ZOU De-gao, TIAN Ji-rong, LIU Jing-mao, et al. Three-dimensional shape of rockfill material and its influence on particle breakage[J]. 2018, 39(10): 3525-3530.
DOI:
ZOU De-gao, TIAN Ji-rong, LIU Jing-mao, et al. Three-dimensional shape of rockfill material and its influence on particle breakage[J]. 2018, 39(10): 3525-3530.DOI: 10.16285/j.rsm.2017.0259.
Three-dimensional shape of rockfill material and its influence on particle breakage
筑坝堆石料由于尺寸较大,必须对其按一定比例缩尺后才能用来开展室内三轴试验。但缩尺前后颗粒形状难免会有差异,如何评价颗粒形状变化对堆石料变形特性的影响是十分重要的。引入了高精度的三维激光扫描技术对紫坪铺面板坝筑坝堆石料2.5~5、5~10、10~20 mm以及20~40 mm 4个粒径组的颗粒进行了空间形状分析,在此基础上进一步开展了单一粒组的三轴试验,研究了4个粒组的颗粒形状指标与颗粒破碎率的相关性。试验表明,紫坪铺堆石料颗粒破碎率随着其平均球度的增加而减小,并且呈近似半对数线性关系;随着围压的增加,颗粒形状对颗粒破碎的影响逐渐减弱,颗粒强度的影响逐渐增大。紫坪铺堆石料的颗粒强度随着颗粒尺寸的增加逐渐减小,但其破碎率反而随着颗粒尺寸的增加而逐渐减小,主要是因为试验所采用的紫坪铺堆石料颗粒尺寸越小时,其形状越不规则。因此,研究缩尺效应对颗粒破碎率的影响时,要同时考虑颗粒尺寸和颗粒形状。
Abstract
Due to the large size of rockfill
it must be scaled by a certain percentage so that it can be used to carry out laboratorial triaxial test. However
the particle shape of rockfill may be different before and after scaling. Therefore
it is important to evaluate the effect of particle shape on the deformation behavior of rockfill material. In this study
a high-precision 3D laser scanning technology was introduced to analyze the spatial shape of the rockfill particles with the sizes of 2.5-5 mm
5-10 mm
10-20 mm and 20-40 mm of Zipingpu concrete face rockfill dam. Further
triaxial tests were carried out to determine the correlation between particle shape index and particle breakage. The results show that there exists an approximate semi-logarithmic linear relationship between the particle breakage and the particle sphericity for Zipingpu rockfill. With the increase of confining pressure
the effect of particle shape on particle breakage decreases and the effect of particle strength on particle breakage increases. The particle strength of Zipingpu rockfill gradually decreases with the increase of the particle size
but the particle breakage decreases with the increase of the particle size
which may be due to that the particle shape of Zipingpu rockfill become more and more irregular with the decrease of particle size. Therefore
the impact of the particle shape on the particle breakage should be paid enough attention before and after scaling.