Numerical analysis of soil desaturation by an air injection method

Abstract

A numerical analysis is conducted to evaluate the effective radius of air advance (Reff) in coarse-grained, saturated, sandy deposits improved by means of air injection (i.e., soil desaturation). It is well-known that the cyclic resistance to liquefaction of a saturated sandy deposit is highly affected by the presence of gas in the void space. A parametric study is performed to investigate the soil’s main hydraulic parameters and air-injection conditions of the transient gas affecting Reff and controlling the desaturation process. The effects of the a) soil-water characteristic curve, b) intrinsic permeability, c) injection pressure, and d) duration of air injection are investigated. It is shown that the injection pressure and soil’s intrinsic permeability are the main factors influencing the extent of Reff. The analysed cases showed that, for a fixed injection pressure, the soil will achieve a maximum value for Reff. This threshold value is reached more rapidly when the soil’s intrinsic permeability increases. The results aim to shorten existing knowledge gaps and contribute to the development of design methodologies for air-injection desaturation techniques.