Mechanical properties and fracture behaviors of sandstone in dry and saturated states with tip intersecting cracks
The existence of cracks in rock mass can affect the stability of rock engineering,and the distribution form of cracks and the groundwater have a significant impact on the mechanical properties and fracture evolution law of rock mass.By conducting uniaxial compression tests on sandstone samples with tip intersecting cracks,the effects of the intersecting angle between tip intersecting cracks and the groundwater on the strength,deformation,and fracture evolution characteristics of sandstone were studied.The research results indicate that the intersecting angle between the tip intersecting cracks and the groundwater have a significant impact on the mechanical properties and fracture evolution law of sandstone.The tip intersecting cracks will cause the stress-strain curve of the rock sample to enter the crack initiation and propagation stage earlier,and there will be a significant stress drop phenomenon before the peak stress,while a stepped drop phenomenon will appear in the post peak failure stage.As the angle between the tip intersecting cracks increases,the peak stress and initiation stress of the sample gradually increase,and the stress concentration area transitions from the inner tip of the inclined crack to the outer tip.The presence of groundwater will increase the ductility of rock samples with tip intersecting cracks,weaken the stress drop and step drop phenomenon generated by tip intersecting cracks in the stress-strain curve,and make the peak stress and initiation stress of rock samples show a trend of first decreasing,then increasing,and then decreasing with the increase of the angle between tip intersecting cracks at.In addition,the presence of groundwater will weaken the degree of stress concentration at the cracks of rock samples,reduce the number of crack initiation,and make horizontal crack the dominant crack for the failure of saturated rock samples with tip intersecting fractures.
rock mechanicstip intersectingstrength characteristicscrack initiation modefailure modesaturationsandstone
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