汶川强震区公路沿线地震崩滑灾害发育规律研究
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摘要
汶川强震区地处龙门山区,在深切河谷地貌条件下,地震诱发大量崩塌及滑坡地质灾害,给沿河谷布线的公路造成严重损毁。在调查掌握约6 056 km灾区公路沿线地震崩滑灾害详细资料基础上,根据地质构造、地震烈度进行段落划分,研究分析各段灾害特征及其与地质构造部位、地震烈度、岩性等之间的关系,统计分析各段落灾害点密度及平均规模。提出汶川地震崩滑灾害分区,将受灾区划分为极强烈发育区、强烈发育区、较强烈发育区、中等发育区和弱发育区等5个区域。得出汶川地震崩滑灾害如下发育规律:(1)3条断裂带对崩滑灾害发育的控制作用:前山断裂都江堰—竹园坝段为山前弱发育区和上盘中等～强烈发育区的明显界线,竹园坝NE方向则控制作用减弱;中央主断裂自映秀至东河口段上下盘灾害有显著差异,2个极强烈发育区均位于上盘,且被后山断裂及重要岩性界线所严格限制,东河口NE方向控制作用减弱;后山断裂之茂汶断裂为极强烈发育区和较强烈发育区的明显界线;后山断裂之青川—平武断裂在青川—沙洲段呈现出明显的断层上盘效应。(2)岩性控制作用:不同岩性类别地震崩滑灾害发育程度有显著差异,侵入岩体和灰岩、白云岩类地震地质灾害发育密度最高、平均规模最大,千枚岩类灾害发育密度最低、规模最小,碎屑岩类和砂板岩类介于其间。(3)地貌控制作用:河谷岸坡相对高差越大、地面横坡越陡峻,地震崩滑灾害越发育。陡坡硬岩段为地震崩滑灾害高发区,失稳主要发生在斜坡中上部、陡缓变坡点附近。(4)399条实测地质剖面的统计分析表明,地震诱发崩塌失稳部位坡度一般在40°以上。(5)动力条件下,坡体结构是边坡岩土体变形破坏的控制性因素,土层及强风化层-基岩斜坡、发育外倾结构面斜坡更易失稳。
The highly seismic region of Wenchuan earthquake locates in the Longmeng mountainous area,due to the landform condition of deep valleys,the earthquake induced a large numbers of landslide and collapse disasters.The disasters caused serious damage to the roads along the river valley.After the earthquake,site investigation on earthquake-induced landslide and collapse had been conducted along the highway with a total length about 6 056 km.According to geologic tectonics and seismic intensity,the studied area is divided into different sections.In this paper,the seismic landslide and collapse characteristics of each section is summarized and their relationship with the tectonic position,seismic intensity and lithology,the density and average scale of the geological hazards are calculated.According the density and the scale,the whole area is divided into five subareas,i.e.the strongest-developed area,the stronger-developed area,the strong-developed area,the medium-developed area and the less-developed area.The development rules of the earthquake-induced landslide and collapse are shown as follows:(1) Three deep fault zones controlled the distribution of hazards.The Dujiangyan—Zhuyuanba section of the front fault is the clear boundary of less-developed area of the footwall and medium-and strong-developed areas of the hanging wall;but there is not clear boundary at the NE direction of Zhuyuanba.There are significant differences on the two sides of the central fault from Yingxiu to Donghekou.The two strongest-developed areas are all on the hanging wall and strictly limited by the back fault and lithologic boundary;but the boundaries is not clear at the NE direction of Dongkehou.The Maoxian—Wenchuan fault,which is one of the back fault,is the clear boundary of the strongest-developed area and stronger-developed area.The Qingchuan—Pingwu fault,which is one of the back fault,shows a clear effect of hanging wall at the Qingchuan to Shazhou section.(2) There are significant differences among different lithologies.The hazards with the highest density and average largest scale occur in intrusive rocks and hard sedimentary rocks like limestone and dolomite,while those with the lowest density and smallest scale occur in phyllite.Sandy slate and petroclastic rock are in the middle level.(3) There are significant differences among different landforms.The steeper and greater the relative altitude of salley slope is,more developed the disasters are.The positions of steep slope and hard rock are the high incidence area of seismic landslide and collapse;and the failure position of slopes mainly distribute on the upside of slopes,near the point of gradient change.(4) The statistical results of 399 geological sections show the slope gradients of collapse are larger than 40°.(5) Under dynamic conditions,the slope structures have important controlling effect on the development of geological hazards.Generally,soil slopes,strong-weathered rock slopes and slopes with outward-inclined discontinuities are easier to failure.
