Research On Caving Mechanism And Evolution Law Of Roof Rock Of Inclined Thick-large Ore Body By Caving Method

Caving mining often causes the cavities of overlying strata to form hidden goaf.Caving method has the characteristics of strong concealment,complex shape and instability.It is of great theoretical and engineering significance to study the mechanism and evolution of roof caving in caving mining.Xia Dian gold mine as engineering background,this paper reveals inclined large and thick ore body mechanism and evolution laws of sublevel caving mining of roof caving as the goal,the comprehensive use of indoor mechanics experiment,theoretical analysis,numerical simulation and field detection technology,such as around the joint equivalent parameters of rock mass,the tilting mechanism of the gob roof caving and evolution regularity,high depth of concealed goaf comprehensive detection and test the content such as in-depth theory study.Based on the field engineering geological survey and ShapeMetrix 3D non-contact scanning of joints,the generalized diagram of the dominant joints in the longitudinal section of the xiadian gold mine was established.By means of laboratory test,numerical simulation and theoretical analysis,the mechanical parameters and collapsibility of the joints in the xiadian gold mine were studied.The results show that the ore rocks of xiadian gold mine are typical hard and brittle rocks with good collapse ability,and the caving can be well achieved in a certain period of time.The REV size of the rock mass is 25m in height and 12.5m in diameter.By establishing the random joint model of inclined orebody,the mechanism and influencing factors of roof surrounding rock caving in mining with inclined thick and large orebody caving method are studied.The results show that the roof surrounding rock of goaf has the double arch characteristic of "stress-caving"when mining with inclined ore-body caving method.The caving arch is symmetrical arch along the strike,and asymmetrical arch along the dip.The relation between the maximum caving displacement and the thickness of ore body is quadratic polynomial.The lower the dip Angle is,the larger the roof caving range is,but the smaller the maximum caving displacement is.Joint set Angle of 30°/60°,the horizontal displacement of surrounding rock of offset is larger and minimal impact on surface subsidence,but the impact range is the most widely;The larger the horizontal tectonic stress is,the larger the horizontal displacement of surrounding rock is.The existence of upper wall fault will affect the spreading path of roof caving,but make the roof caving more sufficient.Based on the field joint distribution and parameters,the numerical model of the ore body of the caving method in xiadian gold mine was established,and the highest point of the caving zone in the concealed goaf was simulated at the level of-231.7m.The physical similarity model of mining in hidden goaf was constructed,and the roof caving process was repeated and verified.The highest point of the caving zone was-246m.Based on the time-delay nonlinear model,the development peak of the caving zone is predicted to be-236m.Therefore,based on a variety of calculation and test models,the highest point between the cavities falling and the dispersion filling is about-230m?-250m,which is about 350m-370m away from the surface.On the basis of theoretical research,in combination with the practical conditions of Xia Dian gold mine,puts forward the 500 m deep concealed goaf comprehensive detection,the method by high density resistivity method to the surface of the drilling technology to detect found no large-scale mined-out area,combining with borehole camera long-term monitoring and empty area boundary of ground penetrating radar(GPR),test results prove that concealed basic medium has been caving goaf filled with dense,verify the accuracy of numerical simulation and theoretical calculation.