菌液浓度对SHMP改性微生物碳化活性MgO法固化黏土强度与微观结构影响

Effect of Bacterial Solution Concentration on the Strength and Microstructure of Clay Solidified by SHMP Modified Bio-carbonated Reactive MgO Method

每年清淤疏浚过程都不可避免地会产生大量软弱土,亟须探寻环保有效的固化方法来对这些软土进行固化处理。微生物碳化活性MgO技术在土体改性中有着较好的应用前景与可持续性,将六偏磷酸钠(SHMP)、活性MgO以及巴氏芽孢杆菌诱导尿素水解过程引入到软土固化中,制备了不同稀释程度菌液的高初始含水率三轴试样,开展了无侧限抗压强度实验与扫描电镜实验,探讨了不同稀释程度菌液对固化试样的强度及微观胶结结构的影响。研究结果表明:泥浆状态的试样强度在养护1 d后即可显著提高,最高可超1 MPa;菌液浓度的下降使得试样的强度逐渐下降、胶结结构更加稀疏、颗粒间更加松散;当菌液稀释3倍后固化试样的强度接近无菌组试样的强度,表明菌液可作适当稀释使用,但稀释倍数不宜超过2倍。

Every year,the dredging process inevitably produces abundant soft soils,and it is urgent to explore environmentally friendly and effective solidification methods to treat these soft soils.Bio-carbonated reactive MgO technology has good application prospects and sustainability in soil improvement.Sodium hexametaphosphate(SHMP),reactive MgO and urea hydrolysis induced by Bacillus pasteurii were introduced into soft soil solidification,and triaxial specimens with high initial moisture content were prepared with different dilution degrees of bacterial solution.Unconfined compressive strength tests and scanning electron microscope tests were carried out to investigate the influence of different dilutions of bacterial solution on the strength and microstructure of solidified specimens.The results show that the strength of slurry-like specimens can be obviously improved after curing for one day,and the maximum strength can exceed 1 MPa.As the concentration of bacterial solution decreased,the strength of the specimens decreased gradually,the cemented structure became sparser,and the particles were much looser.When the bacterial solution was diluted 3 times,the strength of the cured specimens was close to those without bacteria,which indicated that the bacterial solution could be properly diluted,but the dilution ratio should not exceed 2 times.