微生物诱导碳酸钙沉积加固有机质黏土的试验研究

Experimental research on MICP-treated organic clay

利用尿素水解菌ATCC 11859,开展了不同胶结液浓度下MICP压力灌浆加固有机质黏土的研究试验。通过试验前后试样的无侧限抗压强度、CaCO_3含量、渗透系数、有机质含量以及灌浆过程中流出液Ca^(2+)与NH_4^+浓度的变化,综合评价了MICP压力灌浆加固有机质黏土的效果。结果表明:MICP压力灌浆加固有机质黏土是有效的,处理后试样有机质含量可降低1%～4%,无侧限抗压强度提高可达370%,渗透系数可降低约1个数量级;在本试验的菌液活性(即每分钟水解尿素的量为9.68毫摩尔每升)及浓度(约108 cell/mL)下,胶结液浓度对处理效果有明显影响,提高0.25M胶结液中的urea浓度,可显著提高处理后土体的无侧限抗压强度。

A series of tests using ureolytic bacteria ATCC 11859 are conducted to reinforce the organic clay,with cementation reagent with different concentrations flowing to the soil under pressures.The reinforcement effect is comprehensively evaluated by comparing the changes of unconfined compressive strength,content of calcium carbonate,permeability,content of organic matter and concentration of ammonia and Ca2+in the effluent.The results show that it is effective to treat the organic clay using pressure grouting.After treatment,the content of organic matter can be reduced by 1%~4%,the unconfined compression strength can increase by up to 370%,and the permeability coefficient can be reduced by about one order of magnitude.Under this bacteria condition(activity with 9.68 m M-urea hydrolysed·min-1 and concentration with about 108 cell/mL),the concentration of cementation reagent has a significant influence on the treatment effect.The unconfined compressive strength of the soil can be improved significantly by increasing the concentration of urea in 0.25 M-cementation reagent.