安全监测在大型地下洞室围岩变形中的应用

Application of Safety Monitoring in Surrounding Rock Deformation of Large Underground Caverns

为了保证大型地下洞室施工期安全,以安全监测为主要手段了解围岩状态,为围岩稳定性评价提供依据.本文以乌东德水电站右岸主厂房7~8号机组段上游边墙变形为研究对象,基于安全监测成果,结合地质及施工等对围岩变形进行分析,利用结论采取相应工程措施,并对措施实施后的效果进行评价.主要结论为:右岸主厂房7~8号机组段上游边墙变形主要发生在第Ⅵ层与下方L3施工支洞贯通开挖期间,爆破开挖导致陡倾顺层岩体切脚,产生向临空面顺层滑移;基于安全监测成果进行措施前后对比分析,措施后围岩变形及应力应变变化速率明显减小,实践证明工程措施有效控制了围岩变形,截至目前,该部位围岩稳定;安全监测成果的应用,有效指导了工程施工,为围岩稳定性评价提供了依据,在大型地下洞室开挖中发挥了重要的应用价值.

In order to ensure the safety of the large-scale cavern construction period,the safety monitoring is the main means to understand the surrounding rock state,which provides a basis for the stability evaluation of the surrounding rock.This paper takes the deformation of the upstream side wall of the 7#~8#unit section of the main plant on the right bank of Wudongde hydropower station as the research object.Based on the results of safety monitoring,combined with geology and construction,the deformation of surrounding rock is analyzed,and the corresponding engineering measures are taken according to the conclusion,and the effect of the measures is evaluated.The main conclusions are:The deformation of the upstream side wall of the 7#~8#unit section mainly occurs during the excavation of the sixth layer and the lower L3 construction branch hole.Blasting excavation causes the steeply inclined bedding rock to cut the foot,resulting in a smooth slip to the free surface.Comparative analysis before and after measures based on safety monitoring results,the deformation and stress-strain rate of the surrounding rock decreased significantly after the measures.It is proved that the engineering measures effectively control the deformation of the surrounding rock.Up to now,the surrounding rock is stable.The application of safety monitoring results has effectively guided the construction of the project,provided a basis for the stability evaluation of surrounding rock,and played an important application value in the excavation of large underground caverns.