Induced Partial Saturation Using Pseudomonas stutzeri Biogas for Mitigate Structure Settlement

Induced partial saturation (IPS) is a new foundation treatment method for mitigating soil liquefaction using biogas. A series of laboratory tests were performed to demonstrate the influencing factors of IPS using Pseudomonas stutzeri biogas. On the basis of the optimal biogas production conditions, the intervention effect of Pseudomonas stutzeri biogas on the foundation deformation under buildings was investigated based on shaking table tests. The test results showed that the best carbon source in the denitrification process of Pseudomonas stutzeri biogas is sodium citrate. The most effective initial value of optical density-based concentration was 0.1. The carbon–nitrogen ratio (C/N) of the bacterium suspension was used as the index to control the saturation. The degree of saturation reduction showed a good linear correlation with the C/N. The optimum temperature of this method was between 20 °C and 30 °C. The most suitable pH value was between 7 and 9. The environmental factors had minimal influence on the degree of saturation reduction but had a significant effect on the average rate of gas generation and the period of initial stagnation. After Pseudomonas stutzeri biogas desaturation, the settlement of the building was greatly reduced. The settlement of saturation of 92.5% sand foundation reached 17.1 mm, and the 85% saturation was only 10.6 mm. These results provide a good foundation for the feasibility of utilizing Pseudomonas stutzeri biogas mitigation of the liquefaction hazard of sand.

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