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为了获得浅埋隧道破裂面稳定性定量评判指标,采用极限平衡原理与变分方法分析浅埋隧道破裂面的分布状态,以此为基础,建立以安全系数为评判指标的浅埋隧道稳定性分析方法。结合数值模拟分析得出,围岩破裂面接近直线,起始点位于隧道拱腰至拱顶区域,随着隧道埋深的减小,产生冒顶的区域越向拱顶集中,且数值模拟获得的破裂区域与理论结果较接近;埋深对隧道安全系数影响较小,围岩内聚力和内摩擦角对隧道安全系数影响显著,随着内聚力和内摩擦角增加,隧道安全系数增加;F为静止土压力时,理论分析和数值模拟所获安全系数发展趋势一致,且所获得安全系数小于数值模拟结果,较为保守。
In order to obtain the quantitative evaluation index of the stability of shallow tunnel, the limit equilibrium principle and variational method are used to analyze the distribution of the rupture surface of shallow tunnel. Based on this, the stability analysis of shallow tunnel with safety factor as evaluation index is established method. According to the numerical simulation, the rupture surface of the surrounding rock is close to a straight line, and the starting point lies in the arched area from the arch to the arch of the tunnel. As the depth of the tunnel decreases, the area where the roof falls is more concentrated on the arch, and the rupture obtained by numerical simulation And the results are close to the theoretical ones. The depth has little influence on the tunnel safety coefficient, and the cohesion and internal friction angle of the surrounding rock have a significant impact on the tunnel safety coefficient. The tunnel safety factor increases with the increase of cohesion and internal friction angle. F is the static earth pressure , The development trend of the safety factor obtained by theoretical analysis and numerical simulation is consistent, and the obtained safety factor is less than the numerical simulation result, which is more conservative.