双线铁路隧道软弱围岩施工方法分析

首先建立了基于正交试验的隧道开挖力学参数数值模拟智能反演模型,为数值模拟确定力学参数提供科学依据,在此基础上建立FLAC3D数值模拟模型,分别研究了四步CD法、三台阶临时仰拱法及三台阶七步法施工围岩变形规律,然后结合现场实测情况分析三种施工方法对围岩稳定性的影响。四步CD法施工进度最慢,但是能及早封闭成环,围岩变形较小;三台阶七步法施工成本最低,施工速度最快,掌子面比较稳定,但是围岩变形较大;三台阶临时仰拱法变形较小,施工速度和三台阶七步法相差不大,在围岩情况较差时还可以采取上台阶加中支撑或上台阶留3~5 m核心土的方式保证围岩稳定性,是综合性最好的施工方法。

Analysis of Construction Method for Soft Surrounding Rock of Double Track Railway Tunnel

In the paper,it first established an intelligent inversion model based on numerical simulation of mechanical parameters of orthogonal tests,which provided a scientific basis for the determination of mechanical parameters by numerical simulation.Based on this,FLAC3D numerical simulation models were established,and the deformation law of surrounding rock with the four-foot CD method,the three-step temporary inverted arch method,three-step and seven-foot method were studied separately.Then the effects of the three construction methods on the stability of surrounding rocks were analyzed in combination with the actual field measurement.The four-step CD method has slower construction progress than that of the other two methods,but it can be closed and formed early,and the surrounding rock deformation is small.The three-step and seven-foot methods has the lowest construction cost,a fast construction speed,and a stable face,but the surrounding rock deformation is larger.The three-step temporary inverted arch method has a smaller deformation,and the construction speed is not much different from the three-step and seven-foot method.When the surrounding rock conditions are poor,it can also add middle support to the upper step or leave 3~5 m core soil in the upper step to guarantee the stability of surrounding rocks,so it is the best construction method in terms of comprehensive considerations.