The highly seismic region of Wenchuan earthquake locates in the Longmeng mountainous area,due to the landform condition of deep valleys,the earthquake induced a large numbers of landslide and collapse disasters.The disasters caused serious damage to the roads along the river valley.After the earthquake,site investigation on earthquake-induced landslide and collapse had been conducted along the highway with a total length about 6 056 km.According to geologic tectonics and seismic intensity,the studied area is divided into different sections.In this paper,the seismic landslide and collapse characteristics of each section is summarized and their relationship with the tectonic position,seismic intensity and lithology,the density and average scale of the geological hazards are calculated.According the density and the scale,the whole area is divided into five subareas,i.e.the strongest-developed area,the stronger-developed area,the strong-developed area,the medium-developed area and the less-developed area.The development rules of the earthquake-induced landslide and collapse are shown as follows:(1) Three deep fault zones controlled the distribution of hazards.The Dujiangyan—Zhuyuanba section of the front fault is the clear boundary of less-developed area of the footwall and medium-and strong-developed areas of the hanging wall;but there is not clear boundary at the NE direction of Zhuyuanba.There are significant differences on the two sides of the central fault from Yingxiu to Donghekou.The two strongest-developed areas are all on the hanging wall and strictly limited by the back fault and lithologic boundary;but the boundaries is not clear at the NE direction of Dongkehou.The Maoxian—Wenchuan fault,which is one of the back fault,is the clear boundary of the strongest-developed area and stronger-developed area.The Qingchuan—Pingwu fault,which is one of the back fault,shows a clear effect of hanging wall at the Qingchuan to Shazhou section.(2) There are significant differences among different lithologies.The hazards with the highest density and average largest scale occur in intrusive rocks and hard sedimentary rocks like limestone and dolomite,while those with the lowest density and smallest scale occur in phyllite.Sandy slate and petroclastic rock are in the middle level.(3) There are significant differences among different landforms.The steeper and greater the relative altitude of salley slope is,more developed the disasters are.The positions of steep slope and hard rock are the high incidence area of seismic landslide and collapse;and the failure position of slopes mainly distribute on the upside of slopes,near the point of gradient change.(4) The statistical results of 399 geological sections show the slope gradients of collapse are larger than 40°.(5) Under dynamic conditions,the slope structures have important controlling effect on the development of geological hazards.Generally,soil slopes,strong-weathered rock slopes and slopes with outward-inclined discontinuities are easier to failure.
引文
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[9]祁生文,许强,刘春玲,等.汶川地震极重灾区地质背景及次生斜坡灾害空间发育规律[J].工程地质学报,2009,17(1):39-49.(QIShengwen,XU Qiang,LIU Chunling,et al.Geological backgroundin the severest disaster areas of 5.12 Wenchuan earthquake and spatialdistribution of earthquake-induced slope instabilities[J].Journal ofEngineering Geology,2009,17(1):39-49.(in Chinese))
[10]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.(LIXiuzhen,KONG Jiming,CUI Yun,et al.Statistical relations betweenlandslides induced by Wenchuan earthquake and earthquakeparameters,geological as well as geomorphological factors[J].Journalof Engineering Geology,2010,18(1):8-14.(in Chinese))
[11]殷跃平.汶川八级地震地质灾害研究[J].工程地质学报,2008,16(4):433-444.(YIN Yueping.Researches on the geohazardstriggered by Wenchuan earthquake,Sichuan[J].Journal of EngineeringGeology,2008,16(4):433-444.(in Chinese))
[12]程强,吴事贵,苏玉杰.映秀至卧龙公路沿线汶川地震地质灾害研究[J].工程地质学报,2010,18(2):160-167.(CHENG Qiang,WU Shigui,SU Yujie.Geological hazards due to Wenchuan earthquakealong Yingxiu to Wolong highway[J].Journal of Engineering Geology,2010,18(2):160-167.(in Chinese))
[13]谷德振.岩体工程地质力学基础[M].北京:科学出版社,1979:198-247.(GU Dezhen.Foundation of rock mass engineering geomechanics[M].Beijing:Science Press,1979:198-247.(in Chinese))
[14]孙广忠.岩体结构力学[M].北京:科学出版社,1988:182-251.(SUN Guangzhong.Rockmass structural mechanics[M].Beijing:Science Press,1988:182-251.(in Chinese))
[15]BUECH F,DAVIES T R,PETTINGA J R.The little red hill seismicexperimental study:topographic effects on ground motion at abedrock-dominated mountain edifice[J].Bulletin of the SeismologicalSociety of America,2010,100(5A):2 219-2 229.
