Experimental Study On Dynamic Mechanical Properties Of Layered Purple Sand Rock Under Uniaxial Impact

The mechanical properties,deformation and failure characteristics of layered purple sandstone under impact load are of great significance for studying the failure mechanism of layered rock mass and rock mass engineering construction.In this paper,the compression impact failure tests of layered violet sandstone specimens with different bedding dip angles and prefabricated holes were carried out by using the Hopkinson pressure bar,and the dynamic compression stress-strain curves and energy dissipation data were obtained.The dynamic deformation field of specimen failure process was obtained by digital image correlation technology,and the effects of bedding dip angles and prefabricated holes on the dynamic mechanical parameters,failure modes and energy conversion characteristics of layered violet sandstone were emphatically studied.The main contents and conclusions of this paper are as follows :1)The uniaxial impact failure test of Hopkinson compression rod was carried out on layered purple sandstone without holes.The influence of bedding angle on the bearing capacity,failure mode and energy conversion characteristics of purple sandstone was analyzed.The results show that with the increase of bedding angle,the dynamic compressive strength of purple sandstone increases first and then decreases,and reaches the maximum value when the bedding angle is 45 °.Through the analysis of failure morphology,the failure mode and dynamic compressive strength of rock corresponding to bedding angle can be obtained.At the same time,the absorption energy density and absorption energy / incident energy ratio are closely related to the bedding angle.Reasonable bedding angle can improve the bearing capacity and stability of rock mass.2)The uniaxial impact test of Hopkinson compression rod was carried out on layered purple sandstone with prefabricated holes.The dynamic fracture process of rock was analyzed by digital image correlation technology.The influence of hole and bedding angle on the bearing capacity,failure mode and energy conversion characteristics of purple sandstone was studied.The results show that for the layered purple sandstone with holes,when the bedding dip angle is less than 60 °,the rock failure is mainly affected by the weak bedding plane.When bedding dip angle is greater than 60°,rock failure is mainly affected by holes.The stress concentration near the hole increases with the increase of dip angle.The absorption energy density and absorption energy / incident energy ratio of rock failure process are positively correlated with the dynamic compressive strength of rock.the dynamic strength of rock.