多年冻土区碎石路基的变形机理与长期稳定性研究

Crushed rock subgrade as one of roadbed-cooling methods has been widely used in permafrost regions. Current researches mainly focus on the cooling mechanism and cooling effect. However, its long-term stability during the running of the railway has rarely been studied. Based on Qinghai-Tibet railway, this project mainly focuses on the long-term stability of the crushed rock subgrade under coupled effect of dynamic load and environment. Systematically study will be carried out on the stability of crushed rock subgrade on permafrost considering both the cooling effect and the deformation behavior. Dynamic load and environmental effect (temperature and moisture) will be examined as the main influencing factors for long-term stability of crushed stone roadbed. Laboratory tests will be conducted for selection of proper physical properties to obtain optimal cooling effect and mechanistic stability. Theoretical and numerical model (DEM) for crushed rock subgrade and base coupled with temperature and moisture will be developed for studying the long-term stability of crushed rock subgrade considering the temperature-moisture influence. Image-based serve ability assessment method will also be studied for the crushed rock subgrade. This project has both significant theoretical and practical importance. The research output will definitely give guidance to the railway construction in permafrost region, and the theory on the interaction of permafrost and crushed rock behavior under coupled effect of dynamic loading and temperature will be a new prospect of this area.

碎石路基是一种广泛应用在多年冻土区的路基形式，目前的研究主要集中在降温机理以及如何发挥其效果方面,缺少对其长期稳定性的研究。在前人研究工作的基础上，本项目以青藏铁路为依托，拟开展多年冻土地基上环境与动载荷耦合作用下碎石路基力学性能研究，通过现场观测，室内大型实验和理论研究，从碎石块体相互作用的本质出发，考虑温度、动载荷等因素的影响，在大量室内实验的基础上，结合图像评估方法，建立基于孔隙介质传热理论和考虑碎石相互作用机理的碎石路基与地基的数值模型，分析不同的设计参数条件下冻土路基的热稳定性和力学稳定性，建议关键参数。在此基础上，提出确保降温效果和路基长期变形稳定性的最优化的多年冻土区碎石路基结构型式。

碎石路基是一种广泛应用在多年冻土区的路基形式，目前的研究主要集中在降温机理以及如何发挥其效果方面,缺少对碎石集料力学性质和碎石路基长期稳定性的研究。在前人研究工作的基础上，本项目以青藏铁路为依托，开展了静、动载荷耦合作用下碎石路基力学性能研究，在此基础上，也分析了温度对碎石集料抗剪强度特性的影响。通过现场观测，结合大量室内大型实验和理论研究，从碎石块体相互作用的本质出发，考虑静、动载荷和温度等因素的影响，使用颗粒流评估方法，建立了考虑碎石集料相互作用机理的力学分析数值模型，分析了不同的设计参数条件下碎石集料的力学稳定性。主要研究结果具有重大的理论和实践意义。