A dynamic point-load test for quantifying rock dynamic strength parameters

Rev Sci Instrum. 2017 Nov;88(11):113901. doi: 10.1063/1.4995609.

Abstract

The point-load test (PLT) has been widely used in the field and in the laboratory to estimate the strength of rock materials. The PLT is easy and quick to perform and it is suitable for samples with irregular shapes and therefore has found wide applications. The measured point-load strength (PLS) is considered as a strength index and it has been correlated to the rock compressive strength. To address the engineering applications where the loading is dynamic, the PLT is extended to its dynamic version in this study. The dynamic loading is exerted to the rock specimen using a split Hopkinson pressure bar system. Two conical steel platens are attached to the incident bar and transmitted bar, respectively, to apply the point load to the disc specimen. To enable quasi-static analysis, the pulse shaper technique is utilized to achieve the dynamic force balance. The flexibility of the dynamic PLT method is demonstrated by the application to a well-studied granitic rock-Laurentian granite. The correlation between the dynamic PLS and the dynamic strength of the same rock is established.