马河崩塌堆积体结构特征与稳定性评价
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摘要
马河崩塌体堆积边坡坡度陡峭,起伏变化大,钻孔勘探难以准确查明边坡松散覆盖层厚度、边坡下伏基岩起伏情况及其风化发育程度。选用地震散射剖面的物探方法探明了马河崩塌堆积体结构特征,并采用多种极限平衡法(BishopJ、anbu、Morgenstern-Price)计算和对比基覆界面的安全系数,评价马河崩塌堆积体在三种不同工况下(自然工况、地震工况、降雨工况)的稳定性。得出结论为:马河崩塌堆积体的地质结构可分为三层:靠近地表为厚度为30～40m左右的松散覆盖层,未胶结;中间为厚度10～15m的中-强风化层,节理裂隙发育;40～50m以下为完整性较好的基岩,波速在2500m.s-1以上。对地震和降雨2种不利工况进行了稳定性评价:在地震工况下,崩塌体可沿着覆盖层底界面或者风化层底界面发生失稳破坏;在降雨工况下,崩塌体可沿着风化层底界面发生失稳破坏。
This paper mainly researches the structural characteristic and the stability analysis of Mahe collapse body.First of all,the range of slope and changing shape in landscape orientation restraint the application of drilling exploration.It is difficult to figure out the loose coverage thickness,fluctuating bedrock beneath and situation of developing weathered layer exactly.Hence,this paper adopts SSP(Seismic Scatter Profile)method to explore the structural characteristic of Mahe collapse body.Furthermore,this paper evaluates the stability of Mahe collapse body under three conditions(natural condition、earthquake condition and rainfall condition)by using various LEM(Bishop、Janbu、Morgenstern-Price)and then calculating and comparing the safety factors of discontinuity between bedrock and coverage.Finally,this paper concludes that the geological structure of Mahe collapse body is approximately sorted into three layers.The upper layer close to surface is loose coverage with a thickness about 30～40mm,not cementitious;The medium layer is a medium to strong weathered layer with a thickness about 10～15mm,weathered strongly,fractured intensively;The bottom layer is a relatively intact rock mass under 40～50m depth with a wave velocity above 2500m·s-1;As to stability evaluation,there are two unstable conditions:the collapse body may occur failure along the bottom boundary of coverage or weathered layer under earthquake condition,while the collapse body may also occur failure along the bottom boundary of weathered layer under rainfall condition.
This paper mainly researches the structural characteristic and the stability analysis of Mahe collapse body.First of all,the range of slope and changing shape in landscape orientation restraint the application of drilling exploration.It is difficult to figure out the loose coverage thickness,fluctuating bedrock beneath and situation of developing weathered layer exactly.Hence,this paper adopts SSP(Seismic Scatter Profile)method to explore the structural characteristic of Mahe collapse body.Furthermore,this paper evaluates the stability of Mahe collapse body under three conditions(natural condition、earthquake condition and rainfall condition)by using various LEM(Bishop、Janbu、Morgenstern-Price)and then calculating and comparing the safety factors of discontinuity between bedrock and coverage.Finally,this paper concludes that the geological structure of Mahe collapse body is approximately sorted into three layers.The upper layer close to surface is loose coverage with a thickness about 30～40mm,not cementitious;The medium layer is a medium to strong weathered layer with a thickness about 10～15mm,weathered strongly,fractured intensively;The bottom layer is a relatively intact rock mass under 40～50m depth with a wave velocity above 2500m·s-1;As to stability evaluation,there are two unstable conditions:the collapse body may occur failure along the bottom boundary of coverage or weathered layer under earthquake condition,while the collapse body may also occur failure along the bottom boundary of weathered layer under rainfall condition.
引文
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[12]何思明,吴永,李新坡.地震诱发岩体崩塌的力学机制[J].岩石力学与工程学报,2010,29(S1):3359～3363.He Siming,Wu Yong,Li Xinpo.Collapse mechanism of dangerrock triggered by earthquake.Chinese Journal of Rock Mechanicsand Engineering,2010,29(S1):3359～3363.
[13]赵伟华,黄润秋,赵建军,巨能攀,李果.强震条件下碎裂岩体崩塌机理及崩塌后壁对堆积体稳定性影响研究[J].工程地质学报,201,119(2):205～213.Zhao Weihua,Huang Runqiu,Zhao Jianjun,JU Nengpan,Li Guo.Rcokfall mechanism of cataclastic rock mass and influence ofback wall upon the stability of accumulation under strong earth-quake.Journal of Engineering Geology,201,119(2):205～213.
