Experimental and numerical investigation of the size effect of rockfill particles on crushing strength

The size-dependent crushing strength of single rockfill particles affects the mechanical behavior of rockfill materials. Understanding and capturing the size effect of single particle crushing strength accurately is essential to investigate the gradation evolution and the mechanism of the scaling effect of rockfill materials. However, laboratory rockfill particle crushing tests are mainly carried out for sizes below 60 mm, which is much smaller than the size of rockfill particles in engineering. To study the topic, the crushing characteristics of limestone particles were investigated by laboratory single-particle crushing tests with a wide range of particle sizes (10-240 mm). The results show that the crushing strength of limestone particles obeyed the Weibull distribution and the particle size had a relatively small effect on the Weibull modulus. The characteristic strength of the particles decreased with increasing size, but it tended to stabilize when the particle size reached 240 mm. The exponential size effect equation was more suitable to describe the relationship between the characteristic strength and size of limestone particles. Then, a numerical simulation method was developed to capture the size effect of the crushing strength of rockfill particles by discounting the bond strength of the numerical sample with increasing particle size. In the approach, an exponential relationship between bond strength and particle size was adopted, which was derived based on the relationship between the characteristic strength and size of laboratory limestone particles. The simulation results of the distribution characteristics of the crushing strength of limestone particles with different size fractions are basically in agreement with the results of the laboratory tests, indicating that the method developed in this study can capture the size effect of the crushing strength of rockfill particles well. Finally, the damage evolution of rockfill particles was analyzed by capturing the broken bonds during loading.