基于上覆机场跑道安全的盾构隧道拱顶沉降控制基准研究

Research on control criteria of shield tunnel crown settlement based on safety of overlying airport runway

针对下穿机场跑道盾构隧道施工中的跑道沉降监测和预警的问题,运用力学方法分析了机场跑道结构的受力及变形特征,结合Peck沉降槽修正计算公式和材料力学第一强度理论,提出了跑道下部土体沉降槽限值和拱顶控制基准值的计算方法和流程。研究表明机场混凝土跑道面层同下部土层刚度差异较大,可将跑道面层简化为弹性地基梁,得到机场跑道的弯矩、挠度、剪力最大值计算公式;由于跑道面刚度较大,借鉴建筑物刚度对Peck公式修正的方法考虑跑道面刚度对Peck理论计算公式影响并修正,结合第一强度理论提出跑道下部土体与拱顶变形控制基准值的计算方法和流程。基于仙霞西路下穿虹桥机场绕滑道工程,按照计算流程计算得到了跑道下部土体沉降槽限值为5.74 mm;根据跑道沉降与拱顶沉降的关系,进而得到隧道拱顶沉降控制基准值下限值为17.39 mm、上限值为13.67 mm。

In response to the problems of runway settlement monitoring and early warning during the construction of shield tunnels underneath airport runways,the force and deformation characteristics of the airport runway structure are analyzed based on mechanics method and,combined with the Peck settlement trough modified calculation formula and the first strength theory of material mechanics,a calculation method and the corresponding flow of the limit value of the soil settlement trough under the runway and the reference value of the vault control are put forward. The research shows that the stiffness of the airport concrete runway surface is quite different from that of the lower soil layers. The runway surface can be simplified as an elastic foundation beam to obtain the maximum values of the bending moment,the deflection and the shear force of the airport runway. Due to the greater stiffness of the runway surface,the method of modifying Peck formula based on the stiffness of the building is used to consider the influence of the runway surface stiffness on the Peck theoretical calculation formula. Combined with the first strength theory,the calculation method and flow of the reference value of the deformation control of the soil and the vault under the runway are proposed. Taking Xianxia West Road underpassing the Hongqiao Airport bypass slide project as an example,the limit of the soil settlement trough under the runway is 5.74 mm calculated by the proposed method,and the lower and upper limits of the tunnel vault settlement control benchmark are respectively 17.39 mm and 13.67 mm according to the relationship between the runway settlement and the vault settlement.