Development of a New Experimental Technique for Dynamic Fracture Toughness Measurement of Rocks using Drop Weight Test

Khandouzi, Gh.; Memarian, H.; Khosravi, M. H.

doi:10.22044/jme.2020.9818.1903

Document Type : Original Research Paper

Authors

School of Mining Engineering, College of Engineering, University of Tehran, Tehran, Iran

https://doi.org/10.22044/jme.2020.9818.1903

Abstract

The dynamic fracture characteristics of rock specimens play an important role in analyzing the fracture issues such as blasting, hydraulic fracturing, and design of supports. Several experimental methods have been developed for determining the dynamic fracture properties of the rock samples. However, many used setups have been manufactured for metal specimens, and are not suitable and efficient for rocks. In this work, a new technique is developed to measure the dynamic fracture toughness of rock samples and fracture energy by modifying the drop weight test machine. The idea of wave transmission bar from the Hopkinson pressure bar test is applied to drop weight test. The intact samples of limestone are tested using the modified machine, and the results obtained are analyzed. The results indicate that the dynamic fracture toughness and dynamic fracture energy have a direct linear relationship with the loading rate. The dynamic fracture toughness and dynamic fracture energy of limestone core specimens under the loading rates of 0.12-0.56kN/µS are measured between 9.6-18.51MPa√m and 1249.73-4646.08J/m2, respectively. In order to verify the experimental results, a series of numerical simulation are conducted in the ABAQUS software. Comparison of the results show a good agreement where the difference between the numerical and experimental outputs is less than 4%. It can be concluded that the new technique on modifying the drop weight test can be applicable for measurement of the dynamic behavior of rock samples. However, more tests on different rock types are recommended for confirmation of the application of the developed technique for a wider range of rocks.

Keywords

References

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Journal of Mining and Environment

Development of a New Experimental Technique for Dynamic Fracture Toughness Measurement of Rocks using Drop Weight Test

References

References

Volume 11, Issue 3
July 2020
Pages 909-920

Development of a New Experimental Technique for Dynamic Fracture Toughness Measurement of Rocks using Drop Weight Test

References

References

Volume 11, Issue 3July 2020Pages 909-920

Volume 11, Issue 3
July 2020
Pages 909-920