灌注次数过多制约了微生物诱导碳酸钙沉积（MICP）在实际工程中的应用。为了减少灌注次数、提高胶结效率，提出一种MICP加固强化方法，即在胶结液中添加铝离子絮凝剂，以提高MICP加固速率和增强加固效果。开展MICP砂柱试验，在胶结液中加入不同浓度AlCl₃?6H₂O进行灌注试验，然后测试加固砂柱碳酸钙含量及无侧限抗压强度（UCS）。在水溶液试验中，观察不同溶液条件下沉积物生成情况及溶液的pH值变化，并通过XRD、SEM试验研究铝离子絮凝剂对沉积碳酸钙的成分及形态的影响。结果表明：与常规方法的对照组比较，胶结液中加入适量铝离子絮凝剂，灌注3次后砂柱即可形成有强度的固结体，灌注5次后砂柱无侧限抗压强度可达到1.7 MPa，而常规对照组达到相同的强度需要灌注9次。铝离子絮凝剂的掺入有效减少了MICP灌注处理次数，对实际应用有重要意义。

The excessive number of cementing solution injections required for MICP limits its practical engineering application. In order to reduce the number of injections and improve the efficiency of the cementing process, an enhancement method was investigated in this study in which aluminum ion flocculant was added to the cementing solution to enhance the curing rate and effectiveness of MICP. Experiments were carried out on MICP-reinforced sand columns, and the influence of different concentrations of AlCl₃?6H₂O on the cementing solution was studied. Then the influence of AlCl₃?6H₂O on production of calcium carbonate and unconfined compressive strength (UCS) was studied. In the aqueous solution test, the changes of precipitation and solution pH under different solution conditions were observed, and the effects of the aluminum ion flocculant on the composition and morphology of the deposited calcium carbonate were investigated using XRD and SEM tests. The results show that, compared with the control group, after adding an appropriate amount of aluminum ion flocculant to the cementing solution, the proposed method resulted in the experimental sand column being reinforced after 3 treatments of the cementing solution. The UCS reaches 1.7 MPa after 5 treatments of the cementing solution, compared to 9 treatments using the conventional method. The addition of AlCl₃?6H₂O to the cementing solution significantly reduced the number of MICP injections required compared to the control group. This study provides an important reference for applying MICP-reinforced sand in practical engineering.

TU441;TU472.5

国家自然科学基金（51578214）；江苏省交通运输厅科技成果转化项目（2021QD07）