顺层浅埋偏压隧道围岩压力计算模型

Calculation Model for Surrounding Rock Pressure in Shallow Tunnel under Asymmetrical Loading in Bedded Geological Strata

  • 摘要: 顺层浅埋偏压隧道围岩压力的计算是山区隧道支护设计的关键环节,但目前尚缺乏相应的理论计算模型。为此,考虑隧道上方覆盖多层不同岩性的顺层岩体,对潜在滑移面两侧的多边形块体进行受力分析,利用力平衡方程和力矩平衡方程求解潜在滑移面上的侧阻力合力,推导出竖向与水平围岩压力的计算公式,进而建立顺层浅埋偏压隧道围岩压力的理论计算模型。结果表明:所提模型可退化为传统浅埋偏压隧道的围岩压力计算模型;该模型与有限元模拟在竖向围岩压力预测上吻合较好,但水平围岩压力的预测值较有限元模拟结果偏低。

     

    Abstract: For the tunnel supporting design in mountain area, the determining factor is the calculation for surrounding rock pressure in shallow tunnel under asymmetrical loading in bedded geological strata. The calculation model for surrounding rock pressure in shallow tunnel under asymmetrical loading in bedded geological strata is lacking in the present, thus this model is urgently needed. There are multi-layers bedded geological strata above the tunnel which have different properties. Then, forces of polygonal blocks on both sides of potential slip planes are analyzed, and the resultant forces of side resistance in potential slip planes are obtained by the equilibrium equations of forces and torques. Furthermore, the calculation equations of surrounding rock pressure in both vertical and horizontal directions can be obtained. Finally, the calculation model for the surrounding rock pressure of shallow tunnel under asymmetrical loading in bedded geological strata is proposed. It is found that this calculation model can transform to the general model for surrounding rock pressure in shallow tunnel under asymmetrical loading. The surrounding rock pressures in the vertical direction predicted by the calculation model and finite element simulation are similar, but it in the horizontal direction predicted by the calculation model is smaller than that predicted by the finite element simulation.

     

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