The use of crushed rock sand in construction projects has recently increased. Because the crushed rock sand has not undergone any weathering processes, it has a higher breakage potential than that of natural sand. This experimental investigation aims at developing a reliable method for the determination of the minimum void ratio (emin) of crushed rock sand using a vibrating table test. The minimum void ratios of one natural sand (Toyoura sand) and five commercially available crushed sands were measured using both vibrating table and pluviation tests. Additionally, the vibrating table tests were repeatedly conducted on the same soil specimen to measure both the emin and relative breakage as a function of the number of retests. The results of this study demonstrate that a vibrating table test induces noticeable breakage of the tested crushed sands, regardless of the initial relative densities and operating frequencies of a vibrating table. Therefore, the extrapolating method, which determines the emin of the artificial sand as the y-intercept in the relation between emin and relative breakage, is suggested in this study, and the determined emin values using the suggested method are compared with the measured emin using pluviation tests.
Although the internal stress state of soils can be affected by repetitive loading, there are few studies evaluating the lateral stress (or K0) of soils under repetitive loading. This study investigates the changes in K0 and directional shear wave velocity (Vs) in samples of two granular materials with different particle shapes during repetitive loading. A modified oedometer cell equipped with bender elements and a diaphragm transducer was developed to measure the variations in the lateral stress and the shear wave velocity, under repetitive loading on the loading and unloading paths. The study produced the following results: (1) Repetitive loading on the loading path resulted in an increase in the K0 of test samples as a function of cyclic loading number (i), and (2) Repetitive loading on the unloading path resulted in a decrease in K0 according to i. The shear wave velocity ratio (i.e. Vs(HH)/Vs(VH), where the first and second letters in parentheses corresponds to the directions of wave propagation and particle motion, respectively, and V and H corresponds to the vertical and horizontal directions, respectively) according to i supports the experimental observations of this study. However, when the tested material was in lightly over-consolidated state, there was an increase in K0 during repetitive loading, indicating that it was the initial K0, rather than the loading path, which is responsible for the change in K0. The power model can capture the variation in the K0 of samples according to i. Notably, the K0 = 1 line acts as the boundary between the increase and decrease in K0 under repetitive loading.
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