Study on the Relationship between Stress and Charge of Coal Mass under Uniaxial Compression

Abstract

This paper presents a new method to identify the stress concentration degree and stress distribution characteristics in front of working face in coal mine, based on the close relationship between charge and stress during fracture of coal mass. This method overcomes many disadvantages of conventional stress‐monitored methods. First, the stress and charge relationship of coal mass was established through damage theory and statistical strength theory. Then, the relationship between stress and charge was studied by a laboratory test, and finally, the field charge monitoring test was performed. The results show that there is a nonlinear relationship between loading stress (σ) and cumulative charge (Q), which can be represented by polynomials. The fitting results of the laboratory test between σ and Q conform to a cubic polynomial function, Q = aσ3 + bσ2 + cσ + d. It verifies the rationality of the theoretical relationship formula. The field monitoring results show that average charge is great and cumulative charge changes from rapid upward to sharp upward before roof falling. The magnitude and position of average charge and the upward trend of cumulative charge can be used to identify the stress concentration and stress distribution in front of working face, and the abnormal stress area can be predicted. The results can provide certain guidance for the forecast of rock burst in coal mine.