藏东南某隧道水文地质特征及突涌水危险性评价

Hydrogeological Characteristics of A Tunnel in Southeastern Tibet and Risk Assessment of Water Burst

某铁路隧道位于印度板块与欧亚板块大规模碰撞而隆升的青藏高原东南方,区域地质构造作用强烈,水文地质条件复杂,隧道突涌水成为制约隧道勘察设计和施工的重大难题。通过现场水文地质调查、理论分析计算等方法相结合,对工程区水文地质条件及主要水文地质问题进行了详细的研究、分析和评价。研究结果表明:(1)藏东南某隧道波里拉组(T_(3)b)灰岩段多为强富水性,察朗噶组(J_(1)ch)和甲丕拉组(T_(3)j)为弱-中等富水性,阿堵拉组(T_(3)a)、夺盖拉组(T_(3)d)和土脱组(J_(2)t)为弱富水性;(2)隧道波里拉组(T_(3)b)岩溶垂向分带特征较明显,其中3700~3900 m高程段岩溶较发育;(3)隧道全长20247 m,极高危险段654 m,位于波里拉组灰岩中段水平径流带内和阿托卡巴断层处,占比3.23%;高危险段670 m,分布于波里拉组灰岩条带两侧与碎屑岩的接触带附近,占比3.31%。本文研究成果对类似地质条件下的岩溶地区高压富水隧道选线、设计和施工具有一定的参考价值。

A railway tunnel is located in the southeast of the Qinghai-Tibet Plateau,which is uplifted due to the large-scale collision between the Indian Plate and the Eurasian Plate.The regional geological tectonism is strong and the hydrogeological conditions are complex.The water burst in the tunnel has become a major difficulty restricting the survey,design,and construction of the tunnel.Through the combination of on-site hydrogeological investigation,theoretical analysis and calculation,the hydrogeological conditions and main hydrogeological problems in the project area are studied,analyzed,and evaluated in detail.The findings suggest:(1)The limestone section of Bolila Formation(T_(3)b)in a tunnel in southeastern Tibet is mostly strongly water-rich,the Chalangga Formation(J_(1)ch)and the Jiapila Formation(T_(3)j)are weakly-moderately water-rich,and the Adula Formation(T_(3)a),the Duogaila Formation(T_(3)d)and the Tutuo Formation(J_(2)t)are weakly water-rich.(2)The vertical zoning characteristics of karst in the Bolila Formation(T_(3)b)of the tunnel are obvious,and the karst is relatively developed at the elevation of 3700~3900 m.(3)The total length of the tunnel is 20247 m,and the extremely high dangerous section is 654 m,which is located in the horizontal runoff zone of the middle section of the limestone of the Bolila Formation and the Atuokaba Fault,accounting for 3.23%;the high-risk section is 670 m long,distributed near the contact zone between both sides of the limestone strip of the Bolila Formation and the clastic rock,accounting for 3.31%.The research results of this paper have a certain reference value for the route selection,design,and construction of high-pressure water-rich tunnels in karst areas under similar geological conditions.