Experimental Investigation into Limit Void Ratio Characteristics of Calcareous Sands considering Various Factors

Abstract

Relative density is an important index affecting the mechanical behaviors of calcareous sands. The dense sands present softening strength, whereas the loose sands exhibit hardening strength. Furthermore, the relative density is determined based on the maximum and minimum void ratios obtained by using the maximum and minimum dry density test. In this study, a series of tests were carried out on various mixed graded sands to explore their material properties and the relationship between the limit void ratio, considering the effects of test methods, equipment, and fine content. It is shown that a more accurate maximum void ratio can be attained by using the 1000 mL measuring cylinder with low rotation speed. In addition, in order to avoid particle breakage of calcareous sands, it is suggested that the minimum void ratio should be obtained with the 1000 mL compaction cylinder combining vibration with hit. The results also show that a linear relationship exists among the limit void ratio of various mixed graded sands. Besides, the void ratio is significantly affected by the fine content. 40% is the critical fine content corresponding to the lowest value of the limit void ratio.

Robotic drilling for the Chinese Chang’E 5 lunar sample-return mission

“…In regolith mechanics and geotechnical engineering, relative density D r is an extremely important aggregate property that measures regolith compactness and can be calculated as followswhere ρ is the measured dry (bulk) density, and ρ max and ρ min are the maximum and minimum dry densities, respectively. For granular materials, ρ max can be measured using the vibration-hammer method, and ρ min can be obtained using the measuring cylinder method (Li et al, 2021). When ρ = ρ max , the regolith cannot be compressed further ( D r = 100%), whereas ρ min reflects the loosest state of regolith ( D r = 0%).…”