The tunnels on Menghua Railway cross many strata with bad geological conditions,of which the construction difficulty and risk are high.On the basis of summary on construction technologies of railway tunnels in China and abroad,a series of applications and innovations have been carried out.1) As a result of rapid ring closure for soft and weak surrounding rock,the CD method and CRD method are replaced by full-face method or bench method.2) The primary support quality is improved;and "two close",i.e.grid steel frame of primary support closes to tunnel face and ring closure of primary support inverted arch closes to lower bench,is carried out.3) The advanced geological prediction is improved;and monitoring-based informatized platform is established.4) The parameters of system anchor bolt,steel frame and secondary lining are optimized by scientific test to guarantee the structural stability.5) The mechanization of the tunnel construction,i.e.wet spray manipulator,self-propelled inverted arch long trestle,horseshoe-shaped shield,pre-cutting machine and improved secondary lining trolley,is carried out.6) The engineering alteration is carried out in accordance to actual conditions so as to rationalize engineering cost and improve the management effect of contract and investment.The discoveries and innovations of Menghua Railway have successfully guaranteed the construction safety and quality.%蒙华铁路隧道沿线穿越多种不良地质,工程施工难度大、风险高,控制性工程多.在总结和借鉴国内外铁路隧道修建技术的基础上,开展系列实践和创新:针对软弱围岩确立快挖快支快封闭成环的施工原则,取消CD法、CRD法等复杂工法,优先选用全断面法,其次选用台阶法;强化初期支护结构实体质量,推行初期支护格栅钢架紧跟掌子面和初期支护仰拱及时封闭成环紧跟下台阶的“两紧跟”措施;优化超前预报,把监控量测纳入工序管理,建立信息化平台,严格监控量测;依托科研试验,优化系统锚杆、钢架和二次衬砌等支护参数,保证结构稳定;推行机械作业,全面使用湿喷机械手、自行式仰拱长栈桥,研发应用马蹄形盾构,开展黄土隧道预切槽技术研究,改造二次衬砌台车等工装设备,确保工程质量;据实及时变更,合理工程造价,提高合同及投资管理效果.蒙华铁路通过多方面的探索和创新,有效解决隧道建设中一些突出的质量安全问题,保证隧道施工质量和施工安全.
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