地震作用下岩质边坡动力响应特性及变形破坏机制研究
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摘要
以汶川地震诱发大型岩质边坡为研究对象,基于相似理论,采用室内大型振动台模型试验,通过输入不同频率、不同持时以及不同幅值的正弦波,研究顺层及均质结构岩质边坡的动力加速度响应特征及动力输入参数对边坡动力特性的影响。试验结果表明,模型边坡动力加速度分布存在明显的而非线性高程放大特性及非线性趋表特性;且边坡对加速度的放大存在高度效应,即边坡中上部大约3/4坡高以上对水平加速度放大明显,而中下部对竖直加速度放大明显;受地形作用影响,边坡坡脚对加速度具有明显的抑制作用;地震波输入的动力参数对加速度动力特性有影响,地震波频率对加速度影响最为明显,边坡动力加速度随频率的增加而呈非线性增大的趋势,当地震波频率接近边坡模型自振频率时影响最大,且频率的增加改变坡体内加速度的分布特征;动力加速度随边坡输入加速度峰值的增加而增加,但幅值的变化并不改变加速度在坡体内的分布;地震波持时对动力加速度影响轻微。边坡坡体结构是影响其动力特性的重要因素,顺层结构边坡由于存在大量的结构面其动力加速度放大系数要高于均质结构边坡15%左右。
Large-scale shaking table test was performed to study dynamic response characters and failure mechanism of rock slopes triggered by Wenchuan earthquake.Sine waves with different frequencies,amplitudes and duration times were mainly input.Testing results show that:acceleration amplification coefficients increased nonlinearly with the increasing elevation,and they almost reach to maximum at slope surface and shoulder.Horizontal acceleration is amplified more obvious than vertical acceleration at top part of slope(above three-quarters of slope height) which is the opposite at the lower part.Acceleration amplification coefficients increased with the increasing seismic frequency nonlinearly;distribution of acceleration in slope body changed with variation of frequency.Once the input frequency approximated to the natural frequency of model slope,dynamic acceleration is amplified most obviously.Acceleration amplification coefficients increased with the increment of seismic wave amplitude;but amplitude doesn t change the distribution of acceleration in slope body.Duration time of seismic wave has little influence on dynamic characters.Slope structure controls the deformation modes of rock slope;and acceleration amplification coefficients of bedding slope are about 15% more than those of the homogeneous slope,because of a large amount of structural surfaces in bedding slope which can make propagation of seismic wave more complex.
Large-scale shaking table test was performed to study dynamic response characters and failure mechanism of rock slopes triggered by Wenchuan earthquake.Sine waves with different frequencies,amplitudes and duration times were mainly input.Testing results show that:acceleration amplification coefficients increased nonlinearly with the increasing elevation,and they almost reach to maximum at slope surface and shoulder.Horizontal acceleration is amplified more obvious than vertical acceleration at top part of slope(above three-quarters of slope height) which is the opposite at the lower part.Acceleration amplification coefficients increased with the increasing seismic frequency nonlinearly;distribution of acceleration in slope body changed with variation of frequency.Once the input frequency approximated to the natural frequency of model slope,dynamic acceleration is amplified most obviously.Acceleration amplification coefficients increased with the increment of seismic wave amplitude;but amplitude doesn t change the distribution of acceleration in slope body.Duration time of seismic wave has little influence on dynamic characters.Slope structure controls the deformation modes of rock slope;and acceleration amplification coefficients of bedding slope are about 15% more than those of the homogeneous slope,because of a large amount of structural surfaces in bedding slope which can make propagation of seismic wave more complex.
引文
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[2]许强,陈建君,冯文凯,等.斜坡地震响应的物理模拟试验研究[J].四川大学学报:工程科学版,2009,41(3):266–272.(XU Qiang,CHEN Jianjun,FENG Wenkai,et al.Experimental study of theseismic response of slopes by physical modeling[J].Journal of SichuanUniversity:Engineering Science,2009,41(3):266–272.(in Chinese))
[3]董金玉.地震作用下岩质边坡的动力响应和滑动破坏过程研究[博士学位论文][D].北京:中国科学院地质与地球物理研究所,2010.(DONG Jinyu.Study on dynamic response and sliding failureprocess of rock slope under earthquake[Ph.D.Thesis][D].Beijing:Institute of Geology and Geophysics,Chinese Academy of Sciences,2010.(in Chinese))
[4]董金玉,杨国香,伍法权,等.地震作用下顺层岩质边坡动力响应和破坏模式大型振动台模型试验研究[J].岩土力学,2011,32(10):2 977–2 983.(DONG Jinyu,YANG Guoxiang,WU Faquan,et al.Thelarge-scale shaking table test study of dynamic response and failuremode of bedding rock slope under earthquake[J].Rock and SoilMechanics,2011,32(10):2 977–2 983.(in Chinese))
[5]杨国香.地震条件下岩质边坡动力破坏及动力响应规律研究[博士学位论文][D].北京:中国科学院地质与地球物理研究所,2011.(YANG Guoxiang.Study on failure mechanism and dynamicresponse rules of rock slope under earthquake[Ph.D.Thesis][D].Beijing:Institute of Geology and Geophysics,Chinese Academy ofSciences,2011.(in Chinese))
[6]罗先启,葛修润.滑坡模型试验理论及其应用[M].北京:中国水利水电出版社,2008:84–92.(LUO Xianqi,GE Xiurun.Theory andapplication of model test on landslide[M].Beijing:China Water PowerPress,2008:84–92.(in Chinese))
[7]韩伯鲤,陈霞龄,宋一乐,等.岩体相似材料的研究[J].武汉水利电力大学学报,1997,30(2):6–9.(HAN Boli,CHEN Xialing,SONGYile,et al.Research on similar material of rock mass[J].Journal ofWuhan University of Hydraulic and Electric Engineering,1997,30(2):6–9.(in Chinese))
[8]王汉鹏,李术才,郑学芬,等.地质力学模型试验新技术研究进展及工程应用[J].岩石力学与工程学报,2009,28(增1):2765–2771.(WANG Hanpeng,LI Shucai,ZHENG Xuefen,et al.Researchprogress of geomechanical model test with new technology and itsengineering application[J].Chinese Journal of Rock Mechanics andEngineering,2009,28(Supp.1):2 765–2 771.(in Chinese))
[9]王汉鹏,李术才,张强勇,等.新型地质力学模型试验相似材料的研制[J].岩石力学与工程学报,2006,25(9):1842–1847.(WANG Hanpeng,LI Shucai,ZHANG Qiangyong,et al.Developmentof a new geomechanical similar material[J].Chinese Journal of RockMechanics and Engineering,2006,25(9):1 842–1 847.(in Chinese))
[10]孙玉科.我国岩质边坡变形破坏的主要地质模式[J].岩石力学与工程学报,1983,2(1):67–76.(SUNYuke.Principal geological modesof deformation and failure of rock slopes in China[J].Chinese Journalof Rock Mechanics and Engineering,1983,2(1):67–76.(in Chinese))
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