支洞 meaning in Chinese

adit
lateral tunnel

On the backfilling grouting technique to blook up the branch tunnel
隧洞支洞封堵混凝土回填灌浆技术
Analysis of pressured diversion system with irrigation discharge branch tunnel of stone river reservoir
石头河水库灌溉支洞对发电引水系统的影响分析
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。