工业废弃木质素固化改良粉土路基技术与应用研究

为研究工业废弃木质素改良粉土路基技术的可行性，通过室内无侧限抗压强度、水稳性和干湿循环试验，分析掺量（质量分数）、龄期等因素对木质素改良粉土力学特性和耐久性的影响，并与石灰改良进行对比；基于微观分析结果，阐明木质素改良土体的机理；同时开展木质素改良粉土路基填料现场试验，对改良路基土进行加州承载比、回弹弯沉值、轻型动力触探等路用性能测试和环境影响评价。研究结果表明：木质素可有效提高粉土的抗压强度和耐久性，其改良粉土的最优掺量为12%，28 d龄期养护12%掺量试样的水稳系数为0.52，经历4次干湿循环后，质量损失率低于20%，木质素改良粉土的耐久性能显著优于石灰土；木质素与粉土主要发生了水解反应、质子化反应和静电引力作用，最终形成致密稳定的土体结构；15 d龄期养护后，12%掺量木质素改良路基粉土的路用性能指标均优于8%掺量生石灰土，回弹弯沉值在1 mm以内，贯入阻力随养护龄期和贯入深度的变化可表征改良路基土的强度特征；木质素改良路基粉土的土壤质量符合二级标准，论证了木质素固化改良粉土路基技术的可行性和环境友好性。

Research on Technology and Engineering Application of Silt Subgrade Solidified by Lignin-based Industrial By-product

To investigate the feasibility of the silt subgrade solidified by lignin-based industrial by-product, a series of laboratory tests including unconfined compression strength test, water resistance test, and wetting-drying test were conducted to analyze the effect of the additive content and the curing period on mechanical properties and durability of lignin treated silt. The improvement of lignin was also compared with the lime. Based on the results of microscopic analysis, the stabilization mechanism of lignin solidified silt was explained. Moreover, the field test of subgrade silt solidified by lignin was carried out, whilst the road performance tests including California bearing capacity ratio (CBR) test, rebound deflection value test, dynamic cone penetrometer (DCP) test and evaluation of environmental impact of solidified silt were conducted. The results show that lignin can effectively improve the compression strength and durability of silt. The optimum percentage of lignin of the silt is 12%. The specimen treated with 12% lignin after 28 days of curing has a water resistance coefficient of 0.52. And after suffering 4 times wetting-drying cycle, the mass loss rate of sample is less than 20%. The durability of lignin treated silt is much better than that of lime treated silt. Hydrolysis, protonation, and electrostatic reaction between lignin and silt take place, and a more stable and compact soil structure is formed after the treatment. The road performance indicators of 12% lignin solidified silt after 15 days of curing are better than those of 8% lime treated silt, and the rebound deflection value is not more than 1mm. The penetration resistance with the variation of the curing period and depth can be employed to reflect the strength characteristics of treated silt subgrade. In addition, the environmental quality of the silt subgrade solidified by lignin meets the requirements of the secondary quality standard. The feasibility and environmental friendliness of the technology of silt subgrade solidified by lignin based industrial by-product is well verified.