正削式隧道洞门结构简化计算方法的研究

Research on simplified structural calculation method for up bamboo-truncated tunnel portal

切削式隧道洞门结构处于复杂的三维受力状态,需要采用三维数值计算才能得到相对正确的结果,为对计算模式进行简化,对Ⅴ级围岩条件下,1:1.5坡度的正削式隧道洞门结构进行了尝试。首先对明挖法施工的洞门模型试验和三维数值计算所得到的拱顶围岩压力进行了验证,接着从研究围岩压力分布和结构受力特性着手,得到了结构横、纵向内力的控制截面,拱顶荷载q与γh的关系,绘制了横向的压力分布图式,并给出了纵向荷载的计算方法,从而将三维地层结构数值计算模式简化成横向封闭环和纵向弹性地基的平面荷载-结构计算模式,分别计算横、纵向内力。

The bamboo-truncating tunnel portal＇s structure is at complicated 3D stress condition, so 3D numerical calculation method is necessary to used for correct result relatively. For the simplifying calculation model, the trial was carried out for up bamboo-truncating tunnel portal which with the slope 1 ： 1.5 in Class V surrounding rock. Firstly, the model test result was used to proof the arch crown surrounding rock stress which gained by 3D numerical analysis, both have good compatibility. Secondly proceed from the structural stress character and the distribution of surrounding rock stress, the inner force controlling cross-section of structural transverse and longitudinal direction were gained. Through the research, the relationship between q and yh of arch crown load in each pressure distribution figure was also obtained. Furthermore, the pressure distribution graphics in transverse direction was plotted; and load value calculation methods in longitudinal direction was provided. Therefore, the calculation model was simplified from 3D numerical structural calculation to load-structure model with transverse and longitudinal direction to calculate its inner force separately.