贵阳地区红黏土动力参数计算模型研究

A Calculation Model of Red Clay Dynamic Parameters in the Guiyang Area

利用室内SDT-20动三轴试验机对贵阳原状红黏土进行循环荷载作用下动力特性试验,探究不同围压、固结应力比和振动频率对红黏土动力学参数的影响,结合实验数据及参数模型拟合贵阳红黏土动应力应变关系、动弹性模量及阻尼比经验公式,结果表明:贵阳红黏土动本构关系仍符合H-D双曲线增长模型,动弹性模量随动应变增长非线性衰减,阻尼比随动应变增长非线性增加。围压及固结应力比对红黏土动力学参数具有显著影响,围压及固结应力比增大,动变形减小,动弹性模量增加,阻尼比降低,同等条件下,提高振动频率,动力学参数显示出与围压及固结应力比相同规律,但不显著。基于H-D模型,给出了贵阳原状红黏土双曲线模型参数,通过多元回归分析,拟合并提出针对贵阳红黏土的在不同试验条件下动弹性模量衰减及阻尼比经验公式,给出相应的拟合参数。

The dynamic characteristics of undisturbed red clay in Guiyang under cyclic loading were tested by a SDT-20 dynamic triaxial testing machine in the laboratory.Effects of confining pressure,consolidation stress ratio,and vibration frequency on the dynamic parameters of red clay were investigated.Results showed that the dynamic constitutive relationship of Guiyang red clay conforms to the H-D hyperbolic growth model.Dynamic elastic modulus decreases nonlinearly with increasing dynamic strain,and the damping ratio increases nonlinearly with increasing dynamic strain.In addition,confining pressure and consolidation stress have a significant influence on the dynamic parameters of red clay.Details are as follows:with increasing confining pressure and consolidation stress ratio,dynamic deformation and damping ratio decrease,and dynamic elastic modulus increases.Under the same conditions,if the vibration frequency is increased,the kinetic parameters will follow the same law as confining pressure and consolidation stress ratio,though not significantly.Based on the H-D model,the hyperbolic model parameters of undisturbed red clay in Guiyang are given.The empirical model of dynamic elastic modulus attenuation and damping ratio of Guiyang red clay under different test conditions is proposed by multiple regression analysis,and the corresponding fitting parameters are given.