高拱坝坝踵真实工作机制宏细观研究与安全评价方法

The dam heel is an important zone of a high arch dam for its operation safety. Analysis used multi arch beam method or finite element method provides large tensile stress in the dam heel of an arch dam. The result is inconsistent with the in situ monitoring of many arch dams in China, which demonstrates that compression stress appears in the dam heel. However, several high arch dams have suffered dam heel cracking and the rehabilitation was extremely expensive. The objective of this study is to explain the real working mechanism of the dam heel of a high arch dam, and to fully understand its working performance in both the meso and macro levels, thereby the risk of dam heel cracking can be accurately evaluated. The working performance of dam heel is influenced by the process of construction. The mechanical behavior of concrete-rock biomaterial in the dam heel and the swelling of concrete due to water absorption also affect the stress conditions of the dam heel. Experiments will be conducted and a bond-based particle element-finite volume coupling model will be proposed to achieve the topic of this study. The evolution of damage in concrete-rock biomaterial and the subsequent self-organizing stress adjustment of the system are investigated in the meso level. The mechanism of swelling of concrete under high hydrostatic pressure is also studied. Based on the meso-scale results, we will present a damage constitutive model for the concrete-rock biomaterial, which involves the effect of self-organizing stress adjustment. A macro-scale simulation method will be developed for the real working performance of dam heel of high arch dams. In this model, the concrete pouring process, the effect of grouting arches, the process of impoundment, variable temperature, damage of concrete-rock biomaterial and swelling effect of concrete under water can be all considered. Cracking of the dam heel can be quantitatively analyzed based on the real working performance. It provides scientific basis for the safety evaluation of dam heel of high arch dams.

坝踵区是决定高拱坝运行安全性的一个重要部位。多拱梁法和有限元分析均表明，坝踵部位是高拱坝的高拉应力区，而我国多座高拱坝实际观测到较大的坝踵压应力，与计算结果相悖。然而，国内外却不乏由于坝踵开裂而付出惨重代价的工程实例。本项目的目标是探求高拱坝坝踵的真实工作机制，充分掌握其细宏观工作性态，进而准确评价坝踵开裂风险。坝踵工作性态受施工过程影响，同时坝踵区混凝土-基岩力学性能和混凝土湿胀效应也影响其应力状态。通过物理试验和建立黏结颗粒元-有限体积耦合数值模型，从细观层面揭示混凝土-岩石体系损伤演化及其自组织受力调整规律，研究高压水环境下水-砼耦联致胀机理，构建基于细观机理的混凝土-岩石损伤本构模型。发展考虑混凝土分仓浇筑、封拱灌浆、分期蓄水、温度变化，以及坝踵混凝土-基岩损伤演化和高压水-砼致胀效应的宏观仿真方法，计算坝踵真实工作性态，定量分析坝踵开裂状态，为高拱坝坝踵安全评价提供科学依据。

坝踵区是决定高拱坝运行安全性的一个重要部位。多拱梁法和有限元分析均表明，坝踵部位是高拱坝的高拉应力区，而我国多座高拱坝实际观测到较大的坝踵压应力，与计算结果相悖。然而，国内外却不乏由于坝踵开裂而付出惨重代价的工程实例。本项目的目标是探求高拱坝坝踵的真实工作机制，充分掌握其细宏观工作性态，进而准确评价坝踵开裂风险。基于此，本项目建立了混凝土-岩石细观数值模型，可研究混凝土与岩石系统的相互作用损伤演化机理，研究混凝土-岩石系统力学性能的自调整规律，是高混凝土坝坝基真实工作性态研究的基础模型。考虑混凝土非均匀性、地基因素、谷幅变形等效应，揭示了高拱坝强震破损机理，为保障高坝工程抗震安全性提供理论和技术支持。建立了基于真实测量数据的混凝土坝真实性态仿真分析方法，揭示混凝土坝从施工过程到运行期的行为，对保障大坝安全运行有重要意义。提出的水泥基胶凝颗粒料，在土石边坡、土石坝等水工结构的加固和维护、提高结构韧性和安全性方面，有广阔的应用前景。发表学术论文14篇，其中SCI收录论文9篇，授权发明专利1项。获得2016年教育部技术发明奖一等奖1项，2017年四川省科学技术进步奖一等奖1项，2017年中国水力发电工程学会科学技术奖一等奖1项。获2019年中国水力发电学会第七届水工抗震防灾学术交流会优秀论文奖。项目负责人入选中国水利学会青年人才助力计划，北京市优秀人才培养资助计划青年骨干项目。培养毕业博士研究生2人，硕士研究生5人。