地形地貌对地震波放大效应数值模拟研究
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摘要
采用FLAC3D软件进行大量数值模拟,研究了地形地貌对地震波放大效应规律。结果表明:对于单面坡模型,斜坡较低时,坡体对天然地震波和简谐波的峰值加速度在竖直向和顺坡面向产生线性放大效应。斜坡较高时,若坡角低,两种波形的加速度等值线近似平行于坡面,天然地震波坡顶正下方极值性不明显,但随坡角增大而明显,坡面正下方可见若干条与坡面相平行具节律性的极小值条带,随坡角增大向一条极值带转化,简谐波在高低坡脚时坡顶面正下方区域内都出现等间距相间分布具节律性的极值条带,坡面正下方的极值带状性不如天然地震波明显,随坡角增大而消失;若坡角高,两波形加速度放大系数顺坡面呈相间的极值圈分布。双面坡坡顶宽度越小,山脊越单薄,加速度放大效应越强烈,随坡顶宽度增大,坡肩加速度放大系数趋于稳定,双面坡对加速度放大效应强于单面坡。对加速度放大效应,多峰形>双峰形>单峰形,坡顶越不规则,加速度放大效应越强烈。V形河谷坡面上半部分加速度放大效应要强于U形河谷,U形河谷的谷底中部对地震波动力响应要强于V形谷。坡面局部不规则性只影响到坡面局部范围内的峰值加速度分布,坡高、坡角、坡顶几何特征为整个峰值加速度分布的控制因素。
Many numerical analyses are carried out using the software Flac3 Dto investigate the amplification effect of topography and geomorphology on seismic waves. Research findings indicate that both the peak acceleration of natural seismic wave and harmonic wave can be amplified linearly in the vertical direction and along the surface of the slope when the single-sided slope is low. When the single-sided slope is high and the slope angle is small,the acceleration contour lines of the two waveforms can be parallel to the slope surface approximately. At the same time,the effect of extremum under the top of the single-sided slope is unobvious,and becomes more obvious withthe slope angle increasing and there are some rhythmical local minimum strips which are parallel to the slope surface and have the tend to become one strip with the slope angle increasing for natural seismic waves. There are some rhythmical local minimum strips which are parallel to the slope surface for harmonic wave no matter the slope angle is low or high and the effect of extremum under the top of the single-sided slope is not as obvious as natural seismic waves and can disappear with the slope angle increasing. When the slope angle is high,there are some extremal circles in the peak acceleration profiles along the slope surface. The amplification effect on peak acceleration is more intense for thinner ridge of the two-sided slope. The amplification coefficient of crest of two-sided slope tends to be a stable value with the width of the two-sided slope increasing. The amplification effect of two-sided slope on peak acceleration is more intense than the single-sided slope. The amplification effect of multimodal slope on peak acceleration is more intense than that of bimodal slope and the amplification effect of bimodal slope on peak acceleration is more intense than that of unimodal slope. The amplification effect on peak acceleration is more obvious on the upper half of the V-shaped valley than that of U-shaped valley. However,the dynamic response on the middle bottom of U-shaped valley is stronger than that of U-shaped valley. The local irregularities on the surface of a slope can only have effect on the local distribution of peak acceleration near the surface of the slope. The key factors to the distribution of peak acceleration are slope height,slope angle and geometry of the slope top.
Many numerical analyses are carried out using the software Flac3 Dto investigate the amplification effect of topography and geomorphology on seismic waves. Research findings indicate that both the peak acceleration of natural seismic wave and harmonic wave can be amplified linearly in the vertical direction and along the surface of the slope when the single-sided slope is low. When the single-sided slope is high and the slope angle is small,the acceleration contour lines of the two waveforms can be parallel to the slope surface approximately. At the same time,the effect of extremum under the top of the single-sided slope is unobvious,and becomes more obvious withthe slope angle increasing and there are some rhythmical local minimum strips which are parallel to the slope surface and have the tend to become one strip with the slope angle increasing for natural seismic waves. There are some rhythmical local minimum strips which are parallel to the slope surface for harmonic wave no matter the slope angle is low or high and the effect of extremum under the top of the single-sided slope is not as obvious as natural seismic waves and can disappear with the slope angle increasing. When the slope angle is high,there are some extremal circles in the peak acceleration profiles along the slope surface. The amplification effect on peak acceleration is more intense for thinner ridge of the two-sided slope. The amplification coefficient of crest of two-sided slope tends to be a stable value with the width of the two-sided slope increasing. The amplification effect of two-sided slope on peak acceleration is more intense than the single-sided slope. The amplification effect of multimodal slope on peak acceleration is more intense than that of bimodal slope and the amplification effect of bimodal slope on peak acceleration is more intense than that of unimodal slope. The amplification effect on peak acceleration is more obvious on the upper half of the V-shaped valley than that of U-shaped valley. However,the dynamic response on the middle bottom of U-shaped valley is stronger than that of U-shaped valley. The local irregularities on the surface of a slope can only have effect on the local distribution of peak acceleration near the surface of the slope. The key factors to the distribution of peak acceleration are slope height,slope angle and geometry of the slope top.
