Experimental Study On Damage Characteristics Of Sandstone Under Static And Dynamic Loads

With the large-scale construction of deep mining of metal mines,western water conservancy and hydropower and traffic engineering in our country,due to the high ground stress,rock blasting operation and rock burst of engineering disasters in the process of safety excavation(mining)of deep engineering are dynamic failure process under high stress environment.Rock failure mechanism and characteristics under combined dynamic and static loading is one of the key scientific issues needing to find out importantly,the research of rock failure characteristics and revealing the failure mechanism under the condition of combined dynamic and static loading have theoretical and application value for the safe and efficient production of deep engineering.The main research contents are as follows:(1)The design of the test system.The test system is mainly composed of the self-designed static load device,the Hopkinson bar system and the ultra-high speed camera in this paper,the static load device providing a one-way pressure on rock,split Hopkinson pressure bar applying impact load,failure process of the rock sample recorded by ultra-high speed camera.(2)The impact test of rock plate prefabricated I crack.Using rock plate prefabricated I crack,propagation process of one-dimensional crack is recorded by super high-speed camera,researching the influence of impact velocity on the rate of crack propagation,and analyzing the influence of impact rate on open displacement and strain of rock fracture by digital scattered technical at the same time.Spraying white paint evenly,adding a random distribution and sizes of black spots on the rock surface before the test,can achieve better speckle field,greatly enhancing the accuracy of measuring the specimen deformation.(3)The impact test of the rock plate prefabricated groove.Prefabricating groove in the central of rock plate,split Hopkinson pressure bar applying dynamic load in the groove through the punch,the formation process of two-dimensional funnel recorded by ultra-high speed camera,analysis failure area,fragmentation and destruction form and the relationship between the crack growth rate and impact speed.(4)Loading test of dynamic and static combined.Prefabricating round hole in the central of massive rock,firstly applying one-way static pressure on the side of the sample,then the dynamic load applied through the middle hole.The test operation process of rock samples is divided into two ways:One way is that transforming impact dynamic load under a certain static load,and another way is to change the static load in a certain range and apply the same impact load;(5)Numerical simulation.Simulating and calculating using the current widespread finite element software ABAQUS,simulate the failure of the prefabricated groove and the massive rock under load,to eliminate the accidental factor in the actual operation,make the test results more reasonable.