三峡库区大型滑坡发育机理
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摘要
体积超过1×107m3的大型滑坡是三峡库区主要地质灾害,其发育机理包括形成机理和诱发机理两方面。通过大量现场调查和观测,运用地貌学方法,揭示了三峡库区大型滑坡在地质历史时期的3种形成机理即危岩链式崩落、泥石流堆积和地震,所占比例分别约为70%、10%和20%;发现存在于斜坡表面的大量危岩链式崩落堆积物是形成大型滑坡的基本条件,滑坡类型主要属于堆积层滑坡,而地震作用主要形成基岩滑坡。通过大量室内土工试验和模型试验,揭示了滑坡目前的3种诱发机理即降雨软化滑坡土体、坡顶加载和坡脚切割或工程弃渣堆积等人类工程活动、库水位变化和滑坡体周期性浸泡等;其中前两类诱发机理主要出现在175 m水位以上大量城镇、交通干线及移民等工程建设区段,后一类诱发机理出现在库水位变动带内;位于库水位变动带的大型滑坡,滑坡土体被库水周期性浸泡,强度非线性衰减,同时,库水位降落期间在滑坡体内产生较大的渗透力,两者耦合作用,加速了库岸滑坡的变形与破坏过程。以上研究成果基本概括了三峡库区大型滑坡的主要发育机理。
Giant landslides over 1×107 m3 for a single landslide volume are dominant geological disasters in the area of the Three Gorges reservoir,whose developing mechanism include two aspects,i.e.,forming mechanism and triggering mechanism.Based on investigations in real-time field,forming mechanism of giant landslides in the area are revealed by using Geomorphology and are classified into chain avalanching of perilous rock,debris flow deposits,and earthquake,appearing about 70%,10% and 20% respectively.Meanwhile,lots of loose deposits sitting on slopes are initial conditions to form landslides,and almost all landslides are composed of loose deposits;while that by earthquake belongs to rock landslides.According to many geotechnical observations and physical simulations in laboratory,three triggering mechanisms of landslides are promulgated obviously,i.e,(1) softening landslide earth by precipitation;(2) unreasonable mankind actions,such as loading on top and cutting at foot of slope and engineering refuse dump,etc.;(3) variation between 145 m a.s.l.and 175 m a.s.l.of water level of the reservoir,and alternatively soaking of earth at the variation region.In the three mechanisms,the first and the second extensively appear in engineering construction sits,such as urban,roads and highways,villages of immigrants above 175 m a.s.l.,while the third plays a role frequently in landslides locating in the variation region.Giant landslides locating in the variation region are soaked by water of the reservoir totally or partially,so strength of earth is composed of the landslide attenuate by a big margin.Additionally,greater seepage forces exist in these landslides during descending of water level of the reservoir,and coupling both of the aspects speed up forming and rupture processes of landslides sitting on the slope.All results above reveal initially developing mechanisms of giant landslides in the area.
Giant landslides over 1×107 m3 for a single landslide volume are dominant geological disasters in the area of the Three Gorges reservoir,whose developing mechanism include two aspects,i.e.,forming mechanism and triggering mechanism.Based on investigations in real-time field,forming mechanism of giant landslides in the area are revealed by using Geomorphology and are classified into chain avalanching of perilous rock,debris flow deposits,and earthquake,appearing about 70%,10% and 20% respectively.Meanwhile,lots of loose deposits sitting on slopes are initial conditions to form landslides,and almost all landslides are composed of loose deposits;while that by earthquake belongs to rock landslides.According to many geotechnical observations and physical simulations in laboratory,three triggering mechanisms of landslides are promulgated obviously,i.e,(1) softening landslide earth by precipitation;(2) unreasonable mankind actions,such as loading on top and cutting at foot of slope and engineering refuse dump,etc.;(3) variation between 145 m a.s.l.and 175 m a.s.l.of water level of the reservoir,and alternatively soaking of earth at the variation region.In the three mechanisms,the first and the second extensively appear in engineering construction sits,such as urban,roads and highways,villages of immigrants above 175 m a.s.l.,while the third plays a role frequently in landslides locating in the variation region.Giant landslides locating in the variation region are soaked by water of the reservoir totally or partially,so strength of earth is composed of the landslide attenuate by a big margin.Additionally,greater seepage forces exist in these landslides during descending of water level of the reservoir,and coupling both of the aspects speed up forming and rupture processes of landslides sitting on the slope.All results above reveal initially developing mechanisms of giant landslides in the area.
引文
[1]张家桂.三峡库区别奉节县宝塔坪小区大型复杂滑坡特征及成因机制[J].地质论评,2000,46(4):431-436.
[2]李守定,李晓,张年学,等.三峡库区宝塔滑坡泥化夹层泥化过程的水岩作用[J].岩土力学,2006,27(10):1841-1846.
[3]陆关祥,李林.重庆市滑坡、崩塌的发育规律及区域危险性程度区划[J].地质科学,2001,36(3):335-341.
[4]蔡永胜,郑建芳.长江三峡库区巴东县黄土坡滑坡稳态分析及防滑措施[J].东南大学学报(自科版),2001,31(5):53-57.
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[8]李长安.三峡库区滑坡与构造运动/气候变化的关系[J].地质科技情报,1997,16(3):88-91.
[9]唐红梅,陈洪凯,耿大玉,等.重庆库区新构造应力场及其对滑坡宏观活动规律的控制[J].岩石力学与工程学报,2000,19(3):352-356.
[10]陈洪凯,艾南山.岩石边坡中地下水压力的基本特性及作用[J].兰州大学学报(自科版),1998,34(4):171-175.
[11]陈洪凯,唐红梅.散体滑坡室内启动模型试验[J].山地学报,2002,20(1):112-115.
