考虑震害机制的黄土地基木质素改良加固机理与动力特性研究

Lignin as an effective, economical and environmentally friendly modified material which has been studied and applied in the field of soil improved and foundation treatment, but the research on the dynamic behaviors and stabilization mechanism of lignin improved loess has not been carried out. This application for the loess earthquake disaster research，prevention and control of the hot issues in the " The Belt and The Road" strategy background. Means and methods of indoor soil dynamics test, SEM test and chemical composition analysis, model test, in-situ test, physical analysis, numerical simulation and theoretical analysis are synthetically used. In the research, dynamic characteristics of lignin improved loess will be studied, dynamic constitutive relationship of lignin improved loess by considering the influence of humidity and grain size will be constructed. Physical and chemical properties of the improved soil and the evolution characteristics of the pore will be analyzed, and the physical and chemical mechanism of lignin improved and stabilized loess were clarified. Moreover, ground motion characteristics of the improved loess foundation will be obtained, and the key indexes to control seismic damages of the improved loess foundation will be determined. Finally, seismic treatment method for lignin improved loess foundation based on the performance-based seismic design will be proposed. The expected results of the application will provide a reference for the seismic design of lignin improved loess foundation. In addition, application of the results will effectively reduce the risk of potential damage to loess foundation, which can promote the recycling of resources, with significant environmental benefits.

木质素作为一种有效、经济和环保的新型改良剂，已在地基改良处理领域展开了研究和应用，但有关木质素改良黄土动力特性和加固机制的研究尚未开展。本项申请针对 “一带一路”战略背景下黄土地震灾害研究与防控的热点问题，综合运用室内土动力学试验、细观结构测试及化学成分分析、模型试验、现场原位测试、物理模拟、数值分析和理论分析等综合的手段和方法，研究木质素改良黄土的动力特性，构建考虑湿度和粒度影响的木质素改良黄土动力本构关系，分析改良生成物的物化特性和孔隙结构演化特征，阐明木质素改良固化黄土的物理化学机制，得出改良黄土地基的地震动特征，厘定改良黄土地基震害的关键性控制指标，并提出基于性态设计的木质素改良黄土地基抗震处理方法。项目预期成果将为木质素改良加固黄土地基的抗震设计及工程应用提供参考依据，其推广应用将有效减轻黄土地基的潜在震害风险，同时可促进资源的循环利用，具有显著的环保效益。

木质素作为一种储量大、易获取的新型环保地基改良材料，针对其改良土的力学性能已开展了较多的研究，并在工程设计和施工过程中开展了一定的应用。然而，已有的研究针对木质素改良土的动力特性研究较少，对改良后地基的抗震性能评价关注不足。本项目以木质素改良黄土为研究对象，以木质素改良黄土的动力特性-加固机制-改良地基的地震动特征-震害控制的关键指标-基于性态设计的地基改良加固方法为研究主线，通过室内土力学试验、细观结构测试及矿物成分分析、现场模型试体试验、室内振动台模型试验、物理模拟、数值分析和理论分析及多学科交叉集成等综合的手段和方法，较为系统的研究了木质素改良黄土地基的动力特性，阐明了木质素改良加固黄土的物化机制，分析了木质素改良黄土地基的地震动特征，提取了改良黄土地基震害控制的关键性指标，提出了基于性态的木质素改良黄土地基工程抗震技术方法。项目主要研究成果包括：(1)考虑黄土场地震害的特征机制，构建了木质素改良黄土动力本构关系，研究了木质素改良黄土的动力特性参数的变化规律。(2)研究了木质素改良黄土的细观结构特性、主要矿物组成、水稳性和持水特性，结合改良土宏观力学参数的变化特征，系统探讨了木质素改良黄土的物化特性和孔隙结构演化特征，阐明了木质素改良固化黄土的物理化学机制。(3)通过场地地震反应分析和数值模拟分析，研究了木质素改良黄土地基的地震动参数及其反应谱特征，提出了木质素改良黄土地基动力变形演化的物理过程和力学机制，厘定了木质素改良黄土地基震害的关键性控制指标。(4)提出了基于性态的木质素改良黄土地基抗震技术方法，并通过模型试验进行了实例验证。基于上述研究，项目共资助发表学术论文41篇（其中SCI收录论文10篇，EI收录论文13篇），授权专利6件，培养研究生5名（已毕业2名），达到了预期的研究效果。