延安地区压实Q2、Q3黄土变形特性分析

Study of deformation characteristics of compacted Q2、Q3 loess in Yan’an region

本项研究针对延安地区压实Q2、Q3黄土做了大量的室内侧限压缩固结试验.针对压实黄土变形特性的影响因素,建立适用于表征侧限条件下压实黄土应力-应变关系的最佳拟合模型.在此基础上分析了最优含水率条件下割线模量与垂直压应力及割线模量与压实度的关系,提出了普遍适用的压实黄土加载本构模型.研究结果表明:压实Q2黄土固结完成之后土体密实度高,含气量少,渗透性小,外加荷载作用下附加变形量小,是良好的地基填筑材料.Gunary模型适用于表征侧限条件下压实Q2、Q3黄土的应力-应变关系,拟合精度高,稳定性好.由Gunary模型转化后得到的割线模量与垂直压应力的关系式涵盖了低压实度情况下的线性关系和高压实度情况下的非线性关系两种情况,具有更好的适用性.

Indoor confined consolidation tests of compacted Q2、Q3 loess in Yan’an region are carried out in this research work.Factors to influence deformation characteristics of the compacted loess are discussed either.A best fitting model is established to characterize stress-strain relationship of the compacted loess under lateral conditions.On this basis,this paper analyzes the relationship between secant modulus and vertical compressive stress and the relationship between secant modulus and compactness under the condition of optimal water content,and puts forward a generally applicable constitutive model for the compacted loess.The results show that:After the consolidation of compacted Q2 loess,the soil has high compactness,low gas content,low permeability and small additional deformation under applied load,so it is a good filling-material in the foundation.The Gunary model,with high fitting accuracy and good stability,is suitable for characterizing the stress-strain relationship of the compacted Q2 and Q3 loess under lateral conditions.The relationship between secant modulus and vertical compressive stress obtained from the transformation of Gunary model covers the linear relationship in the case of low pressure compactness and the nonlinear relationship in the case of high pressure compactness,which has better applicability.