采用工业固体废弃物磷石膏、木质素对人工配制铅污染土进行固化处理，通过无侧限抗压强度（UCS）试验探究固化剂掺量、养护龄期对不同程度铅污染土固化后应力-应变曲线、破坏形态及无侧限抗压强度的影响规律，对比分析两种固化剂的固化效果，并采用扫描电镜（SEM）试验分析土样固化前后的微观特性。试验结果表明，磷石膏、木质素均能增大固化土的无侧限抗压强度，减小破坏应变；固化土的无侧限抗压强度随磷石膏掺量增加呈持续上升趋势，随木质素掺量增加呈先上升后下降趋势；延长养护时间能有效提高固化土无侧限抗压强度。随固化剂掺量和养护龄期的增加，土体内部胶结水平提高，土样破坏形态从局部张裂逐渐转变为剪切破坏，呈现脆性破坏特征。两种固化剂固化土效果各有优劣，木质素对高浓度铅污染土的固化效果优于磷石膏，抵抗变形能力更好，而磷石膏短期内提升强度能力及对铅的固定效果更好。扫描电镜试验表明，固化剂可起到填充孔隙、胶结土颗粒的作用，水化产物在土体内形成致密结构，宏观表现为强度增强。

Industrial solid waste phosphogypsum and lignin were used to solidify the artificially formulated lead contaminated soil. Through the unconfined compressive strength (UCS) test, the effect of curing agent dosage and curing age on the stress-strain curve, failure pattern and UCS of the soil with different levels of lead contamination after solidification were investigated, and the curing effects of the two curing agents were compared and analyzed. The microscopic characteristics of soil samples before and after curing were analyzed by scanning electron microscopy (SEM) test. The results show that both phosphogypsum and lignin can increase the UCS of stabilized soil and reduce the failure strain. UCS of solidified soil increases continuously with the increase of phosphogypsum content, and increases first and then decreases with the increase of lignin content. Extended curing time can effectively improve the UCS of stabilized soil. With the increase of dosage and curing age, the internal cementation level of soil increases, and the failure pattern of soil sample gradually changes from local tension cracking to shear failure, showing brittle failure characteristics. The two curing agents have their own advantages and disadvantages in curing soil. Lignin is more effective than phosphogypsum in curing high concentration lead contaminated soil and has better resistance to deformation, while phosphogypsum has better ability to improve strength and fix lead in a short time. SEM tests show that the curing agent can fill the pores and cement soil particles, and the hydration products form a dense structure in the soil, which is macroscopically expressed as strength enhancement.

TU411.6

国家自然科学基金（52079116、51579215）；中央高校基本科研业务费（2452019062）