青藏高原东南缘自然地理对铁路交通廊道提出的挑战

The Challenge of Physical Geography on the Southeast Edge of Qinghai Tibet Plateau to Railway Transportation Corridor

位于青藏高原东南缘的川藏交通廊道将面临极其复杂的工程环境,全线复杂结构桥梁、超长深埋隧道众多、长大坡道客货共线运行,使其安全高效建设和长期稳定运营面临巨大挑战。首先阐释青藏高原东南缘地形地貌、气候环境、新构造活动以及自然灾害等方面的特征与规律;深入分析高原东南缘独特自然地理对川藏交通廊道提出的挑战及应对策略;最后提出如何改进和强化轨道结构来应对面临的挑战。研究结果表明:①沿线区域大地貌格局以高山峡谷为主体,具山高、坡陡、谷深的险峻地形和极致地貌景观;②沿线各地具有气候垂直分带明显和区域差异大等特点,灾害性天气如雷暴、冰雹、大风、大雪及暴雨频现;③沿线行经青藏高原周缘挤压转换造山带以及向东和南东方向“逃逸”的侧向挤出地体群,区域断裂构造极为发育,断裂活动性强,具有强构造应力和高地热;④沿线区域为高灾害风险区,尤以强震、地震滑坡、高位远程滑坡、冰湖溃决以及大型滑坡堵江事件等致灾因子危险性高;⑤建议采取增加钢轨重量和采用合金轨、强化无缝线路结构稳定性以及轮轨系统动力学性能合理匹配等措施改进和强化现行轨道结构。

Sichuan-Tibet transportation corridor in the Southeast Edge of Qinghai-Tibet Plateau faces an extremely challenging engineering environment.There are many complex structural bridges,superlong and deep-buried tunnels and long ramps for both passenger and freight trains along the whole line,which pose great challenges to its safe and efficient construction and long-term stable operation.First,the characteristics and laws of the topography,climate environment,neotectonic activities,and natural disasters in the southeastern margin of the Qinghai-Tibet Plateau are explained.Then,the challenges and countermeasures to the Sichuan-Tibet transportation corridor brought by the unique physical geography of the southeastern margin of the Plateau are analyzed.Finally,the method to improve and strengthen the track structure is proposed to meet the challenges.The results show that:(1)The large geomorphic pattern of the region along the line is dominated by high mountains and valleys,with steep terrain and extreme geomorphic landscape of high mountains,steep slopes and deep valleys.(2)The climate along the line is characterized by obvious vertical zonation and great regional differences,and severe weather such as thunderstorms,hail,strong winds,heavy snow,and heavy rainfall occur frequently.(3)The Sichuan-Tibet transportation corridor passes through the compression conversion orogenic belt around the Qinghai-Tibet Plateau and the lateral extrusion terrane group"escaping"to the East and Southeast.The regional fault structure is extremely developed with strong fault activities,as well as strong tectonic stress and highland heat.(4)The areas along the SichuanTibet transportation corridor has high disaster risks from strong earthquakes,seismic landslides,high distance landslides,glacial lake outburst,and large landslides blocking the river.(5)It is proposed to improve and strengthen the current track structure by increasing the rail weight,adopting alloy rail,enhancing the structural stability of continuously welded rail track and matching the dynamic performance of wheel-rail system reasonably.