基于多尺度方法的堆石体宏细观变形演化规律研究

In western China, a number of high rockfill dams are under construction or to be constructed. The heights of the dams are mostly more than 200m, which is beyond the scope of current specifications. A few problems such as large deformation have arisen in some high rockfill dams. In terms of rockfill dam numerical simulation, the calculated deformation of high dam is lower than the practical value, while the calculated deformation of low dam is higher than the practical one. These problems demonstrate that there is still lack of basic theory research in rockfill mechanical behavior and deformation mechanism. High rockfill dam deformation calculation theory and methods need to be improved. Laboratory experiments, theoretical studies and numerical simulations are combined in this work. The study focuses on macro-mesoscopic deformation evolution process of rockfill. Mesoscopic fabric of rockfill is associated with macroscopic mechanical behavior. The mesoscopic mechanism of rockfill deformation is revealed. By linking the macro and mesoscopic scales, a multiscale simulation method hierarchically coupled discrete particle model and continuum model is proposed. The multiscale method is an effective approach to study rockfill or other complex particle systems. The research results can provide important theoretical basis and technical support for high rockfill dam construction, and promote fundamental research in the related fields of macro-mesoscopic mechanical characteristics of rockfill.

我国西部地区正在或即将建设一批高堆石坝，坝高大多在200m以上，超出了现行规范的适用范围。部分已建高堆石坝出现的坝体变形偏大的问题以及在堆石坝变形数值模拟方面存在“低坝算大、高坝算小”的现状，表明学界对堆石体力学行为与变形机理等基础理论研究方面还存在不足，高堆石坝变形的计算理论和方法亟待突破。本项目拟结合室内试验、理论研究以及数值模拟，以堆石体宏细观变形演化过程为研究主线，探寻堆石体细观组构与宏观力学行为的内联机制，揭示堆石体宏观变形的细观机理；建立宏观和细观两个尺度间的关联，提出一种堆石体细观离散颗粒集合-宏观连续体模型的多尺度模拟方法，为研究堆石体等复杂颗粒体系提供一条新途径。研究成果可为高堆石坝建设提供重要的理论依据和技术支持，并推动堆石体宏细观力学相关领域的基础研究工作。

我国西部地区正在或即将建设一批高堆石坝，坝高大多在200m以上，超出了现行规范的适用范围。部分已建高堆石坝出现的坝体变形偏大的问题以及在堆石坝变形数值模拟方面存在“低坝算大、高坝算小”的现状，表明学界对堆石体力学行为与变形机理等基础理论研究方面还存在不足，高堆石坝变形的计算理论和方法亟待突破。本项目提出了一种堆石体细观离散颗粒集合-宏观连续体模型的多尺度模拟方法，分析和推导了该多尺度方法中的关键关系式，构建了相应计算框架。该多尺度方法采用有限元模拟边值问题，并从对应于每个高斯积分点的离散颗粒集合体提取本构关系用于整体求解。该方法既能避免传统连续方法对基于唯象假定的本构关系的依赖，又能克服单纯离散元不能有效模拟大尺度工程问题的缺点，同时还可以将宏观响应与颗粒材料的细观机制有效关联。通过堆石体双轴压缩多尺度试验，对堆石颗粒材料的宏细观特性进行了研究。分析了细观组构量在加载过程中的演化规律，建立了细观组构量与宏观力学特性的内在联系，从细观层次解释了堆石颗粒体系的宏观力学性质。项目成果可为研究堆石体等复杂颗粒体系提供一条新途径，并推动堆石体宏细观力学相关领域的基础研究工作。