黄土边坡动力响应分析
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摘要
运用有限差分软件FLAC3D,建立了某一黄土边坡三维模型,首先对其在地震作用下的动力响应规律进行了总结,然后探讨了地震动参数对黄土边坡动力响应的影响。结果表明:黄土边坡对地震波存在垂直放大和临空面放大作用;当输入地震波振幅或频率增加时,坡面监测点加速度放大系数随坡高增加呈"增加→衰减→增加"的三段形态;速度放大系数随坡高的增大而增大,并在坡顶达到最大值;位移放大系数随振幅和频率的增加而增加;地震持时对加速度、速度峰值的影响不大,但坡体位移随持时的增加而显著增加。强震作用下的最大剪应变增量区域的位置和形状表明,黄土边坡的破坏模式仍是沿着某一弧形潜在滑动面失稳破坏。研究结果有助于进一步揭示黄土边坡在地震作用下的失稳机制,为黄土地区边坡抗震设计与防灾减灾提供参考。
A three-dimensional dynamic numerical simulation model of loess slopes was established with FLAC3D program,the dynamic response laws and the influence of parameters of ground motion on the responses of slopes under earthquakes were analyzed.It is shown that the input seismic waves are affected by vertical and surface amplification of the slopes;with increase of amplitude and frequency of input seismic wave,the amplification factors of PGA at monitoring points on slope surface display a pattern of three segments of increase,decrease and increase as the height of slope increases;amplification factors of PGV and PGD increase with the amplitude and frequencys increasing;while these factors are less affected by the duration;slope displacement increases obviously with duration increasing;the location and the shape of the maximum shear-strain increment region under the action of strong earthquake show that the failure pattern of homogeneous loess slopes under earthquakes is still the instability along a potential sliding surface,similar to that under static condition.Results can help further reveal the failure mechanism of loess slope under earthquake and give a reference to seismic design of slope in loess regions and to disaster prevention and reduction.
A three-dimensional dynamic numerical simulation model of loess slopes was established with FLAC3D program,the dynamic response laws and the influence of parameters of ground motion on the responses of slopes under earthquakes were analyzed.It is shown that the input seismic waves are affected by vertical and surface amplification of the slopes;with increase of amplitude and frequency of input seismic wave,the amplification factors of PGA at monitoring points on slope surface display a pattern of three segments of increase,decrease and increase as the height of slope increases;amplification factors of PGV and PGD increase with the amplitude and frequencys increasing;while these factors are less affected by the duration;slope displacement increases obviously with duration increasing;the location and the shape of the maximum shear-strain increment region under the action of strong earthquake show that the failure pattern of homogeneous loess slopes under earthquakes is still the instability along a potential sliding surface,similar to that under static condition.Results can help further reveal the failure mechanism of loess slope under earthquake and give a reference to seismic design of slope in loess regions and to disaster prevention and reduction.
引文
[1]王念秦,张倬元.黄土滑坡灾害研究[M].兰州:兰州大学出版社,2005.3.Wang N Q,Zhang Zh Y.Study on Loess LandslideDisaster[M].Lanzhou:Lanzhou University Press,2005.3.
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[4]徐光兴,姚令侃,李朝红,等.边坡地震动力响应规律及地震动参数影响研究[J].岩土工程学报,2008,30(6):918-923.Xu G X,Yao L K,Li Zh H,et al.Dynamic response ofslopes under earthquakes and influence of groundmotion parameters[J].Chinese Journal ofGeotechnical Engineering,2008,30(6):918-923.
[5]何丽君,石玉成,杨惠林,等.地震动作用下黄土边坡稳定性分析[J].西北地震学报,2009,31(2):142-143.He L J,Shi Y Ch,Yang H L,et al.Analysis onstability of loess slope during different ground motion[J].Northwestern Seismological Journal,2009,31(2):142-143.
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[7]刘春玲,祁生文,童立强,等.利用FLAC3D分析某边坡地震稳定性[J].岩石力学与工程学报,2004,23(16):2730-2733.Liu Ch L,Qi Sh W,Tong L Q,et al.Stabilityanalysis of slope under earthquake with FLAC3D[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(16):2730-2733.
[8]王建,姚令侃,吴伟.路堤震害模式及路堤动力特性研究[J].岩土力学,2010,31(12):3801-3808.Wang J,Yao L K,Wu W.Research on seismic damagemode and dynamic characteristics of road embankment[J].Rock and Soil Mechanics,2010,31(12):3801-3808.
[9]徐光兴,姚令侃,高召宁,等.边坡动力特性与动力响应的大型振动台模型试验研究[J].岩石力学与工程学报,2008,27(3):624-632.Xu G X,Yao L K,Gao Zh N,et al.Large-scaleshaking table model test on the dynamiccharacteristics and seismic responses of slope[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(3):624-632.
[10]郑颖人,叶海林,黄润秋.地震边坡破坏机制及其破裂面的分析探讨[J].岩石力学与工程学报,2009,28(8):1715-1720.Zheng Y R,Ye H L,Huang R Q.Analysis anddiscussion of failure mechanism and fracture surface ofslope under earthquake[J].Chinese Journal of RockMechanics and Engineering,2009,28(8):1715-1720.
[11]钟冬望,吴亮,陈浩.爆炸荷载下岩质边坡动力特性试验及数值分析研究[J].岩石力学与工程学报,2010,29(增1):2965-2966.Zhong D W,Wu L,Chen H.Model test and numericalsimulation study of dynamic characteristics of rockslope under blast loading[J].Chinese Journal of RockMechanics and Engineering,2010,29(S1):2965-2966.
