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.