Similar articles

Abstract: soil liquefaction can cause disastrous consequences to buildings and human lives. Regular countermeasures against soil liquefaction are often overly expensive for normal buildings and structures. This could be the major reason that liquefaction induced damage is still widely encountered in large- and mid-size earthquakes in recent years. In this paper, a new method for the mitigation of soil liquefaction using the microbially induced soil desaturation is proposed and tested. The desaturation effect in soil is achieved by the generation of nitrogen gas produced from the microbial denitrification process. Some major issues related to this method are experimentally investigated. These include soil desaturation procedures, shapes and distribution of gas bubbles in soil, mechanical responses and liquefaction resistance of desaturated soils, and stability of gas in soils. The desaturation treatment of soils is made simply by introducing denitrifying bacteria and a desaturation solution into soil pores by mixing, flushing, or injection. The degree of saturation can be reduced as the microbial reaction proceeds. Experimental results show that the final degree of saturation is related to the initial nitrate concentration added to the soil: the higher the concentration of nitrate in the desaturation solution, the lower the degree of saturation that can be achieved. The existence of gas bubbles in soil is evidenced by computer tomography (CT) technology. The CT images reveal that gas is in the form of small pockets which has a size a little larger than the mean size of sand grains. It is shown in the shaking table tests that microbially induced desaturation can effectively improve the liquefaction resistance of soil by showing a much lower pore pressure generation, much smaller volumetric strain, and much smaller settlement of the structure in desaturated soil, as compared with those in saturated soil. Triaxial consolidated undrained tests reveal that the desaturation treatment of soil can improve the undrained shear strength of loose sand. The stability of gas is tested under hydrostatic and water flow conditions. The gas phase is stable under the hydrostatic condition, but unstable under water flow conditions. So measures ought to be taken to prevent steady flow in practice.

Liquefaction risk mitigation by means of soil desaturation is a relatively new and potentially very useful method of ground improvement. It offers a number of advantages over other methods for ground improvement as stated by the authors. In this paper the authors present several sets of laboratory test data that demonstrate potential improvements in properties that may be attained through desaturation of saturated loose sand subjected to earthquake-type loading. Also included are test results showing that in the presence of flowing groundwater the beneficial effects of desaturation can be reversed as a result of resaturation. These results are valuable additions to our knowledge of this subject.

基于微生物诱导减饱和作用降低地基液化风险的研究

[1]Blaszczyk, M., Galka, E., Sakowicz, E., et al., 1985. Denitrification of high-concentrations of nitrites and nitrates in synthetic medium with different sources of organic-carbon. 3. Methanol. Acta Microbiologica Polonica, 34(2):195-205.

[2]Eseller-Bayat, E., Yegian, M., Alshawabkeh, A., et al., 2013. Liquefaction response of partially saturated sands. I: Experimental results. Journal of Geotechnical and Geoenvironmental Engineering, 139(6):863-871.

[3]Glass, C., Silverstein, J., 1998. Denitrification kinetics of high nitrate concentration water: pH effect on inhibition and nitrite accumulation. Water Research, 32(3):831-839.

[4]He, J., Chu, J., 2014. Undrained responses of microbially desaturated sand under monotonic loading. Journal of Geotechnical and Geoenvironmental Engineering, 140(5):04014003.

[5]He, J., Chu, J., Ivanov, V., 2013a. Mitigation of liquefaction of saturated sand using biogas. Géotechnique, 63(4):267-275.

[6]He, J., Chu, J., Ivanov, V., 2013b. Remediation of liquefaction potential of sand using the biogas method. ASCE Geo-Congress, San Diego, CA, USA, p.879-887.

[7]He, J., Chu, J., Liu, H., 2014. Undrained shear strength of desaturated loose sand under monotonic shearing. Soils and Foundations, 54(4):910-916.

[8]Ivanov, V., Chu, J., 2008. Applications of microorganisms to geotechnical engineering for bioclogging and biocementation of soil in situ. Reviews in Environmental Science and Bio/Technology, 7(2):139-153.

[9]Lee, K.L., Albaisa, A., 1974. Earthquake induced settlements in saturated sands. Journal of Geotechnical Engineering Division, 100(4):387-406.

[10]Mitchell, J., Santamarina, J., 2005. Biological considerations in geotechnical engineering. Journal of Geotechnical and Geoenvironmental Engineering, 131(10):1222-1233.

[11]Okamura, M., Teraoka, T., 2005. Shaking table tests to investigate soil desaturation as a liquefaction countermeasure. Seismic Performance and Simulation of Pile Foundations in Liquefied and Laterally Spreading Ground, University of California, Davis, CA, USA, p.282-293.

[12]Okamura, M., Soga, Y., 2006. Effects of pore fluid compressibility on liquefaction resistance of partially saturated sand. Soils and Foundations, 46(5):695-700.

[13]Okamura, M., Takebayashi, M., Nishida, K., et al., 2011. In-situ desaturation test by air injection and its evaluation through field monitoring and multiphase flow simulation. Journal of Geotechnical and Geoenvironmental Engineering, 137(7):643-652.

[14]Rad, N.S., Vianna, A.J.D., Berre, T., 1994. Gas in soils. II: Effect of gas on undrained static and cyclic strength of sand. Journal of Geotechnical Engineering, 120(4):716-736.

[15]Rebata-Landa, V., Santamarina, J.C., 2012. Mechanical effects of biogenic nitrogen gas bubbles in soils. Journal of Geotechnical and Geoenvironmental Engineering, 138(2):128-137.

[16]Saleh-Lakha, S., Shannon, K.E., Henderson, S.L., et al., 2009. Effect of pH and temperature on denitrification gene expression and activity in Pseudomonas mandelii. Applied and Environmental Microbiology, 75(12):3903-3911.

[17]Stanford, G., Dzienia, S., Vanderpol, R.A., 1975. Effect of temperature on denitrification rate in soils. Soil Science Society of America Journal, 39(5):867-870.

[18]Tokimatsu, K., Seed, H.B., 1987. Evaluation of settlements in sands due to earthquake shaking. Journal of Geotechnical Engineering, 113(8):861-878.

[19]van Paassen, L.A., Daza, C.M., Staal, M., et al., 2010a. Potential soil reinforcement by biological denitrification. Ecological Engineering, 36(2):168-175.

[20]van Paassen, L.A., Ghose, R., van der Linden, T., et al., 2010b. Quantifying biomediated ground improvement by ureolysis: large-scale biogrout experiment. Journal of Geotechnical and Geoenvironmental Engineering, 136(12):1721-1728.

[21]Whiffin, V.S., van Paassen, L.A., Harkes, M.P., 2007. Microbial carbonate precipitation as a soil improvement technique. Geomicrobiology Journal, 24(5):417-423.

[22]Wu, S., 2015. Mitigation of Liquefaction Hazards Using the Combined Biodesaturation and Bioclogging Method. PhD Thesis, Iowa State University, Ames, USA.

[23]Yang, J., Savidis, S., Roemer, M., 2004. Evaluating liquefaction strength of partially saturated sand. Journal of Geotechnical and Geoenvironmental Engineering, 130(9):975-979.

[24]Yegian, M.K., Eseller-Bayat, E., Alshawabkeh, A., et al., 2007. Induced-partial saturation for liquefaction mitigation: experimental investigation. Journal of Geotechnical and Geoenvironmental Engineering, 133(4):372-380.