To soil shear strength, plastic limit, liquid limit and the liquidity index of clay soil, undrained triaxial compression test, empirical correlations, and statistical analysis of geotechnical

Soils for engineering use are often classified based on properties relative to foundation support or as they might perform under pavements and in earthworks. Geotechnical classification systems today are designed to make it easy to equate field observations to estimates of engineering properties. As moisture content of a clay-like soil increases, it goes through four distinct states of consistency: solid, semi-solid, plastic, and liquid. Each stage is defined by significant changes in strength, consistency and behaviour. The soil sample used for this project is undisturbed sample obtained from Ikorodu local government area, Ibese Town of Lagos state. Tests carried out in the laboratory on the soil samples include (liquid limit and plastic limit tests), moisture content and Triaxial test to determine the shear strength of the clay sample. Microsoft Excel and SPSS statistical package was used to perform linear and multiple exponential regression to established empirical models between the liquidity index and the shear strength and among the liquidity index, shear strength and angle of internal friction, the coefficient of correlation R was used to determine the quality of the relationships; the higher the value of R, the higher the quality of the relationship among the variables. Regression analysis is as follows: Cu = 72.5LI + 298.3 with R = 0.908 for linear equation, Cu = 319.8e0.158LI with R= 0.908 for linear exponential equation, multiple linear equation gives the value of shear strength as CU = 698.371+ 42.271LI - 5.585Φ, with intercept (c) of 698.371 and the multiple exponential regression equation given by; CU = (6.64407)(0.09110)LI(0.01206)Φ, with intercept (c) of 6.64407 on the y-axis. It was concluded that, the correlation equations obtained as a result of regression analyses are in satisfactory agreement with the test results and recommended that the proposed correlations will be useful for a preliminary design of a project where there is a financial limitation and limited time.