对滇藏铁路三江段工程地质问题的深化认识

滇藏铁路三江段东起云南省丽江城,西至西藏自治区八宿县城,是铁路建设最艰难的地段,特别是工程地质问题纷繁复杂。通过作者近几年来的工作,取得了对该区基础地质问题的一些新认识,据此从根本上来认识铁路可能存在的工程地质问题。三江地区广泛分布的地层岩性是古生界灰岩和中生界砂质泥岩,灰岩往往呈岛状被中生界砂质泥岩所围陷,以及燕山晚期岩浆岩。地震与活动断裂关系不密切,调查中未见区域性大断裂迹象。综合分析三江段存在的深层次铁路工程地质问题有:灰岩区岩溶引起的工程地质问题、碎屑岩区易溶盐析出引起的工程地质问题、坐滑体内工程地质问题、地震引起的工程地质问题、高地温区工程地质问题和劈理化带引起的工程地质问题,各类工程地质问题之间相互联系。工程地质问题严重的地段有玉龙县拉市海至香格里拉县虎跳镇街段、德钦县白马雪山段、德钦县梅里雪山段和八宿县冷曲段,对这些地段的工程地质问题应开展深入研究并采取工程对策。

DEEPLY REALIZATION ON THE ENGINEERING GEOLOGICAL PROBLEMS ALONG THE NU RIVER-LANCANG RIVER-JINSHA RIVER SECTOR OF YUNNAN—TIBET RAILWAY LINE

It was named as Sanjiang(which mean Nu River,Lancang River and Jinsha River in English)Sector on Yunnan—Tibet railway east from Lijiang city in Yunnan province and west to Basu county in Tibet Autonomous region,and it was conformed the Sanjiang sector was the most difficult sector on railway construction,especially there exited complex engineering geological problems.By the authors recent-year study,some new understandings on fundamental geology were put forward,thus recognitions on the possible railway engineering geological problems were fundamentally rooted out.The strata or rock distributed extensively in Sanjiang region were Paleozoic limestone like islands surrounded by Mesozoic sandy mudstone,and then the late Yanshan period magmatite was developed there.The connection between earthquake and active fault was not very close,and there were no obvious regional fault signs.It was comprehensively realized there existed many deep-level railway engineering geological problems in Sanjiang sector including the problem caused by karstification in limestone areas,the problem caused by soluble salts precipitation in clastic rocks areas,the problem in drop-style slide rockmasses,the problem caused by earthquake,the problem in high geothermal temperature areas and the problem caused by cleavable zone.Each type of the problems were corelated.The sub sectors with serious problems were the sector from Lashi lake in Yulong county to Hutiao town street in Sangrila county,Baima Snow Mountain sector in Deqin county,Meili Snow Mountain sector in Deqin county and Lengqu sector in Basu county,which should be deeply researched and treated by countermeasures.