Experimental Study of the Filling Effect of MICP Microbial Grouting in Silt

摘要

MICP (Microbial Induced Carbonate Precipitation) technology was used for silt biological grouting to improve soil. First, the changes of calcium carbonate precipitation volume with different concentrations of Ca/urea reaction solution or in different inducing environments (such as culture, filtrate and thallus) were studied after the filtrate and thallus were separated from the Sporosarcina pasteurii broth. The microbial induced carbonate precipitation mechanism was also analyzed. Then, the crystalline morphology of precipitation under different concentrations of the reaction solution was researched by SEM and XRD. Finally, the cycle grouting method was used for bio-grouting in silt, from which the distribution and amount of change regarding pores in silt were analyzed through a CT scan before and after grouting. The results of this study show that the calcium carbonate precipitation was the result of urease action. Precipitation contained both vaterite and calcite. The study also found that Ca/urea concentration changes could affect the crystalline morphology of calcium carbonate. MICP could be realized in porous medium like silt by step cycle grouting. The precipitation and filling effect was increased by the number of bio-grouting. After grouting five times, soil porosity decreased from 27.27% to 11.34%. This study concludes that this method has good application potential for silt foundation reinforcement.