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
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摘要
5.12汶川大地震触发了大量的顺层岩质滑坡,对其进行研究很有必要。根据动力模型试验的相似关系,设计制作了1个坡角大于岩层倾角的尺寸(高×长×宽)为1.6 m×1.75 m×0.8 m的顺层模型边坡,并完成了大型振动台试验。试验结果表明,在坡体表面和内部竖直方向上,加速度放大系数随着坡体高程增加而增大,并且随着高程增加,加速度放大系数增大的速度加快;在坡体内同一高程上,坡面处的加速度放大系数大于一定水平深度坡体内部的加速度放大系数,表现出趋表效应;地震波输入频率对坡体动力响应有明显影响,随着频率的增加,越接近坡体的自振频率,加速度放大效应越显著;加速度放大系数随着输入波振幅的增加,总体上表现为递减趋势;通过和均质边坡振动台试验加速度监测数据对比,发现坡体结构对坡体加速度放大系数也有一定的影响,结构面对地震波的反射和折射作用加大了坡体加速度的放大效应。,对试验过程中坡体破坏特征的描述和分析发现,边坡的破坏模式为地震诱发-坡肩拉裂张开-坡面中部出现裂缝-裂缝贯通-发生高位滑坡-转化为碎屑流-堆积坡脚。研究成果对地震灾区滑坡形成机制的认识和减灾防灾有一定的价值。
It is necessary to study bedding rock landslides induced by "5?12" Wenchuan earthquake.According to the similar relationship of dynamic model test,a bedding model slope is built with a height of 1.6 m,length of 1.75 m,width of 0.8 m and a slope angle larger than the dip angle of the rock stratum.A large-scale shaking table test of the model slope is performed.The results show that amplification coefficients of the acceleration along slope surface and in vertical direction increase with the elevation increasing.And its increment speeds also increase with the elevation increasing.At the same elevation,the amplification coefficients of the acceleration on slope surface are larger than that in slope body.The input frequency of seismic waves has obvious effects on dynamic responses of slope.The amplification effect of acceleration enhances evidently with the frequency increasing and approach to the natural frequency of the model slope.The amplification coefficients of the acceleration decrease with the earthquake amplitudes increasing.Comparing with the acceleration monitoring data obtained by the shaking table test of the homogeneous slope,it is found that structural surface of the slope also has effects on the amplification coefficients of the acceleration.Because of reflection and refraction of structural surface,the amplification effect of acceleration enhances evidently.Based on analysis of failure features of the slope,the failure process is described as earthquake induction-loosening of rock mass and tensile failure of the crest of the slope-propagation and coalescence of cracks in the middle part of slope surface-occurrence of high locality landslide-formation of debris flow-accumulation at the slope toe.The study results are helpful to reveal the formation mechanism of landslide under earthquake and provide valuable references for disaster prevention and reduction.
It is necessary to study bedding rock landslides induced by "5?12" Wenchuan earthquake.According to the similar relationship of dynamic model test,a bedding model slope is built with a height of 1.6 m,length of 1.75 m,width of 0.8 m and a slope angle larger than the dip angle of the rock stratum.A large-scale shaking table test of the model slope is performed.The results show that amplification coefficients of the acceleration along slope surface and in vertical direction increase with the elevation increasing.And its increment speeds also increase with the elevation increasing.At the same elevation,the amplification coefficients of the acceleration on slope surface are larger than that in slope body.The input frequency of seismic waves has obvious effects on dynamic responses of slope.The amplification effect of acceleration enhances evidently with the frequency increasing and approach to the natural frequency of the model slope.The amplification coefficients of the acceleration decrease with the earthquake amplitudes increasing.Comparing with the acceleration monitoring data obtained by the shaking table test of the homogeneous slope,it is found that structural surface of the slope also has effects on the amplification coefficients of the acceleration.Because of reflection and refraction of structural surface,the amplification effect of acceleration enhances evidently.Based on analysis of failure features of the slope,the failure process is described as earthquake induction-loosening of rock mass and tensile failure of the crest of the slope-propagation and coalescence of cracks in the middle part of slope surface-occurrence of high locality landslide-formation of debris flow-accumulation at the slope toe.The study results are helpful to reveal the formation mechanism of landslide under earthquake and provide valuable references for disaster prevention and reduction.
引文
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[14]徐光兴,姚令侃,高召宁,等.斜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 Guang-xing,YAO Ling-kan,GAO Zhao-ning,et al.Large-scale shaking table model test study on dynamiccharacteristics and dynamic responses of slope[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(3):624-632.
[15]许强,刘汉香,邹威,等.斜坡加速度动力响应特性的大型振动台试验研究[J].岩石力学与工程学报,2010,29(12):2420-2428.XU Qiang,LIU Han-xiang,ZOU Wei,et al.Study onslope dynamic responses of accelerations by large-scaleshaking table test[J].Chinese Journal of RockMechanics and Engineering,2010,29(12):2420-2428.
[16]袁文忠.相似理论与静力学模型试验[M].成都:西南交通大学出版社,1998.
