Activation Mechanism And Long-term Mechanical Behavior Of The Fault Zone In The North Side Of Fushun West Open-pit Mine

Factors such as the underground and open-pit excavation of Fushun West Open-pit Mine,pore water seepage and seismic disturbance of surrounding mines accelerate the fault activation in the north Side,resulting in the occurrence of ground fissures and uneven settlement near the fault,and causing the surface deformation with a wide range of ripples.The surrounding urban environment and structures are particularly sensitive to the surface geological disasters in the north Side.In view of the causes of the geological disasters mentioned above,this paper studies the activation mechanism and long-term mechanical behavior of the fault zone in the north side of Fushun West Open-pit Mine.By analyzing the engineering geology,engineering disturbance and environmental conditions of the West Open-pit Mine,the geological characteristics of the mining zone are revealed,and the geological disaster in the north side is controlled by the fault zone.By means of shear rheological test of fractured rock with filling under stage unloading condition,photo-elastic test of fault fracture zone under shear,rheology-instability theory of fault under multiple factors,and numerical simulation of fault zone activation process in north side of West Open-pit Mine,the mechanical characteristics and macro-and meso-mechanism of shear rheology-instability of fractured rock with filling under unloading condition are described,and the structure and evolution of photo-elastic chain in broken zone are analyzed,and the shear activation mechanism of fault fracture zone in the north side of West Open-pit Mine is revealed.A single degree of freedom spring-slider model considering the pressure rate in the far-field of fault is established.The activation mechanism and long-term rheological properties of the fault zone in the north side of Fushun West Open-pit Mine are mastered and predicted,which can provide basis for the planning,sustainable development and environmental management of Fushun West Open-pit mine.The main research achievements of this paper are as follows:(1)Based on the analysis of engineering geology,engineering disturbance and environmental conditions of Fushun West Open-pit Mine,the geological characteristics of the mining zone are revealed,and the causes of geological disasters in the north Side are clarified.By means of numerical analysis,the unloading effect of the fault zone in the north side of West Open-pit Mine is revealed,and the influence range of mining activities on the surface of the north side is determined.(2)Under the condition of graded unloading,shear rheological tests of fractured rocks with filling are carried out to investigate the effects of filling degree and initial stress state on shear rheological characteristics of fault in the north side of West Open-pit Mine.Considering the three-dimensional meso-morphology and acoustic emission characteristics of rock fracture surface,the mechanical characteristics and macro-meso-mechanism of shear rheo-instability of fractured rock with filling are revealed.Combined with the fracture surface morphology of samples after shear rheology,the shear failure mode and shear strength characteristics of fractured rock with filling are analyzed,and the movement characteristics and rheological properties of the fault zone in the north side under complex geological conditions are clarified.(3)The structure and evolution characteristics of force chain in fault fracture zone under shear load are described quantitatively.Based on shear photo-elastic test of fault fracture zone,the macroscopic mechanical properties and meso-force chain evolution characteristics of fault fracture zone are clarified.The influence of load and thickness on force chain structure and evolution law of fault fracture zone is studied,and the active mechanism of fault fracture zone in the north side of West Open-pit Mine is revealed.The force chain network is analyzed based on topology,and the configuration distribution and topology evolution of force chain are revealed.(4)Considering the normal stress,pore water and seismic dynamic disturbance,a comprehensive mechanical model is established.Based on the shear rheological test results of fractured rock with filling,the nonlinear viscoelastic-plastic rheological model of fault is established,the parameters in which reflect the effect of excavation unloading.Based on Terzaghi effective stress principle,a fault rheological model under pore water superposition is established by introducing water-induced weakening function.Based on the assumption of displacement discontinuity method,the nonlinear differential equation of fault friction slip is derived.Considering excavation unloading,pore water and mine seismic dynamic disturbance,a comprehensive mechanical model is established.(5)A single degree of freedom spring-slider model considering the pressure rate in the far-field of fault is established.The coupled first-order differential equations describing the frictional sliding state of the spring-slider system are derived.The effect of the pressure rate in the far-field on the slip type,frequency and velocity of the fault and the frictional shear force drop law accompanying the stick-slip phenomenon is analyzed.The activation mechanism and long-term mechanical behavior of faults in the north side of Fushun West Open-pit Mine are revealed.(6)The activation and long-term rheological law of the fault zone in the north side of the West Open-pit Mine are mastered and predicted.The secondary development of FLAC3D software is carried out by C++language,and a three dimensional numerical calculation model for the fault zone in the north side of Fushun West Open-pit Mine is established.The activation process and surface deformation characteristics of the fault zone in the north side of the affected area are numerically analyzed under the influence of underground and open-pit mining,groundwater seepage and mine seismic dynamic disturbance.On this basis,the newly developed rheological constitutive model is adopted to reveal the movement characteristics and long-term rheological law of the north fault zone.