Stability Analysis Of Surrounding Rock Of Large Size Underground Cavern Base On ABAQUS

China’s water resources development is at an unprecedented high-speed construction period, a number of hydropower stations in the state of under construction or to be built since entering the 21 st century。Due to limit of the topography and impact of the other factors,underground powerhouse arrangement must be used in large or extra large hydropower stations,and thus will generate corresponding underground cavern。Large underground cavern usually huge, complex spatial distribution, the occurrence cavern geological conditions are also very complicated。Beside excavation is an irreversible act which cannot be restored or rebuilt after damage occurred。Therefore,research on stability analysis of surrounding rock of large size underground caverns,providing reliable theoretical support for practical engineering,Contributing to ensuring the long-running safety and stability of large underground project,which has great social significance and enormous economic benefits。In this paper,engineering background are based on central cavern “Venaus”of Pont Ventoux hydropower station in Italy,obtaining important parameters related to surrounding rocks and the initial stress on the basis of summarizing the previous geological data and the test data on the rock。Using Mohr-Coulomb yield model provided by ABAQUS finite element software, and numerical simulation of surrounding rock stability analysis of dynamic processes in the hard rock underground cavern after excavation。In the case of the control of the same material parameters were established 2D reinforced、2D intrinsic、3D reinforced and 3D intrinsic models under four different conditions。 Mainly analyze the distribution of plastic zone, stress, displacement, and axial load distribution characteristics of each reinforced components induced by cavern excavation of the four evaluation indices。Firstly,by comparing the difference of evaluation indices between reinforced and intrinsic condition under the same dimension, we analyze the effect of reinforcement system for surrounding rock stability;secondly,analyzed the influence on surrounding rock’s plastic zone and principal stress distribution caused by different stages of excavation by studying on 3D model,and obtained dynamic trends of plastic zone and stress。Focus on the vertical displacement of the center of the vault surrounding rock were analyzed,we obtained the impact on vertical displacement of the center of the vault induced by various excavation steps;then,the 2D model and 3D models were compared under conditions of reinforcement in the plastic zone, the minimum principal stress and vertical displacement of these three sides,obtained differences of simulation results between different dimension circumstances;then vertical displacement of vault center calculated by four numerical models,and the actual displacement monitored by multi-point borehole extensometers were compared to further verify the reliability of the numerical simulation results。Finally,based on 2D plane model with reinforcement conditions,using interval analysis method with parameters changing,calculated and analyzed the sensitivity surrounding rock parameters, obtained various parameters of the sensitivity of representative evaluation indices in engineering。And distinguish between main and secondary sensitivity parameter which affect the calculation results,for the selection of surrounding rock parameters of similar projects has certain guiding significance。...