某水电站检修洞断层破碎带分析及处理建议

Analysis and treatment suggestions on fault fracture zone of No.1 maintenance tunnel of a hydropower station

某水电站引水隧洞1号检修洞施工开挖过程中,发生了较大范围的塌方和大量涌水。现场技术人员通过调查发现,检修洞斜穿一水平宽约54 m的断层破碎带(F1),且根据地面附近冲沟水流减少的情况判断检修洞地下水与地表水相通,断层与地下水对隧洞开挖施工具有较大影响。经分析研究,确定了新的检修洞线路,并采取"先固结灌浆+管棚+锚杆超前支护+随后加强钢拱架喷护跟进和地下水引排,采用短进尺、先小范围后全断面开挖,最后进行混凝土衬砌加固"的总体处理措施。新的施工线路和施工方案保证了检修洞的顺利施工,取得了良好的效果,检修洞至今没有发生变形破坏。

In tbe excavation process of No. 1 maintenance tunnel of a hydropower station, a massive collapse and water burst happened. Through field investigation, it is found that the maintenance tunnel diagonally passes through a fault fracture zone （ F1 ） of about 54 m wide and the fault fracture zone was concluded to connect with surface water according to the flow reduced in nearby gullies. The fault fracture zone and underground water have greater influence on the tunnel excavation. Through analysis and research, the new tunnel line is determined and the comprehensive treatment measures of ＂ consolidation grouting ＋ pipe roof ＋ advanced bolt support ＋ subsequent strengthening steel arch and concrete spraying support and underground water drainage ＋ full - section excavation with short footage and small scope at first and then full - section concrete lining at last＂ are adopted. The new tunnel line and construction scheme ensured the smooth construction of the maintenance tunnel and satisfactory effect, up to now, no deformation failure happens.