5):691―704.
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