Improved Duncan-Chang model for coal containing gas under different water content

Abstract

This paper aims to establish a model that can reasonably reflect the mechanical properties of coal containing gas under different water content and confining pressure conditions. Firstly, the stress-strain characteristics of coal containing gas under different water content and confining pressure conditions are analyzed based on triaxial tests. Afterwards, this paper obtains the Duncan-Chang model parameters by combining the Duncan-Chang model and Janbu formula. Moreover, it establishes the fitting formulas of initial elastic modulus failure stress and various influencing factors, and conducts an improved Duncan-Chang model to characterize the deformation law of coal containing gas under different stress levels. Finally, this paper verifies the improved model and evaluate the accuracy of the mode. The results show that the increase of water content is an important reason for the dynamic change of coal model parameters of coal containing gas. The prediction curve of the improved model is in good agreement with the actual test curve, and the improved model can accurately reflect the stress-strain characteristics of coal containing gas under different confining pressures and water contents.

Keywords

• coal containing methane
• coal deformation law
• duncan-chang model
• janbu formula
• modified model
• stress-strain characteristics of coal