下台阶含仰拱一次开挖工法特性研究

A study on characteristics of simultaneous excavation method of lower bench and inverted arch

基于传统台阶法中仰拱单独开挖会造成初支封闭滞后存在的安全隐患,提出一种台阶法下台阶和仰拱一次开挖支护的施工方法,通过数值模拟和现场实测分析,探明新工法中支护结构施工力学特征及工程应用经济性,验证新工法施工的安全可行性,确定其对沉降变形起控制作用的关键工序。研究结果表明:新工法结构的应力值量值变化不大,应力分布状态改变;新工法结构变形明显减少,施工工效显著提高;新工法在控制沉降变形、地层适用性、施工组织方面具有综合优势,具备一定的工程推广价值。

The invert arch separated excavation leads to closed hysteresis of primary support in traditional bench cut method.Based on the potential risk of the traditional bench cut method that contains the single cut,a new bench cut method where the lower step and invert arch are excavated and supported was proposed.Through numerical simulation and field measurement analysis,the mechanical characteristics of the support structure and the economic application of the project were proved.Safety feasibility of the construction was verified.The key process to control settlement deformation was determined.The results of this study show that the change of the distribution and increment of stress are not obvious.Structural deformation is reduced overall.Progress index increases overall.The new method has comprehensive advantages in the aspects of controlling settlement formation,applicability,construction organization and thus certain engineering application value.