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煤与其它岩石类材料一样,在力学特性等方面具有尺度效应,基于Weibull理论和脆性材料强度的随机分布假设,采用损伤力学的方法建立了考虑端面摩擦效应的煤样单轴压缩尺度本构模型,并结合试验对模型进行了分析和验证。结果表明,煤样抗压强度随高宽比的增加明显减小,端面摩擦效应是导致Weibull理论与试验结果产生较大差异的主要原因,修正之后的本构关系与试验结果具有较好的相符性,其不仅能很好地反映煤样单轴压缩强度随尺寸的变化规律,而且能更好的描述单轴压缩的整个加载过程。
Like other rock materials, coal has a scale effect on the mechanical properties. Based on the Weibull theory and the random distribution of brittle material strength, a uniaxial compression constitutive model of coal sample is established by using the damage mechanics method The model was analyzed and verified with experiments. The results show that the compressive strength of coal samples decreases obviously with the increase of aspect ratio, and the friction effect of end faces is the main reason for the large difference between Weibull theory and experimental results. The modified constitutive relationship is in good agreement with the experimental results It can not only reflect the change law of uniaxial compressive strength of coal sample with the size well, but also better describe the whole loading process of uniaxial compression.