[2]Ambraseys N,Srbulov M.Earthquake induced displacements ofslopes.Soil Dynamics and Earthquake Engineering,1995,14(1):59～71.
[3]MArzorati S,Luzi L,Amicismd.Rock falls induced byearthquakes:a statistical approach.Soil Dynamics and EarthquakeEngineering,2002,22(7):565～577.
[4]陶志平,周德培,王亨林.三峡库区巨鱼沱滑坡地质特征及防治研究[J].工程地质学报,2003,11(4):406～410.Tao Zhiping,Zhou Depei,Wang Henglin.Geological characteristicsand treatment of the Juyutuo landslide in the Three Gorges reservoirarea.Journal of Engineering Geology,2003,11(4):406～410.
[5]石广斌,杨经会,安盛勋,李宁.石泉水电站陡高边坡崩塌机理分析及加固设计[J].岩石力学与工程学报,2004,23(7):1186～1192.Shi Guangbin,Yang Jinghui,An Shengxun,Li Ning.Collapsemechanism analysis of steep-high rock slope of Shiquan hydropowerstation and reinforcement design.Chinese Journal of RockMechanics and Engineering,2004,23(7):1186～1192.
[6]朱飞.常张高速公路风化岩边坡稳定性分析及加固[J].公路与汽运,2004,8(4):51～53.Zhu Fei.The stability analysis and support of weathering rock slopeof the Chang Zhang exp ressway.Highways&AutomotiveApllication s,2004,8(4):51～53.
[7]张倬元,王士天,王兰生.工程地质分析原理[M].北京:地质出版社,2005.Zhang Zuoyuan,Wang Shitian,Wang Lansheng.AnalyticalPrinciples of Engineering Geology.Beijing:Geological PublishingHouse,2005.
[8]常中华,陈厚军,张乐中,杨天亮.奎屯河新龙口右岸山体崩塌原因及再次失稳可能性分析[J].工程地质学报,2005,13(1):76～81.Chang Zhonghua,Chen Houjun,Zhang Lezhong,Yang Tianliang.Causes for the rock avalanche on the right bank of Xinlongkou onthe Kuitun river and probability of its reoccurrence.Journal of En-gineering Geology,2005,13(1):76～81.
[9]张管宏.交河故城崖体稳定性及崩塌机理研究[D].兰州:兰州大学,2007.Zhang Guanhong.The Study of Stability and Collapsibility Mecha-nism of cliff mass of Jiaohe ruins.Lanzhou:LanzhouUniversity,2007.
[10]许强,黄润秋,殷跃平,等.2009年6.5重庆武隆鸡尾山崩滑灾害基本特征与成因机理初步研究[J].工程地质学报,2009,17(4):433～444.Xu Qiang,Huang Runqiu,Yin Yueping,et al.The Jiweishanlandslide of June 5,2009 in Wulong,Chongqing:characteristicsand failure mechanismJ,ournal of Engineering Geology,2009,17(4):433～444.
[11]胡斌,黄润秋.软硬互层边坡崩塌机理及治理对策研究[J].工程地质学报,2009,17(2):200～205.Hu Bin,Huang Runqiu.Collapse mechanism and treatment meas-ures of slopes with interbeddings of soft and hard rocks.Journal ofEngineering Geology,2009,17(2):200～205.
[12]何思明,吴永,李新坡.地震诱发岩体崩塌的力学机制[J].岩石力学与工程学报,2010,29(S1):3359～3363.He Siming,Wu Yong,Li Xinpo.Collapse mechanism of dangerrock triggered by earthquake.Chinese Journal of Rock Mechanicsand Engineering,2010,29(S1):3359～3363.
[13]赵伟华,黄润秋,赵建军,巨能攀,李果.强震条件下碎裂岩体崩塌机理及崩塌后壁对堆积体稳定性影响研究[J].工程地质学报,201,119(2):205～213.Zhao Weihua,Huang Runqiu,Zhao Jianjun,JU Nengpan,Li Guo.Rcokfall mechanism of cataclastic rock mass and influence ofback wall upon the stability of accumulation under strong earth-quake.Journal of Engineering Geology,201,119(2):205～213.
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