Study Of Numerical Simulation Of Rockburst Based On Energy Principle And Engineering Application

Through theoretical deduction and numerical experiments,the mechanism of rock burst formation is analyzed in detail from the perspective of energy transformation.On this basis,the rock burst numerical analysis method based on energy principle is established and applied to the rock burst calculation in the Huanggou pumped storage power station engineering and Tianhuashan tunnel engineering.The specific contents are as follows:(1)The formation mechanism of rock burst is analyzed through theoretical deduction and related test results:The external force produces energy for the work of the rock mass,part of which is used to produce micro cracks and non recoverable plastic deformation of the rock,which is called dissipative energy,the other part causes elastic resilience of rock,which is called elastic strain energy.When the rock mass is excavated and unloaded,the rock mass changes from three directions to two directions,the elastic strain stored in the rock mass is larger than the energy required for rock mass destruction,and the elastic strain can be released and the rock mass is dynamically destroyed.The energy difference constitutes the energy required for the ejection and spatter of the split rock mass,so that the rock burst occurs.(2)Based on the mechanism of rock burst formation,a numerical analysis method for rock burst is established.The Mohr-Coulomb plasticity model is used to simulate the mechanical properties of rock mass materials,and rock burst is based on the understanding that the elastic strain accumulated in rock can exceed its energy storage limit and causes sudden release of superfluous energy,and the elastic strain energy release of rock mass unit,that is,the elastic strain energy difference before and after the brittle failure of rock mass unit,is used as an index to measure the occurrence of rock burst.The theoretical calculation formula and numerical implementation method of the index are given.Finally,according to the research results of predecessors,the energy criterion of rock burst is selected to analyze the numerical results,and then the strength of rock burst is judged.(3)On the basis of summarizing and analyzing the engineering situation and the initial stress field of the Huanggou pumped storage power station engineering,the numerical analysis method of the above rock burst is applied to the rock burst calculation in the underground powerhouse and the diversion tunnel.Through the numerical results,it is found that the rock burst location in the underground powerhouse is mainly concentrated in the cavern arch,the arch shoulder and the floor,and the location of the rock burst in the diversion tunnel and the tailwater tunnel is mainly concentrated in the vault.Comparing the numerical results of rock burst with the statistical results of rock burst on-site,it is found that the numerical results well simulate the rockburst phenomenon in actual engineering.(4)On the basis of summarizing and analyzing the engineering situation and the initial stress field of Tianhuashan tunnel engineering,combined with the above numerical analysis method,the rock burst analysis and calculation are carried out in four working conditions,which are 200m(low stress level),500m(medium stress level),800m(high stress level),and 1000 m buried depth(extremely high stress level).The results show that rock burst will not occur in the surrounding rock under the low stress condition of buried depth of 200 m,and the surrounding rock may occur slightly rock burst under the medium stress level of 500 m buried depth,the surrounding rock may have last medium strength rock burst under the high stress level of the buried depth of 800 m,and the surrounding rock may have medium strong range under the high stress level of the depth of 1000 m.