Application of the finite element analysis in coal and rock stress-sensitivity

This paper utilizes finite element software to compare fracture interface strain distribution in coalbed and sandstone. Finite element method shows that the stress distribution of coalbed and sandstone is quite different, coalbed fracture maximum strain is 25 times as the sandstone fracture, and the fracture closure is easier for coalbed, combined with the regular pattern of coalbed fracture in the conditions of different effective stress, a fitting formula of permeability change with effective stress was given. Following the laboratory procedure of stress sensitivity in sandstone, the experiment about the permeability change in mineral coal in different confinement pressures indicates that values computed by fitting formula change in the same tendency compared with measured values and some of the errors between them are less than 10% which shows a high fitting accuracy. This prediction of coalbed under effective stress at different permeability has certain practical significance.