Statistical analysis on the relationship between shear strength and water saturation of cohesive soils.

This paper presents a statistical analysis on the relationship between shear strength and water saturation of cohesive soils based on a comprehensive database (labeled as Cohesive Soil/3/2119). In this study, the cohesive soils are categorized into three general types including clay, silty clay, and silt. For each of the three types, the statistical characteristics including mean, standard deviation (SD), coefficient of variation (COV), standard error of mean (SEM), and distribution type of the shear strength parameters at different water saturation intervals are derived. Further, several empirical formulas are proposed for predicting the statistical characteristics of shear strength of cohesive soils as a function of degree of saturation. The empirical formulas and relationships for different soil types are compared. For the three soil types, the decreasing rate of mean cohesion with the increase of water saturation is highest for silt and lowest for clay; however, the decreasing rate for mean friction angle is highest for clay and lowest for silt. The statistics in terms of SD and COV for shear strength versus water saturation are also analyzed. The developed correlations provide useful guidelines in the reliability-based geotechnical design for estimating the statistical characteristics of shear strength of cohesive soils based on the moisture conditions. [ABSTRACT FROM AUTHOR]