高频次微小地震下顺倾软硬互层边坡动力稳定性研究
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摘要
三峡库区(TGR)自蓄水以来微震活动加剧、强度增大,频发微震会对库区边坡产生一定影响。采用振动台模型试验和UDEC数值模拟方法,对库区顺倾软硬互层边坡在不断微、小地震作用下的破坏失稳演化过程及动力稳定性进行了研究。研究成果如下:在不断地震作用后,边坡自振频率下降、阻尼比上升,自振频率下降的速度随加载次数和加载幅值的增加而增大;在不同加载阶段,边坡坡面PGA放大系数不断降低,动力响应呈现减弱趋势;弱层成为顺倾软硬互层边坡变形破坏的优势区域;边坡的破坏失稳演化过程为分段式的滑移破坏过程,上部软、硬层滑落后,剩余滑体沿着由上部弱层剪切裂缝、中部硬层次级节理拉裂缝和下部弱层剪切裂缝贯通形成的滑移面滑移破坏;UDEC数值模拟表明顺倾软硬互层边坡的累积永久位移随微震作用次数的增加而增加,稳定性系数则呈现递减趋势。研究成果对库区滑坡形成机制的认识和减灾、防灾有一定的价值。
Since the impounding of Three Gorges Reservoir(TGR), the microseismic activity is intensified and the earthquake intensity is increased. The high-frequency microseisms induced by TGR will have some influence on the slopes. The evolution process of failure and dynamic stability are studied based on the shaking table tests and UDEC numerical analysis method. The results are as follows: the natural frequencies decrease with the loading times, while the damping ratios increase. The descending rate of the frequencies increases with the loading times and earthquake amplitude. The PGA magnification factors decrease at different loading stages, showing that the dynamic response becomes weaker. The soft layers tend to be the dominant areas where shear failure occurs in the slopes. The whole model slope eventually presents a segmented failure process,whose upper part of soft and hard layers slides and then the slope slides along the transfixion surface forming with the shear fracture in the upper soft layer, tension fracture of secondary joint in the intermediate hard layer and shear fracture in the lower soft layer. UDEC numerical simulation shows that the permanent displacement increases with the loading times, while the stability coefficient decreases. The research results are of some value to the understanding of the formation mechanism of reservoir landslides and the prevention of disasters.
Since the impounding of Three Gorges Reservoir(TGR), the microseismic activity is intensified and the earthquake intensity is increased. The high-frequency microseisms induced by TGR will have some influence on the slopes. The evolution process of failure and dynamic stability are studied based on the shaking table tests and UDEC numerical analysis method. The results are as follows: the natural frequencies decrease with the loading times, while the damping ratios increase. The descending rate of the frequencies increases with the loading times and earthquake amplitude. The PGA magnification factors decrease at different loading stages, showing that the dynamic response becomes weaker. The soft layers tend to be the dominant areas where shear failure occurs in the slopes. The whole model slope eventually presents a segmented failure process,whose upper part of soft and hard layers slides and then the slope slides along the transfixion surface forming with the shear fracture in the upper soft layer, tension fracture of secondary joint in the intermediate hard layer and shear fracture in the lower soft layer. UDEC numerical simulation shows that the permanent displacement increases with the loading times, while the stability coefficient decreases. The research results are of some value to the understanding of the formation mechanism of reservoir landslides and the prevention of disasters.
引文
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[14]江洎洧.频发微震作用下三峡库首段典型滑坡变形机制及动力响应研究[D].北京:中国地质大学,2012.(JIANGJi-wei.Research on the deformation mechanism and dynamic response of typical landslides in three gorges reservoir in case of frequent microseisms[D].Beijing:China University of Geosciences,2012.(in Chinese))
[15]LI D L,LIU X R,LI X W,et al.The impact of microearthquakes induced by reservoir water level rise on stability of rock slope[J].Shock and Vibration,2016(2):1-13.
