Influence of Water Pressure on Crack Propagation of Sandstone under Compression

Cracks propagate under compression of rocks and these cracks are mainly tensile. Shear band can be formed as the result of interaction of tensile cracks and shear failure finally occurs with propagation and interaction of cracks in the rock. It has been found that progressive failure process of rocks is affected by mineralogical composition, grain size, texture and foliation etc. External factors such as the confinement and excavation disturbance also have great effect on progressive failure process of rocks. The influence of water pressure on progressive failure process of sandstone was studied based on the experiment. It was indicated that with increase of water pressure at both ends of the rock sample, crack initiation stress sigma(ci) had a tendency to increase and crack damage stress sigma(cd) and peak strength sigma(f) decreased gradually. With increase of the confinement, stress thresholds during progressive failure process of sandstone decreased gradually.