川藏铁路廊道泸定段地质灾害孕育过程及成灾机制

川藏铁路建设面临脆弱地质环境的约束，沿线重大地质灾害的孕灾过程及成灾机理研究能为有效防灾提供技术支撑.基于详细的现场调查，揭示川藏铁路廊道泸定段发育3处大型滑坡及4条泥石流沟.区内大型滑坡的孕灾因素主要有以下3点: (1)康滇古隆起多期强烈东西向挤压，致使近南北向长大结构面发育且与河谷岸坡大致平行; (2)河谷走向与最大主应力方向垂直，谷坡岩体强烈卸荷; (3)鲜水河断裂活动产生震动作用，在三面临空的突出地形、坡折微地貌处地震波放大效应叠加背坡效应，导致地震波被放大3至6倍，使得顺坡向陡缓结构面控制的高位岩体发生大规模失稳，从而导致大型滑坡发生.区内构造破碎，且受强震震裂作用影响，支沟沟谷物源丰富，沟域形态利于汇水及物源启动，受汛期7~9月集中降雨影响，易激发群发性泥石流.泥石流活动影响施工营地安全，边坡地震动放大效应影响桥位区仰坡岩体稳定性. 

Forming Process and Mechanisms of Geo-Hazards in Luding Section of the Sichuan-Tibet Railway

The construction of the Sichuan-Tibet Railway is dominated by the fragile geological environment. Research on the forming process and mechanism of geo-hazards along the rail track can provide technical support for hazards prevention. Based on field surveys, this study reveals that there are three large-scale landslides and four debris flow gullies in the Luding section of the Sichuan-Tibet Railway corridor. The disaster-pregnant factors of large-scale landslides in the area mainly include the following three points: (1) the Kangdian paleo-uplift has been squeezed strongly from east to west for several times in geo-history, resulting in the formation of a giant near-north-south structural plane, which is roughly parallel to the valley bank slope; (2) the valley trend is perpendicular to the direction of the crustal stress, and the rock mass of slope unloads strongly; (3) confronting the seismic events induced by Xianshuihe fault and the following back slope effect, the seismic wave is amplified in certain parts of mountain, like the isolated peaks with unconstrained surfaces and the thin ridges, and the amplification factors are nearly 3 to 6. Large-scale instability occurs in the high-level rock mass controlled by the steep and gentle structural plane along the slope, resulting in the occurrence of large-scale landslides. The structure in the area is broken, and it is affected by strong earthquake cracking, rich debris sources in branch groove and ditch morphology are conducive to water catchment and provenance start, under the influence of concentrated rainfall from July to September in the flood season, it is easy to trigger mass debris flows. Debris flow activities affect the safety of construction camps, and the amplification effect of seismic wave affects the stability of the rock mass on the uphill slope in the bridge location area.