考虑多因素耦合效应的冻结兰州黄土动力学参数研究

Study on dynamic parameters of frozen Lanzhou loess considering multi-factor coupling effect

为了探究多因素耦合效应对冻结兰州黄土动力参数的影响,以分布在我国西部季节冻土区的兰州黄土为研究对象,通过动三轴试验研究了不同围压(0.1、0.2、0.3 MPa)、温度(−1、−3、−5℃)、含水率(14%、16%、18%)及加载频率(1、2、4 Hz)影响下冻结兰州黄土的动力参数变化特征。基于试验结果,分析了冻结兰州黄土最大动弹性模量、等效黏滞阻尼系数、参考应变幅值在温度、围压、含水率、加载频率等多因素耦合影响下的变化规律。结果表明,温度、含水率、加载频率和围压等耦合因素对冻结兰州黄土动弹性模量、参考应变幅值和等效黏滞阻尼系数的影响程度有差异。可以发现,冻结兰州黄土动弹性模量和参考应变幅值随温度变化的影响最显著,等效黏滞阻尼系数随加载频率变化表现最敏感。基于试验数据,对影响冻结兰州黄土的4种因素进行归一化和无量纲化处理,采用多元回归分析方法提出了冻结兰州黄土动力学参数的预测公式,有助于快速预测冻结兰州黄土在多因素耦合效应影响下的动力学参数变化特征。

In order to investigate the influence of multi-factor coupling effects on frozen Lanzhou loess dynamic parameters,Lanzhou loess distributed in seasonal frozen soil region of western China was investigated experimentally.The dynamic parameters of frozen Lanzhou loess under different conditions were examined by dynamic triaxial test,including confining pressure(0.1,0.2,0.3 MPa),soil temperature(−1,−3,−5℃),soil water content(14%,16%,18%)and vibration frequency(1,2,4 Hz).Based on the test results,the changing rules of the maximum dynamic elastic modulus,equivalent viscous damping coefficient and reference strain amplitude of frozen Lanzhou loess under the coupling influence factors of temperature,confining pressure,water content and loading frequency were analyzed.Test results show that the coupling factors including temperature,water content,loading frequency and confining pressure have different influences on the dynamic elastic modulus,reference strain amplitude and equivalent viscous damping coefficient of frozen Lanzhou loess.It can be found that the dynamic elastic modulus and reference strain amplitude of frozen Lanzhou loess are influenced most significantly by soil temperature,and the equivalent viscous damping coefficient is the most sensitive to the loading frequency.Moreover,based on the experimental results,the four factors affecting the frozen Lanzhou loess are normalized and dimensionlessized,and the prediction formulas of the dynamic parameters of the frozen Lanzhou loess are proposed using multiple regression analysis method.This will be beneficial to quickly predict the changing characteristics of the dynamic parameters of the frozen Lanzhou loess under the influence of the coupling effect of multiple factors.The formulas are helpful for rapid prediction of dynamic parameters of frozen Lanzhou loess under the multi-factor coupling influence effects.