青藏铁路设兴村段崩塌特征分析与运动学模拟

CHARACTERISTIC ANALYSIS AND KINEMATIC SIMULATION OF ROCKFALL ALONG SHEXING VILLAGE SECTION OF QINGHAI-TIBET RAILWAY

西藏拉萨—羊八井段建有青藏铁路、京拉公路(G109)、京藏高速(G6)三大重要交通工程和大量输电线路。然而,该区段山高坡陡,崩塌灾害频发,给交通和输电的安全运营带来极大的威胁。现阶段对崩塌灾害的分析与预测多是基于地形剖面的二维方法,限制了崩塌块石的运动方向,难以对崩塌的影响范围进行有效的评估。鉴于此,作者借助现场调查、基于无人机航摄的高精度三维地表形貌建模、崩塌运动的三维数值模拟等方法,以青藏铁路设兴村段崩塌为例,分析了历史崩塌块石分布、岩体结构面产状和危岩区特征,并进行了崩塌块石的运动学模拟。通过模拟获得了崩塌的影响范围和到达概率、优势运动路径以及优势运动路径下危岩区块石距坡面的高度和动能,结果表明危岩区的崩塌块石主要威胁输电线路和京拉公路,对青藏铁路和京藏高速无影响。相关模拟结果还对于崩塌防护范围、高度和强度的确定具有指导意义。

Three important traffic projects were built along Lhasa-Yangbajing section of Tibet.They include Qinghai-Tibet Railway,109 national highway(G109)and the 6 th national highway(G6),as well as a large number of transmission lines.However,the mountains in this area are high and steep,thus rockfalls frequently occur.The rockfall poses a great threat to the safe operation of transportation and transmission.At present,the analysis and prediction of rockfall hazards are mostly based on the two-dimensional method of topographic profiles,which limits the movement direction of rockfall and makes it difficult to effectively assess their impact range.To solve these problems,the authors take the rockfall along Shexing village section of Qinghai-Tibet Railway as an example.They analyze the distribution of fallen rocks,the occurrences of rock mass structural planes,the characteristics of dangerous rock areas,and the kinematic simulation of rockfall.They use the methods of field investigation,highprecision three-dimensional surface topography modeling based on UAV aerial photography,and three-dimensional numerical simulation of rockfall.Through the simulation,the influence range,the arrival probability,the dominant motion paths,the height and kinetic energy of the fallen rocks are obtained.The results show that the rockfall mainly threatens the transmission lines and 109 national highway,and have rarely effects on Qinghai-Tibet Railway and the 6 th national highway.The relevant simulation results are also instructive for the determination of the extent,height and mechanical strength of the protection facilities for rockfall.