Numerical Simulation And Early Warning Of Surrounding Rock Deformation On The Bank Of Baihetan Hydropoeer Station

At present,Baihetan Hydropower Station is the largest hydropower station under construction in China.Its underground powerhouse has a large excavation span,high magnitude of geostress,complex structure and stress conditions,and is the crown of the world.Therefore,the stability of surrounding rock deformation has always been the focus and difficulty of engineering research.In order to effectively feedback the construction design and accumulate experience for the further application of the surrounding rock safety monitoring model of the underground cavern,this paper carried out the research“Numerical Simulation and Early Warning of the Surrounding Rock Deformation of the Underground Powerhouse on the Left Bank of Baihetan Hydropower Station”.The main research contents are as follows:（1）The Distribution feature charts of surrounding rock deformation of the underground powerhouse on the left bank of Baihetan Hydropower Station are plotted.Synthetically analyzed the main factors,lithology,geostress,surrounding rock type,rock mass structure,construction excavation method and support measures,etc,which are considered to affect the deformation of surrounding rock;（2）The simulation methods of surrounding rock mass,fault,anchor and anchor cable and concrete spray layer of underground powerhouse are studied by using FLAC^3D,and the geological generalization model of surrounding rock is established.Numerically simulated the corresponding deformation process of the surrounding rock when the process of excavation and support,and the numerical calculation results are consistent with the field measured data.The law that the deformation of surrounding rock decreases with the increase of the depth of the excavation face is obtained.And the analysis shows that the system support has obvious effect on reducing the deformation of surrounding rock.The design parameters and construction methods of the plant are reasonable,and the construction safety is guaranteed;（3）By using the established numerical model,the excavation progress of the VIII₂layer is simulated,and the deformation of the surrounding arch,the upstream arch,the downstream rock anchor beam and the surrounding rock at the side wall are numerically calculated,and the corresponding prediction curves are plotted.And the total deformations and deformation rates when the displacement convergence tends to be stable are determined;（4）The relationship between surrounding rock deformation and time and excavation length is analyzed.The surrounding rock failure curve and its instability criterion are drawn.The strength reduction coefficient of the surrounding rock is determined by the strength reduction factor method.Two levels of deformation warning standards and corresponding measures are established.