Pressure and suction plate tests are among the most common techniques for determining the soil–water characteristic curve. The required testing period depends on many parameters and equilibrium times may vary from a few minutes to several weeks. This paper presents a numerical evaluation of the equilibrium process, considering the influence of soil type, equipment specifications, the use of thin high air-entry value (HAEV) membranes, and the employment of the interrupted outflow method (IOM). A fully coupled numerical model was developed and verified for the analysis of the conservation and flow of water and air in the specimen-HAEV interface system. Verification and sensitivity analyses showed, however, that the suction and pressure plate tests may be adequately represented using a simplified decoupled version of the full model. The results of the sensitivity analysis showed not only the role of the HAEV interface characteristics, but also the effect of soil type, suction value, suction step magnitude, and the suction path. It was found that the IOM offers greater control over testing times, but may cause undesirable suction reversals within the specimen. Finally, a simple method is presented to estimate the equilibrium times using basic testing parameters.

压力和吸盘测试是确定土壤水特征曲线的最常用技术之一。所需的测试时间取决于许多参数，平衡时间可能从几分钟到几周不等。本文介绍了平衡过程的数值评估，其中考虑了土壤类型，设备规格，薄薄的高空气进入值（HAEV）膜的使用以及采用中断流出法（IOM）的影响。开发并验证了一个完全耦合的数值模型，用于分析样品-HAEV接口系统中水和空气的守恒和流动。验证和灵敏度分析表明，使用完整模型的简化解耦版本可以充分代表吸力和压力板测试。灵敏度分析的结果不仅显示了HAEV界面特性的作用，还显示了土壤类型，吸力值，吸力步幅和吸力路径的影响。已发现，IOM可以更好地控制测试时间，但可能会导致样本内出现不良的吸力反转。最后，提出了一种使用基本测试参数估算平衡时间的简单方法。