Study on micromechanism of water absorption and its softening effect on shale rock in deep coal measures

Water absorption experiments under ietnt inae using a self-developed hydrophilic experishale samples collected from Shenyang of Liaoning province using a self-developed hydrophilic experimental system.At the same time,X-ray diffraction , high pressure mercury intrusion , scanning electron microscope and uniaxial compression experiments were periormea on lteosthadl water increases with time after water absorption.The experimental results are as follows:①the absorbed water increases with time while the water absorption rate decreases with ume and wttlh slale sam ples under different water presexponential function;②the water absorption capacities of the shale samples under different water pressures are remarkably different which are suggesting that water pressure can significantly increase the water absorptivity;③the water absorption capacity and the clay mineral content are positively correlated which indicates that the clay minerals ,specifically illite , plays an important role in water absorption process of the shale samples;④the water absorption capacity and the effective porosity are negatively correlated and the reasons are closely related to a micro-structural perspective;⑤the uniaxial compression strength(UCS)of the hydrated shale samples is negatively correlated with their water content and the increase of the porosity after water absorption may be an important reason for decreased strength of the hydrated shale samples.