[17]林皋,朱彤,林蓓.结构动力模型试验的相似技巧[J].大连理工大学学报,2000,40(1):1-8.LIN Gao,ZHU Tong,LIN Bei.Similarity technique fordynamic structural model test[J].Journal of DalianUniversity of Technology,2000,40(1):1-8.
[2]SEED H B,CLOUGH R W.Earthquake resistance ofsloping core dam[J].Journal of the Soil Mechanics andFoundations Division,ASCE,1963,89(1):209-242.
[3]刘小生,王钟宁,汪小刚,等.面板坝大型振动台模型试验与动力分析[M].北京:中国水利水电出版社,2005.
[4]凌贤长,郭明珠,王东升,等.液化场地桩基桥梁震害响应大型振动台模型试验研究[J].岩土力学,2006,27(1):7-10.LING Xian-zhang,GUO Ming-zhu,WANG Dong-sheng,et al.Large-scale shaking table model test of seismicresponse of bridge of pile foundation in ground ofliquefaction[J].Rock and Soil Mechanics,2006,27(1):7-10.
[5]左熹,陈国兴,王志华,等.近远场地地震动作用下地铁车站结构地基液化效应的振动台试验[J].岩土力学,2010,31(12):3733-3740.ZUO Xi,CHEN Guo-xing,WANG Zhi-hua,et al.Shaking table on ground liquefaction effect of soil-metrostation structure under near-and-far field groundmotions[J].Rock and Soil Mechanics,2010,31(12):3733-3740.
[6]王思敬.岩石边坡动态稳定性的初步探讨[J].地质科学,1977,(4):372-376.WANG Si-jing.Preliminary notes on the dynamicstability of rock slopes[J].Chinese Journal of Geology,1977,(4):372-376.
[7]王存玉,王思敬.斜坡模型振动试验研究[M]//岩体工程地质力学问题(七).北京:科学出版社,1987.
[8]WANG S J,ZHANG J M.On the dynamic stability ofblock sliding on rock slopes[C]//Proc.of the Int.Cont.onRecent Advances in Geotechnical Earthquake Engineeringand Soil Dynamics.Louis:[s.n.],1987:431-434.
[9]门玉明,彭建兵,李寻昌,等.层状结构岩质边坡动力稳定性试验研究[J].世界地震工程,2004,20(4):131-136.MEN Yu-ming,PENG Jian-bin,LI Xun-chang,et al.Research on vibration testing of models for dynamicstability of rock slope with layered structures[J].WorldEarthquake Engineering,2004,20(4):131-136.
[10]王勇智,戚炜,门玉明,等.大柳树坝址岩体松动机制物理模拟研究[J].西安科技大学学报,2004,24(3):305-308.WANG Yong-zhi,QI Wei,MEN Yu-ming,et al.Physicalsimulation of dynam-relaxed mechanism of rock mass atDaliushu dam site[J].Journal of Xi’an University ofScience and Technology,2004,24(3):305-308.
[11]王勇智,戚炜,门玉明,等.强震区岩体动力破坏机制研究[J].岩土力学,2005,26(11):1841-1844.WANG Yong-zhi,QI Wei,MEN Yu-ming,et al.Experimental research of dynamic failure mechanism ofrockmass in meizoseismal area[J].Rock and SoilMechanics,2005,26(11):1841-1844.
[12]郝建斌,门玉明,彭建兵,等.层状岩体边坡动力稳定性模型试验研究[J].公路交通科技,2005,22(6):72-75.HAO Jian-bin,MEN Yu-ming,PENG Jian-bin,et al.Research on dynamic stability of layered rocky slope withmodel test[J].Journal of Highway and TransportationResearch and Developmen,2005,26(6):72-75.
[13]许强,陈建君,冯文凯.斜坡地震响应的物理模拟试验研究[J].四川大学学报(工学版),2009,41(3):266-272.XU Qiang,CHEN Jian-jun,FENG Wen-kai,et al.Studyof the seismic response of slopes by physical modeling[J].Journal of Sichuan University(Engineering ScienceEdition),2009,41(3):266-272.
[14]徐光兴,姚令侃,高召宁,等.斜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 Guang-xing,YAO Ling-kan,GAO Zhao-ning,et al.Large-scale shaking table model test study on dynamiccharacteristics and dynamic responses of slope[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(3):624-632.
[15]许强,刘汉香,邹威,等.斜坡加速度动力响应特性的大型振动台试验研究[J].岩石力学与工程学报,2010,29(12):2420-2428.XU Qiang,LIU Han-xiang,ZOU Wei,et al.Study onslope dynamic responses of accelerations by large-scaleshaking table test[J].Chinese Journal of RockMechanics and Engineering,2010,29(12):2420-2428.
[16]袁文忠.相似理论与静力学模型试验[M].成都:西南交通大学出版社,1998.
[17]林皋,朱彤,林蓓.结构动力模型试验的相似技巧[J].大连理工大学学报,2000,40(1):1-8.LIN Gao,ZHU Tong,LIN Bei.Similarity technique fordynamic structural model test[J].Journal of DalianUniversity of Technology,2000,40(1):1-8.
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