乌东德水电站导流洞极薄～薄层岩体垮塌洞段支护回填方式探讨

On the Supporting and Backfilling of the Extremely Thin and Thin Layered Rock Masses in the Collapsed Section of the Diversion Tunnel in Wudongde Hydropower Station

乌东德水电站右岸导流洞围岩中极薄～薄层大理岩化白云岩洞段占整个洞长67%以上,在施工过程中洞内出现了大量局部垮塌,给施工人员和设备带来重大威胁。以右岸导流洞一垮塌洞段的典型断面为对象,借助数值分析方法和工程实践经验对上述垮塌洞段的先钢筋拱支撑再回填混凝土方案和先回填混凝土后钢筋拱支撑方案进行对比分析。分析结果表明,前者优于后者,并得到现场实践验证。

In the right side diversion tunnel in Wudongde Hydropower Station, the surrounding rock masses of the tunnel for over 67% of the total length are extremely thin and thin layered marbleized dolomite. During the tunnel excavation, a large number of local collapses are encountered, which poses a serious threat to the construction personnel and equipment. A typical profile of the collapsed tunnel section is thus studied with the numerical simulation method and the practical engineering experience. Two schemes, i.e. supporting with steel bar arch first and then backfilling with concrete, or backfilling with concrete first and then supporting with steel bar arch, are compared. The results show that the former one is superior to the latter. Practice also proves the effect of the scheme.