基质吸力对巴东组软岩碎屑土夹层强度影响的试验研究
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摘要
宜昌—巴东高速路部分路堑边坡因发育碎屑土夹层而稳定性变差,影响高速公路的建设与运营。水对巴东组软岩碎屑土夹层的强度与变形特性影响显著,而目前针对其非饱和强度特性开展的研究并不多。为探索基质吸力对碎屑土夹层强度的影响,利用GDS非饱和三轴仪开展其强度试验研究,得到碎屑土夹层的非饱和强度指标。结果表明基质吸力对巴东组软岩碎屑土夹层强度影响显著,碎屑土夹层的总黏聚力与峰值强度都随基质吸力的增大而呈非线性增长,内摩擦角φb则随基质吸力的增大先减小而后趋于稳定,且都小于有效内摩擦角φ'。研究表明基质吸力碎屑土夹层的强度特性影响较大。
Lots of cutting slopes with weak intercalated soils in soft rocks were developed in building the highway from Yichang to Badong. They have important influences on construction and operation of the highway. It is found that water has a significant effect on the strength and deformation characteristics. The unsaturated strength characteristic of weak intercalated soils are seldom examined. To investigate the effect of matrix suction on shear strength and obtain the intensity indexes of weak intercalated soils,the triaxial shear test was conducted by using GDS triaxial system with a double pressure chamber. The results show that the matrix suction has a major influence on shear strength characteristic of the weak intercalated soils. The growth of total cohesion and peak strength of weak intercalated soils along with the augment of matrix suction is nonlinear. The index φb,which decreases with the increase of matrix suction and gets to a stable value at last,is less than the effective internal friction angle φ'.
Lots of cutting slopes with weak intercalated soils in soft rocks were developed in building the highway from Yichang to Badong. They have important influences on construction and operation of the highway. It is found that water has a significant effect on the strength and deformation characteristics. The unsaturated strength characteristic of weak intercalated soils are seldom examined. To investigate the effect of matrix suction on shear strength and obtain the intensity indexes of weak intercalated soils,the triaxial shear test was conducted by using GDS triaxial system with a double pressure chamber. The results show that the matrix suction has a major influence on shear strength characteristic of the weak intercalated soils. The growth of total cohesion and peak strength of weak intercalated soils along with the augment of matrix suction is nonlinear. The index φb,which decreases with the increase of matrix suction and gets to a stable value at last,is less than the effective internal friction angle φ'.
引文
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[2]林伟平,田开圣.成层岩体中软弱层带的工程特性[J].长江水利水电科学研究院院报,1986(2):30-39.[LIN W P,TIAN K S.The Engineering characteristics of weak zone in Layered rock mass[J].Journal of Yangtze River Scientific Research Institute,1986(2):30-39.(in Chinese)]
[3]徐瑞春.葛洲坝红层中软弱夹层的构造类型研究[J].人民长江,1981(2):44-50.[XU R C.Research on interlayer type of weak intercalation in Gezhouba red layer[J].Yangtze River,1981(2):44-50.(in Chinese)]
[4]陆恩施.“红层”软弱泥化夹层抗剪强度研究方法探讨[J].水电工程研究,2001(3):47-50.[LU E S.Research methods of shear strength of soft clay interlayer in“Red layer”[J].Water and Electricity Engineering Research,2001(3):47-50.(in Chinese)]
[5]程强,周德培,封志军.典型红层软岩软弱夹层剪切蠕变性质研究[J].岩石力学与工程学报,2009,28(增刊1):3176-3180.[CHENG Q,ZHOU D P,FENG Z J.Research on shear creep property of typical week intercalation in redbed soft rock[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(Sup1):3176-3180.(in Chinese)]
[6]柴波,殷坤龙.三峡库区巴东新城区库岸三叠系巴东组层间软弱带[J].工程地质学报,2009,17(6):809-816.[CHAI B,YIN K L.Interlayer weakness zones in Badong formation of middle triassic forming bank slopes of Three Gorges reservoir in new Badong country[J].Journal of Engineering Geology,2009,17(6):809-816.(in Chinese)]
[7]龚裔芳,金福喜,张可能,等.红砂岩泥化夹层力学特性及其对边坡稳定性的影响[J].重庆交通大学学报(自然科学版),2010,29(2):220-223.[GONG Y F,JIN F X,ZHANG K N,et al.Influence on Slope Stability of Physical-mechanical Property of Clayer Thin Interlayer in Red Sandstone[J].Journal of Chongqing Jiaotong University(Natural Science),2010,29(2):220-223.(in Chinese)]
[8]卢海峰,陈从新,沈强,等.鄂西南巴东组红层边坡夹层成因及特性[J].水文地质工程地质,2010,37(1):54-61.[LU H F,CHEN C X,SHEN Q,et al.Genesis and characteristic of weak intercalation existed in the red-bed slope of Badong formation in southwestern Hubei Province[J].Hydrogeology&Engineering Geology,2010,37(1):54-61.(in Chinese)]
[9]柳群义,朱自强.不同含水量条件下红砂岩泥化夹层的剪切特性[J].沈阳工业大学学报,2012,34(2):220-223.[LIU Q Y,ZHU Z Q.Shear characteristics of siltized intercalation in red sandstone at different water contents[J].Journal of Shenyang University of Technology,2012,34(2):220-223.(in Chinese)]
[10]Fredlund D G,Rahardjo H.非饱和土土力学[M].陈仲颐,等,译,北京:中国建筑工业出版社,1997.[Fredlund D G,Rahardjo H.Soil mechanical for unsaturated soils[M].CHEN Z Y,et al,traslated,Beijing:China Building Industry Press,1997.(in Chinese)]
[11]ZHAN Liang-tong.Field and laboratory study of an unsaturated expansive soil associated with rain-induced slope instability[D].Hong Kong:The Hong Kong University of Science and Technology,2003.
[12]詹良通,吴宏伟.非饱和膨胀土变形和强度特性的三轴试验研究[J].岩土工程学报,2006,28(2):196-201.[ZHAN L T,NG C W W.Experimental study on mechanical behavior of recompacted unsaturated expansive clay[J].Chinese Journal of Geotechnical Engineering,2006,28(2):196-201.(in Chinese)]
[13]NG C W W,ZHAN L T,CUI Y J.A new simple system for measuring volume changes in unsaturated soils[J].Canadian Geotechnical Journal,2002,39(2):757-764.
[14]Chen Zhenghan,Zhou Haiqing,Fredlund D G.A nonlinear model for unsaturated soils[C]//Pro of 2nd Int Conf on Unsat Soils,1998.