Study on the geometry and spatial distribution characteristics of physical and mechanical indexes of soft clay

The engineering characteristics of soft clay vary depending on its formation conditions and geological evolution. This study explored the empirical relationships and parameter predictions among indexes of the physical and mechanical properties of soft clay based on its geological origin, sedimentary characteristics, and distribution. In combination with statistical theory, the distribution characteristics and rules of the physical and mechanical properties indexes of soft clay were discussed and the correlation between each index was investigated. Results revealed reasonably small variability of certain physical indexes, such as density, specific gravity, plastic limit, and liquid limit, whereas the coefficient of variation of mechanical indexes was large. The minimum (maximum) values of physical (mechanical) indexes were observed in fluvial and lacustrine sedimentary soft clay or urban dredging soft clay, whereas the maximum (minimum) values were mostly observed in marine sedimentary soft clay. The physical and mechanical indexes of soft clay exhibit reasonable correlation and unknown parameters can easily be estimated using linear regression. However, the direct shear test was affected by the material’s regional characteristics; thus, mechanical indexes with poor correlation should be regarded as independent random variables for the parameter prediction. These findings improve understanding of the application of soft clay in engineering.