铁路隧道三台阶七步法出洞施工技术的应用

Application of Three-step and Seven-step Tunnel Construction Technique in Railway Tunnel

本文以某铁路隧道的出洞施工为例,探究了三台阶七步法技术的具体应用。在出洞施工前,对隧洞拱部软弱围岩采取了小导管注浆加固措施,经检查围岩加固效果符合出洞施工要求后,应用三台阶七步法按照由上到下的顺序,依次完成上部弧形导坑、中部左右侧台阶以及隧底的开挖。其中,开挖左右侧中、下台阶时,采取了喷射混凝土、打设锚杆和挂钢筋网的初喷支护措施。出洞施工完毕后,进行了洞内观察和沉降观测。结果表明,混凝土表面有基础细微裂缝,为混凝土干燥硬化过程中形成;拱顶沉降速度为1.16 mm/d,最大沉降量为3.48 cm,属于正常沉降。

This paper takes the tunneling construction of a railway tunnel as an example to explore the specific application of three-step and seven-step method.Before the tunnel exit construction,small pipe grouting is adopted to strengthen the weak surrounding rock of the tunnel arch.After checking the reinforcement effect of surrounding rock meets the construction requirements of the tunnel exit,the excavation of the upper arc heading,the left and right steps of the middle side and the tunnel bottom are completed by using the three-step and seven-step method from top to bottom.Among them,when excavating the left and right side of the middle and lower steps,the initial shotcrete support measures of shotcrete,anchoring rod and hanging steel mesh are adopted.After the completion of the construction of the tunnel,the observation in the tunnel and the settlement observation were carried out.The results show that there are basic fine cracks on the surface of concrete,which are formed in the process of concrete drying and hardening.The settlement velocity of the vault is 1.16 mm/d,and the maximum settlement is 3.48 cm,which belongs to normal settlement.