冻结层上水对冻土路基稳定性的影响和水害防治研究

Researches on road damages in permafrost regions indicated that suprapermafrost water is one of important factors to induce embankment damages such as frost heave, thaw settlement, etc. and to affect the stability of embankments in the slope wetlands. However, past researches and engineering constructions did not pay enough attention to the influence and harm of suprapermafrost water. The project intends to supplement suprapermafrost water monitoring system at Beiluhe test embankment of the Qinghai-Tibet Railway, and to study the influence of embankment construction on suprapermafrost water transport dynamics by the hydrogeological tracer method and soil freezing experiment. Moreover, we plan to reveal the role of suprapermafrost water in water-heat transport and the formation of freezing-thawing damages. We also plan to develop a coupled model including water-heat exchange between suprapermafrost water and embankment and to quantitatively explain the water-heat interaction process. Finally, some countermeasures to prevent suprapermafrost water damages will be put forward and the evaluation of countermeasures including the effects, application conditions, and optimal design parameters will be conducted. The study will not only deepen the understanding of the significance of hydrogeologic conditions on the stability of cold regions engineering, but also help to develop suprapermafrost water treatment measures, to prevent the occurrence of engineering and environmental problems, and to promote cold regions engineering service performance. So it is important in both science and engineering practice.

多年冻土区道路病害研究表明，冻结层上水是诱发冻胀、融沉等冻土路基病害发生，影响斜坡湿地路段工程稳定性的重要因素。然而，过去的研究和工程建设并未重视冻结层上水的影响和危害。本项目拟依托青藏铁路北麓河原试验工程，补充冻结层上水监测系统，并借助水文地质示踪方法(碘131和玫瑰红)和室内试验，研究路基修筑对含水层介质物理性质、冻结层上水运移动态和地表水-地下水转化的影响，阐释冻结层上水与冻土路基能水输运、冻融灾害孕育的关键过程和作用机制，构建耦合冻结层上水与冻土路基能水交换过程的耦合计算模型，定量刻画冻结层上水与路基水热互馈过程，研究新型隔水板、保温截水盲沟防治寒区水害的原理、效果和适用条件。此项研究不但可以深化“水文地质条件”这一关键要素对寒区工程稳定性的意义，而且能为冻结层上水疏导方案制定、工程病害与环境问题防治以及冻土工程服役性能提升提供理论依据与新的思路，具有重要的科学和实践意义。

多年冻土区道路病害研究表明，冻结层上水是诱发冻胀、融沉等冻土路基病害发生，影响斜坡湿地路段工程稳定性的重要因素。然而，过去的研究和工程建设并未重视冻结层上水的影响和危害。本项目采用现场调查、室内试验以及数值模拟相结合的方法，通过四年的研究工作，完成各项预定研究内容，实现了研究目标。研究结果表明，路侧冻结层上水富集条件下，会在冻土路基下活动层内形成可观的水分渗流迁移和热量迁移过程，导致明显的不对称路基温度场，这种热侵蚀作用与浅地表渗透系数、斜坡斜率有关。发现承压冻结层上水会加剧冻胀灾害，作用在土颗粒上的渗流力改变了孔隙结构，改变了水分输运通道，进而加剧冻胀发生。发现冻结降温可阻断冻结层上水的渗流路径，提出利用人工冻结法防控冻土路基水害的新设想，发现每两年间歇冻结达到长期调控冻土路基温度场、防控冻结层上水危害的效果。研究成果不仅深化了对冻结层上水工程危害机理的认识，提出了冻土路基水害防控方案，更能为冻土路基水害防治提供理论依据，具有重要的科学和实践意义。通过四年的研究工作，完成各项预定研究内容，完成了研究目标。.项目共发表科技论文9篇，其中SCI收录5篇，EI收录1篇。项目授权发明专利1项。实用新型专利1项。项目资助3名硕士研究生开展相关科研工作。项目资助课题组10人 次参加国内会议和软件培训。