[12]Bouckovalas G D,Papadimitriou A G.Numericalevaluation of slope topography effects on seismicground motion[J].Soil Dynamics and EarthquakeEngineering,2005,25(7-10):547-558.
[13]祁生文.单面边坡的两种动力反应形式及其临界高度[J].地球物理学报,2006,49(2):518-523.Qi Sh W.Two patterns of dynamic responses ofsingle free surface slopes and their threshold height[J].Chinese Journal of Geophysics,2006,49(2):518-523.
[14]祁生文,伍法权.边坡动力响应规律研究[J].中国科学(E辑,技术科学),2003,33(增):28-40.Qi Sh W,W F Q.Study on the regularity of dynamicresponse for slope[J].Science in China,Series E,2003,33(S):28-40.
[15]张鲁渝,郑颖人,赵尚毅,等.有限元强度折减系数法计算土坡稳定安全系数的精度研究[J].水利学报,2003,(1):21-26.Zhang L Y,Zheng Y R,Zhao Sh Y,et al.Thefeasibility study of strength-reduction method withFEM for calculating safety factors of soil slopestability[J].Journal of Hydraulic Engineering,2003,(1):21-26.
[2]刘东生.黄土与环境[M].北京:科学出版社,1985.Liu D Sh.Loess and Environment[M].Beijing:Science Press,1985.
[3]徐张建,林在贯,张茂省.中国黄土与黄土滑坡[J].岩石力学与工程学报,2007,26(7):1297-1312.Xu Zh J,Lin Z G,Zhang M Sh.Loess in China andloess landslides[J].Chinese Journal of RockMechanics and Engineering,2007,26(7):1297-1312.
[4]徐光兴,姚令侃,李朝红,等.边坡地震动力响应规律及地震动参数影响研究[J].岩土工程学报,2008,30(6):918-923.Xu G X,Yao L K,Li Zh H,et al.Dynamic response ofslopes under earthquakes and influence of groundmotion parameters[J].Chinese Journal ofGeotechnical Engineering,2008,30(6):918-923.
[5]何丽君,石玉成,杨惠林,等.地震动作用下黄土边坡稳定性分析[J].西北地震学报,2009,31(2):142-143.He L J,Shi Y Ch,Yang H L,et al.Analysis onstability of loess slope during different ground motion[J].Northwestern Seismological Journal,2009,31(2):142-143.
[6]Clough R W,Chopra A K.Earthquake stress analysisin earth dams[J].Journal of Engineering Mechanics,ASCE,1966,92(EM2):51-60.
[7]刘春玲,祁生文,童立强,等.利用FLAC3D分析某边坡地震稳定性[J].岩石力学与工程学报,2004,23(16):2730-2733.Liu Ch L,Qi Sh W,Tong L Q,et al.Stabilityanalysis of slope under earthquake with FLAC3D[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(16):2730-2733.
[8]王建,姚令侃,吴伟.路堤震害模式及路堤动力特性研究[J].岩土力学,2010,31(12):3801-3808.Wang J,Yao L K,Wu W.Research on seismic damagemode and dynamic characteristics of road embankment[J].Rock and Soil Mechanics,2010,31(12):3801-3808.
[9]徐光兴,姚令侃,高召宁,等.边坡动力特性与动力响应的大型振动台模型试验研究[J].岩石力学与工程学报,2008,27(3):624-632.Xu G X,Yao L K,Gao Zh N,et al.Large-scaleshaking table model test on the dynamiccharacteristics and seismic responses of slope[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(3):624-632.
[10]郑颖人,叶海林,黄润秋.地震边坡破坏机制及其破裂面的分析探讨[J].岩石力学与工程学报,2009,28(8):1715-1720.Zheng Y R,Ye H L,Huang R Q.Analysis anddiscussion of failure mechanism and fracture surface ofslope under earthquake[J].Chinese Journal of RockMechanics and Engineering,2009,28(8):1715-1720.
[11]钟冬望,吴亮,陈浩.爆炸荷载下岩质边坡动力特性试验及数值分析研究[J].岩石力学与工程学报,2010,29(增1):2965-2966.Zhong D W,Wu L,Chen H.Model test and numericalsimulation study of dynamic characteristics of rockslope under blast loading[J].Chinese Journal of RockMechanics and Engineering,2010,29(S1):2965-2966.
[12]Bouckovalas G D,Papadimitriou A G.Numericalevaluation of slope topography effects on seismicground motion[J].Soil Dynamics and EarthquakeEngineering,2005,25(7-10):547-558.
[13]祁生文.单面边坡的两种动力反应形式及其临界高度[J].地球物理学报,2006,49(2):518-523.Qi Sh W.Two patterns of dynamic responses ofsingle free surface slopes and their threshold height[J].Chinese Journal of Geophysics,2006,49(2):518-523.
[14]祁生文,伍法权.边坡动力响应规律研究[J].中国科学(E辑,技术科学),2003,33(增):28-40.Qi Sh W,W F Q.Study on the regularity of dynamicresponse for slope[J].Science in China,Series E,2003,33(S):28-40.
[15]张鲁渝,郑颖人,赵尚毅,等.有限元强度折减系数法计算土坡稳定安全系数的精度研究[J].水利学报,2003,(1):21-26.Zhang L Y,Zheng Y R,Zhao Sh Y,et al.Thefeasibility study of strength-reduction method withFEM for calculating safety factors of soil slopestability[J].Journal of Hydraulic Engineering,2003,(1):21-26.
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