在大厚度湿陷性黄土地区开展公路改扩建工程，将面临拓宽路基增湿稳定性评价、地基处理深度和剩余湿陷量的控制标准等技术难题。本项目在青年科学基金项目研究的基础上，针对关键问题，对增湿条件下的大厚度湿陷性黄土地基上拓宽路基进行较系统的离心模型试验，再现多种工况下拓宽路基的真实应力环境，揭示黄土地基增湿水分迁移规律及湿陷性黄土地区拓宽路基变形破坏的基本规律，分析大厚度湿陷性黄土复合地基加固机制并论述人工复合地基对土层剩余湿陷性的抵御能力。研究还基于大型通用有限元程序及岩土工程专业理论，对有限元软件进行二次开发，开展数值模拟研究工作，明确拓宽路基荷载下人工复合地基在发生剪切破坏时的湿陷面积和处理深度的关系及规律，建立大厚度湿陷性黄土地基剩余湿陷量的控制标准，优化相关处治措施设计参数。

Typical issues encountered on highway widening projects in thick collapsible loess area include the ground deformation evaluation,the determination of ground treatment depth,and the control of residual ground settlement. To evaluate the water translocation characteristics in collapsible loess ground and the deformation characteristics of the widened subgrade, the widened subgrade in real construction was simulated using centrifuge model test. under and. Meanwhile, the mechanism and effect of composite foundation reinforcement was also evaluated. Finite element numerical analysis is performaed by using geotechnical theories and the centrifuge model test results to identify the relation between the area of collapsible loess and the depth of ground treatment at the point of shear failure in widened subgrade. The control standard for the residual settlement of thick collapsible loess foundation was established andthe foundation treatment was optimized according to technical and economic conditions. This study is expected to provide theoretical basis as well as technical support for highway widening projects in large thick collapsible loess area.