| 张文兵,李青铭,李明超,沈振中,甘磊,史旦达.考虑渗流溶蚀耦合效应的土石坝防渗墙长期服役性能研究[J].水利学报,2025,56(10):1314-1325 |
| 考虑渗流溶蚀耦合效应的土石坝防渗墙长期服役性能研究 |
| Study on the long-term service performance of anti-seepage walls of earth-rock dams under coupled effect of seepage and calcium leaching |
| 投稿时间：2024-08-05 修订日期：2025-10-17 |
| DOI：10.13243/j.cnki.slxb.20240501 |
| 中文关键词: 土石坝 混凝土防渗墙 渗透溶蚀 水力梯度 安全服役年限 |
| 英文关键词: earth-rock dam concrete cutoff wall seepage dissolution hydraulic gradient safe service life |
| 基金项目:国家自然科学基金项目（52409162，52571297）；上海市“科技创新行动计划”启明星项目（扬帆专项）（23YF141600）；上海市自然科学基金项目（24ZR1427900） |
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| 中文摘要: |
| 土石坝混凝土防渗墙服役过程中常受到渗透溶蚀的影响，易诱发结构性能退化并导致防渗系统失效和坝基渗透破坏等问题。本文在饱和-非饱和渗流及传统接触溶蚀理论的基础上，考虑渗流作用对混凝土内固相钙非平衡分解过程的影响，建立了针对土石坝防渗墙性能劣化分析的新渗流-溶蚀耦合模型，并通过室内渗透溶蚀试验验证了该模型的合理性。本文以某土石坝工程为例，研究了土石坝防渗墙长期服役过程中的渗透溶蚀演化特征，分析并揭示了渗透溶蚀过程中混凝土防渗墙的性能演化规律，提出了以临界水力梯度作为新的判别标准，用于估算混凝土防渗墙安全服役年限的方法。研究结果表明，防渗墙混凝土的钙溶蚀主要发生在上游迎水面、绕渗部位以及相邻土层分界高程位置；渗透溶蚀过程中，混凝土防渗墙固相钙的溶出量、平均孔隙率、扩散系数和渗透系数均随时间增加呈指数型增长，防渗性能逐渐削弱；对于完全渗透溶蚀的混凝土防渗墙，较其初始平均孔隙率增长约7倍，较其初始平均渗透系数与扩散系数增加约2~3个数量级。大坝服役过程中，渗流溶蚀耦合效应会导致混凝土防渗墙内水力梯度逐渐增大，采用临界水力梯度判别法能够较为准确地估算出土石坝防渗墙的安全服役年限。 |
| 英文摘要: |
| In the course of service，concrete cutoff walls in earth-rock dams are often affected by seepage dissolution，which can lead to structural performance degradation，failure of the anti-seepage system，and seepage-related damage to the dam foundation. This study presents a new coupled seepage-dissolution model for analyzing the perfor-mance deterioration of the anti-seepage walls in earth-rock dams. The model is developed based on the theories of saturated-unsaturated seepage and conventional calcium leaching，taking into account the effect of seepage on the non-equilibrium dissolution of solid-phase calcium within the concrete. The model's validity is verified through laboratory seepage-dissolution tests. The long-term seepage-dissolution evolution characteristics of the anti-seepage walls in a specific earth-rock dam project are investigated. The performance evolution of the anti-seepage walls during the seepage-dissolution process is analyzed，revealing the degradation patterns. A new criterion based on the critical hydraulic gradient is proposed to estimate the safe service life of the concrete cutoff wall. The results show that calcium leaching from the anti-seepage wall mainly occurs at the upstream water-facing surface，at the locations of seepage bypasses，and at the interface between adjacent soil layers. During the seepage-dissolution process，the leaching of solid-phase calcium，the average porosity，the diffusion coefficient，and the permeability coefficient all increase exponentially over time，leading to a gradual weakening of impermeability. For a completely dissolved concrete cutoff wall，the porosity increases by approximately sevenfold，while the permeability and diffusion coefficients increase by about 2-3 orders of magnitude. Throughout the dam's service life，the coupled effects of seepage and dissolution result in an increasing hydraulic gradient within the anti-seepage wall. The critical hydraulic gradient-based method provides a reliable estimate of the safe service life of the concrete cutoff wall. |
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