Study on long-term direct shear effects on the particle breakage characteristics of calcium sand

The particle breakage characteristics of calcium sand under long-term direct shear are important factors affecting the shear creep deformation of calcium sand. In order to explore the particle breakage characteristics of calcium sand under long-term direct shear, direct shear creep tests were conducted on calcium sand with specific fractal dimensions at different stress levels. The experimental results show that the shear creep of calcium sand can be divided into three stages: rapid shear, deceleration creep, and steady-state creep. Compared to the small particle size group, particles in the large particle size group are more prone to shear breakage. After the particles in the large particle size group break, they migrate towards the adjacent small particle size group, and the closer the particle sizes are, the greater the migration amount. The degree of particle breakage of calcium sand is positively correlated with the normal stress and stress level, but the final degree of breakage is determined by the combined effect of both. There is a linear correlation between the relative particle breakage rate and fractal dimension under long-term direct shear, with a better correlation as the normal stress increases. The relationship between the relative particle breakage rate and the total input work shows a hyperbolic curve.