超大断面隧道软弱围岩控制机制及应用

为明确超大断面隧道软弱围岩破坏及控制机制,系统开展交叉中隔墙(center cross diagram, CRD)法和双侧壁导洞开挖方法下超大断面隧道软弱围岩控制机制数值试验,对比分析不同强度等级围岩、不同开挖方法在无支护、锚杆支护、H型钢拱架支护和H型钢拱架+锚杆支护四种支护方式下隧道围岩变形、支护构件受力变化规律,并研究超大断面隧道软弱围岩控制机制。同时对H型钢+锚网喷联合支护方式在超大断面破碎围岩隧道进行了CRD和双侧壁导洞两种开挖方法下的现场试验,拱顶沉降分别稳定在27.2 mm和18.7 mm,很好地控制了围岩变形、保证了现场初期支护安全。

The control mechanism for super section tunnel on weak surrounding rock and its application

For making clear the failure control mechanism of super section tunnel, numerical experiments of weak rock control mechanism applied to super section tunnel were systematically carried out by the excavation methods that included CRD and double side wall drift methods. The change laws of tunnel surrounding rock deformation and supporting components force were compared and analyzed under four types of supporting schemes and different excavation methods, which included excavation without support, bolt support, H-beam arch support and H-beam-bolt support. The control mechanism of super section tunnel with weak surrounding rock was acquired. Field experiments of H type steel and anchor net shot rete combined support section tunnel were carried out by the excavation methods that including CRD and double side wall drift methods, and the vault settlement were 27.2 mm and 18.7 mm. The results showed that this support system had great effect on the stability control of surrounding rock and could ensure the safety of the site.