地震在滑坡体上的响应形式研究:以苦地瓜子滑坡为例
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摘要
地震滑坡分为三大类,即高度破裂或严重高度破裂滑坡、存在分离剪切面的滑坡以及以流相为主的滑坡。在中国西南地区,根据地震滑坡特点,按其运动方式划分为:推移式滑坡、牵引式滑坡、溜滑性滑坡和崩塌性滑坡四大类。在四川省茂县苦地瓜子滑坡特征的调查中,发现了一些较为特殊的地质现象,主要包括以下几点:(1)滑坡上游边界冲沟中湖相沉积和滑坡体上分布的湖积物表明苦地瓜子滑坡曾经发生过堵江事件,部分为堵江后的堰塞湖区域,在此区域发生河湖相沉积,其结果是滑坡此部分被湖积物所覆盖,呈现出了与其他几个区覆盖物截然不同的现象;(2)苦地瓜子滑坡中下部发现砂土液化现象及规律性排列的裂缝;(3)踏勘时在滑坡中下部发现直立错坎,错坎两侧土性不同,在颜色和物质组成上都有较明显不同。错坎左侧为粉土状物质,而右侧以碎石土为主;(4)在滑坡的中部以及中偏下部位都发现有平行于滑动方向的裂缝;(5)现场调查时在坡体中上部发现有充填楔,充填物颗粒较大、磨圆度较好,与地面盖层的颜色、岩性条件相同。综合各种现象进行分析,室内试验和数据统计,认为茂县苦地瓜子滑坡为地震诱发的滑坡,并且可以从此滑坡中发现地震滑坡与普通滑坡明显不同,往往在现场留下自重引起的滑坡不好解释的现象,主要有砂土液化迹象、充填楔、地震陡坎、平行于滑动方向的裂隙;此外地震滑坡还具有等时性和群发性的特点。
Seismic landslides are divided into three categories, namely high rupture or serious landslide, landslide associated with theseparated shear surface rupture, landslide in stream facies. In the southwest China, landslides are divided into four types: lapsed,tractive, sliding, and collapsed landslide according to the characteristics of seismic landslides. Some special geological phenomena arefound during the investigation of the characteristics of landslides in Kushuiguazi, Maoxian, Sichuan Province. The special features are:(1) the upstream boundary thrust of landslide lake sediments and landslide groove body distribution of lake sediments show thatKushuiguazi landslide damming events have occurred. As a result, part of the landslide is covered by lake sediments and part of it ispresent, showing different covering phenomena from several other areas;(2) liquification phenomenon is found in Kushuiguazilandslide and regular arrangement of carcks are noticed;(3) the upright scarp is discovered in the lower part of the landslide. Soils onboth sides are different in color and composition. The left side consists of silty soil, while the right side is dominated by gravel soil;(4) cracks parallel to the sliding direction are found in the middle and lower slope;(5) the field investigation on the upper slope found afilling wedge that consists of the large, rounded particles derived from the overlying soil. Synthesis of all kinds of features, indoor testsand statistics analysis of data, Kushuiguazi landslide of Maoxian may be earthquake induced based on features that cannot beexplained by landslide associated with self-weight such as sand liqu fication, filling wedge, earthquake and steep scarp, fracturesparallel to the sliding direction. Also, the occurrence of lots of landslides at the same time point to earthquake as cause of the Kuguazilandslide. The results of this study can provide some basis for the study of seismic landslides.
Seismic landslides are divided into three categories, namely high rupture or serious landslide, landslide associated with theseparated shear surface rupture, landslide in stream facies. In the southwest China, landslides are divided into four types: lapsed,tractive, sliding, and collapsed landslide according to the characteristics of seismic landslides. Some special geological phenomena arefound during the investigation of the characteristics of landslides in Kushuiguazi, Maoxian, Sichuan Province. The special features are:(1) the upstream boundary thrust of landslide lake sediments and landslide groove body distribution of lake sediments show thatKushuiguazi landslide damming events have occurred. As a result, part of the landslide is covered by lake sediments and part of it ispresent, showing different covering phenomena from several other areas;(2) liquification phenomenon is found in Kushuiguazilandslide and regular arrangement of carcks are noticed;(3) the upright scarp is discovered in the lower part of the landslide. Soils onboth sides are different in color and composition. The left side consists of silty soil, while the right side is dominated by gravel soil;(4) cracks parallel to the sliding direction are found in the middle and lower slope;(5) the field investigation on the upper slope found afilling wedge that consists of the large, rounded particles derived from the overlying soil. Synthesis of all kinds of features, indoor testsand statistics analysis of data, Kushuiguazi landslide of Maoxian may be earthquake induced based on features that cannot beexplained by landslide associated with self-weight such as sand liqu fication, filling wedge, earthquake and steep scarp, fracturesparallel to the sliding direction. Also, the occurrence of lots of landslides at the same time point to earthquake as cause of the Kuguazilandslide. The results of this study can provide some basis for the study of seismic landslides.
