黏弹-塑性岩体中锚注与衬砌联合支护的解析解
ANALYTICAL SOLUTIONS FOR COMBINED BOLT-GROUTING AND LINING SUPPORTING IN VISCOELASTIC-PLASTIC ROCK MASS
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摘要: 针对黏弹-塑性岩体中深埋圆形隧洞锚注、衬砌联合支护问题,导出开挖、锚注加固和衬砌支护阶段位移、应力的解析解。在开挖段,用随时间变化的半径函数模拟扩孔式断面开挖过程,并同时考虑纵向开挖的空间效应,给出黏弹区和塑性区应力、位移及塑性区半径随时间变化的解答。某时刻施加锚注支护后,将锚注岩体等效为弹塑性材料,用圆柱型正交各向异性体现锚杆对径向刚度加强,用强度指标的增强体现锚注的加固作用,分别对锚注区完全弹性和部分达到塑性的情况导出了锚注和衬砌支护阶段应力、位移的解答,并给出判断再次出现塑性的条件和塑性区半径的表达式。根据解答,分析了不同位置应力和位移随时间变化情况;不同加固程度、锚注时刻对洞口应力、位移的影响。该文的解答可用于相似条件下隧洞初步设计。Abstract: The analytical solutions were derived for a deeply buried circular tunnel in a viscoelastic-plastic rock mass accounting for sequential excavation, bolt-grouting, and lining support. The solutions of stress and displacement as well as the radius of the plastic zone were presented for an enlargement excavation process with a time-dependent tunnel radius. The effect of longitudinal excavation was also considered. After reinforcement with bolt-grouting at any time, the reinforced rock mass was treated as homogeneous elastic-plastic material, with cylindrical orthogonal anisotropic characteristics to reflect the radial strengthening of the bolts in the elastic phase, as well as enhanced strength parameters to reflect the role of bolt-grouting in the plastic phase. The solutions for rock and liner in supporting stage were derived for the two cases, elastic and elasto-plastic, for reinforced rock. Moreover, the conditions were also given for emerging new plastic zones and the expression for plastic radius in reinforced rock. According to the solutions, stresses and displacements over time were analyzed at positions with different radii, and the influence of reinforcement and installation times of bolt-grouting reinforcement were illustrated. The solutions can be applied to the preliminary design of tunnel construction in similar conditions.