Abstract: Activated magnesium oxide (MgO), desulfurization gypsum (DG) and steel slag (SS) were used for solidification treatment of dredged sediment. The main factors affecting the strength of solidified sediment, the optimum content of solidified materials and the microscopic solidification mechanism were studied through the single-doping test, response surface test and microscopic characteristics test. The test results show that the single-doped solidification effect of MgO is the most significant, followed by DG, and the single-doped solidification effect of SS is the poorest. The strength of MgO solidified soil increases rapidly in the first 7 days, while that of DG solidified soil grows gently with age. While the strength of SS solidified soil mainly increases in the later curing period due to the slow hydration reaction. According to the response surface test, the interaction between MgO-DG and DG-SS is significant, and the optimum content of MgO, DG and SS in the solidified sediment is 7.62%, 11.31% and 5.80%, respectively. Through the XRD and SEM analysis, it is found that the hydration reaction in the MgO-DG-SS composite cementing system is mutually promoted, and the encapsulation, cementation and filling effect of hydration products make the soil microstructure more compact and stable. Based on the test results, a microscopic mechanism model of MgO-DG-SS solidified sediment is proposed.

Key words: geotechnical engineering; dredged sediment; magnesium oxide; desulfurization gypsum; steel slag; response surface methodology; microscopic characteristics

摘要： 采用活性氧化镁（MgO）、脱硫石膏（DG）和钢渣（SS）对疏浚底泥进行固化处理，通过单掺试验、响应面试验和微观特性试验，研究了影响固化底泥强度的主要因素、固化材料的最佳掺量，以及微观固化机理。结果表明：在单掺时，MgO的固化效果最为显著，DG次之，SS单掺固化效果较差；MgO固化土在前7 d时的强度增长迅速，DG固化土强度随龄期增长平缓，而SS由于水化反应慢，SS固化土的强度增长主要发生在养护后期。由响应面试验可知，MgO-DG、DG-SS之间的交互作用显著，MgO、DG、SS在固化底泥中的最佳掺量分别为7.62%、11.31%和5.80%。通过XRD和SEM分析，发现MgO-DG-SS复合胶凝体系中的水化反应是相互促进的，水化产物的包裹、胶结与填充作用，使得土体微观结构更加致密稳定。基于试验结果，提出了MgO-DG-SS固化底泥的微观机制模型。

关键词: 岩土工程； 疏浚底泥；氧化镁；脱硫石膏；钢渣；响应面法；微观特性