Considering the soil improvement effect of micro-organic metabolites, Aspergillus niger, Agrobacterium radiobacter and Bacillus licheniformis were selected for experiments on the microbial improvement of hydraulic fill soil. Specifically, different microbial strains and culture media were added to hydraulic fill soil, and subjected to triaxial shear tests. Then, the specific surface area (SSA), chemical composition and mineral composition of the microorganism-modified soil were measured and analysed. The results show that, the soil samples mixed with all microbial strains, except Aspergillus niger, underwent the reduction of the peak deviator stress, the increase of cohensive force and the decrease of the internal friction angle. The soil samples had similar mineral composition. After the introduction of microbial strains and culture media, the valent cation content and the friction between soil grains of all samples both dropped, leading to a decline in the internal friction angle. The SSA of soil grains added with Agrobacterium radiobacter increased by 49%, while that of soil grains added with Bacillus licheniformis grew by 45%. This is because the strains altered the connection state between soil grains and the soil structure, which enlarged the soil particles and enhanced the cohesive force. The research findings reveal the good effect of microbial technology in the improvement of hydraulic fill soil, and lays a soild basis for the application of the microbial improvement technology
microbial improvement, hydraulic fill, triaxial shear test, osmotic coefficient
Project funded by National Natural Science Foundation (51768006)
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