缓倾岩层地下厂房洞室围岩稳定性评价——以某抽水蓄能电站地下厂房为例

Stability Evaluation of Surrounding Rock of Underground Powerhouse Cavern in Gently Dipping Rock Layers

结合现场调查、有限元整体模拟、局部块体稳定分析对地下洞室围岩稳定进行分析,对缓倾岩层围岩分类尤其是拱顶围岩分类提出了建议,评价缓倾岩层地下洞室围岩稳定情况。结果表明:由于缓倾岩层在厂房洞室展布较广,洞室开挖时顶拱部位易产生塌落,同时在陡倾结构面相互切割下,易产生楔形破坏,围岩岩体不稳定,建议围岩分类时等级适当降低;洞室围岩块体破坏模式主要有洞顶部位的块体掉落、层状剥离,洞壁部位的块体掉落、洞壁块体滑移-掉落、块体倾倒、块体层状剥离等6种破坏模式,缓倾岩层地下厂房的不稳定块体多分布于拱顶、边墙上部,应采取相应的补强措施;洞室开挖后,拱角、墙角等转折处易产生应力集中,可能发生强烈破坏,需及时采取支护措施或预防措施。

Combined with on-site investigation,overall finite element simulation and local block stability analysis,the stability of the surrounding rock of the underground cavern is analyzed,and suggestions are put forward for the classification of the surrounding rock of the gently dipping rock layer,especially the classification of the surrounding rock of the vault,and the stability of the surrounding rock of the underground cavern of the gently dipping rock layer is evaluated.The results show that due to the wide spread of the gent-dipping rock layer in the cave chamber of the powerhouse,the top arch part is prone to collapse during the excavation of the cavern,and at the same time,under the mutual cutting of the steep-dipping structural surface,it is easy to produce wedge failure,and the surrounding rock mass is unstable.It is suggested to appropriately lower the grade of the surrounding rock mass.The failure mode of the rock block around the cavern mainly includes block drop and layered peeling at the top of the cavern,block drop at the cavern wall,block slip-fall of the cavern wall,block dumping,block layered peeling,etc.,and the unstable blocks of the underground powerhouse in the gent-dipping rock layer are mostly distributed in the vault and the upper part of the side wall,and corresponding reinforcement measures should be taken;After the excavation of the cavern,stress concentration is easy to occur at the turning points such as arch corners and wall corners,and strong damage may occur,and supporting measures or preventive measures need to be taken timely.