Experimental Study On Mechanical Properties And Permeability Of Weakly Weathered Granite Under Impact Load

Based on the national fund as the basis for the ion type rare earth ore leaching characteristics of low efficiency,the small charge blasting to improve the permeability of ore weathering layer idea,by using Hopkinson's rod(SHPB)instrument test system and GDS-VIS three axis rheogeniometer,velocity of different impact deformation characteristics of weak weathered granite and infiltration,providing a certain reference value to in situ leaching method using small dosage of blasting to enhance permeability.The main work and research results are as follows:(1)Porosity,wave velocity and uniaxial compressive strength of weak weathered granite samples were measured.The relationship between porosity and wave velocity and the stressstrain curves under uniaxial compression were analyzed.The experiment shows that porosity develops well,and is affected by porosity development.The uniaxial compressive strength of weak weathered granite is low,and the compaction stage of stress-strain curve is longer.(2)The impact tests of four groups of similar Porosity tests under different impact speeds were carried out by using the SHPB test system.The relationship between impact velocity and porosity,strain characteristics and wave velocity was analyzed.It is found that the deformation of the specimen is related to the initial porosity and the impact velocity.With the increase of the impact velocity,the greater the porosity rate and deformation of the specimen,the more obvious the wave velocity decreases.The effect of the four speeds on the deformation of the specimen is compared,and it is found that the impact velocity of 6m/s has the greatest influence on the sample.(3)At different velocity of shock,the study found that the specimen with large porosity has a lower threshold of energy to begin to produce damage and deformation.The relationship between total incident energy and total absorption energy under 4 kinds of impact velocity is compared.The threshold of absorption energy for deformation test is about 5J~10J,and the corresponding total incident energy is between 25J~30J.(4)GDS-VIS was used to test the penetration test under the same test conditions before and after the impact.The relationship between the initial porosity of the specimen and the permeability flow is analyzed,and the change of the permeability of the specimen under different shock velocities is compared.It is concluded that the flow rate of different porosity increases with the increase of porosity under the same test conditions.The flow rate of the specimen before and after the impact increases with the increase of porosity.It is concluded that 6m/s is the best impact velocity in the four kinds of impact velocity tests.