Generalized effective stress applied to evaluation on multiphase coupling seepage of coal-rock

Based on analysis of the fluid-solid coupling mechanics features of the porous media,a general effective stress principle was derived and a conception of th e general effective stress coefficient a was provided. The paper held that the general effective stress was a comprehensive characterization of the multiphase coupling see page mechanics role in the coal reservoir. The multiphase coupling macro dynamic strength features of the coal reservoir could be centrally reflected with the a. Two metho ds of the coal-rock permeability dynamic prediction were discussed and they were the mathematic model method and the direct ftting method. The study showed that the di rect fitting method could not consider different coupling mechanism within the reservoir and could be easily operated. The paper summarized that with the ftting permeabili ty,the general equation could obtain three methods of the a and they were the Equation Deformation Method,Cross-plotting Method and Differential Method. With the case application,the Cross-plotting Method and Differential Method could be applied to obtain the a. The paper discussed the generalized effective stress features of the coal-ro ck. The paper verified the understand correction of the a and the generalized effective stress principle and the generalized effective stress principle was correct to predict t he permeability variation of the coal reservoir in the fluid-solid complicated coupling process of the comprehensive evaluation.