引文
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[6]李秀珍,孔纪名,崔云,等.汶川地震滑坡与地震参数及地质地貌因素之间的相关关系[J].工程地质学报,2010,18(1):8~14.Li Xiuzhen,Kong Jiming,Cui Yun,et al.Statistical relations between landslides induced by Wenchuan earthquake and earthquake parameters,geological as well as geomorphological factors[J].Journal of Engineering Geology,2010,18(1):8~14.
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[9]祁生文.单面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 Shengwen.Two patterns of dynamic response of single-freesurface slopes and their threshold height[J].Chinese Journal of Geophysics,2006,49(2):518~523.
[10]王海云,谢礼立.自贡市西山公园地形对地震动的影响[J].地球物理学报,2010,53(7):1631~1638.Wang Haiyun,Xie Lili.Effects of topography on the ground motion in the Xishan park,Zigong city[J].Chinese Journal of Geophysics,2010,53(7):1631~1638.
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[12]罗永红,王运生.汶川地震诱发山地斜坡振动的地形放大效应[J].山地学报,2013,31(2):200~210.Luo Yonghong,Wang Yunsheng.Mountain slope ground motion topography amplification effect induced by Wenchuan earthquake[J].Journal of Mountain Science,2013,31(2):200~210.
[13]杨国香,伍法权,董金玉,等.地震作用下岩质边坡动力响应特性及变形破坏机制研究[J].岩石力学与工程学报,2012,31(4):696~702.Yang Guoxiang,Wu Faquan,Dong Jinyu,et al.Study of dynamic response characters and failure mechanism of rock slope under earthquake[J].Chinese Journal of Rock Mechanics and Engineering,2013,31(4):696~702.
[14]杨国香,叶海林,伍法权,等.反倾层状结构岩质边坡动力响应特性及破坏机制振动台模型试验研究[J].岩石力学与工程学报,2012,31(11):2214~2221.Yang Guoxiang,Ye Hailin,Wu Faquan,et al.Shaking table model test on dynamic response Characteristics and failure mechanism of antidip layered rock slope[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(11):2214~2221.
[15]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试验研究[J].岩土力学,2011,32(10):2977~2982,2988.Dong Jinyu,Yang Guoxiang,Wu Faquan,et al.The large-scale shaking table test study of dynamic response and failure mode of bedding rock slope under earthquake[J].Rock and soil Mechanics,2011,32(10):2977~2982,2988.
[16]刘汉香,许强,范宣梅,等.地震动强度对斜坡动力响应规律的影响[J].岩土力学,2012,33(5):1357~1365.Liu Hanxiang,Xu Qiang,Fan Xuanmei,et al.Influence of ground motion intensity on dynamic response laws of slope accelerations[J].Rock and Soil Mechanics,2012,33(5):1357~1365.
[17]Itasca Consulting Group,Inc.Flac3D3.0 User's Manual[Z].Minneapolis,USA:Itasca Consulting Group,Inc.,2005.
[2]Murphy W.The role of topographic amplification on the iniation of rock slopes failures during earthquake[A]∥Evans S G,Mugnozza G S,Strom A,et al.Landslides from Massive Rock Slope Failure[C].Celano,Italy:2006,49(2):139~154.
[3]Mitani Yasuhiro,Wang Fawu,Austin Chukwueloka Okeke,et al.Dynamic analysis of earthquake amplification effect of slopes in different topographic and geological conditions by using ABAQUS[J].Environmental Science and Engineering,2013,doi:10.1007/978-3-642-29107-4_27.
