基于变基床系数的管棚变形机制研究

Deformation mechanism of pipe-roof based on variablesubgrade reaction coefficient

在浅埋软弱围岩隧道施工中,要求严格控制地面沉降,管棚作为一种超前预支护工法,可以有效地控制施工对地层的扰动,在隧道施工中得到了广泛应用,因而对管棚受力变形机制的研究非常有必要.目前,大多数对长大管棚受力变形机制的研究中未考虑初期支护和土体扰动引起地基基床系数变化对管棚变形影响.本文通过建立管棚受力的双参数弹性地基梁模型,推导出考虑初期支护和土体扰动引起地基基床系数变化时管棚挠度函数,并用数值模拟和郑西客运专线阌乡隧道的现场实测数据进行对比验证,同时与未考虑初期支护和土体扰动时管棚的变形做对比,结果表明:考虑初期支护和土体扰动引起地基基床系数变化时,管棚的变形更符合实际;通过对管棚变形的研究可以对管棚的选型和布置提供依据,从而更好地为实际工程提供理论参考.

In shallow weak rock tunnel construction,ground settlement needs to be controlled strictly,and piperoof,as a kind of advance pre-support technology,can effectively protect stratum from construction disturbance,which has been widely applied in tunnel construction,so it is necessary to study on the stress deformation mechanism of piperoof.At present,the study that how the change of subgrade reaction coefficient caused by primary support and construction influences piperoof deformation mechanism is less.In this paper,by building the model of double parameters elastic foundation beam,the piperoof deflection function is derived based on variable subgrade reaction coefficient caused by primary support and construction,comparing with the deflection function without considering the change of subgrade reaction coefficient caused by primary support and construction.Besides,numerical simulation and the actual measured data from Wenxiang tunnel are used to be compared,the result of which shows that the piperoof deformation mechanism of considering the change of subgrade reaction coefficient caused by primary support and construction is more tally with the actual;besides,it can provide basis for selecting and arranging piperoof and provide theoretical reference for practical engineering better.