Liquid-retention characteristics of diesel-contaminated soil considering water-diesel separation

To investigate the liquid-retention characteristics of soils with immiscible liquid of water and diesel, and analysis the distribution and evolution of pore water-diesel during the dehumidification process, a centrifuge method is used to test the liquid-retention characteristics of soils with different water-diesel contents. Additionally, the modified interface of the centrifuge cup and the volumetric measurement method are used to achieve the micro-loss collection and quantitative separation of the soil and diesel. On this basis, the relationship among centrifugal equivalent suction, water content, diesel content and total liquid content is respectively analyzed considering the soil deformation during the centrifugal process. Furthermore, the influence mechanism of the diesel content on the liquid-retention characteristics of soils and the pore evolution is analyzed. The results show that the liquid-retention characteristics of the contaminated soil are related to its diesel content. The air entry value and residual liquid content of the soil decrease as the increase of the diesel content, indicating a weakening of the liquid retention capability of the soil. The soil with high diesel content undergoes small shrinkage deformation and large pore content under the same centrifugal loads. The diesel is preferred to fill larger pores due to its high viscosity and low surface tension, while the water is preferred to exist in smaller pores due to its strong polarity and wettability. The water-diesel ratio in the pores trends to reach a constant range as the matric suction increases.