1. Deformation and permeability evolution of coals considering the effect of beddings.
- Author
-
Liu, Chao, Yin, Guangzhi, Li, Minghui, Shang, Delei, Deng, Bozhi, and Song, Zhenlong
- Subjects
- *
BEDS (Stratigraphy) , *PERMEABILITY , *ELASTIC modulus , *COAL , *SHIELDS (Geology) , *SEDIMENTARY rocks - Abstract
Coal belongs to sedimentary rock with obvious bedding planes. The existence of bedding weakens the continuity and integrity of coal. Deformation and permeability anisotropy of coals, to a certain extent, is attributed to the bedding planes. We performed experiments of deformation and permeability evolution of coals under true triaxial stress conditions. The experimental results indicate that the volumetric strain and bedding jointly affect permeability. An analytical model for stress-strain relationship of coals containing beddings is developed to quantify the bedding effects under true triaxial stress conditions. In the model, the deformation and permeability of the bedding and non-bedding are separated through bedding ratio and bedding elastic modulus. The bedding ratio is defined as the ratio of the total length of bedding to the total length of coal normal to bedding planes, which is a parameter closely related to the porosity. The elastic modulus is divided into four parts: a bedding elastic modulus and a non-bedding elastic modulus in the direction normal to bedding planes, and two elastic moduli in the direction parallel to bedding planes. The four elastic moduli are calculated by the analytical model. The bedding elastic modulus is relatively small, which shows that the bedding effect cannot be ignored. The permeability is highly sensitive to the bedding of coal with low stress in the direction normal to the bedding. The bedding ratio always affects the volumetric strain. The permeability of the coal is divided into bedding and non-bedding permeability. The ratio of the bedding permeability to the total permeability is different due to different stresses in the direction normal to bedding planes, which is linking with the compression of bedding. A permeability model which can reflect the different effects of beddings and non-beddings to the total permeability is proposed and verified. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF