This paper introduces a hypothesis to link the soil pore size distribution curve (PSDC) to the bimodal soil–water characteristic curve (SWCC). The relationships between the PSDC and the bimodal SWCC equations are discussed extending a novel modeling method using two equations; namely, the rigid equation and the simplified equation extending two well-known traditional unimodal SWCC equations from the literature. The calibration processes built for both the equations performance was evaluated for various types of soils. The results suggest that both the modified equations provide excellent comparisons with the measured data. The rigid equations provide comprehensive information about the macropores and the micropores of the bimodal SWCC; however, the simplified equations facilitate a flexible and simple curve-fitting process. The relationships between the proposed equations and the available methods for the bimodal SWCC from the literature are also discussed. In addition, a technique is developed based on regression analysis to estimate the key features for bimodal SWCC without bias. Similar to the unimodal SWCC equations the proposed equations are promising tools for predicting the properties of unsaturated soils; they are also valuable for use in numerical techniques for addressing complex nonlinear problems in engineering practice for unsaturated soils.

本文介绍了将土壤孔径分布曲线 (PSDC) 与双峰土壤-水特征曲线 (SWCC) 联系起来的假设。讨论了 PSDC 和双峰 SWCC 方程之间的关系，使用两个方程扩展了一种新的建模方法；即，刚性方程和简化方程扩展了文献中两个著名的传统单峰 SWCC 方程。针对各种类型的土壤评估了为这两种方程性能建立的校准过程。结果表明，两个修改后的方程都提供了与测量数据的极好比较。刚性方程提供了关于双峰 SWCC 的大孔和微孔的综合信息；然而，简化的方程有助于灵活和简单的曲线拟合过程。还讨论了所提出的方程与文献中双峰 SWCC 的可用方法之间的关系。此外，还开发了一种基于回归分析的技术，可以无偏差地估计双峰 SWCC 的关键特征。与单峰 SWCC 方程相似，所提出的方程是预测非饱和土特性的有前途的工具；它们对于解决非饱和土工程实践中复杂非线性问题的数值技术也很有价值。与单峰 SWCC 方程相似，所提出的方程是预测非饱和土特性的有前途的工具；它们对于解决非饱和土工程实践中复杂非线性问题的数值技术也很有价值。与单峰 SWCC 方程相似，所提出的方程是预测非饱和土特性的有前途的工具；它们对于解决非饱和土工程实践中复杂非线性问题的数值技术也很有价值。