Yuan Hua, Wang Shuaiqi, Zhu Ziqi, Ru Mengyao, Wan Aochong, Zhu Xiang
School of Civil Engineering and Architecture, Henan University, Kaifeng, 475004, China.
School of Civil Engineering and Architecture, Henan University, Kaifeng, 475004, China.
Environ Res. 2025 Jul 12;285(Pt 1):122350. doi: 10.1016/j.envres.2025.122350.
Enzyme-induced carbonate precipitation (EICP) technology holds significant potential for applications in geotechnical engineering. While prior research has primarily focused on the mechanical enhancement of EICP-treated soils, limited attention has been paid to their long-term stability and durability. This study addresses the deterioration of foundation soils in the seasonally frozen region of the lower reaches of the Yellow River, where repeated freeze-thaw (FT) cycles pose a major challenge. To enhance silt stability under such conditions, a novel approach combining EICP with magnesite mine tailings (MMT) was investigated. The effects of FT cycles on the mechanical properties, physical characteristics, and microstructure of the treated silt were evaluated, alongside an environmental risk assessment. Results showed that prior to FT exposure, the unconfined compressive strength and secant modulus of the treated soil increased by 1.67 and 3 times, respectively, than those of the untreated soil, while apparent porosity and permeability coefficient decreased by 20 % and 93 %, respectively. Under increasing FT cycles and wider FT temperature variations, the EICP-MMT-treated soil maintained lower apparent porosity and higher strength, toughness, and stiffness compared to untreated silt. However, the degree of improvement gradually diminished with increasing number of FT cycles. Furthermore, the treatment significantly reduced the leaching and bioavailability of heavy metals, thereby lowering environmental pollution risks. These findings suggest that EICP-MMT treatment provides a promising strategy for reinforcing road or building foundations in seasonal permafrost regions.
酶诱导碳酸盐沉淀（EICP）技术在岩土工程应用中具有巨大潜力。虽然先前的研究主要集中在EICP处理土壤的力学增强方面，但对其长期稳定性和耐久性的关注较少。本研究针对黄河下游季节性冻土地区地基土的劣化问题，在该地区反复冻融（FT）循环是一个重大挑战。为提高这种条件下粉土的稳定性，研究了一种将EICP与菱镁矿尾矿（MMT）相结合的新方法。评估了冻融循环对处理后粉土的力学性能、物理特性和微观结构的影响，并进行了环境风险评估。结果表明，在经历冻融之前，处理后土壤的无侧限抗压强度和割线模量分别比未处理土壤提高了1.67倍和3倍，而表观孔隙率和渗透系数分别降低了20%和93%。在冻融循环次数增加和冻融温度变化范围扩大的情况下，与未处理的粉土相比，EICP-MMT处理的土壤保持了较低的表观孔隙率和较高的强度、韧性及刚度。然而，随着冻融循环次数的增加，改善程度逐渐减小。此外，该处理显著降低了重金属的浸出和生物有效性，从而降低了环境污染风险。这些发现表明，EICP-MMT处理为季节性冻土地区道路或建筑地基加固提供了一种有前景的策略。
