考虑堆石料级配和破碎效应的宏细观多尺度研究

For high rockfill dam construction, prediction and control of the stress and deformation is an important technical challenge, and yet to be solved satisfactorily. Like other natural geo-materials, its constitutive relationship is nonlinear and sensitive to a number of factors, including material anisotropy, loading path and loading history et al. It also exhibits the well-known material dilatancy. Moreover, rockfill materials consist of very large particles and have a high coefficient of non-uniformity. Particle breakage becomes significant even at moderate confining pressures. These particle-scale characteristics contribute further to the complexity in their stress-strain behaviours. A deep understanding in the strength and deformation mechanisms of rockfill materials is important. To achieve this, we aim at establishing the macro-micro relationship between the particle-scale characteristics and the continuum-scale mechanical properties of rockfill materials. The project will examine the applicability of the multi-scale homogenization theory, previously developed by the applicant for sand, to rockfill materials. It will be based on the Discrete Element simulation of rockfill materials with various particle size distributions, and focused on analyzing the statistics and evolutions of the internal structure and the particle interactions. Built upon it, we will also investigate the particle breakage induced change in particle size distribution under various loading conditions, and its effect on the material critical state, strength and deformation. The research outcomes will make important contributions to the development of the multi-scale approach. It will help the development of micro-mechanics based constitutive model for satisfactory prediction of material responses to general loading conditions. It will also help support the advancement of design approach and optimise the project design and construction.

坝体应力应变的预测和控制是目前高堆石坝建设的关键技术问题。堆石料是高堆石坝的主要筑坝材料，除了具有天然岩土材料共有的非线性、各向异性、加载路径与历史的敏感性、剪胀性等力学特性外，堆石料具有粒径大、不均匀系数高、颗粒易破碎等特点。这些细观颗粒尺度上的特点使其宏观响学更为复杂。加深对堆石料的强度和变形机理的认识是迫切需要解决的问题。为此，本项目以申请人前期建立的宏细观均匀化理论为基础，通过分析观测不同级配的堆石料内部结构和粒间作用力的统计特性及演化规律并验证其适用性，建立堆石料细观特性与宏观工程力学特性的多尺度关联。在此基础上，本项目还将考虑颗粒破碎引起的级配变化，分析其对材料临界状态、强度和变形的影响。研究成果将推动堆石体多尺度研究方法的发展，有助于发展适用于复杂应力状态的堆石料宏观本构模型的建立，也可为进一步完善高堆石坝设计理论，优化设计、施工提供技术支撑。

坝体应力应变的预测和控制是目前高堆石坝建设的关键技术问题。堆石料是高堆石坝的主要筑坝材料，围绕堆石料具有粒径大、不均匀系数高、颗粒易破碎等特点，本项目以颗粒级配为侧重点开展了基于离散元的多尺度研究。该项目以申请人前期建立的宏细观均匀化理论为基础，通过分析不同级配的堆石料内部结构和粒间作用力的统计特性及演化规律并验证其适用性，建立堆石料细观特性与宏观工程力学特性的多尺度关联。在项目开展过程中，依托单位发生变化，项目组及时进行调整，并随着研究的推进，开展了堆石料抗剪强度数据库的开发、颗粒材料内部结构的CT扫描等工作，为原课题的有益补充。研究成果将推动堆石体多尺度研究方法的发展，有助于发展适用于复杂应力状态的堆石料宏观本构模型的建立，服务工程需要。