微生物矿化加固含镉黏土的无侧限抗压强度影响因素研究

Study on Factors Affecting Unconfined Compressive Strength of Cadmium--Containing Clays Reinforced by Microbial Mineralization

微生物矿化技术因其环境友好性,成为土体加固技术的研究热点。采用课题组提取的Kp-22土著菌诱导矿化处理黏土并开展无侧限抗压强度试验,研究了菌液OD_(600)为0.3~1.2、胶结液浓度为0.4~1.0 M/L、土中镉含量为2~16 mg/kg组合时,矿化后土样的碳酸盐含量和无侧限抗压强度随各因素的变化规律。通过逐步回归方法建立了考虑多因素的抗压强度经验公式。结果表明:菌液OD_(600)从0.3增大至0.9时,矿化的碳酸盐含量和强度逐渐升高,OD_(600)大于0.9后,增大菌液浓度对碳酸盐含量和强度的影响不大;随着胶结液浓度增大,黏土的碳酸盐含量和强度先升高后降低,胶结液浓度为0.8 M/L时碳酸盐含量和强度最高;随着镉含量增大,土样碳酸盐含量和强度均逐渐降低。此外,提出的抗压强度经验公式计算值与实测值吻合较好,可为微生物矿化处理后强度的预测提供参考。

Due to environmental friendliness,microbial mineralization technology has become a research hotspot.The Kp-22 Indigenous bacteria extracted by the author's group were used to induce the mineralization treatment of clay and the the unconfined compressive strength test was conducted.The laws of the carbonate content and unconfined compressive strength of the mineralized soil samples varied with each factor were investigated when the bacterial solution OD_(600)value was 0.3–1.2,the concentration of the cementitious solution was 0.4–1.0 M/L,and the cadmium content of the soil was 2–16 mg/kg.An empirical formula for compressive strength considering multiple factors was developed using the stepwise regression method.The results showed that when the OD_(600)value increased from 0.3 to 0.9,the carbonate content and strength of the clay gradually increased;when the OD_(600)value was over 0.9,increasing the concentration of the bacterial solution had little effect.The carbonate content and strength of the clay increased and then decreased with the increase of the concentration of the cementitious solution,peaking at the concentration of 0.8 M/L.The carbonate content and strength of the clay gradually decreased as the cadmium content increased.In addition,the calculated value of the compressive strength empirical formula was in good agreement with the test value,which can provide a reference for predicting soil strength after microbial mineralization.