基于低场核磁共振技术面膜堆石坝中PVC膜渗透机理  

Mechanism of PVC Membrane Permeation in Face Rock Fill Dam Based on Low-field NMR Technology

作　　者：徐国雷 张宪雷 马仲阳 XU Guo-lei;ZHANG Xian-lei;MA Zhong-yang(l.School of Water Conservancy,North China University of Water Resources and Electric Power,Zhengzhou 450046,China;Gansu Water Resources and Hydroelectric Investigation and Design and Research Institute Corporation Limited,Lanzhou 730030,China;Engineering Technology Research Center for Safety of Hydro structure in Henan Province,Zhengzhou 450046,China)

机构地区：[1]华北水利水电大学水利学院,河南郑州450045 [2]甘肃省水利水电勘测设计研究院有限责任公司,甘肃兰州730030 [3]河南省水工结构安全工程技术研究中心,河南郑州450046

出　　处：《水电能源科学》2022年第12期138-142,共5页Water Resources and Power

基　　金：国家自然科学基金项目(52009045);河南省科技攻关项目(212102310539)。

摘　　要：为探究渗透压力作用下PVC土工膜内水分的演变规律,开展了不同渗透压力下材料渗透特性试验,利用低场核磁共振技术以~1H为探针分析了渗透压力由1.0 MPa增至1.8 MPa过程中膜内水分相态及其分布特征,构建了渗透压力与低场核磁总信号幅值、渗漏量的关系及核磁总信号幅值与渗漏量的关系曲线。试验结果表明,渗漏量与低场核磁共振测得的首点信号相关性强,低场核磁共振技术成果可支撑PVC膜渗透机理分析;膜内水分含量和微小孔隙在渗透压力不大于1.5 MPa和大于1.7 MPa时,随渗透压力增大而发育,1.6 MPa时出现萎缩。PVC膜内孔径变化与渗透压力和内部微观结构形态有关,可通过改善膜内微观结构形态提高材料防渗性能,研究结果对面膜堆石坝防渗选材具有一定的指导意义。In order to explore the evolution of moisture in PVC geomembrane(GEM)under the action of seepage pressure,an experimental study on the permeability characteristics of materials was carried out under different seepage pressures.The low-field nuclear magnetic resonance technique was used to analyze the seepage pressure from 1.0 to 1.8 MPa as a probe.In the process of pressure growth,the water phase state and its distribution characteristics in the GEM were constructed to establish the relationship between the seepage pressure and the total low-field NMR signal amplitude and leakage,as well as the relationship between the total NMR signal amplitude and the leakage.The test analysis results show that the leakage amount correlated strongly with the first point signal measured by low-field NMR;The low-field NMR technique results can support the analysis of the permeation mechanism of the PVC GEM;The water content and tiny pores within the GEM developed with increasing permeate pressure at permeate pressures not greater than 1.5 MPa and greater than 1.7 MPa,and shrinkage occurred at 1.6 MPa;The change of the pore size of the PVC GEM is related to the seepage pressure and the internal microstructure morphology.The anti-seepage performance of the material can be improved by modifying the microstructure morphology in the membrane.The research results have certain guiding significance for the selection of anti-seepage materials for membrane faced rockfill dam.

关 键 词：PVC土工膜 低场核磁共振技术 渗透机理 微观孔径 

分 类 号：TV52[水利工程—水利水电工程]