Empirical equation for evaluating the dispersivity of cohesive soil

As indicated by the theory of a clay-water-electrolyte system, the dispersive mechanism of cohesive soil involves three aspects: low clay content, high sodium ion percentage, and strongly alkaline pH. Accordingly, an empirical equation was established with an associated procedure and criteria proposed for evaluating the dispersivity of cohesive soil. The equation consists of four soil physical and chemical indicators: liquid limit (W-L), clay content (P-C), sodium percentage in the pore water (P-S), and pH. The equation is F = 4 - 0.01(2W(L) + P-C - P-S) + 0.1 pH, where F is the soil dispersivity value. Compared with the evaluation based on laboratory tests, the empirical equation had higher accuracy for the evaluation of the dispersivity of cohesive soil, and was thus conducive to greater engineering safety. This indicates that the proposed empirical equation is applicable for evaluating the dispersivity of cohesive soil in general engineering.