颗粒形状对堆石颗粒破碎强度尺寸效应的影响

Influence of particle shape on size effect of crushing strength of rockfill particles

大量的颗粒破碎试验结果表明,颗粒破碎强度存在明显的尺寸效应,即颗粒破碎强度随着粒径的增大而减小,但颗粒形状对破碎强度尺寸效应的影响研究较少。首先对大石峡堆石坝工程的砂砾石料和灰岩混合料进行了颗粒扫描、形状分析和单颗粒压缩试验。砂砾石料的球度和凸度明显大于灰岩混合料,砂砾石料颗粒偏向于浑圆状,而灰岩混合料颗粒棱角状突出。试验结果表明,两组堆石颗粒的破碎强度均存在明显的尺寸效应,并评估了不同强度尺寸效应模型的适用性。综合分析试验结果和收集、整理的文献中的数据,颗粒形状对破碎强度的尺寸效应有较为明显的影响,颗粒形状越不规则,其颗粒破碎强度的Weibull模数越小,颗粒破碎强度的尺寸效应越明显。

A large number of particle crushing test results show that there is a noticeable size effect on the particle crushing strength.The particle crushing strength decreases with the increase of particle size.However,the influence of particle shape on the size effect of particle crushing strength is still unclear.In this paper,particle scanning,particle shape analysis,and single particle compression test of sand-gravel and limestone mixture of Dashixia rockfill dam are carried out.The sphericity and convexity of sand-gravel are larger than those of the limestone mixture.The particles of sand-gravel tend to be round,while the particles of limestone mixture are angular.The test results show that the crushing strength of both kinds of rockfill particles exists noticeable size effect.The applicability of different strength size effect models is then evaluated.Comprehensive analysis of the test results together with the data collected from literature shows that the particle shape has a significant influence on the size effect of the particle crushing strength.The more irregular the particle shape is,the smaller the Weibull modulus of the particle crushing strength is,and the more obvious the size effect of the particle crushing strength is.