Abstract
The authors aim to develop a numerical analysis method that can appropriately assess the impact on the surrounding environment when designing disposal sites for excavated rock that contains naturally occurring arsenic. We investigated the elution behavior of arsenic in embankments made using tunnel excavation rock, and we confirmed the permeability characteristics of the embankments and the elution characteristics of the excavated rock. In addition, we conducted unsaturated column tests using excavated rock taken from this embankment, and, by formulating the elution rate of the advection-dispersion equation based on the results, the amount of arsenic elution was reproduced with a certain degree of accuracy. This time, we conducted unsaturated column tests under multiple conditions with different particle sizes and water spray rates, narrowed down the parameters related to arsenic elution, and improved the elution model. In addition, the environment within the embankment may change to a reducing environment over time, and the amount of arsenic eluted may increase. Therefore, we conducted unsaturated column tests using a reducing agent solution to confirm the effect on arsenic elution characteristics and considered incorporating this into the elution model.
