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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。
As a kind of embankment filler, the modulus and damping ratio of EPS mixed soil under dynamic load are important parameters for dynamic stability analysis of embankment. 15 cyclic torsional shear tests were carried out to study the dynamic characteristics of EPS mixed soil. The characteristics of backbone curve, modulus and damping ratio of EPS mixed soil were analyzed. The effects of mixing ratio and initial consolidation conditions were discussed. The results show that the EPS hybrid soil has typical dynamic nonlinear characteristics and is controlled by the strength and initial stress state of the cement soil. EPS incorporation ratio has little effect on the initial shear modulus of the mixed soil. However, after the soil enters the non-linear phase, The weakening effect of EPS particles on the strength of the mixed soil is obvious. The dynamic behavior of the weak contact surface between the EPS particles and the cement-soil leads to the “structural damping” effect, which is an important component of the damping mechanism of the mixed soil. The initial shear modulus As the initial small principal stress increases, the modulus decay characteristics are significantly correlated with the initial small principal stress and the EPS incorporation ratio. Based on the experimental results, an empirical model describing the characteristics of backbone curve, modulus attenuation and damping ratio of EPS mixed soil is given.