Mitigation of environmental risk of waste ground for contribution to sustainable society

由于日本的土地空间有限，有必要利用封闭的垃圾填埋场和自然污染的土壤作为资源。在这项研究中，进行了废弃地、底层粘土层和污染土壤的特性试验研究。主要验证了以下几点：1)由于从初始刚度和内摩擦角的角度来看，废弃地可以具有与砂土地基一样高的强度，因此根据结构类型适用于扩散式基础；2)当桩基础到达底部粘土层下的持力层时，由于粘土变形的影响，钢与粘土之间的渠道在正常固结条件下足够闭合；3)膨润土屏障材料，如GCL，即使在含有重金属的酸性岩石排水的情况下，也能保持极低的渗透系数，并可以缓解重金属的向外渗漏。

Since Japan has limited land space, it it essential to utilize closed waste landfills and naturally contaminated soil as resources. In this research, experimental studies were conducted to characterize waste ground, bottom clay layer and contaminated soil. The following items are mainly verified: 1) since waste ground can has as high strength as sandy ground from the viewpoint of initial stiffness and internal frictional angle, spread foundations are applicable according to type of structures, 2) when pile foundations are installed to reach the bearing layer beneath a bottom clay layer, the channel between the steel and the clay closed enough under the normally consolidated condition by the effect of clay deformation, and 3) the bentonitic barrier material, such as GCL, can maintains extremely low hydraulic conductivity even against acid rock drainage containing heavy metals, and can mitigate outward leakage of heavy metals.