川藏铁路主要地质灾害特征及地质选线探析

拟建川藏铁路横穿三山,跨越五水;沿线地形起伏大、构造活动强烈、地层岩性及气候复杂多变;大型崩滑体、高位危岩落石、泥石流、碎屑坡、水毁、雪崩、冰害及生长期高陡岩质边坡等山地灾害发育,其具有规模大、破坏力强、灾害发生频繁且难于治理等特点。在调查拟建川藏铁路沿线主要地质灾害及分析其特征的基础上,从地质角度研究其选线原则。研究认为:拟建川藏铁路高山峡谷地貌段选线首先应遵循线位服从桥位、桥位服从地质及线位服从车站、车站服从地质的两大总体选线原则;对于高山峡谷地貌段,铁路选线宜应先确定桥位,再以越岭的长隧方案或以傍山的长隧短打方案展线为宜,尽可能地绕避大型不良地质体;对于藏东南宽广的高山峡谷地貌段,铁路选线宜外移绕避大型滑坡、岩屑坡或展线于对岸避开泥石流,主要以路基或桥的方式、局部可辅以隧道绕避大型不良地质体通过为佳;而针对迫龙藏布峡谷段,铁路选线宜以傍山的长隧短打的方案通过为佳,尽可能减少线位露头以绕避地质灾害体。

Analysis of the Characteristics of Major Geological Disasters and Geological Alignment of Sichuan-Tibet Railway

The proposed Sichuan- Tibet Railway traverses the N-S Mountains, Nyainqntanglha Mountains and Himalayas,and Dadu River,Yalung River,Chin- sha River,Lantsang River and Nujiang River. It is characteristic of high-relief,strong tectonic activities,varied stratum and lithology,and complex climate conditions. The mountain disasters,such as large scale landslide and avalanche,rockfall halfway up a steep hill,debris flow,debris slope,washout,snow avalanche,ice trouble and growing steep-high rock slope are posing great and frequent challenges. Based on the investigation of major geological disasters and analysis of its characteristics of the proposed railway,this paper researches the geological alignment fundamentals of the proposed Sichuan- Tibet railway in a geological perspective.The results suggest that the proposed Sichuan- Tibet railway should first adhere to the following geological alignment principles that the railway alignment follows the position of bridge,the location of bridge follows the geological condition,the location of the line follows the location of the station,and the location of the station follows the geological conditions; and in mountain valley sections,the perfect railway alignment scheme is firstly to determine the position of the bridge and extends with the long tunnel through the mountain or the long tunnel with short access adit by the mountain to avoid weak geological conditions; in the widesoutheast of Tibet canyon section,the expected railway alignment is to run away from the landslide,avalanche and debris slope distributed slope toe or extends to other side of slope to avoid debris flow; the line should be dominated with bridge and embankment with local tunnels to avoid geological disaster;however,in the Palongsangpo canyon section,the best choice is the long tunnel with short access adit to reduce the outcrop of the line and avoid geological disaster as much as possible.