为揭示工业副产品木质素与土体间的相互作用机制,将木质素应用于路基粉土改良,通过对木质素及其改良土进行无侧限抗压强度、pH值、微观结构、化学元素、矿物成分和官能团等试验分析,研究不同掺量下木质素改良土的力学性能和pH值变化,对比分析改良前后粉土的微观结构变化,并基于化学分析结果探讨木质素的分子结构及与土体间的相互作用,提出木质素改良土体的机制。试验结果表明,改良土强度随木质素掺量增加而增加,掺量超过一定范围时,土体强度降低,木质素改良粉土的最优掺量为12%,且龄期对土体强度有着重要影响;强度与pH值基本呈线性相关关系;改良土微观结构更为致密、稳定,胶结物质将土颗粒相互联结,且未生成新的矿物;木质素通过水解、离子交换、质子化和静电引力等作用,导致双电层厚度减小,带正电荷的木质素高分子聚合物联结土颗粒并填充孔隙,改良土工程性质得以改善。提出的木质素改良土体机制可为工业副产品木质素的工程应用提供理论参考。 In order to reveal the mechanism of the interaction between industrial lignin and soil, lignin was applied to the improvement of subgrade silty soil. Through unconfined compressive strength, pH, microstructure, chemical elements, Mineral composition and functional groups, the mechanical properties and pH value of modified lignin were studied. The microstructure changes of silt before and after the improvement were analyzed. Based on the results of chemical analysis, the molecular structure of lignin and its relationship with soil Interaction between the body, put forward the mechanism of lignin to improve soil. The results showed that the strength of improved soil increased with the increase of lignin content. When the content exceeded a certain range, the soil strength decreased, the optimal content of lignin-modified silt was 12%, and the age had a significant effect on soil strength The results showed that there was a linear relationship between the strength and pH value. The microstructure of the modified soil was more compact and stable. The cementitious material interconnected the soil particles and did not generate new minerals. The hydrolysis, ion exchange, protonation and electrostatic charge Gravity and other effects, leading to the reduction of the thickness of the electric double layer, the positive charge of the lignin polymer link the soil particles and fill pores, improved soil engineering properties can be improved. The proposed mechanism of lignin soil improvement can provide theoretical reference for the engineering application of industrial byproduct lignin.