Study on the mechanical properties of lignin fiber-MICP solidified silt under freezing and thawing cycles
This study investigates the mechanical properties of silty soil in seasonally frozen regions,stabilized using lignin fibers in conjunction with microbially induced carbonate precipitation(MICP).A series of experi-ments were conducted,including assessments of calcium carbonate production influenced by lignin fibers,un-confined compressive strength tests,direct shear tests,and scanning electron microscopy(SEM)analysis of lig-nin fiber-MICP stabilized samples subjected to freeze-thaw cycles.The results indicate a linear increase in calci-um carbonate content with increasing fiber content,with the calcium carbonate content in the SF2M sample ex-hibiting a 426.6％increase compared to the SF0M sample.With an increase in freeze-thaw cycles,both the un-confined compressive strength and shear strength of all samples diminished,eventually stabilizing.Among the samples,the SF1.5M,containing 1.5％lignin fiber,demonstrated the highest resistance to freeze-thaw degrada-tion.After 10 freeze-thaw cycles,its unconfined compressive strength decreased by only 45.9％,whereas the SF0M and SF0 samples showed reductions of 63.4％and 80.0％,respectively.Furthermore,after 10 freeze-thaw cycles under a normal stress of 400 kPa,the shear strength of the SF1.5M sample increased by 76.4％and 184％compared to the SF0M and SF0 samples,respectively.Cohesion in the SF1.5M sample also improved significantly,with increases of 46.5％and 126.0％over the SF0M and SF0 samples.At a fiber content of 1.5％,a denser cemented structure formed between soil particles,calcium carbonate crystals,and fibers,en-hancing soil stabilization.However,when the fiber content reached 2.0％,calcium carbonate crystals inter-twined with the fibers,forming aggregates that impeded the effective cementation between soil particles,there-by diminishing the stabilization effect.In conclusion,this research offers important data and theoretical guid-ance for soil reinforcement in cold regions,particularly under the influence of freeze-thaw cycles.The findings contribute to the understanding of soil stabilization mechanisms and provide practical insights for improving the mechanical properties of silty soils in seasonally frozen environments.
万方数据
维普
