中文摘要：

为了使工业副产品木质素在粉土路基中得到更好的应用，采用室内无侧限抗压强度试验、三轴压缩试验和扫描电镜试验，研究木质素改良粉土的剪切强度特性和微观结构，分析木质素掺量、养护龄期对改良土强度和破坏特征的影响，探讨不同围压和排水剪切条件下改良土的应力一应变关系，阐述木质素产生的胶结作用对土体剪切特性的影响，并研究临界状态下改良土的剪切强度特征。试验结果表明：改良土体无侧限抗压强度随木质素掺量增加而增加，过高掺量会造成强度降低，木质素的添加可增强粉土的韧性特征，对于江苏粉土的木质素最优掺入质量分数为12％；终值偏应力随围压和掺量增加而增大，其增量随围压增加呈降低趋势；低围压条件下，剪切过程会产生吸力，改良土孔隙水压力在各围压下均小于素土；低围压排水剪切条件下，改良土体积应变存在先“剪缩”后“剪胀”的变化特征，高围压条件下则完全表现为“剪缩”；木质素产生的胶结物质填充孔隙并增强土颗粒间联结，土体形成更为致密、稳定的微观结构；改良土临界状态线相对于素土仅发生平移，黏聚力可用来表征木质素对土体临界状态强度特性的影响；临界状态下木质素改良土剪切特性的研究可为其本构模型建立提供一定的基础。

英文摘要：

To better apply industrial by-product lignin in silt subgrade, the indoor unconfined compressive strength test, triaxial compression test and scanning electron microscope test were carried out to investigate the shear strength behaviours and microstructural characteristics of lignin treated silt. The effects of lignin content and curing time on the strength and failure characteristics of lignin treated silt were analyzed. The strain-stress relationship of lignin treated silt was discussed under different confining pressures and different drainage shear conditions. The effect of cementation induced by lignin on the shear properties of treated silt was illustrated and the shear strength characteristic of lignin treated silt under critical state was also investigated. The results show that the unconfined compressive strength of lignin treated silt increases with the increase of lignin content, while the strength of sample exhibits a decreasing trend when the lignin content exceeds a certain range. The addition of lignin could also enhance the ductile characteristics of silt, and the optimum mass percentage of lignin for silt deposited in Jiangsu province is 12o//00. The ultimate deviator stress of lignin treated silt increases with the increases of confining pressure and lignin content and the increment displays a decline trend with the increase of confining pressure. Suction will be formed in the treated silt during the shearing process at low confining pressure and the ultimate excess pore pressure is lower in the treated silt than its natural counterpart at all levels of confining pressures. Under the condition of low confining pressure and drained shear, the volumetric strain of treated silt changes from shear contraction to dilatancy, however, it is completely shown as dilatancy at the high confining pressure condition. The cementing material induced by lignin fills the pores in the soil, the connections between soil particles are enhanced, therefore a more compact and stable soil microstructure is formed after