EPS混合土的动模量和阻尼比特性

Dynamic modulus and damping ratio characteristics of EPS composite soil

作为一种路堤填料,EPS混合土在动力荷载作用下的模量和阻尼比是进行路堤动力稳定性分析的重要参数。开展了15个循环扭剪试验研究EPS混合土的动力特性,分析了EPS混合土的骨干曲线、模量以及阻尼比特性,重点讨论了配合比和初始固结条件的影响。结果表明,EPS混合土具有典型的动力非线性特征,受水泥土强度和初始应力状态控制;EPS掺入比对混合土的初始剪切模量几乎无影响,但土体进入非线性阶段后,EPS颗粒对混合土强度的削弱作用明显;EPS颗粒与水泥土间薄弱接触面的动力行为导致"结构阻尼"效应,是混合土阻尼机制的重要组成;EPS混合土的初始剪切模量随试样初始小主应力增大而增大,其模量衰减特性与初始小主应力和EPS掺入比显著相关。基于试验结果,给出了描述EPS混合土骨干曲线、模量衰减和阻尼比增长特性的经验模型。

The shear modulus and damping ratio of EPS composite soil, as a kind of artificial filling material, are the key parameters to analyze the dynamic stability of embankment. 15 cyclic torsional tests are conducted on the hollow cylindrical samples of EPS composite soil to study its dynamic characteristics. The characteristics of skeleton curve, dynamic shear modulus and damping ratio for EPS composite soil are analyzed. The influences of mixing ratio and initial consolidation state are discussed. It is found that the EPS composite soil is characterized by typical dynamic non-linearity which is controlled by the strength of cemented soil and the initial stress state, but EPS bead content has no obvious influence on the initial shear modulus. After EPS composite soil enteres the non-linear deformation stage, EPS beads have a remarkable weakening effect on its strength. The ＂structural damping＂ effect induced by the dynamic behavior of the weak interface formed between EPS beads and cemented soil is an important component of the damping mechanism for EPS composite soil. The initial shear modulus increases with the increase of the initial minor principal stress. And the modulus attenuation characteristics are significantly influenced by the initial minor principal stress and EPS bead content. Based on the test results, the empirical models are given to describe the skeleton curve, modulus attenuation and damping growth characteristics for EPS composite soil.