干湿循环作用下堆石料宏细观力学特性的离散元模拟研究

Discrete element simulation study on the macro-and meso-mechanical properties of rockfill materials under wetting-drying cycles

堆石料的物理力学特性在干湿循环作用下会发生明显劣化。基于堆石料颗粒三维扫描结果,建立了宽粒径范围的堆石料颗粒模板库。考虑干湿循环对颗粒强度、颗粒间接触模量和摩擦系数的影响,提出了一种考虑堆石颗粒干湿循环劣化的颗粒破碎模拟方案。在此基础上,采用FDM-DEM耦合方法对不同干湿循环作用下的堆石料试样进行一系列三轴压缩试验,讨论了在三轴压缩条件下干湿循环对堆石料宏细观力学特性的影响规律。结果表明:堆石料的初始模量和峰值强度随着干湿循环次数N的增加而呈非线性降低,干湿循环对体变曲线在初始阶段的剪缩和加载后期的剪胀有抑制作用,当N增大至某一值时,干湿循环对堆石料的宏观变形和强度的影响逐渐不明显。干湿循环次数越大,试样内部平均配位数越大,接触滑移比越大,试样内部的偏组构呈非线性减小,即各向异性程度在逐渐减小,这说明干湿循环对试样内部的各向异性发展有抑制作用。

The physical and mechanical properties of rockfill materials significantly deteriorate when subjected to cyclic wetting-drying.Based on the three-dimensional scanning results of rockfill particles,a comprehensive template library featuring a wide range of particle sizes has been established.Considering the effects of wet-dry cycles on particle strength,effective modulus,and inter-particle friction,a particle crushing simulation scheme has been proposed,taking into account the degradation of rockfill particles caused by wet-dry cycles.On this basis,using the coupled FDM-DEM method,a series of triaxial compression tests have been conducted on rockfill specimens subjected to cyclic wetting and drying.The results reveal that the initial modulus and peak strength of the rockfill materials decrease nonlinearly with an increase in the number of wet-dry cycles(N).Wet-dry cycles exert an inhibitory effect on volumetric strain during the initial stages of shearing and dilation in later stages of loading.However,as N increases to a certain value,the impact of wet-dry cycles on the macroscopic deformation and strength of rockfill materials becomes less significant.As the number of wet-dry cycles increases,both the average coordination number and contact slip ratio within the specimen rise.Additionally,the deviatoric fabric inside the specimen exhibits a nonlinear decrease,indicating a gradual reduction in anisotropy.This suggests that wet-dry cycles have an inhibitory effect on the development of anisotropy within the specimen.