深埋隧道拱部围岩潜在塌落破坏上限有限元分析

Upper bound finite element limit analysis of potential collapse failure on surrounding rock of arch in deep buried tunnel

深埋隧道拱部围岩潜在塌落形态和范围的深入研究,为围岩压力与施工方案的确定提供依据。采用源于塑性极限分析上限理论的刚体平动运动单元上限有限元法,开展不同围岩内摩擦角ϕ,剪胀角ψ和跨度(b/h)条件下的隧道拱部围岩潜在塌落破坏的计算分析。研究结果表明:围岩内摩擦角ϕ减小时,临界容重系数γcrh/c线性减小而破坏范围却显著增加;而隧道跨度(b/h)增加时,破坏范围相应增长而临界容重系数γcrh/c却快速下降;剪胀角ψ增长将约束围岩,减小拱顶潜在塌落范围,γcrh/c上限解相应提高。

Potential collapse form and area in the arch of deep buried tunnel provided guidance for the determining of surrounding rock pressure and construction plans.In the paper various calculations are carried out for the potential collapse failure of tunnel vault for different internal friction angle?,dilatancy angle?and different span(b/h)by using the upper limit finite element method of rigid blocks translational element based on the upper limit theory of plastic limit analysis.The results show that the critical bulk density coefficientγcrh/c decreases linearly and the failure area extends greatly when the internal friction angle?of surrounding rock decreases.In addition,the failure area extends and the critical bulk density coefficientγcrh/c decreases rapidly when the tunnel span(b/h)extends.The increased of dilatancy angle leads to the restraint of the rock,reduced the potential collapse area in the arch and increasing the upper limit solution ofγcrh/c.