Study on dynamic mechanical properties and crack extension law of water-saturated fractured sandstone
In order to study the dynamic mechanical properties and crack extension law of water-saturated fractured sandstone,sandstone specimens with seven prefabricated crack inclinations(0°,15°,30°,45°,60°,75°,and 90°)were saturated with water,and impact compression tests were carried out with the split Hopkinson pressure bar(SHPB)test device.The results show that the dynamic stress-strain curves of prefabricated and natural sandstone samples with different inclination angles are similar,and can be roughly divided into three stages.The dynamic compressive strength,dynamic strain and dynamic elastic modulus all showed an overall trend of decreasing and then increasing with increasing fracture inclination.Compared with prefabricated natural sandstone specimens,the dynamic compressive strength and dynamic elastic modulus of the water-saturated sandstone specimens were slightly increased,while the dynamic strain was reduced,showing the Stefan effect of water action under dynamic loading conditions.With the change of fracture inclination,the failure modes of water-saturated sandstone specimens are tensile,shear and tension-shear composite failure modes.The fracture inclination is 0° and 15° for type Ⅱ failure,30°-75° for Ⅰ-Ⅱ composite failure,and 90° for type Ⅰ failure.The crack initiation position of prefabricated fractured sandstone specimens is mainly concentrated near the fracture tip,and the crack initiation angle decreases with the increase of the fracture inclination angle,and the crack initiation angle at the incident end is larger than that at the transmitted end.
rock mechanicssaturation statefractured sandstoneshock compressionSHPB test device
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