基于结构特征曲线的软岩隧道钢拱架力学效应研究

针对传统锚喷支护难以适应软岩隧道大变形的问题,文章通过把钢拱架和喷射混凝土同时工作分为钢拱架单独工作和联合工作两个阶段,利用SAP2000有限元程序研究了实腹式型钢拱架和空间钢桁架拱的力学特征及其单独工作的力学效应;考虑材料非线性与几何非线性,研究了钢拱架在不同支撑条件下的极限承载力和极限变形能力。结果表明:(1)将钢拱架单独工作作为支护的一个阶段是可行的;(2)侧向支撑及拱脚的约束情况对实腹式型钢拱架的作用效应有决定性影响;(3)空间钢桁架拱的整体刚度大于实腹式钢架拱,受侧向支撑影响小;(4)提出了提高钢拱架承载能力和变形能力的方法,为喷射混凝土及其它支护措施的实施提供了更多的时间和空间选择。

Study on Mechanical Effect of Steel Arch of Soft Rock Tunnel Based on Structural Characteristic Curve

In light of that traditional anchor-shotcrete support is difficult to adapt to large deformation of soft rock tunnel,the steel arch and shotcrete supporting structure is divided into two work stages:individual work stage of steel arch and combination work stage of steel arch and shotecrete.The mechanical behaviors and the mechanical effects of solid web steel arch and spatial steel truss arch in individual work stage are analyzed by using SAP2000 fi nite element program.Considering the material nonlinearity and geometric nonlinearity,the ultimate bearing capaci ty and deformation capacity of steel arches under different support conditions are studied.The results show that:(1)It is feasible for the steel arch to work alone as a support stage;(2)lateral support and restraint of arch springing have a decisive influence on action effect of the solid web steel arch;(3)the overall stiffness of the spatial steel truss arch is higher than that of the solid web steel arch,and it is less affected by lateral support;(4)the methods to im prove the bearing and deformabilities of steel arch are proposed to provide more time and space for the implementa tion of shotcrete and other support measures.