Reserch On Surrounding Rock Stability Of Underground Chambers And Tunnels To Pumped Storage Power Station In Fukang,Xinjiang

The Fukang pumped-storage power station is a first-class large-scale engineering in Baiyang River.The power station is in changji hui autonomous prefecture fukang,xinjiang.The upper reservoir is located in the upstream of Baiyang River and the lower in the West Fork Groovein of the west side of the upstream of the river.The lower reservoir is far away from Fukang about 70km.Hydropower is installed capacity of 1200 MW.The underground building is layout in the right bank of the river upstream mountain,and deeply buried in 200?300 m.The underground powerhouse is composed by three big underground caverns which are the parallel arrangement of the main building,the main transformer room and the tailrace tunnel.The underground caverns height is 22.8?56.3m,span 30?40 m.The lithology of The underground cavern group is mainly conglomerate sandstone and siliceous rocks with sandstone,just in the end 560 m development after massive diabase.Within the scope of the underground cavern is mainly for stratified rock mass structure,a small amount for the massive diabase.In such a complex geological condition,the excavation of large span and high side wall of underground cavities,and the distribution of rock mass structure is complex,the surrounding rock of underground cavern stability problem is one of the main engineering geological problems in the project.Cavities stability of surrounding rock,therefore,the research of underground powerhouse cavern surrounding rock supporting scheme of design and construction to ensure the safety during construction period and operation period of the underground powerhouse has important practical significance.Based on geological conditions of surrounding rock of underground project area,rock mass structure characteristics and quality of rock mass based on the study,the numerical simulation(FLAC30),block analysis(Unwedge),the deformation of surrounding rock of underground cavities stability and block stability are studied,the major knowledge and the results as follows:(1)To study the engineering geological conditions of surrounding rock of under-ground project area and rock mass structure characteristic.project area formation of carboniferous middle(C2),siliceous sandstone lithology with dark gray and diabase,fracture crack development,rock mass structure types are mainly in the massive-thick layered structure and block structure-thick stratified rock mass structure of rock mass is given priority to,PD30 Mosaic of main part hole hole section-layered structure of rock mass is relatively more development also.(2)Based on the research achievement of the rock mass structure,the structural plane,s three-dimensional distribution characteristics of cavities have been studied using space projection.Combined with the qualitative and quantitative ways,the rock mass quality assessment has been made.As a result,the surrounding rock of project area are mainly type ? rock(more than 69%),with little type ?and type ? in development.(3)Using the basic theory and method of complex rock body modeling and the software Flac3D,the distribution of stress and formation,and the dynamic characteris-tics of rock mass of the excavated caverns have been modeled on the basis of the generalized rock structure model.The excavated surrounding rock extruded in the direction of International airport,making the formation of cavity wall(the maximum deformation is about 16mm).With the 5?30m damage depth,plastically deforming area generally developed in the place of cavity wall.(4)Based on FLAC3D numerical simulation based on the simulation of the cavities of different excavation sequence,priority research cavern group excavation sequence on the stability of cavern group.Analyzed three kinds of excavation scheme under the underground cavities after the excavation of cavern surrounding rock stress distribution,plastic failure zone and displacement distribution characteristics,and on the basis of simulation calculation of the stress level of monitoring points and the displacement value,under the three excavation scheme evaluation on the stability of surrounding rock of underground excavation sequence.Analysis of three kinds of solutions of the rationality of the excavation sequence,for the selection of excavation method is to provide a strong basis.(5)Using Unwedge software for potential unstable cavities block distribution characteristics and stability were analyzed,and the evaluation of the block effect on local stability of surrounding rock of underground caverns.Local buckling analysis found that the crown block,the possibility of relatively large,an analysis of the anchorage support cavities of the vault.Through the analysis of the three kinds of supporting schemes in the process of the proposed results,based on indoor block hole distribution and degree of safety,choice of different hole block support scheme,which can increase the effect of the degree of safety.