阳城隧道土砂分界地层隧道围岩变形特征及控制工法研究

为解决采用三台阶法施工的土砂分界地层隧道围岩变形控制难题，以浩吉铁路阳城隧道为依托，采用室内试验、数值模拟和理论分析等方法对不同隧道埋深及土砂分界位置（土砂比，即土层厚度与砂层厚度之比）下的隧道围岩变形规律进行研究，并提出围岩变形控制工法的选取原则。研究结果表明： 1）不同隧道埋深及土砂比情况下的围岩变形曲线可分为变形预发展阶段、变形快速发展阶段、变形缓慢发展阶段和变形稳定阶段4个阶段，且均可采用Boltzmann函数进行良好拟合； 2）当土砂比由0∶1增至1∶0时，隧道拱顶沉降、边墙水平收敛和仰拱隆起对土砂分界面的位置变化具有不同的响应规律； 3）提出适用于采用三台阶法施工的土砂分界地层隧道围岩变形控制工法选取原则，并通过计算证明，该原则可有效指导围岩变形的控制。

Study on Deformation Characteristics and Control Method of Surrounding  Rock of Yangcheng Tunnel in Upper Soil and Lower Sand Strata

The deformation of surrounding rock of tunnel in upper soil and lower sand strata constructed by three bench method is difficult to control. As a result, the surrounding rock deformation laws of Yangcheng Tunnel on Haolebaoji Ji′an Railway under different burial depths and different ratios between upper soil and lower sand are analyzed by laboratory test, numerical simulation and theoretical analysis method; and the selection principles for surrounding rock deformation control method is put forward. The study results show that: (1) The deformation curves of surrounding rock of tunnel with different burial depths and different ratios between upper soil and lower sand can be divided into 4 stages, i.e. pre development, rapid development, slow development and stability; and the curves can be well fitted by Boltzmann function. (2) When the ratio between upper soil and lower sand increases from 0∶1 to 1∶0, the response laws of tunnel crown settlement, horizontal convergence and inverted arch uplift vary. (3) The selection principles for the surrounding rock deformation control methods of the tunnel in upper soil and lower sand strata constructed by three bench method are put forward, which are proved to be effective for surrounding rock deformation control.