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Abstract The exploitation of the protective layer and pressure-relief gas drainage is an effective primary method to eliminate coal and gas outburst and it is widely used in many mineral fields. In order to improve the effectiveness，safety and economy of the protective layer mining，a set of numerical equations of elasto-brittle- plastic constitutive model of coal rock mass damage due to mining are set up based on the plastic flow format of Drucker-Prager constitutive model in fast Lagrangian analysis of Continua in 3-dimension continua(FLAC3D). And the model is modified by using the inscribed circle criterion and the ideal brittle-plastic model. The model is developed into DLL file in VC++2005 programming environment for FLAC3D；and the correctness and rationality of this model used to study the brittle strain-softening characteristics of coal rock mass due to mining are validated by comparing with uniaxial and triaxial compression numerical tests. This model is used to simulate the super-remote protected seams exploitation of Xinjing coal mine in Yangquan coal field. The results show that the protected layer lies in the top edge of fractured zone 125 m away from the protected layer；and the relieved gas in the super-remote protected layers could be better drained utilizing the mining influence of the protective layer. And the conclusions agree with that of the similar experiment，which indicates that the elasto-brittle-plastic constitutive model of coal rock mass damage due to mining could be used to preliminary evaluation of protective layer mining and relief-pressure gas drainage. Simulation results may bring forward reasonable suggestions for the design of protective layer mining and relief-pressure gas drainage.
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Received: 27 July 2009
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