Prevention of Liquefaction of Saturated Sand Using Biogas Produced by Pseudomonas stutzeri

Abstract

Shear strength of sand increases with the decrease of saturation degree. An attempt to develop a more effective biogas desaturation method is made in this study. The microbial denitrification process of pseudomonas stutzeri, which is able to produce nitrogen gas, is selected for the desaturation of liquefiable sand. Frist, to demonstrate the feasibility of induced-partial saturation using nitrogen gas bubbles produced by pseudomonas stutzeri, research on denitrification condition and efficiency are made. The suitable range of temperature is determined. Comparing with existing method using biogas, this bacteria has advantages including faster average rate of generating gas, shorter initial stagnation period and simple technology. Then, to explore the effect of mitigation using this method, full and partially saturated sand samples are prepared and serial of shaking table simulation tests are performed under applying a series of cyclic loading with different acceleration amplitude. The influences of initial samples saturation on the excess pore water pressure, pore pressure ratio and surface settlement are investigated. Finally, the exponential relationship between volumetric strain and average pore water pressure ratio is established for full and partial saturated samples.