[16]王秀英,聂高众,王登伟.利用强震记录分析汶川地震诱发滑坡[J].岩石力学与工程学报,2009,28(11):2 369-2 376.(WANG Xiuying,NIE Gaozhong,WANG Dengwei.Analysis of landslide induced byWenchuan earthquake by strong motion records[J].Chinese Journal ofRock Mechanics and Engineering,2009,28(11):2 369-2 376.(inChinese))
[2]周荣军,黄润秋,雷建成,等.四川汶川8.0级地震地表破裂与震害特点[J].岩石力学与工程学报,2008,27(11):2 173-2 183.(ZHOU Rongjun,HUANG Runqiu,LEI Jiancheng,et al.Surfacerupture and hazard characteristics of Wenchuan earthquake withmagnitude 8.0 in Sichuan province[J].Chinese Journal of RockMechanics and Engineering,2008,27(11):2 173-2 183.(in Chinese))
[3]唐永建,庄卫林,吉随旺,等.“5.12”汶川大地震四川灾区公路应急调查与抢通[M].北京:人民交通出版社,2008:1-15.(TANG Yongjian,ZHUANG Weilin,JI Suiwang,et al.Emergencyinvestigation and reopened of Sichuan highway in“5.12”Wenchuan earthquake[M].Beijing:China Communications Press,2008:1-15.(in Chinese))
[4]吉随旺,唐永建,胡德贵,等.四川省汶川地震灾区干线公路典型震害特征分析[J].岩石力学与工程学报,2009,28(6):1 250-1 260.(JI Suiwang,TANG Yongjian,HU Degui,et al.Analysis of typicalseismic damages of arterial highways in Wenchuan earthquake-induced hazard areas in Sichuan province[J].Chinese Journal of RockMechanics and Engineering,2009,28(6):1 250-1 260.(in Chinese))
[5]黄润秋,李为乐.“5.12”汶川大地震触发地质灾害的发育分布规律研究[J].岩石力学与工程学报,2008,27(12):2 585-2 592.(HUANG Runqiu,LI Weile.Research on development and distributionrules of geohazards induced by Wenchuan earthquake on 12th May,2008[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(12):2 585-2 592.(in Chinese))
[6]黄润秋,李为乐.汶川大地震触发地质灾害的断层效应分析[J].工程地质学报,2009,17(1):19-28.(HUANG Runqiu,LI Weile.Faulteffect analysis of geohazard triggered by Wenchuan earthquake[J].Journal of Engineering Geology,2009,17(1):19-28.(in Chinese))
[7]许强,李为乐.汶川地震诱发大型滑坡分布规律研究[J].工程地质学报,2010,18(6):818-826.(XU Qiang,LI Weile.Distributionof large-scale landslides induced by Wenchuan earthquake[J].Journalof Engineering Geology,2010,18(6):818-826.(in Chinese))
[8]王秀英,聂高众,王登伟.汶川地震诱发滑坡与地震动峰值加速度对应关系研究[J].岩石力学与工程学报,2010,29(1):82-89.(WANG Xiuying,NIE Gaozhong,WANG Dengwei.Research onrelationship between landslides and peak ground accelerations inducedby Wenchuan earthquake[J].Chinese Journal of Rock Mechanics andEngineering,2010,29(1):82-89.(in Chinese))
[9]祁生文,许强,刘春玲,等.汶川地震极重灾区地质背景及次生斜坡灾害空间发育规律[J].工程地质学报,2009,17(1):39-49.(QIShengwen,XU Qiang,LIU Chunling,et al.Geological backgroundin the severest disaster areas of 5.12 Wenchuan earthquake and spatialdistribution of earthquake-induced slope instabilities[J].Journal ofEngineering Geology,2009,17(1):39-49.(in Chinese))
[10]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.(LIXiuzhen,KONG Jiming,CUI Yun,et al.Statistical relations betweenlandslides induced by Wenchuan earthquake and earthquakeparameters,geological as well as geomorphological factors[J].Journalof Engineering Geology,2010,18(1):8-14.(in Chinese))
[11]殷跃平.汶川八级地震地质灾害研究[J].工程地质学报,2008,16(4):433-444.(YIN Yueping.Researches on the geohazardstriggered by Wenchuan earthquake,Sichuan[J].Journal of EngineeringGeology,2008,16(4):433-444.(in Chinese))
[12]程强,吴事贵,苏玉杰.映秀至卧龙公路沿线汶川地震地质灾害研究[J].工程地质学报,2010,18(2):160-167.(CHENG Qiang,WU Shigui,SU Yujie.Geological hazards due to Wenchuan earthquakealong Yingxiu to Wolong highway[J].Journal of Engineering Geology,2010,18(2):160-167.(in Chinese))
[13]谷德振.岩体工程地质力学基础[M].北京:科学出版社,1979:198-247.(GU Dezhen.Foundation of rock mass engineering geomechanics[M].Beijing:Science Press,1979:198-247.(in Chinese))
[14]孙广忠.岩体结构力学[M].北京:科学出版社,1988:182-251.(SUN Guangzhong.Rockmass structural mechanics[M].Beijing:Science Press,1988:182-251.(in Chinese))
[15]BUECH F,DAVIES T R,PETTINGA J R.The little red hill seismicexperimental study:topographic effects on ground motion at abedrock-dominated mountain edifice[J].Bulletin of the SeismologicalSociety of America,2010,100(5A):2 219-2 229.
[16]王秀英,聂高众,王登伟.利用强震记录分析汶川地震诱发滑坡[J].岩石力学与工程学报,2009,28(11):2 369-2 376.(WANG Xiuying,NIE Gaozhong,WANG Dengwei.Analysis of landslide induced byWenchuan earthquake by strong motion records[J].Chinese Journal ofRock Mechanics and Engineering,2009,28(11):2 369-2 376.(inChinese))
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