Development of a Constitutive Model for Clays Based on Disturbed State Concept and Its Application to Simulate Pile Installation and Setup

Abstract

In this paper, an elastoplastic model is proposed to describe the behavior of clayey soils subject to disturbance at the soil-structure interaction for application to pile installation and the following setup. The soil remolding that occurs during deep penetration and the following soils thixotropic strength regaining over time were modeled in this study. The disturbed state concept (DSC) was used as a core of the proposed model, and the critical state theory was adopted to define the main components for the DSC model. The Modified Cam-Clay (MCC) model was implemented within the context of DSC to define the intact state response. A novel approach was applied to define the soil shear response for the MCC model to have it applicable in DSC. Furthermore, the soil remolding during shear loading was related to the deviatoric plastic strain developed in the soil body. The proposed model, referred as Critical State and Disturbed State Concept (CSDSC) model, can capture the elastoplastic behavior of both NC and OC soils. The proposed model was implemented in Abaqus software, and it was then validated using the triaxial test results available in the literatures. Very good agreement was obtained between the triaxial test results and the CSDSC model prediction for different stress paths, stress-strain response and the generated excess porewater pressures. Furthermore, pile installation and the following pile setup behavior were modeled using the proposed CSDSC model. The predicted values for pile resistance using CSDSC model were compared with the values measured from field load tests, which indicated that the proposed model is capable of simulating pile installation and predict appropriately the pile capacity as well as the disturbance behavior at the soil body.