基于可破碎离散元法的堆石料应力变形及剪胀特性缩尺效应研究

Research on the Scaling Effect of the Stress Deformation Feature and the Dilatancy Characteristics of Rockfill Material Based on the Crushable DEM

缩尺效应对堆石料应力变形及剪胀特性有显著的影响,当前对其缩尺规律已有诸多认识,但缩尺机理仍不清晰。为进一步揭示堆石料缩尺效应产生机理,基于可破碎离散元法,通过开展不同尺寸试样的数值三轴剪切试验,探讨堆石料力学变形缩尺规律,并从宏、细观层面深入分析试样剪胀特性的缩尺规律,揭示其产生的细观机理。研究表明:试样尺寸越大,抗剪强度越低,剪缩性越强,且试验围压越高,这一现象越显著;采用相似级配法缩尺得到的不同尺寸试样初始承力结构相似,但尺寸越大的试样其承力结构越稀疏;试样尺寸越大,各粒径组有效配位数分布的降低程度减弱,且围压越大时越明显;各粒径组有效配位数分布的演化与试样颗粒破碎率成正相关,试样颗粒破碎率越大,各粒径组有效配位数分布上抬越多;不同尺寸试样间各粒径组有效配位数分布差演化的差异是试样剪胀特性缩尺规律产生的细观机理之一。

The scaling effect has significant influences on the stress deformation feature and dilatancy characteristics of rockfill materials.Many understandings on the scaling law have been detected,while the underlying mechanism is still unclear. In order to further reveal the mechanism of scaling effect of rockfill material,the numerical triaxial tests of rockfill materials with different sizes are carried out based on the crushable discrete element method(DEM). The results show that the larger the sample size is,the lower the shear strength is and the stronger the shear shrinkage is,and this phenomenon is more significant with increasing confining pressure. The initial load-bearing structures of the specimens generated by similar grading method are similar,while the load-bearing structures will become thinner with increasing sample size. In addition,the reduction of the effective coordination number distribution of each particle size group decreases with an increasing sample size,and this phenomenon becomes more obvious with larger confining pressure. The evolution of the effective coordination number distribution of each particle size group is positively correlated with the particle breakage rate. The higher the particle breakage rate is,the higher the effective coordination number distribution of each particle size group is. It is found that the differences in the evolution of effective coordination number distribution difference among different size groups of rockfill specimens is one of the meso-mechanism of the scaling law of dilatancy characteristics.