Experimental Study On Mechanical Properties Of Limestone Under Dynamic And Static Combined Loading

In order to study the failure of rock subjected to high in-situ stress and dynamic disturbance,limestone is selected as the research object,and dynamic mechanical tests of limestone specimens under one-dimensional combined static and dynamic loading are carried out by using SHPB test device.The dynamic compression tests with and without axial compression were carried out at different strain rates,and the splitting tensile tests with and without radial preloading and static loading were carried out to investigate the mechanical properties of limestone specimens under dynamic and static combined loading.The main research contents and results are as follows:1.The rock sampler,cutting machine and grinder are used to process the specimens to meet the requirements of the specifications and test the basic physical parameters of the specimens.Static compression test and disc splitting tensile test were earied out with RMT-150B test device,and the stress-strain curve and failure mode were analyzed.2.In the dynamic compression test of limestone specimens under one-dimensional combined static and dynamic loading,the dynamic stress-strain curves of the specimens are greatly affected by the axial compression,and the shapes of the curves are different under different axial compression,while the shapes of the curves are basically similar under the same axial compression.The dynamic compressive strength of specimens increases linearly with strain rate.The dynamic compressive strength of specimens with axial compression is larger than that without axial compression.The failure mode of specimens is splitting failure without axial compression and compression-shear failure with axial compression.3.The energy consumption of limestone specimen in SHPB dynamic compression test is analyzed from the angle of energy dissipation.When the specimen is subjected to axial and non-axial compression,the variation trend of energy and time is different;the variation law of energy and average strain rate is basically similar,and the incident energy,reflection energy and transmission energy increase with the increase of strain rate,showing good rate correlation;the absorption energy per unt volume of the specimen increases with the increase of incident energy,and the reflection energy+transmission energy tends to be relatively stable with the increase of incident energy.At this time,the absorption energy per unit volume of the specimen increases rapidly.4.In the splitting tensile test of limestone specimens under one-dimensional dynamic and static combined loading,the dynamic stress-strain curves of specimens with or without radial preloading and static loading are basically similar,experiencing elastic stage,yield stage and failure stage respectively;the dynamic tensile strength of specimens increases with the increase of average strain rate,and has a strong strain rate effect;the energy and time variation of specimens have some rules.The dynamic tensile strength of the specimens increases with the increase of absorption energy.The tangential modulus of specimens decreases with the increase of average strain rate under radial preloading and increases with the increase of average strain rate without radial preloading.The failure mode of the specimens is splitting along the radial direction.Figure[42]table[12]reference[90]...