川藏铁路沿线主要不良地质条件与工程地质问题

Main unfavorable geological conditions and engineering geological problems along Sichuan-Tibet railway

为全面认识川藏铁路沿线主要不良地质条件与工程地质问题,为铁路规划、选线和设计提供科学依据,保障铁路安全施工与运营,通过大量文献调研对现有研究成果进行总结,对铁路沿线不良地质条件与工程地质问题进行分析,最后为川藏铁路沿线潜在问题提出研究建议。研究结果表明:川藏铁路沿线不良地质极为发育,具有"五高"(高海拔、高地震烈度、高地应力、高水压、高地温)、"两活跃"(断裂带活跃、冻土边坡和隧道洞口段冻害破坏活跃)七大显著特征。活动断裂带第四纪以来活动明显且地震频繁,还可诱发地质灾害链,是铁路建设所面临的严峻挑战;浅表层崩塌、滑坡、泥石流灾害的空间分布受活动断裂带控制,灾害在地震后较长时间内仍具有高风险,而冻土边坡热融滑塌与冰湖溃决型泥石流也是铁路沿线典型的工程地质问题;热、冻灾害可使岩石和建筑材料力学性能发生劣化,影响隧道服务寿命。在高地应力、高地温、高渗压及动载荷多场耦合作用下,隧道内突水突泥、塌方冒顶、软岩大变形和岩爆灾害机制具有特殊性和复杂性,灾害防控方法亟需完善。

To entirely understand main unfavorable geological conditions and engineering geological problems along Sichuan-Tibet railway,to offer scientific basis for route planning,selection and design and to ensure the safe construction or operation of railway,the existing research findings were summarized by the comprehensive literature review.Main unfavorable geological conditions and engineering geologicla problems were analyzed,and research proposal was proposed for potential problems.The results indicate that the unfavorable geology conditions are well developed along Sichuan-Tibet railway and have seven significant characteristics named as"five high(high elevation,high earthquake intensity,high geostress,high hydraulic pressure and high geothermal)"and"two active(active fault belt,active frozen soil slope and freezing hazard)".The active fault belts since Quaternary,which maybe trigger intensive earthquakes or geological hazard chains,are the severe challenges for railway construction.The distribution of surface hazards including rock fall,landslide and debris flow is controlled by the active fault belts and these hazards exhibit high-risk properties for a long period after earthquake.The frozen soil slope failure and debris flow triggered by glacier lake outburst are also typical engineering geology problems along the railway.The heat and freezing hazards can deteriorate the mechanical properties of rock or construction materials and reduce the service life of tunnels.Under the coupled high geostress,high geothermal,high seepage pressure and dynamic load condition,the mechanisms of water and mud inrush,collapse,large deformation of soft rock and rock burst hazards are special and complex,and the prevention methods need to be improved.