长期直接剪切作用下钙质砂的颗粒破碎特性研究

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

  • 摘要: 长期直接剪切作用下钙质砂的颗粒破碎特性是影响钙质砂剪切蠕变变形的重要因素。为了探寻钙质砂在长期直接剪切作用下的颗粒破碎特性,在不同应力水平下对具有特定分形维数的钙质砂进行直剪蠕变试验。试验结果表明:钙质砂的剪切蠕变可以分为快速剪切、减速蠕变和稳态蠕变等3个阶段;大粒径组的颗粒相比小粒径组的颗粒更容易被剪切破碎,大粒径组的颗粒破碎后向相邻的小粒径组迁移,且粒径越相近迁移量越大;钙质砂的破碎程度与法向应力和应力水平正相关,但最终的破碎程度由两者共同作用决定;长期直接剪切作用下相对颗粒破碎率和分形维数之间存在线性相关性,法向应力越大相关性越好;相对颗粒破碎率与输入总功之间呈双曲线关系。

     

    Abstract: 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.

     

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