| In the production stage of a coal mine,small geological structures,especially the concealed minor faults and folds that haven’t been detected before mining,are the very critical points that may lead to coal mine gas disasters.Therefore,to effectively survey and predict the outburst coal seam concealed small structures in coal mine production stage is of great significance to the optimization design of coal seam gas treatment engineering and coal mine safety.The concealed small structures of outburst coal seam are selected,including the concealed small faults and folds and macro fractures of coal seam,and the methods to survey and predict them are studied in this paper.Based on the basic data for the surveying and prediction of concealed small faults and folds obtained through gas extraction boreholes,this paper analyzes the influencing factors related to prediction precision,including drilling deviation and data measurement errors,and brings up measures to reduce measurement errors and improve drilling data precision utilizing gas-geology information,and improves the method to calculate the coordinates of the roof(base)plate control points of coal seam with gas extraction boreholes;it also prepares calculation program with MATLAB,and develops the system to predict the concealed small faults/folds of coal seams.This Paper also studies the observation,statistical and analysis methods of the macro fractures of coal seam,which can affect the permeability of coal seams directly and might lead to preferred orientation of gas seepage of coal seam.The traditional method to measure macro fractures of coal seam manually is less effective,and greatly affected by underground mining environment.With MATLAB,this Paper develops computer aided identification and statistical analysis method of macro fractures on coal wall image.The specific process: Firstly,take digital pictures of fractures on coal wall;then,transmit these images to computer for processing,and establish a model with the2-dimensional parameters of fractures extracted,and the convert them into3-dimensional parameters of fractures;at last,obtain the characteristics and rules such as the optimal development direction of macro fractures of coal seam,so as to provide basis for the optimization design of coal seam gas extraction engineering.The concealed small faults and folds survey methods,and macro fracture statistics and prediction methods brought up in this paper have been actually utilized in the exploiting of II-1 coal seam in Guhanshan mine,demonstrating their feasibility and effectiveness. |
