“两隧夹一桥”段落高铁落石脉冲式碰撞防护方案研究

我国建成高铁主要分布在平原区,"十三五"规划中部分高铁位于山区,山区危岩落石多,需加强落石防护。受山区陡峭地形限制,以往的隧道明洞接长防落石方案已经不能满足使用要求,目前没有特别适合的防护方案,陡峭山区的落石防护成了制约我国高铁发展的瓶颈。针对陡峭地形特征建立工程模型,对落石轨迹模拟分析,落石最大速度和动能计算研究,提出适宜防护方案和缓冲层方案,研究结论:(1)落石能量宜分级化,对设防目标分级处理,才能使防护结构进一步精确化;(2)基于落石的脉冲力特性,柔性结构承受脉冲力荷载有天然优势,且柔性结构质量轻,引起下部增加的工程数量小,落石防护方案宜向柔性结构方向靠近;(3)落石防护应与主、被动防护网结合,主要是对漏过主、被动防护网后的"漏网之石"进行二次防护为主,对防护任务分层处理,明确各处防护结构的防护目标。

Study on Pulse Impact Protection Scheme for “Two-tunnel and one-bridge” High-speed Railway Falling Rock

The construction of high speed railways in China is mainly distributed in plain areas. In 13 th Five-Year period, some of the high speed rail projects are located in mountainous areas. Limited by the steep terrain in the mountain area, the old tunnels with extended anti rockfall protection can not meet the requirements of use. At present, there is no specially applicable protection scheme. The rockfall protection in steep mountain areas has become a bottleneck restricting the development of China's high speed railway. According to the engineering model of steep terrain features, suitable protection and buffer layer schemes are proposed based on the simulation analysis of rockfall trajectory, the maximum velocity of rockfall and the calculation of kinetic energy. In the study, it is found that(1) the energy of the rockfall should be graded and the staged treatment of the fortification target can make the protection structure more accurate.(2) based on the pulse force characteristics of the rockfall, the flexible structure bears the natural advantage of the pulse force load, and the flexible structure is light weight with small increase of works in sub-structure, and the rockfall protection works should be close to the direction of the flexible structure.(3) the protection of rockfall should be combined with the main and passive protective screenings, mainly for the second protection of the "escaping stones" from the main and passive protective screenings.