Study On The Rock Mining Response And Multi-field Coupled Time-dependent Disaster-causing Processes Of Slope In High-altitude Cold Regions

In the high-altitude cold region of western China,repeated freeze-thaw cycles cause continuous deterioration of physical and mechanical properties of rock masses,which seriously affects the stability of rock engineering.With the engineering construction in the high altitude cold regions,the problem of freeze-thaw disaster has been paid more and more attention,and it is significant to carry out the research on the damage deterioration and time-effective disaster-causing mechanism of rock mass slope of open pit mine in high altitude cold regions.This paper took the slope of hang-wall mine of prepared iron ore mine in Hejing County,Xinjiang as the engineering background,and used the comprehensive research method of theoretical analysis,field detection,indoor test and numerical simulation to study the rock body mining response and multi-field coupled time-disaster-causing process of the slope,and the main results obtained were as follows:(1)Freeze-thaw cycle tests,uniaxial compression,triaxial compression rock mechanics tests and acoustic emission monitoring tests were carried out on the tuffs of the east slope of Beizhan Iron Mine.The deformation and damage characteristics of the tuffs on the slope of the Beizhan iron ore mine under different stress paths were studied.By calculating the damage degree under the combined effect of freeze-thaw cycles and loads,the deformation and damage mechanisms of freeze-thaw tuff under mining disturbance conditions were revealed.(2)Frequent impact kinetic disturbance tests under three different impact air pressures were conducted on tuff rock samples after 0,20,40,60 and 80 freeze-thaw treatments by the SHPB test system.The kinetic properties of the freeze-thaw tuff specimens under frequent impacts were obtained.The macroscopic and microscopic damage mechanisms of the freeze-thaw tuff under frequent impact loading were revealed by an ultra-high-speed camera and post-test CT scans.(3)The NUBOX-6016 intelligent vibration monitor was used to monitor the vibration of the slope of the hanging-wall mine in the Beizhan iron ore mine.The slope blasting vibration propagation law was fitted by Sadovsky's formula.A numerical model was established for the east slope of Bizhan iron ore mine,and the dynamic response characteristics such as stress,strain and vibration velocity of the slope under the vibration of open-pit blasting were analyzed to reveal the influence law of open-pit blasting on the slope.(4)Based on 3D laser scanning,the spatial morphology and distribution pattern of rock surface and structure of Donggang mine slope were studied.By introducing the "freeze-thaw damage coefficient" to modify the parameters in the generalized Hoek-Brown strength criterion for rock masses,the Hoek-Brown freeze-thaw damage strength damage criterion was established,and the time-dependent process of deterioration of rock mass strength parameters with the number of freeze-thaw cycles was realized.The modified model was imported into COMSOL Multiphysics multi-physics field analysis software using the parameterization function.Considering the water-ice phase change,the rock THM coupled model was established based on the energy conservation equation,mass conservation equation and stress balance equation,and a three-dimensional geomechanical model of the hanging-wall mine slope of the Beizhan iron ore was built.The mining response and the time-dependent damage process of the slope under the action of multi-field coupling were studied.