中尼铁路高地温分布特征及地质选线探析

拟建中尼铁路地形复杂,岩性多变,区域深大断裂发育,新构造运动活跃,地震频发,岩浆多期侵入;线路走行于雅鲁藏布江地热活动带和雅鲁藏布江谷地地热活动带,沿线地热极其发育,且具有温度高、天然热流值大的特点。在收集、调查沿线高地温分布特征、研究高地温对工程的影响及高地温热害分级标准及相应治理措施的基础上,从地质角度研究其选线原则。研究认为:拟建中尼铁路地热以中高温-超高温带为主;线路必须绕避可能大范围出现严重热害的高地温地区;当线路必须通过规模较大的高地温地区时,应选择地热边缘地带、构造简单、地热强度弱的地段以桥梁、路基工程通过;隧道通过高地温区时,宜减少隧道埋深。

Analysis of the Characteristics of High Ground Temperature Distribution and Geological Alignment of China-Nepal Railway

The proposed China-Nepal Railway is unique for the distribution of extremely complicated geological characteristics,including complex terrain,varied lithology,regional deep fractures,active neotectonics,frequent earthquakes,multiphase magmatic activity. The geothermal activity zones of the Yarlung Zangbo River and Brahmaputra Valley,through which the proposed China-Nepal Railway will pass,are characterized with well-developed geothermal belt featured by high temperature and heat flow value. On the basis of collecting and investigating the characteristics of the high temperature distribution along the highlands,the influence of the high ground temperature on the project,classification criteria of the high temperature heat damage and corresponding control measures are studied,and the principle of line selection is defined from the geological point of view. The results show that the proposed railway is dominated by high temperature geothermal ultra high temperature zone. The line must avoid areas with extensive potential serious heat damage. When the line must pass through such an area,the edges of the area with simple structures and low geothermal intensity should be considered and bridge and subgrade engineering is employed. If a tunnel is constructed in such an area,the depth of the tunnel should be reduced.