绿色低碳化学固化技术研发是“双碳”背景之下实现淤泥质地基快速加固的有效保障。为此,创新性提出活性纳米SiO₂联合微生物诱导碳酸盐沉淀(MICP)协同技术对淤泥进行固化改性,通过试样无侧限抗压强度、pH变化、Ca²⁺利用率和扫描电镜等手段分析其加固效能与作用机理。 结果表明: ①当纳米SiO₂掺量不高于0.1%时,SiO₂-MICP固化淤泥试样抗压强度随纳米SiO₂掺量增加而增大;②相比未添加纳米SiO₂的MICP固化试样,0.5、1和2 mol/L Ca²⁺浓度下0.1%纳米SiO₂联合MICP固化试样抗压强度对应提升64.21%、10.28%和75.98%;③纳米SiO₂可为MICP提供新成核位点且填充孔隙,诱导淤泥试样中生物矿物由文石向方解石转化,且凝胶产物生成促进试样强度进一步升高;④纳米SiO₂提高胶结液中Ca²⁺利用量和利用率,并调节液相环境中pH值水平。微生物诱导产生生物CaCO₃(发挥胶结、填充、架桥等作用)和纳米SiO₂物化效应(即矿物生长新成核位点、微集料填充、胶凝产物),二者联合作用促使淤泥固化体力学特性的提升和微观骨架的构建。

The development of green and low-carbon chemical solidification technology is crucial for rapid solidification of soft ground under the “Dual Carbon” context. This study introduces an innovative synergistic technology that combines active nano-SiO₂with microbial induced carbonate precipitation (MICP) for sludge solidification. Through unconfined compressive strength tests, pH monitoring, Ca²⁺ utilization rate analysis, and scanning electron microscopy, the reinforcement efficiency and micromechanisms of this technology are examined. Key findings include: 1) An increase in compressive strength of nano-SiO₂-MICP solidified sludge is observed with increasing nano-SiO₂ content up to 0.1%. 2) Samples treated with 0.1% nano-SiO₂at Ca²⁺ concentrations of 0.5, 1, and 2 mol/L exhibit compressive strength enhancements of 64.21%, 10.28%, and 75.98%, respectively, compared to those without nano-SiO₂. 3) Nano-SiO₂ provides new nucleation sites for MICP, fills pores, induces aragonite-to-calcite transformation, and forms cementitious gels, thereby boosting sample strength. 4) The presence of nano-SiO₂enhances Ca²⁺ utilization and pH regulation within the pore solution. Together, microbial-induced bio-CaCO₃ processes (cementation, filling, bridging) and nano-SiO₂-induced physicochemical effects (new nucleation sites, micro aggregate filling, and gelling products) synergistically improve the mechanical properties of solidified sludge and optimize the microscopic structural construction.