红黏土动剪切模量比与阻尼比概率分布特征研究

Study on Probability Distribution Characteristics of Dynamic Shear Modulus and Damping Ratio of Red Clay

为探讨红黏土的动力学参数特征,揭示动剪切模量比与阻尼比在典型剪应变条件下的概率分布规律,本文以广西红黏土为研究对象,通过收集整理321组动力特性试验基础数据,给出了广西红黏土在典型剪应变条件下动剪切模量比与阻尼比随剪应变的试验推荐关系曲线,分析了不同概率水准条件下动剪切模量比和阻尼比的不确定性分布形态,并利用Boltzmann曲线给出了不同概率水准下动剪切模量比与阻尼比的上下限值及拟合公式。通过与前人给出的常规土类研究结果进行对比,初步揭示了红黏土动力特性与深度和剪应变的关系规律。研究表明:红黏土动剪切模量比、阻尼比在八组典型剪应变条件的上下限值随超越概率的变化呈现一定的规律,在数学形式上均满足Boltzmann方程。当剪应变在1×10^(-4)~1×10^(-3)时,动剪切模量比与阻尼比离散程度均达到最大。在同一剪应变条件下,随着超越概率的增大,红黏土动剪切模量比与阻尼比上下限之间的差距显著增大。

To investigate the dynamic parameter characteristics of red clay and reveal the probability distribution law of dynamic shear modulus ratio and damping ratio under typical shear strain conditions,taking the red clay in Guangxi province as the research object,321 groups of basic data of dynamic characteristics test are collected and sorted out,and the test recommended relationship curves of dynamic shear modulus ratio(G/G_(max)) and damping ratio(λ) with shear strain under typical shear strain conditions are given,and the uncertainty distribution of dynamic modulus damping under different probability levels is analyzed.The upper and lower limit values and fitting formula of G/G_(max) under different probability levels are given by using the Boltzmann curve.The relationship between dynamic characteristics of red clay and depth and shear strain is preliminarily revealed by comparing with the research results of conventional soils given by predecessors.The results show that the upper and lower limits of the G/G_(max) and λ of red clay under typical shear strain conditions exhibit a certain pattern with the variation of exceedance probability,and the Boltzmann equation is applicable in mathematical form.When the shear strain is between 1×10~(-4) to 1×10~(-3),the dispersion degree of dynamic shear modulus ratio and damping ratio reaches the maximum.Under the same shear strain condition,with the increase of exceedance probability,the difference between the upper and lower limits of the G/G_(max) and λ of red clay significantly increases.