Prediction of the in-situ state of stress in soil is one of the important parameters in a wide variety of geotechnical problems. Values of K_0 are used to evaluate lateral thrusts against earth retaining structures, and to predict the vertical and horizontal deformations for foundations. The typical strength-deformation characteristics of a soil, specially of an overconsolidated soil, cannot be evaluated unless the in-situ stresses are known. Simple empirical methods for evaluating the value of K_0 for normally consolidated and overconsolidated soils are presented for practical use. Welldocumented test data for soils from the geotechnical literature world-wide are the basis of this regression analysis study. The validity of the proposed methods is supported by comparison with previous work. On the basis of the results, only the plasticity index and prior stress history are needed to predict the value of K_0. Evaluation based on the critical state concept of Modified Cam Clay Model is also investigated and compared with experimental data.
Although the proposed equations for the derivation of K_0 presented may not be perfect, they are convenient used for a preliminary work in practice.