[16]陈剑,李晓,杨志法.三峡库区滑坡的时空分布特征与成因探讨[J].工程地质学报,2005,13(3):305-309.(CHEN Jian,LI Xiao,YANG Zhi-fa.On the distribution and mechanism of landslides in the Three Gorges Reservoir Area[J].Journal of Engineering Geology,2005,13(3):305-309.(in Chinese))
[17]杨达源,李徐生,柯贤坤,等.长江三峡坝区河谷深槽的地貌特征及其成因[J].地理学报,2002,57(5):547-552.(YANG Da-yuan,LI Xu-sheng,KE Xian-kun,et al.Geomorphic features and origin of the valley bottom troughs at the site of three gorges dam[J].Acta Geographica Sinica,2002,57(5):547-552.(in Chinese))
[18]李祥龙,唐辉明.逆层岩质边坡地震动力破坏离心机试验研究[J].岩土工程学报,2014,36(4):687-694.(LIXiang-long,TANG Hui-ming.Dynamic centrifugal modelling tests on toppling rock slopes[J].Chinese Journal of Geotechnical Engineering,2014,36(4):687-694.(in Chinese))
[19]刘汉香.基于振动台试验的岩质斜坡地震动力响应规律研究[D].成都:成都理工大学,2014.(LIU Han-xiang.Seismic responses of rock slopes in a shaking table test[D].Chengdu:Chengdu University of Technology,2014.(in Chinese))
[20]BRAND L.The Pi theorem of dimensional analysis[J].Archive for Rational Mechanics&Analysis,1957,1(1):35-45.
[21]曹树谦.振动结构模态分析:理论、实验与应用[M].天津:天津大学出版社,2001.(CAO Shu-qian.Modal analysis of vibration structure:theory,experiment and application[M].Tianjin:Tianjin University Press,2001.(in Chinese))
[2]李守定,李晓,吴疆,等.大型基岩顺层滑坡滑带形成演化过程与模式[J].岩石力学与工程学报,2007,26(12):2473-2480.(LI Shou-ding,LI Xiao,WU Jiang,et al.Evolution process and pattern of sliding zone in large consequent bedding rock landslide[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(12):2473-2480.(in Chinese))
[3]殷跃平.三峡库区边坡结构及失稳模式研究[J].工程地质学报,2005,13(2):145-154.(YIN Yue-ping.Human-cutting slope structure and failure pattern at the Three Gorge Reservoir[J].Journal of Engineering Geology,2005,13(2):145-154.(in Chinese))
[4]李愿军,黄国良.对水库诱发地震的两点认识[J].震灾防御技术,2008,3(1):61-71.(LI Yuan-jun,HUANGGuo-liang.Some thoughts on reservoir-induced earthquakes[J].Technology for Earthquake Disaster Prevention,2008,3(1):61-71.(in Chinese))
[5]罗佳宏.长江三峡库区三维速度成像与微震活动性研究[D].北京:中国地震局地质研究所,2016.(LUO Jia-hong.Astudy on the three-dimensional velocity structure imaging from tomography and micro seismicity in the three gorges reservoir area[D].Beijing:Institute of Geology,China Earthquake Administration,2016.(in Chinese))
[6]NAPIER J A L,PCIRCC A P.The use of a multiple expansion techniques to analyze large scale fracture process and seismic recurrence effects in deep level mines[J].International Journal of Rock Mechanics&Mining Sciences,1997,34(3/4):680-691.
[7]HAO H,WU C H,ZHOU Y X.Numerical analysis of blast-induced stress waves in a rock mass with anisotropic continuum damage models:part l equivalent material property approach[J].Rock Mechanics and Rock Engineering,2002,35(2):79-93.
