黄土–基岩滑坡滑带土特性及其演化过程
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摘要
滑坡的演化过程伴随着滑带的形成,故滑带土的物理力学特性在一定程度上决定着滑坡的形成机理和活动趋势。选取延安丁家沟滑坡滑带土为研究对象,通过X射线衍射、电镜扫描、室内实验等手段,对其矿物成分、微观结构、物理特性和力学特性进行研究。结果表明:不同部位滑带土的性质差异明显,前缘滑带土的含水率、天然密度、干密度、黏土矿物、界限含水率以及粒径分布分维值均明显高于后部滑带土;前缘滑带土在任一法向应力作用下均表现为应变软化的剪切特性,而后缘滑带土在低法向应力水平下表现为弱应变软化,在高应力水平下表现为应变稳定。通过前后缘滑带土物理力学特性差异,总结出此类滑坡演化阶段为后缘剪切面形成→剪切面扩展→滑带贯通。
The evolution process of landslide is accompanied by the formation of sliding zone, so the physical and mechanical properties of sliding zone soil determine to a certain extent the formation mechanism and activity trend of landslide. The selected sliding zone soil of Dingjiagou landslide in Yan'an as the research object, through X-ray diffraction, electron microscope scanning and the laboratory tests, the physical properties, mineral composition, microstructure and mechanical properties were studied. Results show that the properties of the different parts of the sliding zone are different apparently. The water content, natural density, dry density, clay minerals, boundary moisture content, and fractal dimension of the particle size distribution of the leading edge sliding zone soil are significantly higher than that of the rear sliding zone soil; The shear curve of the leading edge slide soil shows strain softening under vertical stress. The trailing edge slide soil shows weak strain softening under low vertical stress and stable strain under high vertical stress. Based on the differences in physical and mechanical properties between the front and rear edges of the sliding zone, it is concluded that the evolution stages of this type of landslide is formation of the shear plane of the trailing edge→extension of the shear plane→penetration of the sliding zone.
The evolution process of landslide is accompanied by the formation of sliding zone, so the physical and mechanical properties of sliding zone soil determine to a certain extent the formation mechanism and activity trend of landslide. The selected sliding zone soil of Dingjiagou landslide in Yan'an as the research object, through X-ray diffraction, electron microscope scanning and the laboratory tests, the physical properties, mineral composition, microstructure and mechanical properties were studied. Results show that the properties of the different parts of the sliding zone are different apparently. The water content, natural density, dry density, clay minerals, boundary moisture content, and fractal dimension of the particle size distribution of the leading edge sliding zone soil are significantly higher than that of the rear sliding zone soil; The shear curve of the leading edge slide soil shows strain softening under vertical stress. The trailing edge slide soil shows weak strain softening under low vertical stress and stable strain under high vertical stress. Based on the differences in physical and mechanical properties between the front and rear edges of the sliding zone, it is concluded that the evolution stages of this type of landslide is formation of the shear plane of the trailing edge→extension of the shear plane→penetration of the sliding zone.
引文
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[2]LI Y R,AYDIN A.Shear zone structures and stress fluctuations in large ring shear tests[J].Engineering Geology,2013,167:6–13.
[3]陈小龙,丁建锋,简文星.含水率对滑带土强度参数的影响[J].煤田地质与勘探,2015,43(1):58–61.CHEN Xiaolong,DING Jianfeng,JIAN Wenxing.The influence of water content on the strength parameter of soil in slip zone[J].Coal Geology&Exploration,2015,43(1):58–61.
[4]SKEMPTON A W,PETLEY D J.The strength along structural discontinuities in stiff clays[C]//Proceedings of the Geotechnical Conference.Oslo:Thomas Telford Publishing,1984:29–46.
[5]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 Shouding,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.
[6]程东幸,刘大安,丁恩保,等.滑带土长期强度参数的衰减特性研究[J].岩石力学与工程学报,2005,24(增刊2):5827–5834.CHENG Dongxing,LIU Da’an,DING Enbao,et al.Study on attenuation characteristics of long-term strength for landslide soil[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(S2):5827–5834.
[7]鲁莎.三峡库区黄土坡滑坡滑带特性及变形演化研究[D].武汉:中国地质大学,2017.
[8]王念秦.黄土滑坡发育规律及其防治措施研究[D].成都:成都理工大学,2004.
[9]李瑞娥,徐郝明,王娟娟.黄土滑坡滑带土的特点—以天水椒树湾滑坡为例[J].煤田地质与勘探,2009,37(1):43–47.LI Rui’e,XU Haoming,WANG Juanjuan.Characters of sliding soil of the loess landslide:A case study from Jiaoshuwan,Tianshui[J].Coal Geology&Exploration,2009,37(1):43–47.
[10]龙建辉,李同录,雷晓锋,等.黄土滑坡滑带土的物理特性研究[J].岩土工程学报,2007,29(2):289–293.LONG Jianhui,LI Tonglu,LEI Xiaofeng,et al.Study on physical properties of soil in sliding zone of loess landslip[J].Chinese Journal of Geotechnical Engineering,2007,29(2):289–293.
[11]王雷,赵法锁,程晓辉,等.黄土基岩接触面滑坡滑带土物理力学特性及微观结构[J].地球科学与环境学报,2017,39(3):450–458.WANG Lei,ZHAO Fasuo,CHENG Xiaohui,et al.Physical and mechanical properties and microstructures of slip soil of loess bedrock contact landslide[J].Journal of Earth Sciences and Environment,2017,39(3):450–458.
[12]郑苗苗,郑泓,李同录.关中西部大型黄土滑坡滑带土的物理力学特性研究[J].水土保持研究,2016,23(1):343–348.ZHENG Miaomiao,ZHENG Hong,LI Tonglu.Study on physical-mechanical properties of sliding soil of large-scale loess landslides in western Guanzhong[J].Research of Soil and Water Conservation,2016,23(1):343–348.
[13]谌文武,刘伟,林高潮,等.黄土–泥岩接触面滑坡滑带土力学特征研究[J].冰川冻土,2017,39(3):593–601.CHEN Wenwu,LIU Wei,LIN Gaochao,et al.Study of the mechanical characteristics of slip zone soils sampled from loess-mudstone interface[J].Journal of Glaciology and Geocryology,2017,39(3):593–601.
[14]辛鹏,吴树仁,石菊松,等.簸箕山大型老滑坡滑动带的结构特征及形成机制试验研究[J].岩石力学与工程学报,2013,32(7):1382–1391.XIN Peng,WU Shuren,SHI Jusong,et al.Structural characteristics of soft-rock slip zone and experimental study of its formation mechanism in Boji Mountain large-scale old landslide[J].Chinese Journal of Rock mechanics and Engineering,2013,32(7):1382–1391.
[15]张荣科,范光.黏土矿物X射线衍射相定量分析方法与实验[J].铀矿地质,2003,19(3):180–185.ZHANG Rongke,FAN Guang.Quantitative analytic method and experiments of X-ray diffration phase of clay minerals[J].Uranium Geology,2003,19(3):180–185.
[16]雷祥义.黄土地质灾害的形成机理与防治对策[M].北京:北京大学出版社,2014.
[17]MANDELBROT B B.Multi fractal measures,especially for the geophysicist[J].Pure and Applied Geophysics,1989,131(1/2):5–42.
[18]杨培岭,罗远培,石元春.用粒径的重量分布表征的土壤分形特征[J].科学通报,1993(20):1896–1899.YANG Peiling,LUO Yuanpei,SHI Yuanchun.Soil fractal features characterized by weight distribution of particle size[J].Chinese Science Bulletin,1993(20):1896–1899.