超高面板堆石坝面板结构破损发生机制和模拟方法

Along with the acceleration of the Western Development Program in China, a large number of high concrete-faced rockfill dams are either under design or being planned. The engineering experiences of existing projects have shown that the key safety problem of high concrete-faced rockfill dams is the structural damage of the concrete faces.The main content of this project is as follows. Multi-stage loading triaxial creep tests will be performed to study the creep characteristics and calculation models of rockfill under complex loading conditions, the deformation mechanism of dams during the operating period will be revealed by analysing the monitoring data of earth-rockfill dam. Based on the theory of contact mechanics, non-linear numerical algorithms suitable for concrete-faced rockfill dams will be developed to achieve reasonable simulation results of complex contact problems such as large area of void and sliding. The simulation methods and a program system will be developed to consider the structural damage of the concrete faces in high Concrete-Faced rockfill dams. According to the monitoring data of some typical high Concrete-Faced rockfill dam, the structural damage mechanisms of the concrete face and the deformation control standard will be investigated.At present, the construction technologies of Concrete-Faced rockfill dams with the height of 250 meters and above are facing great challenge. The main achievements of this project will contribute to reveal the structural damage mechanisms of the concrete face, optimize the design scheme and evaluate the safety of high Concrete-Faced rockfill dams. Therefore, this project are of great significance in theory and can be widely applied in practice.

随着我国西部水电开发进程的加快，一大批超高面板堆石坝正在规划设计之中。工程经验表明，面板结构性破损问题是影响超高面板堆石坝安全的核心问题。本项目的主要内容包括，进行分级加载三轴流变试验，研究复杂加载条件下堆石体的流变特性和计算模型，结合工程实测成果揭示运行期坝体变形的发展规律。基于接触力学理论，发展适用于面板堆石坝的非线性接触计算方法，能够对包含脱空和大规模滑移等复杂接触状态的接触问题做出合理的模拟。发展超高面板坝面板结构破损数值计算方法及程序系统。结合实际高面板堆石坝工程观测成果，探讨超高面板堆石坝面板结构破损的发生机制和变形控制标准。目前，我国面板堆石坝建设技术正面临向250m级及以上高度跨越发展的挑战。本项目研究成果在揭示超高面板堆石坝面板破损发生机制、优化设计方案及合理评价工程的安全性等方面具有指导作用，具有较大的理论意义和广阔的应用前景。

我国的面板堆石坝建设技术正面临向250m级及以上高度跨越发展的挑战。近年来的工程实践经验表明，面板的挤压破损已经逐渐成为影响高面板堆石坝安全的关键问题。目前，对这种问题发生机理的认识和评价方法研究尚不深入，尤其是还缺乏合理的数值模拟方法。本项目针对复杂加载条件下堆石体的流变特性和计算模型、运行期坝体变形的发展规律、面板坝非线性接触数值模拟方法以及面板挤压破损发生机理等问题开展了深入地研究工作。主要取得了如下的成果：.（1）进行了复杂应力变化情况下堆石料的多级三轴流变试验，发现流变具有硬化特性，提出了一个新的堆石料流变的累积规则，建立了可考虑堆石料应力加载和流变耦合影响的计算模型；.（2）基于计算接触力学方法发展了一套适用于面板堆石坝的非线性接触算法。该算法能够对包含发生脱空和大规模滑移等复杂接触状态的接触问题做出合理的模拟，具有很强的模拟不连续变形现象和处理非协调网格的能力；.（3）构建了一套可进行混凝土面板破损现象模拟的数值计算方法。在该方法中，嵌入了可硬化的弹塑性模型用于模拟面板的压损破坏，发展了弥散固定脆性裂缝模型用于模拟面板的结构性张拉裂缝，引入了组合式模型用于反映钢筋与混凝土间的相互作用；.（4）总结分析了国内外典型超高面板堆石坝工程中发生的面板挤压破损现象及特征，论证了面板纵缝转动接触挤压效应的发生机制，发现转动挤压和轴向挤压均可在纵缝两侧面板表面部位引发严重的应力集中，是导致面板发生挤压破损的本质原因。.本项目的研究工作紧密结合我国高土石坝工程的实际，研究成果已经应用于天生桥一级、水布垭、洪家渡、古水等高面板堆石坝工程以及红石岩堰塞坝和如美心墙堆石坝等重大土石坝工程。