Designing high mine waste rock piles for long-term behavior requires material mechanical characterization over a large range of stresses and variable environmental conditions. However, representative coarse samples cannot be handled by standard testing devices and the common approach is to test small-scaled samples at the laboratory, which might be affected by particle size effects when compared to the field material. Several reported results indicate that coarser samples present higher amount of particle crushing than small-scaled samples, thus lower dilatancy and higher compressibility. However, specific studies of size effects on time-dependent deformation are lacking. The aim of this paper is to identify the effects of particle size and suction on stress-deformation mechanism of partially saturated mine waste rock. Oedometric compression tests on two parallel graded samples are presented: the gravelly fraction (=50 mm) and the sandy fraction (=2.36 mm). Each stress increment triggers « instantaneous » and delayed strains. The results reveal the combined effects of particle size and humidity on the mechanical behavior. Coarser samples exhibit higher total compressibility and creep deformation, which also increases with the material humidity. The results give empirical support for the development of scaling laws and suggest that total deformation can be decoupled considering a suction dependent index for creep deformation.

中文翻译：

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规模和吸力对矿山废石材料压缩性和随时间变形的影响


设计具有长期性能的高矿山废石堆需要在大范围的应力和变化的环境条件下进行材料机械特性分析。然而，标准测试设备无法处理代表性的粗样品，常见的方法是在实验室测试小规模样品，与现场材料相比，这些样品可能会受到粒度效应的影响。一些报告的结果表明，较粗的样品比小尺寸样品具有更高的颗粒破碎量，因此具有较低的膨胀性和较高的压缩性。然而，缺乏尺寸对时间相关变形影响的具体研究。本文的目的是确定颗粒尺寸和吸力对部分饱和矿山废石应力变形机制的影响。介绍了两个平行分级样品的 Oedometric 压缩测试：砾石部分（= 50 mm）和砂质部分（= 2.36 mm）。每个应力增量都会触发“瞬时”应变和延迟应变。结果揭示了颗粒尺寸和湿度对机械行为的综合影响。较粗的样品表现出较高的总压缩率和蠕变变形，这也随着材料湿度的增加而增加。结果为缩放定律的发展提供了经验支持，并表明考虑蠕变变形的吸力相关指数，可以将总变形解耦。