Test And Study On Dynamic Mechanical Properties Of Different Lengths Of Limestone Specimens

With the expansion of human activity space,more and more engineering construction is carried out in rock mass,such as large-scale hydropower station construction,road tunnel excavation,mining engineering and so on.There is an urgent need for theoretical knowledge of rock mechanics to guide engineering application.Rock materials have the phenomenon of size effect,that is,there are mechanical differences in strength and deformation characteristics of rocks of different sizes,so that the strength and deformation characteristics of rocks of specific sizes can not be directly applied to geotechnical engineering design and the establishment of rock constitutive relationship.For a long time,rock size effect has been one of the problems in rock mechanics that have not been solved thoroughly.Taking Shungengshan limestone in Huainan City of Anhui Province as the research object,the dynamic and static combined loading system(SHPB)of the State Key Laboratory for Mining Response and Disaster Prevention and Control of Deep Coal Mines was built by the Ministry of Anhui Province to study the difference of dynamic mechanical properties of limestone specimens of different sizes.1.The RMT-150B rock mechanics test system was used to conduct uniaxial compression tests on two groups of limestone specimens with the same diameter and length of 50 mm and 100 mm respectively under static load to study the difference of static mechanical properties of limestone specimens with the same diameter and different length.2.The SHPB test system was used to study the difference of dynamic mechanical properties and deformation characteristics of limestone specimens with the same diameter and length of 50 mm in 12 groups of limestone specimens of 15 mm,20 mm,25 mm,30 mm,35 mm,40 mm,45 mm,50 mm,55 mm,60 mm,80 mm and 100 mm by using 0.5 MPa impact pressure.3.Two groups of limestone specimens with the same diameter of 50 mm and the same length of 25 mm and 50 mm were tested by SHPB test system under Uniaxial Impact Loading with 7 kinds of impact pressure gradients of 0.4 MPa,0.5 MPa,0.6 MPa,0.7 MPa,0.8 MPa,0.9 MPa and 1.0 MPa.The dynamic mechanical properties,deformation characteristics and failure morphology of limestone specimens with different aspect ratios were studied with loading strain.The changing law of rate.4.The SHPB test system was used to conduct dynamic splitting tensile tests on 8 groups of limestone specimens with diameters of 50 mm and lengths of 15 mm,20 mm,25 mm,30 mm.35 mm,40 mm.45 mm and 50 mm,respectively,using 0.3 MPa gas pressure to study the differences of dynamic tensile mechanical properties and failure modes of limestone specimens with different lengths.Figure[45]table[8]reference[76].