ベントナイト混合土の内陸廃棄物処分場遮水工への適用性評価

Suitability of the compacted bentonite-soil mixtures as the landfill bottom liner was evaluated, mainly in the aspect of landfill stability, with the focus being on the shear strength properties of bentonite-soil mixtures affected by the increase in water contents. In the laboratory experiments, the hydraulic conductivity and soil-water characteristics curves for two types of bentonite-soil mixtures were determined to estimate the behavior of the water migration to the clay liner, using the unsaturated infiltration numerical analysis. The results showed the bentonite mixture liner constructed in the area where the ground water level is high, such as the canyon area, could easily reach the saturated condition. This increase in the water content had the adverse effect on the internal/interface shear strength parameters for bentonite-soil mixtures, mainly determined in the consolidated constant pressure direct shear tests. Two dimensional stability analyses were also performed on the cross section of a typical canyon solid waste landfills, considering the shear strength reduction due to the increase in the water content and the ground water level. Solid waste landfill stability was confirmed in the application of bentonite-soil mixtures as bottom liner materials, expect in the case that a significantly high level of leachate water existed in the landfill.