目的：常规的地基抗液化技术成本较高或实施复杂，因此有大量的工程建设未得到有效的抗液化处理。本文旨在提出一种新型的、基于微生物诱导减饱和作用的地基液化治理技术，期望能应用到普通的建筑和结构的抗液化治理中。创新点：1.获得一种基于微生物反硝化过程的砂土减饱和方法；2.试验验证微生物减饱和法处理砂土的抗液化性能，获得微生物减饱和法处理砂土中的气泡分布形态以及气泡在静水和渗流条件下的稳定性规律。方法：1.利用微生物反硝化过程中产生的氮气降低饱和液化砂土的饱和度；2.利用电脑断层扫描（CT）技术研究微生物减饱和法处理的砂土中气泡的分布形态；3.利用振动台实验和三轴固结不排水试验研究微生物减饱和法处理的砂土的力学性能和抗液化性能；4.采用一种自行研制的模型试验（图13）研究微生物减饱和法处理的砂土在静水和渗流条件下气泡的稳定性。结论：1.利用微生物反硝化过程可以实现可控的砂土饱和度降低；2.微生物气泡在砂土中以小空隙的形态存在，小空隙的尺寸略大于砂土的平均粒径；3.将饱和松砂的饱和度略作降低，其不排水强度和抗液化性能得到显著提升；4.微生物减饱和法处理的砂土中的气泡在静水条件下是稳定的，但是在稳定渗流条件下会被水流缓慢带走，此时，需要采用一些手段来控制通过减饱和区的渗流。“,”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 injec-tion. 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.