The permeability of plasticised polyvinyl chloride (PVC-P) geomembranes (GMBs) is of significant importance to the safe operation of impermeable structures and even entire projects. To avoid the drawbacks of the traditional method of adopting the permeability coefficient to characterise permeability, this paper presents a mathematical model of porosity and seepage discharge based on the results of the vertical permeability test and porosity obtained from low-field nuclear magnetic resonance (NMR) tests. This paper also explores the applicability of porosity to evaluate permeability combined with the dynamic distribution of pores and pore radius. The results show that low-field NMR technology with ¹H (isotope of hydrogen) atoms as the probe can accurately measure the distribution of pores and pore radius in the PVC-P GMB. The proportion of micropores (Mic), mesopores (Mes) and macropores (Mac) and the shrinkage or development of pore radius are primarily responsible for the variation of porosity. Porosity is closely correlated with seepage discharge, and the constructed model can accurately predict seepage discharge. Furthermore, porosity can provide technical support for the evaluation of the permeability of PVC-P GMBs and the selection of appropriate GMBs for engineering design.

中文翻译：

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基于低场核磁共振技术的PVC-P土工膜渗透机理

增塑聚氯乙烯（PVC-P）土工膜（GMB）的渗透性对于防渗结构乃至整个工程的安全运行具有重要意义。为了避免传统采用渗透系数表征渗透率方法的弊端，根据垂直渗透率测试结果和低场核磁共振（NMR）获得的孔隙度，提出了孔隙度和渗流的数学模型。测试。本文还结合孔隙动态分布和孔隙半径探讨了孔隙度评价渗透率的适用性。结果表明，低场核磁共振技术具有¹以H（氢同位素）原子为探针，可以准确测量PVC-P GMB中的孔隙分布和孔隙半径。微孔（Mic）、中孔（Mes）和大孔（Mac）的比例以及孔隙半径的收缩或发展是孔隙率变化的主要原因。孔隙度与渗流流量密切相关，所构建的模型可以准确预测渗流流量。此外，孔隙率还可以为PVC-P GMB的渗透性评价以及工程设计中选择合适的GMB提供技术支持。