不同颗粒尺寸条件下MICP固化砂土的试验研究

通过选取3种不同颗粒尺寸的砂样进行微生物诱导碳酸钙（MICP）注浆试验，对同一尺寸试验组分别进行8、10、12次胶结液灌注，结合细菌吸附率、流出液Ca2+浓度、试样渗透系数、碳酸钙含量、孔隙结构和最终加固效果等数据，探讨了颗粒尺寸对MICP加固砂土的影响。试验结果表明，细菌吸附率与颗粒尺寸间存在一定联系，颗粒尺寸越大，细菌吸附量相对越少；同时颗粒尺寸会影响试样固化过程及孔隙结构的发展，颗粒尺寸较小的试样能留住更多的营养物质；固化过程中，颗粒尺寸较小的砂样由于孔隙较小、渗透系数小等原因，试样上部易形成淤堵，从而导致试样加固效果不均；大颗粒尺寸的试样，孔隙较大、持水能力弱，产生的碳酸钙含量偏低并在试样下部堆积，从而导致加固效果较差。

Experimental Investigation in MICP Solidified Sands ofDifferent Particle Sizes

Three kinds of sand samples with different particle sizes are selected to carry out microbially induced calcium carbonate (MICP) grouting tests. The effects of particle sizes on sand strength are studied by grouting for 8，10, and 12 times，respectively，in combination with the data such as bacterial adsorption rate, effluent Ca2+ concentration, permeability coefficient, calcium carbonate content, pore structures, and final reinforcement effects. The results show that there is a certain relationship between bacterial adsorption rate and particle size，that is, the larger the particle size, the less bacterial adsorbance. In the meantime, particle size will affect the reinforcement process of samples and the development of pore structures. A sample with a smaller particle size can retain more nutrients. During the reinforcement process, sand samples with small particle sizes is easy to form blockage in the upper part of the sample due to small pores and low permeability coefficients, leading to uneven reinforcement effects. Samples of large particle sizes，large pores，weak water holding capacity，low calcium carbonate content，are mainly deposited in the lower part，leading to poor reinforcement effects.