A simple 3D elastoplastic constitutive model for overconsolidated soils based on the improved Hvorslev envelope

Abstract

Soils encountered in geotechnical engineering exhibit a certain degree of overconsolidation and are in a three-dimensional (3D) stress state. The overconsolidated ratio (OCR) and the intermediate principal stress play a significant role in the strength and deformation of overconsolidated soils. By considering the variation of the peak stress ratio with OCR, and taking the zero-tension line and the critical state line as asymptotes, a continuous and smooth Hvorslev envelope is deduced to describe the peak strength of overconsolidated soils. Based on the proposed Hvorslev envelope, a simple 3D elastoplastic constitutive model for overconsolidated soils is directly established through the characteristic stress method. The constitutive relation of the proposed model is presented by the calculation of the total strain increment. All material parameters have clear physical meanings and can be determined by conventional laboratory tests. The isotropic compression path, the triaxial drained shearing path with constant p, the triaxial undrained shearing path, and the true triaxial drained shearing path with constant p and θ are adopted to demonstrate the essential features of the proposed model. The effectiveness of the proposed model is confirmed by comparing the experimental data from Lower Cromer till, Kaolin clay, and Fujinomori clay with corresponding model predictions.