Research Of Parameter Back Analysis Of Jointed Rock Mass Based On Neural Networks And Surrounding Rock Stability Analysis Of JiaoJia Gold Mine

Mechanical parameters of rock mass are the most important data in theoretical analysis and numerical simulation.Jointed rock mass is randomness and discreteness,taking samples difficultly,in situ test is unrepresentative and high cost,which cause mechanical parameter is too difficult to determine.In this paper,we put forward a jointed rock mass mechanical parameters inversion method which based on neural network,and the parameters inversed are applied to JiaoJia gold mine which can analyze the stability of the stope.The main contents and contributions of this paper are as follows:(1)Studied the inversion method of artificial neural network,achieved the parameter inversion work based on BP neural network,ELM neural network and ESN,and evaluated the advantages and disadvantages of three neural network.(2)Established the inversion method of jointed rock mass parameters.Including:Using Hoek Brown strength criterion to confirm the range of the parameters,using the empirical formulas to confirm the range of jointed rock mass parameters,using discrete element numerical simulation method to establish neural network samples.(3)Carrying out jointed rock mass parameters inversion work based on the JiaoJia gold mine engineering background.Through the survey of the surface of rock mass and fissure,using borehole camera and sonic wave testing to establish the discrete element calculation model,using numerical simulation to establish the neural network samples.It was indicated that ESN was more suitable for jointed rock mass mechanical parameters inversion by testing three neural networks.Importing the measured displacement value and the depth of plastic zone to ESN which can inverse the parameters,and inversion accuracy was good by testing.(4)Analyzing the stability of the stope in JiaoJia-450 sublevel based on the jointed rock mass mechanical parameters which was inversed in Chapter 4.The calculation results indicated:When the sublevel mined finished step by step,the displacement of the floor,the maximum compressive stress,the maximum tension stress,joint shear velocity and joint normal velocity was all less than the sublevel mined one-time.Although the area of the roof was same in two project,step by step mining can make the exposure space less which reduced the disturbance of roof,and the filling belt also improve the stability of the stope.Therefor,the advantage of step by step exploration is obvious for the gentle dip and cracked orebody in JiaoJia gold mine.