施工期岩锚梁岩台破坏模式及稳定性分析

Analysis of Failure Modes and Stability of Rock Bench for Rock-Bolt Crane Beam During Construction Stage

针对西南某大型水电站地下厂房岩锚梁岩台区节理发育的特点,并考虑辉绿岩脉等软弱带的影响因素,结合现场调查,利用关键块体理论方法分析得出开挖过程中岩台主要破坏模式为滑动、滑移-拉裂、弯曲-拉裂以及辉绿岩脉松动溃散4种,其中,上、下直墙的陡倾角结构面组合特征及辉绿岩脉的发育直接影响岩台的成型与稳定,开挖过程中针对各发育特征采取针对性支护措施;为验证分析的可靠性,结合现场变形监测资料分析表明:岩台和岩锚梁混凝土结构之间总体黏合度较好,而岩台开挖破坏段和辉绿岩脉发育区及影响带处的黏合度相对较差,需进一步加强变形监测,必要时采取相关补强措施。

Taking a large-scale underground powerhouse in the Southwest China as example,considering the characteristic of joints developed and the factors of soft strata such as diabasic dikes in the sidewall,using key block theory,combining the field investigations,4 types of failure modes are obtained： sliding,sliding-tension,bending-crack,and the looseness-collapsing of dike itself.Among them,joints with steep dip angle developed in the sidewall,combined with other discontinuities,have negative effects on rock bench＇s shapening quality and stability as well as developing dikes.Targeted supporting measures should be taken according to the kinds of development characteristics during the excavation.To verify the reliability of the analysis,combine the site deformation monitoring,monitoring data show that the total cohesion between rock bench and concrete structure of rock anchor beam is preferable,while that disturbed zones of rock bench in excavation and dyke developing zone are inferior,which suggest that further deformation monitoring should be strengthened,and related remedial measures should be taken if necessary.