Experimental study on effects of shape and content of fine particles on strength of calcareous mixed sand

In order to study the influences of different contents and shapes of fine particle on the mechanical properties of calcareous mixed sand, the angular quartz powder and round glass beads are used as the fine particle materials and mixed with the calcareous sand in different proportions, and the strength characteristics and crushing characteristics of the calcareous mixed sand are studied and analyzed through the ring shear tests. The results show that the softening characteristics of the two kinds of mixed sand are obvious in the medium density state. The softening coefficient increases first and then decreases with the increase of the fine content, and reaches the maximum value when the fine content is 10%. The softening coefficient of the samples containing the glass beads is larger when the fine content is the same. The apparent cohesion of the calcareous sand is obvious and decreases with the increase of the fine content, and the decreasing trend of the samples containing the glass beads is obviously larger than that of the samples containing the quartz powder because of their lower embedding and biting capability. The deformation of the pure calcareous sand appears in the form of dilatancy, and with the increase of the content of the fine particle, the shear shrinkage of the mixed sand gradually increases, the peak strength and relative breakage rate gradually decrease, and the change of the mixed sand containing the glass beads is more significant.