Mechanical behavior of limestone in natural and forced saturation states under uniaxial loading: an experimental study

In the coal mining process, the limestone stratum under coal seams would be affected by high-pressure water, which has a significant influence on its physical and mechanical properties. To study the variation in limestone strength, uniaxial compression tests of three kinds of specimens processed with different water treatment methods are carried out, and the acoustic emission signals are collected during testing to analyze the failure characteristics of the specimens. The results show that the uniaxial compressive strengths of the naturally saturated and forcedly saturated limestone specimens are reduced by 28.01% and 28.27%, respectively, compared to that of the natural limestone specimens. Increasing the water content enhances the plastic deformation properties of this rock. Besides, the failure modes of the limestone specimens change from simple to complex with increasing water content: with increasing water content, it became easier for the specimens to maintain their original shape after failure, which is beneficial to increasing post peak strength.