堤坝混凝土防渗墙渗透溶蚀演化规律研究  

Evolution law of leakage dissolution of concrete cutoff wall of embankments

作　　者：甘磊[1] 陈官运 沈振中[1] 徐力群[1] GAN Lei;CHEN Guanyun;SHEN Zhenzhong;XU Liqun(College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing 210098,China)

机构地区：[1]河海大学水利水电学院,江苏南京210098

出　　处：《水利学报》2022年第8期939-948,共10页Journal of Hydraulic Engineering

基　　金：国家自然科学基金项目(52179130,51609073);江苏省自然科学基金项目(BK20201312);水利部堤防安全与病害防治工程技术研究中心项目(DFZX2020003)。

摘　　要：混凝土防渗墙是堤坝常用防渗结构,其渗透溶蚀不同于一般接触溶蚀,对防渗墙长效特性及使用寿命影响很大。依据流体动力学、对流-扩散方程及化学动力学相关理论,考虑孔隙、骨料和对流对钙离子扩散系数的影响,本文建立了混凝土防渗墙渗流-溶蚀耦合分析模型。结合混凝土钙溶蚀试验验证模型的合理性,采用COMSOL Multiphysics软件建立某堤坝渗透溶蚀计算模型,研究了混凝土防渗墙中钙离子析出对其孔隙率及渗流特性的影响,估算混凝土防渗墙使用年限。结果表明:该模型能较好地反映防渗墙溶蚀过程中孔隙率和渗流特性的变化,可预测防渗墙防渗性能衰减过程;防渗墙中钙离子浓度年平均变化速率约为0.03 mol/(m^(3)·a),运行100年后混凝土防渗墙孔隙率约为0.33,渗透系数增大35倍,堤坝单宽渗流量增大50%;混凝土防渗墙使用年限为44.0年。研究成果可为堤坝工程长效服役性能评估提供理论支撑。Concrete cutoff wall is a common impermeable structure of embankment.Its leakage dissolution process is different from the general contact dissolution, which has a significant influence on the long-term characteristics and service life of concrete cutoff wall.The leakage dissolution coupling model of concrete cutoff wall was proposed based on fluid dynamics, convection-diffusion equation and chemical dynamics theories, considering the influence of porosity, aggregate and convection on diffusion coefficient.The rationality of the model was verified by the results of concrete corrosion test.COMSOL Multiphysics software was used to establish the seepage dissolution calculation model of an embankment, and the influence of calcium ion leaching on the porosity and seepage characteristics of concrete cutoff wall was studied.Then, the service life of concrete cutoff wall of the embankment was proposed.The results show that the model can reflect the changes of porosity and seepage characteristics during the dissolution process of the cutoff wall.The proposed model can also be used to predict the attenuation process of the impermeability of the cutoff wall.The annual average change rate of calcium ion concentration in the cutoff wall was about 0.03 mol/(m^(3)·a).The porosity of the concrete cutoff wall was about 0.33 after 100 years of dissolution.Compared with the initial time, the permeability coefficient of the cutoff wall increased by about 35 times, and the unit discharge of the dam body and dam foundation increased by 0.5 times.The service life of concrete cutoff wall was 44 years.The research results can provide theoretical support for long-term service performance evaluation of dam engineering.

关 键 词：堤坝 混凝土防渗墙 渗透溶蚀 防渗性能 使用年限 

分 类 号：TU502[建筑科学—建筑技术科学]