Tensile Strength Framework for Unsaturated Coarse- and Fine-Grained Soils

The tensile strength of unsaturated soils is essential to assess the safety and reliability of earthen structures over a prolonged period. This specific property of unsaturated soils plays a significant role in desiccation cracking and tensile failure of earth structures. The tensile strength of unsaturated soils can be measured through various direct and indirect testing methods in the laboratory and through different models available in the literature. These models can rapidly predict the tensile strength of unsaturated soils over a wide suction range. However, a practical framework to capture the tensile strength behavior with variations in soil type, tensile strength testing methodologies, and sample preparation methodologies has not been probed. In the present study, a novel tensile strength framework for both coarse- and fine-grained soils is proposed to determine the tensile strength characteristic curve (TSCC) over the entire saturation range from the respective soil water retention curves. A critical assessment of the variation of the parameters for the TSCC model for various types of soils, tensile strength testing methods, and sample preparation methodologies was also performed in this study. Further, the proposed framework was validated with several experimental data sets available in the literature for both coarse- and fine-grained soils. A good agreement was found between the experimental data and predicted results in most cases, with variation in soil type, sample preparation, and testing method. Therefore, the proposed model can be effectively used to determine the tensile strength of unsaturated coarse- and fine-grained soils over the entire saturation range and can be widely utilized for various engineering assessments in real-field situations.