Research On Underground Caverns Adjacent Stabilization And Bracing Design Of Ciha Xia Hydropower Station In Yellow River

With rapid growth of hydropower and water resources,more and more hydropower stations built in mountain ravines,due to the limit of topography conditions,most of hydropower decorate in underground.At the same time,the stability problems of the surrounding rock are becoming increasingly important in relevant underground cavities.The stability of surrounding rock of underground cavities involves the safe operation of hydro-generating unit but different ways of excavation sequence and supporting have a significant impact on deformation and stress distribution of surrounding rock.When adopting different excavation methods,in the choosing of deformation process of surrounding rockmass,internal stress distribution of surrounding rock,support form and supporting time especially gets attention of constructors and designers.It is great significance for ensuring the normal operation of hydropower station to analysis stability of surrounding rock of underground cavern and design reasonable supporting scheme.This study researches arrangement of the underground cavern group,stability of the surrounding rock and supporting methods in Yellow River,Ciha gorge hydropower station:(1)Based on the geological conditions to determine the factory location,axis direction,and the pattern of three Chambers parallel arrangement.By the comprehensive comparison,the left bank of underground powerhouse is recommended.(2)Construction sequence is initially proposed and stabilization of surrounding rock in underground cavern groups is estimated by using 2D FEM.Analysis results show that under the condition of excavation sequences,the plastic zone between main workshop and main transformer room is interconnected after the end of the cavern excavation,it need to take the appropriate supporting measures.In the mass,the displacement and stress of surrounding rock are controlled steady state during the whole process,it shows that the proposed excavation sequence is reasonable.(3)According to the results of the chamber group surrounding rock stability analysis to determine the support scheme of each cavity by using project analogy method.And the surrounding rock with support is analyzed using nonlinear 2D FEM and calculation results show that the plastic zone of the surrounding rock with support is not interconnected and displacement of each key point with support is generally less than no case anchorage support,anchor supporting plays a role in reducing the range of plastic zone of surrounding rock and restricting surrounding rock deformation.In aggregate,positive support schemes are feasible.The support scheme determined comprehensively,is feasible and system support can ensure the stability of the underground group of surrounding rock and the safe operation requirements.Research conclusion of this paper plays a guiding role in the excavation of the underground powerhouse of the Ciha gorge hydropower station and it can also provide a reference for other similar projects.