岩质边坡动力失稳机制及数值模拟研究
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摘要
在分析岩质边坡动力破坏机制的基础上,采用FLAC3D方法,建立了四川震区理县至小金公路工程中豹子嘴岩质边坡三维数值模型.以永久位移作为评价指标,在对四川5.12汶川MS8.0大地震中理县地震台实测地震波校正的基础上,对该岩质边坡在地震荷载作用下的动力稳定性进行了数值模拟.计算结果表明,该岩质边坡在地震荷载作用下并未出现明显的拉应力区,主要以"压-剪"破坏模式为主,由于边坡内部分布的应力并不大,该边坡总体上仍为较稳定边坡;在地震荷载作用下,边坡位移呈现出明显的分层现象,位移分布总体上呈现由坡内向坡外、由坡底向坡顶逐步增大的趋势.考虑到地震动力作用下边坡的永久位移偏大,且边坡坡脚处出现了应力集中,应增设SNS主动防护网及矮脚墙进行防护.
Based on summarizing and analyzing the dynamic unstable mechanism of rock slope,three-dimensional numerical model for rock slope of Lixian-Xiaojin highway in Sichuan province was established by adopting FLAC3D.Based on permanent displacement as evaluation index,the measured seismic wave of Lixian seismic station in 5·12 Wenchuan earthquake with earthquake magnitude of MS8.0 was adopted to analyze dynamic stability for the slope.The calculation results show that obvious tension stress zones don't exist and main failure model is "press-shear" of the rock slope under earthquake wave.As stress of slope interior was not large,the rock slope was relatively stable.Under earthquake loads,displacement,the rock slope had layer phenomenon and displacement distribution trend was step-increasing from slope interior to slope surface and from slope toe to slope top.Considering the permanent displacement,the rock slope was relatively large and stress concentration occurred in slope toe under earthquake loads,the SNS active protection nets and dwarf foot walls were adopted to protect the rock slope.
Based on summarizing and analyzing the dynamic unstable mechanism of rock slope,three-dimensional numerical model for rock slope of Lixian-Xiaojin highway in Sichuan province was established by adopting FLAC3D.Based on permanent displacement as evaluation index,the measured seismic wave of Lixian seismic station in 5·12 Wenchuan earthquake with earthquake magnitude of MS8.0 was adopted to analyze dynamic stability for the slope.The calculation results show that obvious tension stress zones don't exist and main failure model is "press-shear" of the rock slope under earthquake wave.As stress of slope interior was not large,the rock slope was relatively stable.Under earthquake loads,displacement,the rock slope had layer phenomenon and displacement distribution trend was step-increasing from slope interior to slope surface and from slope toe to slope top.Considering the permanent displacement,the rock slope was relatively large and stress concentration occurred in slope toe under earthquake loads,the SNS active protection nets and dwarf foot walls were adopted to protect the rock slope.
引文
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[4]黄润秋.汶川8.0级地震触发崩滑灾害机制及其地质力学模式[J].岩石力学与工程学报,2009,28(6):1239-1249.(HUANG Run-qiu.Mechanism andgeomechanical modes of landslide hazards triggeredby wenchuan 8.0 earthquake[J].Chinese Journal ofRock Mechanics and Engineering,2009,28(6):1239-1249.(in Chinese))
[5]孙玉科,牟会宠,姚宝奎.边坡岩体稳定性分析[M].北京:科学出版社,1988.(SUN Yu-ke,MOU Hui-chong,YAO Bao-kui.Stable analysis for slope rockmass[M].Beijing:Science Press,1998.(in Chinese))
[6]孙广忠.工程地质与地质工程[M].北京:地震出版社,1993.(SUN Guang-zhong.Engineering geologyand geological engineering[M].Beijing:EarthquakePress,1993.(in Chinese))
[7]李铁汉,潘别桐.岩体力学[M].北京:地质出版社,1980.(LI Tie-han,PAN Bie-tong.Rock mechanics[M].Beijing:Geological Press,1980.(in Chinese))
[8]张倬元,王士天,王兰生.工程地质分析原理[M].北京:地质出版社,1981.(ZHANG Zhuo-yuan,WANGShi-tian,WANG Lan-sheng.Analysis theory for en-gineering geology[M].Beijing:Geological Press,1981.(in Chinese))
[9]Kuhlemeyer R L,Lysmer J.Finite element methodaccuracy for wave propagation problems[J].Journalof the Soil Mechanic Sand Foundations Division,1973,99(5):421-427.
[10]Itasca Consulting Group Inc.FLAC-3D(Fast La-grangian Analysis of Continua in 3 Dimensions),Version 2.00,Users Manual(Vol V)[R].[s.l.]:Itasca Consulting Group Inc,1997.
[11]Wilson R C,Keefer D K.A real limits of earth-quake-induced Landsliding[A].Evaluating Earth-quake Hazards in the Los Angeles Region[C].Washington,D C:US Government Printing Office,1985:316-345.
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