| The intellectualization of coal caving is the primary impediment to the development of intelligent top coal caving technology,particularly the theories and key technologies of intelligent coal caving,top-coal caving control and mining and caving coordinative operation in extra-thick coal seam is not mature yet.As a result,a deep research of intelligent top-coal caving theory and control technology has the significant theoretical and engineering value.This paper,taking high efficiency and high recovery rate of top coal caving in extra-thick coal seam and intelligent caving control as the research goal,conducts researches in top-coal group caving methods and its caving law in extra-thick coal seam,mining and caving coordinative operation method of fully-mechanized caving face in extra-thick coal seam and load adaptive control method of rear scraper conveyor,using theoretical analysis,field observation,numerical simulation and field test.Simultaneously,the industrial test of intelligent top-coal caving in the mode of “remote automatic coal caving and manual inspection intervention” was carried out,which provided experience for the improvement of intelligent fully-mechanized top-coal caving technology in extra-thick coal seam.The main research findings are as follows:(1)The characteristics of top-coal caving in extra-thick coal seam under the condition of group caving are revealed,which provides a theoretical basis for high efficiency and high recovery rate of top coal caving in extra-thick coal seam.Top-coal group caving could be split into two types: continuous group caving and interval group caving,based on the spatial distribution characteristics of coal caving openings.The influence mechanism of different group caving methods on top-coal caving law is analyzed using Bergmark-Roos theory and particle discrete element simulation method.The evolution law and the spatial relationship of caving body and boundary of top-coal are revealed,and the influence law of different coal caving process parameters on top coal caving effect is discussed.Under the condition of continuous group caving,the shape of initial caving body changes from "vertical ellipsoid" to "horizontal ellipsoid",and the single caving weight and the caving efficiency increase linearly with the increase of the width of the caving opening.Under the condition of interval group caving,the shape of initial boundary of top-coal is more likely to form an approximate inclined straight line,and the disturbance of coal caving on the boundary of top-coal is reduced with the increase of the number of coal caving rounds and interval counts,which helps smooth the decline of the boundary of top-coal and improve the recovery rate.(2)A coordination control model for mining and caving of fully-mechanized top coal caving face in extra-thick coal seam is constructed.The causes of mining and caving uncoordinated phenomenon in the manual caving stage of fully-mechanized top coal caving face in extra-thick coal seam are investigated using on-site monitoring and statistics.The concept and basic connotation of mining and caving coordination of fully-mechanized top coal caving face in extra-thick coal seam are put forward,and the mining and caving coordination control model and control flow,including time coordination,spatial coordination,and transport capacity coordination,are established,based on the coordination operation logic between various processes of mining and caving cycle of fully-mechanized top coal caving face.The control model establishes a theoretical foundation for mining and caving coordinative operation of intelligent fully-mechanized top coal caving face.(3)An opening degree control model of hydraulic support coal caving mechanism based on robot kinematics is established.The influence law of hydraulic support attitude on the spatial relationship between caving mechanism and rear scraper conveyor is investigated.A kinematics analysis method for the end of hydraulic support caving mechanism is first proposed.The kinematics model of the end of caving mechanism of the low caving coal hydraulic support based on the D-H matrix is established,and the opening degree calculation model of the caving mechanism is constructed accordingly.A closed-loop control method of hydraulic support caving mechanism based on attitude feedback is proposed,which provides theoretical support for the precise control of intelligent top-coal caving.(4)A load adaptive control method of rear scraper conveyor based on load dynamic prediction is proposed.Based on the top coal caving law of group caving method in extra-thick coal seam,the coal volume distribution features of the rear scraper conveyor under different caving methods are analyzed,the nonlinear positive correlation between the load and the motor current of rear scraper conveyor is revealed.Based on the timing characteristics of motor current of rear scraper conveyor,the load prediction model of rear scraper conveyor is constructed using an Elman neural network.A load adaptive control method of rear scraper conveyor based on short time interval coal caving is proposed,which is combined with load prediction model of rear scraper conveyor and the opening degree control model of hydraulic support caving mechanism.This method realizes the load balance of the rear scraper conveyor in the coal caving process,through the cooperative association of the lord of rear scraper conveyor and caving mechanism control.(5)The intelligent top-coal caving decision software of fully-mechanized top coal caving face in extra-thick coal seam is developed by integrating group caving process model,coordination control model for mining and caving of fully-mechanized top coal caving face,opening degree control model of hydraulic support coal caving mechanism,load balance control of the rear scraper conveyor,and the multi-source information database of extra-thick coal seam.An intelligent top-coal caving control platform is built by intelligent top-coal caving decision software,working face communication system and support control system,and the industrial test of intelligent top-coal caving is carried out in Tashan Coal Mine’s 8222 working face,which has achieved good application results and serves as a good reference for the development of technology and theoretical research of intelligent top-coal caving.There are 156 figures,17 tables and 148 references in this doctoral thesis. |
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