不同地区非饱和黄土动力结构性研究
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摘要
对兰州、洛川、杨凌地区黄土在不同含水率与不同应力状态下进行动扭剪三轴试验,测定了黄土的动剪应力-应变关系曲线;同时,依据Hardin-Drnevich双曲线模型,改进了基于动剪应力考虑的土结构性定量化参数,并应用该参数对三地区非饱和黄土的动力结构性进行了分析。结果表明,三地区非饱和黄土的动力结构性参数随动剪应变的增大先降低,而后保持在一个稳定的水平;含水率与固结应力对黄土的动力结构性影响显著,在相同的固结应力条件下,含水率越低,黄土的动力结构性参数越大,在相同的含水率条件下,固结应力越小,黄土的动力结构性参数越大;在相同的条件下,杨凌地区黄土的动力结构性最强,洛川地区黄土次之,兰州地区黄土最弱,即黄土的动力结构性在地理空间分布上存在从西北向东南方向增强的规律。
The dynamic torsional shear triaxial tests are carried out on loesses of Lanzhou,Luochuan and Yangling under different water contents and different stress states;and then the dynamic shear stress-strain curves of loesses are obtained.Besides,according to Hardin-Drnevich hyperbolic model,the soil structural quantitative parameters,which are based on the dynamic shear stress,are developed;and the dynamic structural characteristics of unsaturated loesses in Lanzhou,Luochuan and Yangling are analyzed by using the parameters.Results show that the structural parameters of Lanzhou,Luochuan and Yangling loesses firstly reduce along with the increase of the dynamic shear strain;and then remain at a stable level;water content and consolidation stress have significant influence on the structural parameters.Under the same consolidation stress condition,the lower water content,the greater dynamic structural parameters of the loess;and under the same water content,the smaller consolidation stress,the greater dynamic structural parameters of the loess.In conclusion,under the same condition,the dynamic structural characteristics of Yangling loess is the strongest;the following is Luochuan loess;and Lanzhou loess is the weakest;in other words,the structural characteristics of loesses in the geographical spatial distribution exists a law of increment from the northwest to the southeast.
The dynamic torsional shear triaxial tests are carried out on loesses of Lanzhou,Luochuan and Yangling under different water contents and different stress states;and then the dynamic shear stress-strain curves of loesses are obtained.Besides,according to Hardin-Drnevich hyperbolic model,the soil structural quantitative parameters,which are based on the dynamic shear stress,are developed;and the dynamic structural characteristics of unsaturated loesses in Lanzhou,Luochuan and Yangling are analyzed by using the parameters.Results show that the structural parameters of Lanzhou,Luochuan and Yangling loesses firstly reduce along with the increase of the dynamic shear strain;and then remain at a stable level;water content and consolidation stress have significant influence on the structural parameters.Under the same consolidation stress condition,the lower water content,the greater dynamic structural parameters of the loess;and under the same water content,the smaller consolidation stress,the greater dynamic structural parameters of the loess.In conclusion,under the same condition,the dynamic structural characteristics of Yangling loess is the strongest;the following is Luochuan loess;and Lanzhou loess is the weakest;in other words,the structural characteristics of loesses in the geographical spatial distribution exists a law of increment from the northwest to the southeast.
引文
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[4]谢定义,齐吉琳.土结构性及其定量化参数研究的新途径[J].岩土工程学报,1999,21(6):651-656.XIE Ding-yi,QI Ji-lin.Soil structure characteristics and new approach in research on its quantitative parameters[J].Chinese Journal of Geotechnical Engineering,1999,21(6):651-656.
[5]骆亚生,谢定义,邵生俊,等.复杂应力状态下的土结构性参数[J].岩石力学与工程学报,2004,23(24):4248-4251.LUO Ya-sheng,XIE Ding-yi,SHAO Sheng-jun,et al.Structural parameter of soil under complex stress conditions[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(24):4248-4251.
[6]DIBBEN S C,JEFFERSON I F,SMALLEY I J.The“loughborough loess”Monte Carlo model of soil structure[J].Computers&Geosciences,1998,24(4):345-352.
[7]陈存礼,何军芳,杨鹏.考虑结构性影响的原状黄土本构关系[J].岩土力学,2007,28(11):2284-2290.CHEN Cun-li,HE Jun-fang,YANG Peng.Constitutive relationship of intact loess considering structural effect[J].Rock and Soil Mechanics,2007,28(11):2284-2290.
[8]邵生俊,周飞飞,龙吉勇.原状黄土结构性及其定量化参数研究[J].岩土工程学报,2004,26(4):531-536.SHAO Sheng-jun,ZHOU Fei-fei,LONG Ji-yong.Structural properties of loess and its quantitative parameter[J].Chinese Journal of Geotechnical Engineering,2004,26(4):531-536.
[9]邓津,王兰民,张振中.黄土显微结构特征与震陷性[J].岩石力学与工程学报,2007,29(4):542-548.DENG Jin,WANG Lan-min,ZHANG Zhen-zhong.Microstructure characteristics and seismic subsidence of loess[J].Chinese Journal of Rock Mechanics and Engineering,2007,29(4):542-548.
[10]张腾,胡再强,吴兴辉,等.不同应力路径下非饱和黄土的结构变化特性[J].岩土力学,2006,27(11):1945-1948.ZHANG Teng,HU Zai-qiang,WU Xing-hui,et al.Variation characteristics of soil structure of unsaturated loessunder different stress paths[J].Rock and Soil Mechanics,2006,27(11):1945-1948.
[11]李俊连,姚仰平.结构性黄土临界状态力学性状[J].岩土力学,2008,29(1):63-68.LI Jun-lian,YAO Yang-ping.Mechanical characteristics of structural loess under critical state[J].Rock and Soil Mechanics,2008,29(1):63-68.
[12]HARDIN B O,DRNEVICH V P.Shear modulus and damping in soils:design equations and curves[J].Journal of Soil Mechanics and Foundations,ASCE,1972,(7):667-692.
[13]刘东生.黄土的物质成分和结构[M].北京:科学出版社,1966.
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