The coir fiber combined with MICP technology was used to improve the expansive soil in Nanyang section of the Middle Route of South-to-North Water Transfer Project.The unloaded expansion rate test and loaded expansion rate test were carried out on plain soil,fiber soil,MICP soil and coconut shell fiber-MICP composite improved soil,and the changes of unloaded expansion rate and loaded expansion rate of expansive soil with fiber content before and after im-provement were studied.The effects of fiber content on the expansion characteristics of expansive soil under single im-provement mode and composite improvement mode are compared and analyzed.Finally,through scanning electron mi-croscopy,the microscopic structure of the soil sample was observed to reveal the underlying mechanism of the fiber-MICP composite-enhanced swelling soil properties.The results show that both coconut shell fiber and MICP technology can inhibit the expansive property of expansive soil,and the improvement effect of coconut shell fiber-MICP composite improved soil is the most obvious.With the increase of fiber content,the unloaded expansion rate and loaded expan-sion rate of fiber soil and composite improved soil show a trend of first decreasing and then increasing,and 0.5％ is the best fiber content.Scanning electron microscopy experiments revealed that coconut fiber can act as a bridge to en-hance the improvement effect of MICP-treated expansive soils.
维普
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