Experimental Study on Mechanical Properties of Soil mixed with Deformable Particles

本研究以膨胀塑料废弃物为原料，对可变形颗粒混合土的变形性能等力学性质进行了研究。首先，利用一维固结试验结果，研究了骨架中含有变形颗粒的土体的一维压缩机理。其结果是，在可变形颗粒混合土的情况下，除了由于刚性颗粒骨架的重新排列而引起的普通体积压缩之外，还有两种额外类型的压缩结构配置。一种是可变形颗粒本身的体积压缩，另一种是可变形颗粒的变形引起的进一步的孔相减少。然后，利用X射线CT进行显微观察，评价可变形颗粒的体积压缩情况。从而定量地证实了上述额外成分分类的有效性。同时，利用双室装置进行了三轴压缩试验，尝试将体积压应变单独测量为可变形颗粒本身的压缩和孔隙空间的缩小量。然而，不可能单独估计这两种额外类型的成分，因为水的存在进入了膨胀塑料颗粒表面的孔隙空间。因此，在本研究的后期，对土体的蠕变特性和渗透保水性能进行了研究，以期将这种膨胀塑料废弃物实际应用于轻质土工材料中。结果表明，蠕变引起的沉降量与塑料垃圾的混合比例成正比。在物理性质方面，阐明了塑料废弃物与土壤混合后，除了起到轻化作用外，还提高了透水性和保水性。

In this study, mechanical properties, such as deformability, of deformable particle mixed soil using expanded plastic wastes were investigated. At first, one-dimensional compression mechanism of soil which containing deformable particles in the soil skeleton was examined using the results of one-dimensional consolidation tests. As a result, two extra types of compression structural configurations of the components in addition to the ordinary volumetric compression caused by the rearrengement of a rigid particle skeleton as in the case of the deformable particle mixed soil. One of them was the volumetric compression of the deformable particle itself and the other was a further pore phase reduction caused by the deformation of the deformable particles. Then, microscopic observation using X-ray CT was carried out to evaluate the volumetric compression of deformable particles. Consequently, it was quantitatively confirmed that above-mentioned classification of extra components was valid. And in parallel, triaxial compression tests using double cell apparatus were conducted to attempt the individual measurement of volumetric compressive strain into the compression of deformable particle itself and the amount of pore space reduction. However, it was impossible to estimate these two extra types of components individually, because of the existence of the water getting into the pore spaces of expanded plastic particle's surfaces. Therefore, the latter term of this study, creep property and permeability & water retentivity of soils were investigated, for the purpose of the actual application of this expanded plastic wastes into the lightweight geomaterials. As a result, the amount of settlement caused by creep was in proportion to the mixing ratio of the plastic wastes. And as for the physical properties, it was clarified that the permeability and water retentivity were improved in addition to lightening effect, in case of mixing this plastic wastes with soil.