Macro and micro experimental study on solidification of Yellow River silt based on different biomineralization technologies

摘要

A large amount of silt is deposited in the riverbed of the middle and lower reaches of the Yellow River, in China. The silt content in the Yellow River silt is relatively high and the clay content is relatively low, the engineering application is limited. Based on the Yellow River silt characteristics, it was solidified by microbial induced calcite precipitation (MICP) and enzyme induced calcite precipitation (EICP) technology in this paper. Unconfined compressive strength test, CaCO_3 content test and scanning electron microscope test were used. The effects of cement solution concentration (C), grouting time (N) and relative density (D_r) on the solidification of the Yellow River silt were considered, and the advantages and disadvantages of MICP technology and EICP technology were compared. The test results show that the effect of cement solution concentration on unconfined compressive strength and CaCO_3 production of the Yellow River silt is significantly higher than that of grouting times N and relative compactness D_r, and the effect of relative compactness D_r can be ignored. When the cement solution concentration C and grouting times N are fixed, the compressive strength of EICP solidified samples is always greater than that of MICP solidified samples. The cement solution concentration C=1 mol/L and the grouting times N- 8, the maximum compressive strength of the Yellow River silt solidified by MICP and EICP technology is 674.98 kPa and 954.65 kPa, respectively. The CaCO_3 crystal generated in the sample was attached to the surface of silt particles, and the pores were also filled with CaCO_3 crystal and the particles were connected. In a word, combined with the particle characteristics of the Yellow River silt, the solidification effect of EICP technology on the Yellow River silt is better than MICP technology.