Xu, H.; Cai, L.; Shao, Z.; Wang, Z.; Li, Z., and Huang, C., 2021. Prediction of shear strength of fully weathered coastal red sandstone: Influence of water content, fine content, and relative compaction. Journal of Coastal Research, 37(4), 827–841. Coconut Creek (Florida), ISSN 0749-0208.

Shear strength of coastal rock mass can be characterized by parameters such as cohesion and internal friction angle, which are relatively difficult to measure with accuracy on coastal engineering sites. This paper aims to predict shear strength of fully weathered coastal red sandstone with physical property parameters—water content, fine content, and relative compaction—that are easily measured on site. The variation of shear strength parameters with physical property parameters was obtained with indoor direct shear tests, and the real-time prediction of shear strength of fully weathered coastal red sandstone was realized by employing a decision tree model. The results show that the variation of shear strength parameters with physical properties can be accurately characterized by cubic polynomials and that the cohesion and internal friction angle can be well predicted by a 10-layer decision tree model with high accuracy. This study sheds light on the variation of shear strength of fully weathered coastal red sandstone and similar rock mass with physical properties and has practical significance for engineering conducted in such strata, which require in-time monitoring of shear strength of rock mass.