Research On The Stability Of A Granite High Slope Under The Action Of Dry And Wet Cycles

This paper mainly studies the influence of dry and wet cycle on the stability of high rock slope in open-pit mines which takes an open pit mine as an engineering background.From the footwall of the north mining area of the mine,the granite was retrieved and processed indoors.The tests of the number of dry and wet cycles were carried out on the qualified specimens,and the uniaxial compression test and splitting test were carried out after determining the appropriate number of dry and wet cycles.The obtained experimental data are calculated by the generalized Hoke-Brown criterion.And MIDAS/GTS software is used to simulate the different dry and wet cycle times of the high slope of the lower plate of the 1060 section of the north mining area.(1)Uniaxial compressive strength is used as the criterion in the test of wetting and drying cycles.According to the test results,the total cycle number was 10 times and the rest dry and wet cycles were 0,1,3 and 6 times respectively.(2)The uniaxial compression test and splitting test of granite were carried out in the dry and wet cycle,and the mechanical parameters such as uniaxial compressive strength,modulus of elasticity,poisson's ratio and other mechanical parameters were in inverse proportion to the dry and wet cycles.After the uniaxial compression test,the specimens showed obvious tensile fracture failure characteristics,and with the increase of dry and wet cycles,local shear failure occurred.(3)In the analysis of acoustic emission characteristics,it is found that most of the specimens have no obvious mutation point before failure,and show a stepwise increase at the beginning.With the increase of dry and wet cycle times,the time from pressure to failure gradually decreases,and the accumulative ringing count decreases from 700000 to 300000.It can be used as a reference for the effect of acoustic emission monitoring and wet cycle on the stability of the final slope of the mine.(4)The uniaxial compressive strength,modulus of elasticity,material constant and tensile strength of rock mass calculated based on the generalized Hoke-Brown strength criterion are in accordance with the changes of mechanical parameters of the whole rock.(5)The simulation results show that the maximum principal stress and the maximum shear stress decrease with the increase of dry and wet cycles.The minimum principal stress isoline appears abrupt at the foot of the step slope at the level of 90 m to-6 m,-60 m and-120 m to 240 m.The equivalent plastic strain reaches the maximum value at the foot of-240 m horizontal slope,and the equivalent plastic strain zone at the level of 90 m to 18 m is gradually increasing.(6)After calculating only the factor of dry and wet cycle,the slope is in the unstable state after 10 dry and wet cycles.It is suggested that the final slope angle of the 1060 section of the 1060 section of the design institute is less than 43 degrees,and the final slope angle is re calculated.