Application of biological induced calcium carbonate precipitation in improving soil erosion
[Objective]Rain,snow,waves,and wind often cause soil erosion.The bio-induced calcium carbonate precipitation technology(MICP/EICP)has become one of the research hotspots in the fields of geotechnical and geological engineering due to its environmental friendliness.[Methods]This article introduces the mineralization process of MICP/EICP,and summarizes the improved erosion effects of MICP/EICP on different types of soil based on existing research result.[Results]For soil adaptabili-ty,the unconfined compressive strength and CaCO3 content of MICP-treated coarse sand are higher than those of EICP,while the opposite is true in fine sand.For water-induced disintegration characteristics,the mass of particles below 25 μm in MICP-modi-fied clay decreases,while the mass fraction of particles between 75 and 250 µm increases,[Results]ing in larger aggregates in clay,loess,and sticky purple soil,effectively reducing the disintegration rate and disintegration rate of these soils.For wave ero-sion characteristics,with the increase in the number of spray curing from 1 to 4,the erosion rate of coastal sandy slopes decreases logarithmically.After 18 curing times,the slope angle remains almost unchanged under 30 tidal changes.For the erosion charac-teristics of tangential flow,the erosion resistance of the soil samples treated with 1 g/L xanthan gum solution combined with MICP curing for 2 times and 0.5 mol/L cement solution combined with 0.2％fiber is better than that of the soil samples treated with high-dose MICP alone.For wind erosion,when MICP is cured,0.25 mol/L cement solution can achieve wind erosion resistance,while EICP reacts faster and should be added with inhibitors.For multiple dry-wet and freeze-thaw cycles,the strength and ero-sion amount of MICP/EICP-treated samples are better than those of untreated samples,and the durability effect of EICP-treated sandy soil samples is not as obvious as that of MICP.[Conclusion]MICP is suitable for coarse-grained soil,and the generated CaCO3 has good integrity;EICP has small urease molecules and simple process,and can be applied to fine-grained soil,but the generated CaCO3 is loose.The MICP/EICP effect can effectively reduce the water-induced disintegration characteristics of fine-grained soil,effectively reduce wave erosion of coastal sandy slopes,and improve the brittleness of solidified soil by combining with fibers or biopolymers to resist the erosion of tangential water flow.A low concentration of cementing fluid formula can resist wind erosion.MICP/EICP can improve the durability of solidified soil.
MICPEICPsoil erosioninfluencing factorssoil and water conservationclimate changemechanical proper-tiesCarbon Peaking
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