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小净距隧道在公路隧道中属于一种新型结构型式,目前还处于研究和发展阶段。小净距隧道建设的成败在于中夹岩的稳定情况,采用有限差分法对不同净距下的小净距隧道进行了弹塑性数值模拟研究,对比分析隧道围岩位移和中夹岩应力、塑性区分布、位移随净距的变化规律,探讨Ⅴ级围岩下的中夹岩合理厚度。结果表明,小净距隧道围岩的各项指标与净距的敏感度存在几个阶段性变化的关系,最后提出了把敏感突变阶段出现之前的净距作为小净距隧道的合理净距。
Small clear-distance tunnel in the tunnel belongs to a new type of structure, is still in the research and development stage. The success or failure of tunnel construction with small spacing is due to the stability of medium rock. The finite difference method is used to study the elasto-plastic numerical simulation of small clear tunnel under different clearances. Comparing the analysis of tunnel surrounding rock displacement and medium rock stress, plasticity The variation of distribution and displacement with clear distance, and the reasonable thickness of medium-grade rock in Grade V surrounding rock. The results show that there are several stages of changes in the sensitivity and sensitivity of the indexes of the surrounding rock with small clear distance tunnels. Finally, the clear distance before the emergence of the sensitive mutation stage is proposed as the reasonable clearance of the small clear distance tunnels.