[4]Peng W F,Wang C L,Chen S T,et al.Incorporating the effects of topographic amplification and sliding areas in the modeling of earthquake-induced landslide hazards,using the cumulative displacement method[J].Computers&Geosciences,2009,35(5):946~966.
[5]侯景瑞,袁中夏.汶川地震滑坡与影响因素[J].西北地震学报,2011,33(增刊),:398~402.Hou Jingrui,Yuan Zhongxia.Influence factors of the landslides caused by Wenchuan earthquake[J].Northwestern Seismological Journal,2011,33(S):398~402.
[6]李秀珍,孔纪名,崔云,等.汶川地震滑坡与地震参数及地质地貌因素之间的相关关系[J].工程地质学报,2010,18(1):8~14.Li Xiuzhen,Kong Jiming,Cui Yun,et al.Statistical relations between landslides induced by Wenchuan earthquake and earthquake parameters,geological as well as geomorphological factors[J].Journal of Engineering Geology,2010,18(1):8~14.
[7]宋胜武.汶川大地震工程震害调查分析与研究[M].北京:科学出版社,2009.Song Shengwu.Engineering seismic damage survey analysis and research about Wenchuan Earthquake[M].Beijing:Science Press,2009.
[8]祁生文,伍法权,孙进忠.边坡动力响应规律研究[J].中国科学(E辑),2003,33(增):28~40.Qi Shengwen,Wu Faquan,Sun Jinzhong.Study on dynamic response of slope[J].Science in China(Series E),2003,33(S):28~40.
[9]祁生文.单面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 Shengwen.Two patterns of dynamic response of single-freesurface slopes and their threshold height[J].Chinese Journal of Geophysics,2006,49(2):518~523.
[10]王海云,谢礼立.自贡市西山公园地形对地震动的影响[J].地球物理学报,2010,53(7):1631~1638.Wang Haiyun,Xie Lili.Effects of topography on the ground motion in the Xishan park,Zigong city[J].Chinese Journal of Geophysics,2010,53(7):1631~1638.
[11]罗永红.地震作用下复杂斜坡动力响应规律研究[博士学位论文][D].成都:成都理工大学,2011.Luo Yonghong.Study on Complex Slopes Response Law under Earthquake Action[Doctorate Thesis][D].Chengdu:Chengdu University of Technology,2011.
[12]罗永红,王运生.汶川地震诱发山地斜坡振动的地形放大效应[J].山地学报,2013,31(2):200~210.Luo Yonghong,Wang Yunsheng.Mountain slope ground motion topography amplification effect induced by Wenchuan earthquake[J].Journal of Mountain Science,2013,31(2):200~210.
[13]杨国香,伍法权,董金玉,等.地震作用下岩质边坡动力响应特性及变形破坏机制研究[J].岩石力学与工程学报,2012,31(4):696~702.Yang Guoxiang,Wu Faquan,Dong Jinyu,et al.Study of dynamic response characters and failure mechanism of rock slope under earthquake[J].Chinese Journal of Rock Mechanics and Engineering,2013,31(4):696~702.
[14]杨国香,叶海林,伍法权,等.反倾层状结构岩质边坡动力响应特性及破坏机制振动台模型试验研究[J].岩石力学与工程学报,2012,31(11):2214~2221.Yang Guoxiang,Ye Hailin,Wu Faquan,et al.Shaking table model test on dynamic response Characteristics and failure mechanism of antidip layered rock slope[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(11):2214~2221.
[15]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试验研究[J].岩土力学,2011,32(10):2977~2982,2988.Dong Jinyu,Yang Guoxiang,Wu Faquan,et al.The large-scale shaking table test study of dynamic response and failure mode of bedding rock slope under earthquake[J].Rock and soil Mechanics,2011,32(10):2977~2982,2988.
[16]刘汉香,许强,范宣梅,等.地震动强度对斜坡动力响应规律的影响[J].岩土力学,2012,33(5):1357~1365.Liu Hanxiang,Xu Qiang,Fan Xuanmei,et al.Influence of ground motion intensity on dynamic response laws of slope accelerations[J].Rock and Soil Mechanics,2012,33(5):1357~1365.
[17]Itasca Consulting Group,Inc.Flac3D3.0 User's Manual[Z].Minneapolis,USA:Itasca Consulting Group,Inc.,2005.
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