[8]刘蕾,陈亮,崔振华,等.逆层岩质边坡地震动力破坏过程FLAC/PFC2D耦合数值模拟分析[J].工程地质学报,2014,22(6):1257-1262.(LIU Lei,CHEN Liang,CUIZhen-hua,et al.FLAC/PFC2D hybrid simulation for seismically induced failure process of toppling rock slope[J].Journal of Engineering Geology,2014,22(6):1257-1262.(in Chinese))
[9]胡训健,卞康,李鹏程,等.水平厚层状岩质边坡地震动力破坏过程颗粒流模拟[J].岩石力学与工程学报,2017,36(9):2156-2168.(HU Xun-jian,BIAN Kang,LIPeng-cheng,et al.Simulation of dynamic failure process of horizontal thick-layered rock slopes using particle flow code[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(9):2156-2168.(in Chinese))
[10]简文彬,洪儒宝,樊秀峰,等.循环荷载下节理岩体边坡动力响应的试验研究[J].岩石力学与工程学报,2016,35(12):2409-2416.(JIAN Wen-bin,HONG Ru-bao,FANXiu-feng,et al.Experimental study of dynamic response of jointed rock slopes under cyclic loads[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(12):2409-2416.(in Chinese))
[11]刘汉香,许强,范宣梅,等.地震动强度对斜坡加速度动力响应规律的影响[J].岩土力学,2012,33(5):41-47.(LIU Han-xiang,XU Qiang,FAN Xuan-mei1,et al.Influence of ground motion intensity on dynamic response laws of slope accelerations[J].Rock and Soil Mechanics,2012,33(5):41-47.(in Chinese))
[12]毛文涛.顺层岩质边坡动力破坏机制振动台试验研究[D].成都:西南交通大学,2017.(MAO Wen-tao.The shaking table test study of dynamic failure mechanism of bedding rock slope[D].Chengdu:Southwest Jiaotong University,2017.(in Chinese))
[13]刘云鹏,邓辉,黄润秋,等.反倾软硬互层岩体边坡地震响应的数值模拟研究[J].水文地质工程地质,2012,39(3):30-37.(LIU Yun-peng,DENG Hui,HUANGRun-qiu,et al.Numerical simulation of seismic response of antidumping rock slop interbedded by hard and soft layers[J].Hydrogeology&Engineering Geology,2012,39(3):30-37.(in Chinese))
[14]江洎洧.频发微震作用下三峡库首段典型滑坡变形机制及动力响应研究[D].北京:中国地质大学,2012.(JIANGJi-wei.Research on the deformation mechanism and dynamic response of typical landslides in three gorges reservoir in case of frequent microseisms[D].Beijing:China University of Geosciences,2012.(in Chinese))
[15]LI D L,LIU X R,LI X W,et al.The impact of microearthquakes induced by reservoir water level rise on stability of rock slope[J].Shock and Vibration,2016(2):1-13.
[16]陈剑,李晓,杨志法.三峡库区滑坡的时空分布特征与成因探讨[J].工程地质学报,2005,13(3):305-309.(CHEN Jian,LI Xiao,YANG Zhi-fa.On the distribution and mechanism of landslides in the Three Gorges Reservoir Area[J].Journal of Engineering Geology,2005,13(3):305-309.(in Chinese))
[17]杨达源,李徐生,柯贤坤,等.长江三峡坝区河谷深槽的地貌特征及其成因[J].地理学报,2002,57(5):547-552.(YANG Da-yuan,LI Xu-sheng,KE Xian-kun,et al.Geomorphic features and origin of the valley bottom troughs at the site of three gorges dam[J].Acta Geographica Sinica,2002,57(5):547-552.(in Chinese))
[18]李祥龙,唐辉明.逆层岩质边坡地震动力破坏离心机试验研究[J].岩土工程学报,2014,36(4):687-694.(LIXiang-long,TANG Hui-ming.Dynamic centrifugal modelling tests on toppling rock slopes[J].Chinese Journal of Geotechnical Engineering,2014,36(4):687-694.(in Chinese))
[19]刘汉香.基于振动台试验的岩质斜坡地震动力响应规律研究[D].成都:成都理工大学,2014.(LIU Han-xiang.Seismic responses of rock slopes in a shaking table test[D].Chengdu:Chengdu University of Technology,2014.(in Chinese))
[20]BRAND L.The Pi theorem of dimensional analysis[J].Archive for Rational Mechanics&Analysis,1957,1(1):35-45.
[21]曹树谦.振动结构模态分析:理论、实验与应用[M].天津:天津大学出版社,2001.(CAO Shu-qian.Modal analysis of vibration structure:theory,experiment and application[M].Tianjin:Tianjin University Press,2001.(in Chinese))
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