Research On Rapid Identification Of Rock Mass Discontinuities Geometric Characteristics And Block Instability In Underground Drift

The stability of the surrounding rock in the underground drift directly affects the safe production of the mine,and the discontinuities with different orientation and sizes in the rock mass are one of the main factors.Rock mass is cut by the discontinuities to form different shapes.Some of the rock blocks slide down under the gravity or mining disturbances,may cause serious harm to the safety of the drift.Some Researches show that grasping the information characteristics of the discontinuities in the underground drift is the basis for the stability analysis of the surrounding rock mass.Based on the point cloud data of underground drift acquired by 3D laser scanning technology,the rapid identification of rock mass discontinuities geometric characteristics extraction of underground drift were carried out.Then,the 3DEC software was used to analyze the characteristic of the probability distribution of discontinuities,and the deterministic-random coupling discontinuities model was constructed by the discrete fracture network in3 DEC.Finally,the rock mass is cut by the discontinuities model to obtain the discrete block model of the underground drift.Through numerical analysis,the instability distribution characteristics of underground drift blocks are obtained.The specific research contents and results are as follows:(1)Carried out research on thel extraction of discontinuities based on the point cloud data of underground drift,and conducted engineering case analysis in the 5# drift of 1300 m levels of an iron ore,and obtained 4sets of discontinuities in the study area.By comparing and analyzing the data with the traditional method,the result show that the data of the underground drift can be obtained more comprehensively based on the three-dimensional laser scanning.(2)The three-dimensional reconstruction of the drift model and the discontinuities model as realized by 3DEC software,and the statistical analysis of the geometrical characteristic parameters of the discontinuities was carried out.Based on the proposed statistical analysis method of geometric characteristics parameters of discontinuities,the probability distribution and parameters of 4 set of discontinuities in the study area of5# drift in the 1300 m levels in an iron ore were obtained.(3)Using 3DEC software to carry out discrete fracture network research on discontinuities,constructing 3D network models for 4 set discontinuities,and verifying the validity of the 3D network models used numerical verification method.By constructing the deterministic fault model in the 3D network models,the deterministic-random coupled discontinuities model was obtained.Finally,using the constructed threedimensional model of the structural plane,the discrete block model of the underground roadway in the study area is obtained by block cutting.(4)Based on the discrete block model of the underground drift in the study area,the analysis of the block instability was carried out,and the distribution of the block instability under the gravity and blasting vibration was obtained.Then,analyzed the relationship between the geometric characteristics of the discontinuities and the block instability.The results show that when the size of discontinuities increases,the volume and number of unstable blocks increase,since the accurate analysis of the geometric characteristic parameters of discontinuities is the basic premise for the accurate evaluation of the underground drift stability.