Study On Strength Characteristics Of Rock Joints Under Pre Cyclic Shear

The Three Gorges Reservoir area is a moderate intensity seismic activity area in China.It has been indicated by monitoring that after the impoundment of the Three Gorges reservoir,the microseismic frequency is frequent,and the earthquake shows the characteristics of small magnitude and high frequency of earthquake occurrence.The paper combines the engineering phenomenon and characteristics of reservoir seismic frequency,by laboratory experiments,theoretical analysis and numerical simulation methods,strength characteristics of rock joints under cyclic loading have been studied,focusing on the pre peak cycle law of shear strength of joints cracking,meso crack propagation and frequent tremors under the action of the slope through joint damage evolution,the main research contents and results are as follows:(1)Firstly,using the water jet cutting rock.The production of high precision with two order fluctuation of joint surface,and the mode of failure,climbing climbing-gnawing fracture mode,gnawing fracture mode of 3 kinds of typical failure of jointed rock under cyclic shear peak mode before the indoor direct shear test,the deformation characteristics of rock damage cyclic loading test in,and analyzed the influence factors of the cyclic loading rate,loading amplitude and cyclic number of peak shear strength;(2)Considering the limitation of experimental conditions,based on laboratory tests,using particle flow software PFC(2D)on indoor direct shear test for numerical simulation,from the microscopic view of the crack space of 3 typical failure modes of the evolution and analysis of the more the number of cyclic loading,amplitude effect on peak shear strength the;(3)Based on the introduction of the classic rock strength model,analyzes the factors that affect the strength of rock joints,using PFC software modeling,discussed the cyclic shear under different normal pressure,the influence of different rolling angle and other factors on the shear strength of rock joints and the development law of meso crack;(4)Finally established through the jagged rock slope,based on the preparation of PFC artificial viscous boundary on the dynamic analysis of slope under earthquake,on different rolling angles and different seismic wave loading times,under different earthquake intensity slope through joint damage evolution analysis of rock joints under frequent seismic the face of the impact of slope stability.