引文
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胡广韬.1995.滑坡动力学[M].北京:地质出版社:36-40.
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毛彦龙,胡广韬,赵法锁,等.1998.地震动触发滑坡体滑动的机理[J].西安工程学院学报,19(4);45-48.
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周本刚,张裕明.1994.中国西南地区地震滑坡的基本特征[J].西北地震学报,16(1):95-103.
张贵双,叶洪东,刘继东.2005,邯郸市饱和粉土地震液化判别与差异分析[J].岩土工程技术,19(4):195-198.
郑文俊,李传友,王伟涛,等.2008.汶川8.0级地震陡坎(北川以北段)探槽的记录特征[J].地震地质,30(3):697-709
张倬元,王士天,王兰生,等.2009.工程地质分析原理[M].北京:地质出版社:356-360.
Keefer D V.1984.Landslides caused by earthquakes[J].Geological Societyof America Bulletin,95(4):406-421.
Seed R B,Cetin K O,Moss R E,et al.2001.Recent advances in soilliquefaction engineering and seismic site response evaluation[C]//Proceedings of fourth international conference on recent advances ingeotechnical earthquake engineering and soil dynamics,san diego,california:1-45.
Youd T I,Idriss I M,et al.2001.Liquefaction resistance of soils:summaryreport from the 1996 NCEER and 1998 NCEER/NFS workshops onevaluation of liquefaction resistance of soils[J].Journal of Geotechnicaland Geoenvironmental Engineering,ASCE,127(8):817-833.
东南大学,浙江大学等合编.2007.土力学(第二版)[M].北京:中国建筑工业出版社:308-313.
邓起东,陈社发.1994.龙门山及其邻区的构造和地震活动及动力学[J].地震地质,16(4):389-403.
韩殿忠,雷清清,刘健,等.1991.海城震区发现的古地震事件[J].东北地震研究,7(4):44-48.
韩金良,吴树仁,何淑军,等.2009.5.12汶川8级地震次生地质灾害的基本特征及其形成机制浅析[J].地学前缘,16(3):306-326.
胡广韬.1995.滑坡动力学[M].北京:地质出版社:36-40.
校小娥.2010.地震作用下滑坡稳定性分析—以八浪沟滑坡为例[D].西南交通大学:3-5.
GB 50011—2001.2010.建筑抗震设计规范[S].北京:中国建筑工业出版社:23-25.
林良俊,方成,李小杰,等.2008.5.12汶川地震灾区地质灾害情况初步分析[J].水文地质工程地质,35(4):1-4.
毛彦龙,胡广韬,赵法锁,等.1998.地震动触发滑坡体滑动的机理[J].西安工程学院学报,19(4);45-48.
吴树仁,石菊松,姚鑫,等.2008.四川汶川大地震地质灾害活动强度分析评价[J].地质通报,27(11):1753-1763.
辛鸿博,王余庆.1999.岩土边坡地震崩滑及其初判准则[J].岩土工程学报,21(5):1-6.
周本刚,张裕明.1994.中国西南地区地震滑坡的基本特征[J].西北地震学报,16(1):95-103.
张贵双,叶洪东,刘继东.2005,邯郸市饱和粉土地震液化判别与差异分析[J].岩土工程技术,19(4):195-198.
郑文俊,李传友,王伟涛,等.2008.汶川8.0级地震陡坎(北川以北段)探槽的记录特征[J].地震地质,30(3):697-709
张倬元,王士天,王兰生,等.2009.工程地质分析原理[M].北京:地质出版社:356-360.
Keefer D V.1984.Landslides caused by earthquakes[J].Geological Societyof America Bulletin,95(4):406-421.
Seed R B,Cetin K O,Moss R E,et al.2001.Recent advances in soilliquefaction engineering and seismic site response evaluation[C]//Proceedings of fourth international conference on recent advances ingeotechnical earthquake engineering and soil dynamics,san diego,california:1-45.
Youd T I,Idriss I M,et al.2001.Liquefaction resistance of soils:summaryreport from the 1996 NCEER and 1998 NCEER/NFS workshops onevaluation of liquefaction resistance of soils[J].Journal of Geotechnicaland Geoenvironmental Engineering,ASCE,127(8):817-833.
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