Abstract
The dynamic mechanical properties of limestone are studied with 5 types of impact pressure acting on limestone samples in axial direction in this paper. The rubber shaper with a diameter of 5 mm and thickness of 2 mm is adopted. Besides the conical punch of split pressure bar of Hopkinson with a diameter of 50 mm is also used. The half-sinusoid pulse is obtained by using the pulse shaper method and special punch method; the constant strain rate deformation of the sample is realized. Dynamic compressive properties and failure modes of limestone under different impact pressure are investigated. In addition, energy dissipation is studied in the process of experiment. The results show that the dynamic compressive strength of limestone has an exponent relation to strain rate. The failure strain, degree of fragmentation, incident energy, and absorption energy increase, while the energy absorbency decreases with the increasing of strain rate. However, the initial elastic modulus is not sensitive to the strain rate. The research method and conclusions have reference value for the dynamic mechanical properties of other brittle materials.
Highlights
With the increasing of infrastructure construction and rapid development of the urbanization, there will be many huge projects accompanied with a large number of blasting construction works
The results show that the dynamic compressive strength of limestone has an exponent relation to strain rate
The pulse stress wave generated by the traditional split Hopkinson pressure bar (SHPB) apparatus is high frequency oscillation of square wave and rises in a short time; the samples have always been destroyed before the internal stress balance has been reached and are unable to meet the requirements of the sample uniform deformation
Summary
With the increasing of infrastructure construction and rapid development of the urbanization, there will be many huge projects accompanied with a large number of blasting construction works. Zhou et al [9] got different shapes of incident stress pulse waveform with different forms of bullets and a half-sine wave which reduces the dispersion and oscillation of the wave when propagating along the rod and keeps the stress in sample evenly At present, these methods have been widely used in the study of the dynamic characteristics of engineering materials under high strain rate like rocks, ceramics, and composites. Liu et al [16] used the split Hopkinson pressure bar (SHPB) test apparatus with a diameter of 100 mm and the thin circular copper sheet as a waveform shaper; the amphibolite samples were impacted in axial direction at different speed to test their dynamic mechanical properties in strain rate which ranges from 40 to 150. The research results have certain significance in guiding the actual engineering construction in Guizhou mountainous area
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