考虑颗粒强度尺寸效应的原型堆石料破碎特性研究

高土石坝中，堆石体颗粒破碎是导致坝体变形的主要因素之一。但是由于原型坝料的颗粒尺寸较大，其破碎程度难以直接通过室内试验度量，因此通常要将原型级配缩尺为60 mm以下的小粒径级配堆石料，然后才能进行室内试验。而由于原型和试验级配差异较大，导致试验测得的参数往往和原型坝料实际参数有较大差异，因而影响了原型坝料力学特性的深入研究。这里提出了一种新的实时预测原型坝料破碎的方法。首先在颗粒尺度上，基于单粒强度的Weibull分布理论和颗粒分形破碎理论，阐述了原型堆石料级配演化的推求过程；然后通过单粒强度试验测得了相关参数，并与三轴试验测得的试样级配曲线对比，验证了参数选取的合理性；之后分析了颗粒强度离散程度对于原型坝料级配曲线形状的影响；最后，讨论了加载过程中原型级配和试验级配堆石体的相对破碎参量和受力状态的关系。

Study of breakage behaviour of original rockfill materials considering size effect on particle strength

In high rockfill dam, particle breakage is one of the main factors that lead to dam deformation. However, because of the large size of the rockfill particles, the breakage degree of the prototype rockfill materials is difficult to be measured directly through laboratory test. Therefore, the common practice is to reduce the size of the prototype gradation particle to less than 60 mm before the laboratory test can be carried out. However, due to the significant difference between the prototype and the test gradation, the parameters measured in the test are often quite different from the actual parameters of the prototype rockfill materials, thus affecting the in-depth study of the mechanical properties of the prototype rockfill materials. In this paper, a new method is proposed to describe the change of particle size distribution (PSD). Firstly, based on the theory of Weibull distribution of the particle strength and fractal crushing of the particle, the calculation of PSD change of the original rockfill materials is elaborated. Then, the relevant parameters are obtained by conducting the single-particle crushing test, and by comparing with the triaxial test, the rationality of parameter selection is verified. Moreover, the effects of the discrete degree of particle strength on the shape of the PSD is analyzed. Finally, the relationship between the relative crushing parameters and stress state of the rockfill materials during loading is discussed.