微生物矿化对黏土渗透性影响的试验研究

为探究矿化对黏土渗透性的影响,采用球形赖氨酸芽孢杆菌属kp-22菌诱导矿化处理黏土,测定了碳酸盐生成率,研究了矿化处理后黏土的渗透性,系统分析了渗透系数随菌液OD₆₀₀值、胶结液浓度和土中镉含量变化的规律,探讨了各因素对渗透系数的影响规律及机理,建立了考虑菌液OD₆₀₀值和胶结液浓度影响的矿化后黏土渗透系数的经验公式。结果表明:矿化后的土样中生成了碳酸盐颗粒,填充了部分土体孔隙,渗透系数最多可降低约一个数量级；随着菌液OD₆₀₀值的增大,矿化后黏土的碳酸盐生成率先升高后逐渐稳定,而土样的渗透系数先减小后趋于平稳,当菌液OD₆₀₀值大于0.9时,碳酸盐生成率和渗透系数都变化很小；随着胶结液浓度增大,碳酸盐生成率先升高后下降,而渗透系数先减小后增大,当胶结液浓度为0.8 mol/L时,黏土的渗透系数最小；随着土中镉含量的增大,矿化反应受到抑制,渗透系数逐渐增大；矿化后黏土的渗透系数与碳酸盐生成率负相关,两者满足线性关系；所建立的矿化后黏土渗透系数经验公式计算值与试验结果吻合较好。

Experimental study on influence of microbial mineralization on permeability of clay

In order to explore the influence of mineralization on clay permeability, clay was treated by induction of mineralization through Sporosarcina kp-22. The carbonate formation rate of clay after treatment was measured and the clay permeability characteristics were studied. The permeability coefficient variation with the OD₆₀₀ of bacteria, the concentration of cementation solution and cadmium content were investigated. The influence rule and mechanism of each factor on permeability coefficient were discussed. The empirical formulas to calculate permeability coefficient of clay after mineralization considering the OD₆₀₀ and concentration of cementation solution were established. The results show that carbonate crystal was formed in the mineralized soil samples, which can fill some pores in the soil, and the permeability coefficient of clay can be reduced by at most one order of magnitude. With the increase of OD₆₀₀, the carbonate formation rate in mineralized soil first increased and then gradually stabilized, but the permeability coefficient first decreased and then tended to be stable. When the OD₆₀₀ was greater than 0.9, the carbonate formation rate and the permeability coefficient changed little. With the increasing concentration of cementation solution, the formation rate of carbonate first increased and then decreased. On the contrary, the permeability coefficient first decreased and then increased. When the concentration of cementation solution was 0.8 mol/L, the permeability coefficient was the lowest. With the increasing cadmium content in soil, the mineralization reaction was inhibited and the permeability coefficient increased gradually. Permeability coefficient after mineralization is negatively correlated with carbonate formation rate, which satisfies a linear relationship. The calculated coefficients of the empirical formulas established for permeability coefficient of clay after mineralization agree well with the experimental results.