[12]陈洪凯,唐红梅.三峡库区危岩发育规律研究[C]//第二届全国岩土与工程学术大会委员会.第二届全国岩土与工程学术大会论文集(上).北京:科学出版社,2006:837-842.
[13]Bertran P.The rock-avalanche of february 1995 at claix(french alps)[J].Geomorphology,2003,54(3):339-346.
[14]Braathen A,Blikra L H,Karlsen S S.Rock-slope failure innorway:type,geometry,deformation mechanisms a-nd stabil-ity[J].Norweigian Journal of Geology,2004,84:67-88.
[15]Richard J C,Stanley AS,David E S.Geomorphology[M].Cambridge:Cambridge University Press,1984:255-275.
[16]Chen HK,Tang HM.Chained mechanism and moving ro-utine for perilous rock to avalanche in the area of the threegorges reservoir of china[C]//Anon.The proceedings ofthe china association for science and technology Vol.3No.1.Beijing:Science Press,2006:501-506.
[17]Chen HK,Tang HM.Zhu H.Research on duration for pe-rilous rock to form[J].WSEAS Transactions on Appliedand Theoretical Mechanics,2006,1(2):169-173.
[18]陈洪凯,唐红梅.三峡库区公路缓倾角岩层边坡崩塌机理及警报系统[J].重庆师范大学学报(自然科学版),2009,26(3):26-29.
[19]唐红梅,叶四桥,陈洪凯.危岩主控结构面应力强度因子求解分析[J].地下空间与工程学报,2006,2(3):393-397.
[20]Chen HK,Tang HM,Ye S Q.Research on damage modelof control fissure in perilous rock[J].Applied Mathemat-ics and Mechanics,2006,27(7):967-974.
[21]Chen HK,Tang HM.Method to calculate fatigue fracturelife of control fissure in perilous rock[J].Applied Mathe-matics and Mechanics,2007,28(5):643-649.
[22]任幼蓉,张涛.麻柳嘴滑坡变形监测分析[J].地质灾害与环境保护,2000,11(2):147-151.
[2]李守定,李晓,张年学,等.三峡库区宝塔滑坡泥化夹层泥化过程的水岩作用[J].岩土力学,2006,27(10):1841-1846.
[3]陆关祥,李林.重庆市滑坡、崩塌的发育规律及区域危险性程度区划[J].地质科学,2001,36(3):335-341.
[4]蔡永胜,郑建芳.长江三峡库区巴东县黄土坡滑坡稳态分析及防滑措施[J].东南大学学报(自科版),2001,31(5):53-57.
[5]杨为民,吴树仁,石菊松,等.湖北秭归千将坪滑坡形成机理[J].煤炭工程,2004(4):57-59.
[6]孙云志,张业明.万州和平广场堆积体形成时间与堆积过程[J].人民长江,2005,36(12):44-46.
[7]孙云志,苏爱军,崔政权.三峡库区万州和平广场滑坡成因与防治对策研究[J].武汉理工大学学报(交通科学与工程版),2003,27(6):853-855.
[8]李长安.三峡库区滑坡与构造运动/气候变化的关系[J].地质科技情报,1997,16(3):88-91.
[9]唐红梅,陈洪凯,耿大玉,等.重庆库区新构造应力场及其对滑坡宏观活动规律的控制[J].岩石力学与工程学报,2000,19(3):352-356.
[10]陈洪凯,艾南山.岩石边坡中地下水压力的基本特性及作用[J].兰州大学学报(自科版),1998,34(4):171-175.
[11]陈洪凯,唐红梅.散体滑坡室内启动模型试验[J].山地学报,2002,20(1):112-115.
[12]陈洪凯,唐红梅.三峡库区危岩发育规律研究[C]//第二届全国岩土与工程学术大会委员会.第二届全国岩土与工程学术大会论文集(上).北京:科学出版社,2006:837-842.
[13]Bertran P.The rock-avalanche of february 1995 at claix(french alps)[J].Geomorphology,2003,54(3):339-346.
[14]Braathen A,Blikra L H,Karlsen S S.Rock-slope failure innorway:type,geometry,deformation mechanisms a-nd stabil-ity[J].Norweigian Journal of Geology,2004,84:67-88.
[15]Richard J C,Stanley AS,David E S.Geomorphology[M].Cambridge:Cambridge University Press,1984:255-275.
[16]Chen HK,Tang HM.Chained mechanism and moving ro-utine for perilous rock to avalanche in the area of the threegorges reservoir of china[C]//Anon.The proceedings ofthe china association for science and technology Vol.3No.1.Beijing:Science Press,2006:501-506.
[17]Chen HK,Tang HM.Zhu H.Research on duration for pe-rilous rock to form[J].WSEAS Transactions on Appliedand Theoretical Mechanics,2006,1(2):169-173.
[18]陈洪凯,唐红梅.三峡库区公路缓倾角岩层边坡崩塌机理及警报系统[J].重庆师范大学学报(自然科学版),2009,26(3):26-29.
[19]唐红梅,叶四桥,陈洪凯.危岩主控结构面应力强度因子求解分析[J].地下空间与工程学报,2006,2(3):393-397.
[20]Chen HK,Tang HM,Ye S Q.Research on damage modelof control fissure in perilous rock[J].Applied Mathemat-ics and Mechanics,2006,27(7):967-974.
[21]Chen HK,Tang HM.Method to calculate fatigue fracturelife of control fissure in perilous rock[J].Applied Mathe-matics and Mechanics,2007,28(5):643-649.
[22]任幼蓉,张涛.麻柳嘴滑坡变形监测分析[J].地质灾害与环境保护,2000,11(2):147-151.
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