Influence of the features of the unsaturated zone on the air injection method in a slope

Abstract

The drainage of groundwater is essential to slope stabilisation in both potential and existing landslides. Air injection is a new method for slope drainage that aims to control rapid rises in the groundwater level by creating an artificial unsaturated zone with low permeability. The interception ratio, reflecting the effectiveness of the air injection method in intercepting groundwater, is defined in this paper and the effects of the length and hydraulic conductivity of the unsaturated zone on the interception ratio are studied through theoretical analysis, physical tests and numerical simulations. The results show that, in the initial stage, the interception ratio increases quickly with an increase in the length of the unsaturated zone. The interception ratio then gradually stabilises, with the stable value depending on the decrease in hydraulic conductivity of the unsaturated zone. The findings reported in this paper are important for improving the design of the air injection method.