EPS颗粒轻质混合土的蠕变模型研究

EPS颗粒轻质混合土是一种新型轻质填土材料，相比EPS泡沫块体，具有更广泛的应用前景。EPS颗粒轻质混合土的基本物理及力学性质已得到了较多的研究，但其蠕变特性研究较少。通过不同围压下EPS颗粒轻质混合土的三轴不排水蠕变试验，采用三种常用的经验模型：Singh & Mitchell模型、Mesri模型和Findley模型对EPS颗粒轻质混合土的蠕变变形进行模拟，结果表明：Singh & Mithcell模型和Mesri模型能反映蠕变趋势，但是不能拟合应变初始快速上升段，用来描述EPS泡沫块体的Findley模型在应力水平较高时，拟合效果最好，某种程度上说，EPS颗粒轻质混合土的蠕变性与EPS泡沫块体相似。推导出了一种新的半经验半理论蠕变模型，用元件模型描述弹性变形部分，用经验模型描述塑性变形部分，拟合结果表明，不管应力水平的高低，新推蠕变模型都不仅能够很好地反映EPS颗粒轻质混合土的初始快速上升段变形，也能够比较准确地拟合长期变形，即蠕变性。

Research on creep model of EPS composite soil

Expanded polystyrene(EPS) composite soil is a new kind of lightweight fill material. Compared with well-known EPS geofoam, EPS composite soil will be widely used in the future. The fundamental physico-mechanical properties of EPS composite soil have been studied by many researchers. However, the creep properties of EPS composite soil have not been published in the literatures according to our best knowledge. Firstly, the triaxial undrained creep tests were conducted on EPS composite soil with various confining pressures. Secondly, three well-known empirical creep models were used to simulate the creep behavior of EPS composite soil including Singh & Mitchell model, Mesri model, and Findley model. Singh & Mithcell model and Mesri model were able to predict the long-term deformation of EPS composite soil, however, they could not describe the initial sharp rising deformation. It was observed that Findley model which was firstly used to predict the creep behavior of EPS geofoam had the best fitting results under higher deviator stress level. To some extent, the creep property of EPS composite soil was similar to that of EPS geofoam. Finally, a new creep model was proposed for EPS composite soil, in which the element models were used to describe the elastic strain and empirical models to describe the plastic strain. It was shown that whatever the stress levels were, the proposed new creep model could not only describe the initial sharp rising deformation but also predict the long-term deformation, i.e. creep deformation.