A study on the electrical resistivity and ultrasonic wave velocity characteristics of oil-contaminated soil

With the rapid development of the global oil industry, various oil-contaminated soil problems are on the rise, seriously affecting ecological balance and human health. Compared with traditional complex pollution investigation methods, resistivity method and ultrasonic method are a fast, convenient, and non-intrusive pollution detection method. To investigate the information response of resistivity and ultrasonic to oil-contaminated soil, this paper studied the variation of resistivity and ultrasonic velocity of oil-contaminated soil with moisture content (4 %–12 %) and oil content (3 %–15 %). The results indicate that moisture content is the primary factor influencing the soil's electrical conductivity. When the oil content is between 3 % and 15 %, the resistivity of oil-contaminated soil decreases with the increase of moisture content. The more water in soil pores, the better the soil conductivity and the lower the resistivity. When the soil is in a low saturation state, oil will hinder the soil's electrical conductivity. When the moisture content is below 6 %, the resistivity of the soil shows an increasing trend with the increase of oil content. However, as the moisture content increases, the influence of oil content on resistivity gradually weakens. When the sample's wet density is constant, the soil porosity increases with higher moisture and oil content, resulting in a decrease in wave velocity of the oil-contaminated soil. The influence of moisture on ultrasonic waves is more significant. These findings provide a theoretical basis for the future use of resistivity and ultrasonic detection methods to assess the degree of contamination at polluted sites.