A numerical approach to predict the dynamic compressive strength from the point load test

Abstract

The point load test (PLT) has been widely used to estimate the strength of rock materials in the laboratory due to its convenience and applicability. While most of the traditional methods count on empirical formulas for prediction, the empirical factors have different values for different rocks so the applicability of those empirical formulas is limited. The dynamic compressive strength has been considered as a crucial parameter for rock dynamic mechanical properties. The split Hopkinson pressure bar (SHPB) developed by Kolsky is a common apparatus to perform dynamic rock tests to obtain the dynamic compressive strength. This study proposed a numerical-experiment integration technique for the prediction of dynamic strength from PLT. Using the idea of digital twins, the rock parameters were calibrated to minimize the difference between the experimental curves from PLT and the numerical curves. Then, the calibrated parameters could be employed to reproduce the rock dynamic test numerically to estimate the dynamic compressive strength. The result showed that the proposed method has an acceptable accuracy in estimating the dynamic compressive strength of rocks compared with the SHPB, and the variation of dynamic increase factor (DIF) on strain rates was consistent with the experimental results. Our work provided the feasibility of the numerical-experiment integration approach for estimating other mechanical parameters of rock such as the dynamic compressive strength of rock.