Abstract: In order to grasp the swelling characteristics of argillaceous rock from coal measure strata in Cenozoic era, a self-developed soft rock swelling experiment apparatus is used to analyze swelling anisotropy and cyclic swelling-shrinkage. The essential mechanisms of swelling anisotropy and cyclic swelling-shrinkage of argillaceous rock are discussed by using scanning electron microscope (SEM). Results show that the swelling of argillaceous rock decreases with an increase angle between the horizontal plane of device and bedding plane of specimen, and has obvious anisotropy. The anisotropy property of argillaceous rock swelling with water is caused by the preferred orientation of clay mineral particles arrangement, and it can be quantitative described by swelling anisotropy coefficient. With the increase of wetting-drying cycles, absolute swelling ratio increases and tends to be stable, but relative swelling and relative shrinkage ratios decrease and stabilize. Cyclic swelling-shrinkage of argillaceous rock is the outcome of combined effect, which is alter of arrangement of mineral particles and energy dissipation during the occurrence and development of micro-cracks.

Key words: argillaceous rock, wetting-drying cycles, swelling and shrinkage, swelling anisotropy, absolute swelling, relative swelling