不同土体动力参数曲线分布特征及其对地震动的影响

Distribution characteristics of dynamic parameter curves of different soils and their effects on ground motion

动剪切模量比和阻尼比是表征土体非线性特征的重要动力学参数,也是影响场地地震反应特征的重要因素之一。通过对多篇文献中的常见土类进行统计分析,得到了相应的土体动力参数曲线分布特征,并在此基础上研究了土体动剪切模量比和阻尼比曲线的分布特征对场地效应的影响特点和规律。研究结果表明:各类土体的两条动力曲线统计结果的平均值与推荐值有一定程度的差异,但总体趋势一致,其中砂土、黏土、卵砾土、淤泥质土等土类的两条动力曲线的分布各具特点;受动剪切模量比和阻尼比共同影响,地震动各成分的场地效应表现出不同的特点,总体上表现为低频放大效应与高频滤波效应,动剪切模量比和阻尼比分布特征不同的土类对两种效应的影响程度不同。

The dynamic shear modulus ratio and damping ratio are the important dynamic parameters that characterize the nonlinear characteristics of soils,and are also one of the important factors affecting the seismic response characteristics of the site.The statistical analysis on common soil types in multiple literatures is conducted,and obtains the corresponding distribution characteristics of dynamic parameter curves of soils are obtained.Based on this,the influence characteristics and laws of the distribution characteristics of dynamic shear modulus ratio and damping ratio curves of soils on site effects are studied.The research results indicate that there is a certain degree of difference between the average and recommended values of the two dynamic curves of various types of soils,but the overall trend is consistent.Among them,the distribution of the two dynamic curves of soil types such as sand,clay,gravel soil and muddy soil has their own characteristics.Due to the combined influences of the dynamic shear modulus ratio and damping ratio,the site effects of each component of seismic motion exhibit different characteristics,generally manifested as low-frequency amplification effects and high-frequency filtering effects.The soil types with different distribution characteristics of dynamic shear modulus ratio and damping ratio have different degrees of influences on the two effects.