挤压性围岩大跨隧道扁平率优化研究

Optimization of Span-Ratio of Large-span Tunnel in Squeezing Surrounding Rocks

在大断面扁平隧道设计施工中,选择合适的扁平率对安全施工和降低成本至关重要。文章以兰渝铁路新城子隧道在设计阶段多次调整断面形式为例,采用有限元分析软件,研究了四种扁平率下的初期支护位移和衬砌结构受力。最终认为,在新城子隧道专项设计的大跨断面扁平率调整为0.81的基础上,对大跨断面形式进一步优化是完全可能的,而且将扁平率压缩到0.8以下的空间也完全可行。

Choosing the right flat rate is critical for safe construction and cost reduction in the design and construction of large-section flat tunnels.Taking the Xinchengzi tunnel of Lanzhou-Chongqing railway as an example for adjusting the section form several times during the design phase,it studies the initial support displacement and the lining structure forces at four flat rates by FLAC 3D numerical simulation software,and it comes to the conclusion that it is entirely possible to further optimize the large-span section on the basis of the adjusted span-ratio of the original design of 0.81,and it is also feasible to compress the span-ratio ratio to a space below 0.8,providing a reference for selecting the appropriate span-ratio for large-span tunnels in squeezing rocks.