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颗粒破碎会引起材料的压缩性变大及强度软化,因此颗粒破碎对粒状材料力学特性影响的研究非常重要。首先从试验研究方面着手,总结了颗粒破碎的描述方法、不同加载条件下(一维及等向压缩、三轴剪切、扭剪及单剪)应力应变的颗粒破碎效应;接着总结了考虑颗粒破碎效应的粒状材料力学本构模拟方法,即一维及等向压缩模型、三维剪切模型及基于离散元法的微观土力学模型。最后,通过大量试验结果分析并结合笔者近年来的研究成果,指出可破碎颗粒材料在应力应变过程中的颗粒级配变化可由修正相对破碎指数来表示,可通过塑性功来确定,且塑性功确定法的优越性还体现在循环加载下的累积破碎评价;然后再通过修正相对破碎指数,来确定临界状态线的位置,进而可通过当前状态与临界状态线的相对位置来评价颗粒破碎对颗粒材料力学特性的影响。所提出的以修正相对破碎指数为关键变量的本构方程可直接应用于考虑颗粒破碎效应的粒状材料静动力本构模型的开发。
Particle crushing will cause the material to become more compressible and soften, so the study of the effect of particle crushing on the mechanical properties of granular materials is very important. Firstly, the particle crushing method, the particle crushing effect under different loading conditions (one-dimensional and isotropic compression, triaxial shear, torsional shear and single shear) stress-strain are summarized from the experimental research. The mechanical constitutive modeling method for granular material with crushing effect is one-dimensional and isotropic compression model, three-dimensional shear model and microscopic soil mechanics model based on discrete element method. Finally, a large number of test results are analyzed and combined with the author’s research results in recent years. It is pointed out that the particle size distribution of the crushable granular material in stress-strain process can be expressed by the modified relative crushing index, which can be determined by plastic work, The superiority of the method is also reflected in the cumulative crushing evaluation under cyclic loading. Then the relative crushing index is corrected to determine the position of the critical state line, and then the relative position of the current state and the critical state line can be used to evaluate the effects of particle crushing on the granular material Effect of mechanical properties. The proposed constitutive equation with the relative crushing index as the key variable can be directly applied to the development of the constitutive model of the granular material considering the effect of particle crushing.