| The development of an underground metal mine has to be safe, stable and high efficienct.It is mainly depended on the normal status of all the systems and the advanced technology ofapplied in the mine. During the period of the normal production of the mine, the regularproduction activity and the mine internal and external condition variation can changefrequently the partial parameters of the mine ventilation system, which reduces the safety andstability of the mine ventilation system. With the rapid development of underground metalmine toward the depth, above problems of mine ventilation system become more and obviousthan before. The study of this dissertation is based on the research reviews of the mineventilation system over the world and the generalized analysis, the investigation of the KeyResearch Projects of Chinese Science and Technology of the tenth "Five-Year-Plan" andother mine ventilation system optimization project at several mines. Theory study, in-situ test,numerical analysis and other approaches were comprehensively used in the study ofdissertation. The main research work of this dissertation and results can be summarized asbelow.(1) The fault tree of mine ventilation system of un-stability operation was established.By analyzing the structure characteristics of the fault tree, the nine type factors that influencemine ventilation system stability and its influence scope and degree were obtained.(2) By developing the mine ventilation network analysis program and comparing thecalculating results of the mine ventilation systems in theory with those field measured data,the reliability and applicability of the program were examined.(3) It was proved that analyzing the stability of mine ventilation system by the achieveddata of running the network analysis software on computer is feasible. The relationshipsbetween iterative times of the mine ventilation system network analysis and assigned theprecision, the iterative starting value and the network complex degree were studied. Someinfluence factors on the reliability of mine ventilation network analysis, such as networkstructure, fan characteristic curves and electricity network fluctuation were discussed. At thesame time, the correlation control measures were proposed.(4) By changing the aerodynamic resistance value of characteristic branch and in virtueof the network solution, the mine ventilation system characteristic parameters adjustabilitywas discussed. The coupling relationships between branch aerodynamic resistance and fanoperating points and branch air flux were discussed. The network calculation results ofFankou Lead-Zinc Mine ventilation system show that different branch in the mine ventilationnetwork has different function and branch aerodynamic resistance value input in advance is feasible. The synthesis influence of branch aerodynamic resistance value at entrance and exitto fan equivalent wind pressure were elaborated. Some mine ventilation subsystem stabilityproblem was analyzed and mine ventilation system network calculation experiences wereobtained.(5) The coupling relationship between natural ventilation pressure and mine ventilationsystem stability was discussed. The sensitivity of branch air quantity to the natural ventilationpressure was discussed. The critical state was studied by analyzing phase chart between Qand H. The results show that the direction of mine air flows may be changed when naturalventilation pressure changes.(6) The mine piston wind speed mathematical models of transport and hoist equipmentwere established. The influence factors of piston wind speed were analyzed. The influencedegrees of different type piston wind to mine ventilation system stability were compared. Thecomputational methods of parameters in the mathematical model were determined. Therelationships between the mine piston wind speed and the tunnel length, the running speed,the tunnel area were studied.(7) Used CFD software FLUENT, the three dimensional simulation to piston windorganization at the mine transportation drift were studied. The speeds, static pressuredistribution map at various characteristics sub-plane under different condition were obtained.The entire flow field was divided to different sub-area. The speeds, static pressure changingtendency at the typical position were analyzed. Mechanics origin of the piston wind wasdiscussed.(8) Since a mine ventilation system is an open, far from balance and unstableconstitutionally system, from three necessary conditions of dissipative structure formation,the stability question of mine ventilation system was described. From the point of dissipationbehavior in mine ventilation system, matter and energy accumulation lead to instability of oldstationary state and formation of new dissipative structure. The conditions and process ofcompleting a non-equilibrium phase transition were described. The detailed methods ofcontrolling mine ventilation system stability were proposed.
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