Heterogeneous Mechanical and Sorption Characteristics Induced Interaction Among Different Components in Coal: Experiment and Simulation

Abstract

Coal formation necessitates a long geological age and intricate physical, chemical, and biological processes. Throughout this process, variations in the raw materials and external conditions contribute to the formation of coal, resulting in the final mined coal being a heterogeneous mixture of multiple components. This study takes bituminous coal as the research object to investigate its heterogeneous sorption and mechanical characteristics and their effects. Firstly, various experimental methods were employed to elucidate the heterogeneous structure and spatial distribution of coal. Based on the heterogeneous structure, indentation experiments conducted on multiple coal components demonstrate the heterogeneous mechanical behavior in coal. Simultaneously, sorption deformation kinetics experiments in various areas dominated by different coal components reveal the heterogeneous local sorption deformation characteristics. As a result, interactions among components can be observed throughout the sorption process. According to experimental findings and theoretical analysis, a multi-component contact mechanics model of the heterogeneous coal body was constructed for simulations using a self-developed nonlinear contact finite element program. Utilizing mechanical and sorption deformation data from different components, the program simulated the mechanical response of coal components. In alignment with the experimental results, interaction among components during the coal sorption process can be derived from the simulations. The simulation results confirm that such interactions may be induced by the heterogeneous sorption and mechanical characteristics of coal. These findings provide a deeper understanding of the mechanical behavior of coal bodies in the context of solid-gas coupling and establish a foundation for practical coal-gas engineering applications, such as predicting the geomechanical performance of coal and mitigating potential geohazards (e.g., gas outbursts) associated with heterogeneous coal samples.

Keywords: Heterogeneous coal structure, Heterogeneous mechanical properties, Sorption deformation, Interaction among different components, Contact simulation of coal components