库水涨落区全强风化岩水-力-损伤耦合特性与岸坡失稳机制

The mechanical behavior and the mechanism of completely/highly weathered rock bank slopes in the reservoir level fluctuation zone in high dam engineering, is a key issue that needs to be addressed urgently in the areas of disaster prevention and mitigation for bank slopes, and is also a fundamental subject in the field of rock mechanics. By laboratory tests, theoretical analysis and numerical simulation, the project intends to give an insight into the dilatant damage, time-dependent mechanical behavior and saturated/unsaturated flow for the completely/highly weathered rock masses under the condition of drying-wetting cycles. A mesomechanical creep damage model will be presented with the consideration of the effect of drying-wetting cycles, and the saturated/unsaturated hydraulic conductivity model and a water retention curve model will also be presented to account for the effects of creep damage, which can be able to capture the evolution of dilatant damage of completely/highly weathered rock masses and its induced the change in the properties of saturated/unsaturated conductivity and water retention from the aspect of meso-structure. Then, a mathematical model and a numerical method for coupled hydro-mechanical-damage processes for the completely/highly weathered rock masses will be formulated. Finally, the coupled hydro-mechanical-damage processes under the condition of reservoir level periodic fluctuation will be simulated to capture the time-dependent mechanical behavior and instability of completely/highly weathered rock bank slopes, and the critical criterion for the instability of bank slopes will be further proposed. This study will provide an important theoretical contribution to the issue of coupled hydro-mechanical-damage behaviors for the completely/highly weathered rock masses, and also provide important actual application value for disaster prevention and mitigation of bank slopes in high hydropower engineering in China.

高坝工程库水涨落区全强风化岩岸坡的变形特性与失稳机制是库岸边坡灾害防治迫切需要解决的关键问题，也是岩石力学领域的重要基础性研究课题。本项目以库水涨落区全强风化岩为研究对象，采用试验、理论分析和数值模拟相结合的方法，开展干湿循环条件下全强风化岩的损伤扩容机理、时效变形特性及饱和/非饱和渗流规律研究，建立反映干湿循环作用的全强风化岩细观力学蠕变损伤模型，提出考虑蠕变损伤效应的全强风化岩饱和/非饱和渗透特性与土水特性演化模型，揭示全强风化岩蠕变损伤及其诱发的渗透特性与土水特性演化的细观机制，建立全强风化岩水-力-损伤耦合数学模型与数值模拟方法，揭示库水循环涨落区全强风化岩岸坡时效变形特征与失稳机制，提出库水周期性涨落条件下全强风化岩岸坡失稳的临界判别准则。研究成果对于深化全强风化岩水-力-损伤耦合机理研究具有重要理论意义，对于我国大型水电工程库岸边坡灾害防治具有重要应用价值。

紧密围绕库水涨落区全强风化岩的水-力-损伤耦合特性和岸坡失稳机制等关键科学问题，开展了损伤过程中的时效变形特性、饱和/非饱和渗透特性和土水特性的演化规律，建立了全强风化岩水-力全耦合本构模型，发展了全强风化岩水-力耦合数学模型与数值模拟方法，研究了库水涨落下全强风化岩岸坡时效变形规律、潜在破坏模式与失稳机制。经过三年的，取得了如下成果：. (1) 建立水-力-损伤耦合条件下全强风化岩非饱和渗透特性演化细观模型，揭示了全强风化岩细观结构演化对其宏观渗透特性的影响。渗透特性模型不仅形式简单，而且预测精度比以往经典模型有大幅提高。. (2) 建立了全强风化岩水-力全耦合本构模型，全面揭示了全强风化岩非线性变形和毛细滞回的双向耦合机制，进而深刻揭示了库水涨落条件下全强风化岩的变形机制及其对渗透特性影响机制。. (3) 基于抛物型变分不等式方法和数学证明，提出了能够同时考虑库水涨落、降雨/蒸发、饱和溢出和非饱和溢出的非饱和渗流分析统一边界条件，为全强风化岩的水-力-损伤耦合的数值模拟奠定了基础。. (4) 建立了全强风化岩水-力耦合分析模型与数值模拟方法，发展了弹塑性变形与毛细滞回全耦合本构积分的折返-映射算法，研发了全强风化岩固水气三相全耦合分析软件(F2Mus3D)。. (5) 开展了库水涨落和暴雨条件下全强风化岩岸坡的水力耦合分析，研究了毛细滞回效应对水力耦合过程的影响，揭示了库水和降雨条件下全强风化岩岸坡的渐进破坏机制。. 在本项目资助下，共发表学术论文12篇，其中SCI收录论文11篇，EI收录论文1篇；获教育部科技进步一等奖1项(排名第四)；入选武汉大学珞珈青年学者；培养硕士研究生2名(在读)，协助培养博士研究生4名(3名已毕业)、硕士研究生1名(已毕业)；出国交流访问4次。