土石坝隐患的电阻率-磁共振耦合全息成像诊断方法试验研究

Early identification of internal defects and leakage on embankment dams with defects is of great significance to protect the operation safety of the reservoir. According to resistivity test, the anomaly area of resistivity could be inverted to identify the dam leakage risks. This method has advantages such as non-destructive, high-efficiency and economic. However, during the analysis and forecasting process, several key factors restrict the recognition accuracy, which are accurate characterization of the relationship on soil electrical and physical parameters, effective description of the resistivity dynamic response under complex environment or in the whole slope instability process, and inherent deficiency of "non-unique" electrical inversion results. On the basis of our previous work, regarding the in-depth analysis on relationship of the soil resistivity properties and physical and mechanical parameters as the starting point, the dynamic response characteristics of resistivity and damage evolution mechanism during the soil sample destruction process under shear conditions will be revealed, and the resistivity macro conductive structure model based on damage variable will be established. Throughout a full scale test chain, including small-scale laboratory experiments, majority-scale model tests, field validation tests and in situ reservoir test, with comprehensive utilization of resistivity and magnetic resonance imaging, the resistivity-magnetic resonance sounding coupling holographic imaging diagnosis method will be put forward for embankment dam leakage and other risks detection. The proposed method has great value and can provide substantial theoretical basis for safety diagnosis and emergency treatment of important embankment dam.

土石坝工程内部缺陷和渗漏隐患的早期识别对保障水库大坝安全运行具有重要意义。通过电法测试来反演坝体电阻率异常区域，进而识别土坝缺陷及渗漏隐患，具有无损、高效、经济等优点。然而，在其分析预测过程中，如何精确刻画土体电性与物性参数关系、有效描述电阻率在复杂环境或坝坡失稳全过程中动态响应特征以及克服电法反演成果非唯一性的固有缺陷成为制约电法探测精度的关键因素。本课题拟在项目组前期研究成果的基础上，以深入分析土体介质电阻率特性与物理力学特性参数的关系为出发点，揭示剪切条件下土体破坏全过程电阻率动态响应特征与损伤演化机理，构建基于损伤变量的电阻率宏观导电结构模型，通过小尺度室内试验、大比尺模型试验、野外验证试验、原位试验验证等全比尺试验链，综合运用电法与磁共振技术，建立土石坝隐患和渗漏的电阻率-磁共振耦合全息成像诊断方法。该方法可为重要土石坝工程的安全诊断与应急处置提供理论依据，具有较大的应用价值。

土石坝工程内部缺陷和渗漏隐患的早期识别对保障水库大坝安全运行具有重要意义。通过电法测试来反演坝体电阻率异常区域，进而识别土坝缺陷及渗漏隐患，具有无损、高效、经济等优点。然而，在其分析预测过程中，如何精确刻画土体电性与物性参数关系、有效描述电阻率在复杂环境或坝坡失稳全过程中动态响应特征以及克服电法反演成果非唯一性的固有缺陷成为制约电法探测精度的关键因素。本课题在项目组前期研究成果的基础上，以深入分析土体介质电阻率特性与物理力学特性参数的关系为出发点，对土体介质电阻率特性与物理特性参数关系进行了识别，在深入研究可适用于土石坝隐患探测的地面核磁共振法、高密度电法、跨孔电阻率CT法、地质雷达法及面波法的基本原理与测试方法的基础上，提出了一种基于MRS法与高密度电法联合探测堤坝隐患方法，并开展了多匝小尺寸线圈磁共振探测关键参数优化的野外试验研究，将本项目提出的土石坝隐患及渗漏的电阻率-磁共振耦合全息成像诊断方法分别应用于上海东风水库和京杭大运河堤防隐患探测，通过探测全过程及诊断成果分析，对电阻率-磁共振耦合全息成像诊断方法的关键环节和重要参数进行修正完善，验证其探测精度及有效性。本项目建立土石坝隐患和渗漏的电阻率-磁共振耦合全息成像诊断方法可为重要土石坝工程的安全诊断与应急处置提供理论依据，具有较大的应用价值。