蒙华重载铁路矿山法隧道设计与施工关键技术

为解决铁路隧道施工中存在的忽视围岩的承载主体地位、过分强调支护作用和过度使用支护手段等问题,进一步提高隧道建设技术和管理水平,蒙华铁路公司组织参建各方和科研院所采用科研先行、试验验证、专家论证的技术路线,综合运用模型试验、现场试验和数值模拟等方法对隧道初期支护优化和隧道限阻耗能型支护结构的研发等关键技术进行了研究,形成了适合蒙华铁路建设条件和地质条件的矿山法隧道初期支护体系:在试验表明不设系统锚杆也能满足隧道稳定性要求的前提下,蒙华铁路有钢架的Ⅳ,Ⅴ级围岩地段隧道取消了系统锚杆;隧道喷混凝土结构普遍为小偏心受压状态,格栅钢架代替型钢钢架能够保证隧道的安全,蒙华铁路矿山法隧道的初支钢架全部采用格栅钢架;经全线229座隧道推广应用,支护优化成果得到了充分验证。研发了钢板式限阻耗能型支护新结构,有效解决了老黄土地层和高地应力水平岩层隧道结构开裂破坏的难题,全线推广应用达7 km,取得了显著效益。通过以上矿山法隧道关键技术,实现了全线隧道按时贯通和“0”重伤及以上人身安全事故的总目标。

The Key Technology of Design and Construction on Menghua Heavy-haul Railway Tunnel by Mining Method

To solve existing problems pertaining to the construction of railway tunnels, such as neglecting the main bearing position of surrounding rock, overemphasizing supporting functions, and overusing supporting measures. To improve the management and technology of tunnel construction, the headquarters of Menghua Railway organized all parties associated with construction and scientific research institutes in order to adopt a technical route of scientific research, experimental verification, and expert demonstration. Model tests, field tests, and numerical simulations were comprehensively used to evaluate tunnel construction and management, with the aim of optimizing the primary support of the tunnel and addressing damages to the primary support in loess strata. The primary support of the Menghua Heavy-haul Railway tunnel was established using mining; this approach was deemed suitable for effective construction of this tunnel given the surrounding conditions. Considering that the stability of the tunnel is ensured even without anchor bolts, these anchor bolts were not used in soft and weak rock mass sections of Grades Ⅳ or Ⅴ; instead steel frames and shotcrete were used for supporting the Menghua Railway. Shotcrete used to support tunnels is typically under small eccentric compression, and grid steel frames can ensure the safety of the tunnel instead of the steel frames. Grid steel frames were used as the primary support in the Menghua Railway tunnels. This method has been widely adopted for 229 tunnels along the entire line, and the results of support optimization have been completely verified. A novel steel plate-type resistance limiting and energy dissipating support structure was developed; this structure effectively addresses the problems of the cracking and failure of tunnel structures in old loess strata and high-stress horizontal strata. The entire railway line was popularized and applied for 7 kilometers, which afforded remarkable benefits to a certain extent. Using the abovementioned management and technical approach, the overall goal of punctual service and zero accidents is achieved.