特高土心墙堆石坝长期变形特性和开裂机理研究

The construction of super high core rockfill dam has raised higher requirements on the key technical problems such as the selection of rockfill material, the deformation coordination of dam, hydraulic fracturing and crest crack. In view of the evolution of stress and deformation characteristics of the dam during the operation of the super high core rockfill dam, it is very necessary to carry out the research on the construction of super high core rockfill dam and the long-term safety guarantee technology. The research approaches of this project are based on the prediction of whole life cycle working characters of super high core rockfill dam and crest cracking assessments. The main contents are the engineering mechanical properties of rockfill materials, long-term deformation mechanism and characteristics, the multi-scale rheological constitutive model of considering the aging deformation. The synchrotron radiation X-ray light source and cyclic shear rheological test are utilized to reveal the universal mechanical behavior and mechanism of granular material behind the long deformation of the rockfill dam. The multi-scale rheological constitutive model of the hierarchically coupled finite element and discrete element methods are proposed to reveal the spatial and temporal distribution and the evolution law of the stress and deformation characteristics during the whole life cycle of the high core rockfill dam. Combining with many emerging methods, such as the InSAR time-series analysis of monitoring technology, machine learning, and large data, the mass monitoring data are employed to construct the intelligent dam system. The long-term and real-time prediction of stress and deformation properties of rockfill dams are realized, and the cracking risk assessment of core rockfill dam is allowed. Finally, the optimal control method of space and time for the long-term deformation of the super high core rockfill dam is put forward.

特高土心墙堆石坝的建设对筑坝堆石材料选择、坝体变形协调、心墙水力劈裂和坝顶开裂等关键技术问题提出了更高的要求。针对建设和运行过程中坝体应力变形性状的演化，开展特高土心墙堆石坝建设和长期安全保障技术研究十分必要。本项目以特高土心墙堆石坝全生命周期应力变形性状预测和坝顶开裂风险评估为研究主线，以筑坝堆石材料的工程力学性质、长期变形机理、考虑时效变形的多尺度流变本构模型为主要研究内容。采用同步辐射X-ray光源和循环剪切流变试验，揭示堆石体长期变形背后更为普适的颗粒物质力学行为和细观机制。提出分阶耦合有限元和离散元的多尺度流变本构模型，揭示特高心墙堆石坝全生命周期应力变形的时空分布与演化规律。采用InSAR时序分析监测技术、机器学习和大数据等新兴手段，构建智能大坝平台，实现堆石坝应力变形性状的预测并进行坝顶开裂风险评估，最终提出特高土心墙堆石坝长期变形的时空优化调控方法。

随着西部水能资源开发的深入，我国西南、西藏地区正在或即将建设一批调节性能好的高心墙堆石坝，如双江口(314m)、如美（315m）、两河口（295m）等为代表的工程对特高心墙堆石坝建设技术提出了新的挑战。特高土心墙堆石坝的建设对筑坝堆石材料选择、坝体变形协调、心墙水力劈裂和坝顶开裂等关键技术问题提出了更高的要求。针对建设和运行过程中坝体应力变形性状的演化，开展特高土心墙堆石坝建设和长期安全保障技术研究十分必要。本项目以特高土心墙堆石坝全生命周期应力变形性状预测和坝顶开裂风险评估为研究主线，以筑坝堆石材料的工程力学性质、长期变形机理、考虑时效变形的多尺度流变本构模型为主要研究内容。基于同步辐射X-ray光源和循环剪切流变试验，建立剪切颗粒材料宏细观力学试验平台，根据该项目研发的颗粒匹配算法与CT图像颗粒追踪技术获取剪切颗粒系统位置与方向等动态信息，分析了颗粒的压实作用、弛豫动力学、塑性变形、崩塌以及摩擦作用，直观揭示了堆石体长期变形背后更为普适的颗粒物质力学行为和细观机制。提出分阶耦合有限元和离散元的多尺度流变本构模型，构建基于多尺度力学模型与随机散粒体不连续变形方法的数值平台，揭示特高心墙堆石坝全生命周期应力变形的时空分布与演化规律。提出了离散元-深度学习-有限元的多尺度力学框架（DEM-ML-FEM），突破了堆石体宏观唯象的本构建模思路，对传统本构理论进行了优化与补充。基于坝体内外观一体化的变形监测数据，采用InSAR时序分析监测技术、多源数据融合技术、机器学习和大数据等新兴手段对堆石坝变形进行实时预测，构建智能大坝平台，实现堆石坝应力变形性状的预测并进行坝顶开裂风险评估，最终提出特高土心墙堆石坝长期变形的时空优化调控方法。研究成果将为特高心墙堆石坝工程建设提供科技支撑，进一步提高我国高堆石坝的设计和研究水平，因而具有重要的理论意义和应用价值。