Experimental Study on the Evolution Trend of the Pore Structure and the Permeability of Coal under Cyclic Loading and Unloading

作者：Tianyu Xin, Bing Liang, Junguang Wang, Weiji Sun, Yashengnan Sun · 发表于：ACS Omega · 年份：2021 · DOI：10.1021/acsomega.1c06118 · 被引用次数：20 · 研究领域：Coal Properties and Utilization、Rock Mechanics and Modeling、Geoscience and Mining Technology

In the deep mining process of coal seams, the mechanical environment of the coal body is complex and in the state of cyclic loading and unloading. The change in the stress state leads to the change in the pore characteristics and the permeability. To investigate the effects of cyclic loading and unloading on the pore characteristics and the permeability of coal, the seepage experiment was carried out for the coal samples using the self-developed triaxial permeation instrument. By pressure confining and continuous cyclic loading and unloading, the evolution of the porosity and the permeability of the coal samples was investigated. Under the condition of the experiment, the influences of the initial value of the confining pressure and the cyclic load amplitude on the evolution of the permeability and the pore structure characteristics of the coal samples were clarified. The experimental results showed that the porosity and the permeability decreased exponentially with an increase in the number of loading and unloading cycles, and this decreasing trend gradually weakened until the porosity and the permeability became relatively stable. When the cyclic load amplitude was the same and the confining pressure increased, the effective porosity of the coal body and the bound porosity decreased. When the confining pressure was the same and the cyclic load amplitude increased, the effective porosity of the coal body decreased and the bound porosity increased. The loss rate of the permea...