Liquid-retention behaviors of diesel contaminated soil considering the separation requirement of water and diesel

To investigate the liquid retention characteristics of soil with immiscible liquid of water and diesel, and analysis the distribution and evolution of pore water-diesel during the dehumidification process, a centrifugation method was used to test the liquid retention characteristics of soils with different water-diesel contents. Additionally, the modification of the centrifuge cup’s interface and the volumetric measurement method were used to achieve the micro-loss collection and quantitative separation of the soil and diesel. On this basis, the relationship between centrifugal equivalent suction and water content, diesel content, and total liquid content were respectively analyzed considering the soil deformation during centrifugal process. Furthermore, the influence mechanism of diesel content on the soil liquid retention characteristics and the pore evolution was analyzed. The results showed that, the liquid retention characteristics of contaminated soil was related to it’s diesel content. The air entry value and residual liquid content of the soil decreased as the increase of diesel content, indicating a weakening of the soil’s liquid retention ability. The soil with high diesel content undergoes small shrinkage deformation and large pore content undergoing the same centrifugal load. The diesel is preferred to fill larger pores due to its high viscosity and low surface tension, while 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.