Optimal study of the main tunnel line of yin - xi - ru - lan transporting water engineering 引细入兰输水工程主洞线优化研究
2.
An underground cavity group has a large cross - section main cavity and many branch cavities with short intervals and various cross - sections 摘要某地下洞室群，主洞室断面很大，支洞较多，距离较近，且断面变化复杂。
