Liquefaction mitigation of saturated sand using Air injection method under undrained cyclic loading

Abstract

Liquefaction, a common issue in cohessionless, saturated soils under static and dynamic loading. Inducing partial saturation is a recent method to mitigate the liquefaction of sand by generating gas or air in the pores of saturated sand. Since the fluid bulk stiffness of soil is very sensitive to the presence of gas or air, a small volume of bubbles can significantly affect the pore pressure response to loading. However, conventional measures against soil liquefaction are often expensive and unsuitable for existing structures. This study aimed to assess the effectiveness of the air injection method in preventing liquefaction in saturated sand using cyclic triaxial apparatus. Stress-controlled triaxial tests were performed on loose saturated and treated sand considering different cyclic stress ratio and confining pressure. Additionally, this study examined the durability of entrapped air bubbles under field conditions that may lead to dissolution or escape of air bubbles. To evaluate the long-term stability of the bubbles tests were conducted on partially saturated sand under hydraulic gradient flow condition. The results demonstrated a significant improvement in liquefaction resistance for the treated sand, with a reduced degree of saturation ranging from 95% to 80%. Furthermore, in durability study after downward water flow, the degree of saturation of partially saturated sand slightly increased and remained stable, indicating long-term stability