冻结盐渍土力学性能试验及其本构模型的研究

发布时间：2018-04-07 15:32

  本文选题：人工冻结盐渍土　切入点：单轴压缩强度　出处：《安徽理工大学》2014年硕士论文

【摘要】：盐渍土本身的特殊性质对土壤以及工程建设都具有较大的危害,且高寒地区盐渍土的道路计算与设计牵涉了更为复杂的地质条件和应力状态,原有的冻融土力学概念已不能或完全不能适用于工程实践。本文主要通过室内试验中的单轴压缩、单轴蠕变和三轴剪切试验来研究冻结盐渍土的力学特性及其本构模型。考虑了加载方式、加载速率、冻结温度、易溶盐含量、土的性质、围压大小、试验应力路径等因素对含盐冻土力学特性的影响。经研究获得以下结论： (1)单轴压缩实验结果表明,加载速率、冻结温度、易溶盐含量、含水率等均对冻土的强度有很大的影响。加载速率增大、温度降低、含水率增大均会在不同程度上使冻土强度增大,而含盐量的提高则使冻土的强度降低。 (2)以单轴蠕变实验为基础,采用多元回归法以及非线性拟合法获得时间、温度、易溶盐含量对应力应变关系的蠕变本构公式。 (3)通过三轴试验获得不同温度、不同围压、不同含盐量的三轴剪切试验结果。结果表明不同条件下的应力应变关系曲线基本呈抛物线形状。且随着轴向应变的增大,在轴向应变ε≤(1.0%～7.5%)时,主应力差迅速增长,且此段曲线近似成直线形式,表现为一定得弹性性状,则此时为含盐冻土的弹性体。随着轴向应变的继续增大,主应力差的变化逐渐变小,此时冻土的应力-应变关系曲线呈明显的非线性,为冻土的塑性体。 (4)本文以弹塑性模型中的修正剑桥模型为基础,通过含盐冻土的三轴剪切特性的试验研究,确定模型参数,提出并验证冻结盐渍土的本构模型。
[Abstract]:The special properties of saline soil have great harm to soil and engineering construction, and the road calculation and design of saline soil in alpine area involve more complicated geological conditions and stress state.The original concept of freeze-thaw soil mechanics can not or can not be applied to engineering practice.In this paper, the mechanical properties and constitutive model of frozen saline soil are studied by uniaxial compression, uniaxial creep and triaxial shear tests.The effects of loading mode, loading rate, freezing temperature, soluble salt content, properties of soil, confining pressure and experimental stress path on the mechanical properties of saline frozen soil were considered.The results of the study are as follows:1) the uniaxial compression test results show that loading rate, freezing temperature, soluble salt content and moisture content have great influence on the strength of frozen soil.With the increase of loading rate and the decrease of temperature, the strength of frozen soil is increased with the increase of moisture content, while the strength of frozen soil decreases with the increase of salt content.(2) based on uniaxial creep experiment, the creep constitutive formula of time, temperature and soluble salt content on stress-strain relationship is obtained by multivariate regression method and nonlinear fitting method.The triaxial shear test results of different temperature, confining pressure and salt content are obtained by triaxial test.The results show that the stress-strain curves are parabola under different conditions.With the increase of axial strain, the principal stress difference increases rapidly when the axial strain 蔚 鈮，

本文编号：1719784