利用微生物技术改良泥炭土工程性质试验研究

提出利用微生物技术制备原生菌高浓度菌液,用来加快土中有机质分解速率,实现在较短时间内显著降低有机质含量、改善土的工程性质的目的。为验证其可行性,从昆明市2个场地采取了泥炭土样,研发了2套模型装置,分别模拟厌氧、好氧环境下泥炭土有机质分解过程,并测试分析了分解后泥炭土的烧失量、界限含水率及一维固结蠕变特性。试验结果表明:厌氧环境下,菌液浸泡的泥炭土生物气产量比纯水浸泡的有大幅度提高,其产气动力学特征符合修正Gompertz模型。好氧环境下,分解30 d左右时,2个场地泥炭土烧失量分别减少了10.3%和15.6%,减少量比厌氧环境下的大。界限含水率试验表明,泥炭土液限随微生物分解反应时间的增长有所降低,而塑限变化幅度不大。一维固结蠕变试验表明,有机质分解后的泥炭土次固结系数下降,分解时间越长,次固结系数下降越显著。对新技术的特点进行了分析,并对其理论及应用研究进行了展望;该技术有望发展为一项生态友好型的泥炭土地基新型处理方法,改良泥炭土有望成为微生物岩土技术一个潜在应用领域。

Improving engineering properties of peaty soil by biogeotechnology

It is suggested that the microbial enrichment technology should be used to increase the number and activity of primary bacteria in peaty soil so as to accelerate the degradation rate of organic matters in soil and achieve the purpose of significantly reducing the content of organic matters and improving the engineering properties of soil in a short time. In order to verify its feasibility, peaty soil samples are taken from two sites in Kunming City, and two sets of model devices are developed to simulate the degradation process of organic matters of peaty soil under anaerobic and aerobic environments, respectively. The combustion loss, limit moisture content and one-dimensional consolidation deformation characteristics of peaty soil after being decomposed are tested. The results show that under the anaerobic environment, the biogas yield of peaty soil soaked in the enriched bacteria solution is significantly higher than that of pure water immersion, and its gas production kinetic characteristics are in line with the modified Gompertz model. Under the aerobic environment, when the microbial degradation lasts for about 30 days, the burning loss of peaty soil in the two sites decreases by 10.28% and 15.58%, respectively, which is larger than that under the anaerobic environment. The experimental results show that the liquid limit of peaty soil degraded by microorganism decreases with the increase of the reaction time, and the plastic limit does not change much. The one-dimensional consolidation tests show that the secondary consolidation coefficient of peat soil after degration of organic matters decreases, and the longer the degration time, the more significant the reduction of the secondary consolidation coefficient. The characteristics of the new technology are analyzed, and its theory and application are prospected. This technique is expected to be an ecological friendly new treatment method for peat soil foundation, and improving peat soil foundation is expected to have a potential application field of biogeotechnology.