高原地区特长隧道斜井洞口复杂偏压力学特性研究与施工优化

Analysis on Mechanical Characteristics and Construction Optimization of Complex Bias in Inclined Shaft Entrance of Extra Long Tunnel in the Plateau

以中国一带一路重点项目西藏圭嘎拉超长隧道2#斜井工程为依托,研究了高原地区特长隧道斜井洞口复杂偏压力学特性与施工优化.采用有限元分析软件MIDAS-GTS NX建立2#斜井洞口段模型,分析复杂斜交偏压斜井洞口改线优化前后围岩变形、洞口衬砌结构内力等变化的力学变化规律,通过改变斜井出洞口线路布置,提出新的施工优化方案.研究结果表明:改线优化后斜井两洞口围岩塑性值降低25.72%,竖向应力分别减小20.68%和21.36%;衬砌结构内力均有不同程度降低;围岩竖向沉降最大值降低33.18%;左洞口拱顶沉降位移降低57.58%.2#斜井通过线路优化后改进施工方案,有效降低围岩复杂偏压对斜井洞口段结构影响,将建模理论计算值与施工现场监测数据进行比较分析,验证了线路优化后的施工方案最合理.

Based on China’s Belt and Road project,a key project in Tibet’s Guigala super-long tunnel 2#inclined well project,the mechanical characteristics and construction optimization of the complex bias of the inclined well entrance of the extra-long tunnel in the plateau were studied.The finite element analysis software MIDAS-GTS NX was used to establish a 2#inclined well opening section model,and the mechanical changes of surrounding rock deformation and internal force of the lining structure before and after optimization of the complex oblique biased inclined shaft opening were optimized.By changing the exit of the inclined well Route layout a new construction optimization plan was proposed.The research results show that the plastic value of the surrounding rock at the two holes of the inclined shaft is reduced by 25.72%,and the vertical stress is reduced by 20.68%and 21.36%,respectively.The internal force of the lining structure is reduced to varying degrees,and the maximum vertical settlement of the surrounding rock is reduced by 33.18%.The settlement displacement of the vault at the left entrance is reduced by 57.58%.The 2#inclined shaft improved the construction plan after the optimization of the line,effectively reducing the complex bias of the surrounding rock on the structure of the inclined shaft mouth section.Comparison and analysis of the calculated theoretical modeling values with the construction site monitoring data verifies the optimal construction plan after the line optimization reasonable.