Mitigation of Liquefaction and Lateral Spreading by Biogas Method Using Shaking Table Tests and the Strain Energy Approach

In this study, six shaking table tests were conducted to investigate the effects of two biomaterial solutions on liquefaction and lateral spreading in a sandy layer. The desaturation liquefaction mitigation method, which was induced by biogas bubbles in loose sandy soil, was modeled in a shaking table box that was subjected to sinusoidal motions. The biogas process was based on urea hydrolysis, which was catalyzed by two urease enzymes [e.g., jack bean (Canavalia ensiformis) and soybean], into ammonium (NH₄⁺) and carbonate ions. The strain energy approach, which was based on shear stress–strain hysteresis loops, was implemented and used the recorded accelerations and pore water pressures to evaluate soil liquefaction. In addition, to measure lateral spreading displacements in a block placed on the liquefied soil, direct observation, and grading methods for soil surface displacement, and the particle image velocimetry (PIV) method were utilized. The results showed that accelerations for the treated tests presented less amplification than for the untreated (UT) test, and the pore water pressure ratio decreased by 40% and 47% due to induced biogas bubbles within a soil that used jack bean and soybean solutions, respectively. The soil layer shear wave velocity and the liquefaction energy capacity of the soil significantly increased, by approximately 100%, due to a decrease in the degree of saturation (S_r). In addition, the horizontal displacements, measured by the PIV method, showed a significant decrease in sloped block movement from 0 to 30 to 0 to 7 mm, and the grading line displacement on the soil surface was reduced by approximately 70% based on the direct method. The volumetric strain decreased by 80% when the biomaterial solutions were applied to the sandy layer.