VISCOSITY EFFECT ON SOIL SETTLEMENTS AND PILE SKIN FRICTION DISTRIBUTION DURING PRIMARY CONSOLIDATION

Abstract

Skin friction distribution occurs due to a relative movement between pile and adjacent soil.Varied factors affecting this movement get the soil to, occasionally, settle more than that of the pile. In thiscase, negative skin friction distributes along some part of the pile's shaft. Primary consolidation begins afterapplying surcharge load on ground surface next to pile’s head - where pressure will be carried by the pore wateruntil the entire excess pore pressure dissipates and shear stressis mobilized. This paper presents a finite elementparametric study to investigate the effect of viscosity on soil settlements and skin friction distribution alongthe pile during primary consolidation. Single pile in clay soil is modelled using FORTRAN in conjunction withtwo different soil constitutive models. On the one hand, numerical modeling has been carried out using theelasto-plastic soil behavior – as defined by Matsui-Abe soil constitutive model. On the other hand, the effectof viscosity has been modeled using the elasto-viscoplastic soil model as defined by Sekiguchi-Ohta model. Aparametric study has been conducted in order to compare the results of the above two soil models to clarify theviscous impact. FORTRAN 2-D analytical model has been validated by comparing numerical results with twofield tests measurements. Viscosity is clearly effective when a specific value of surcharge load is applied.Structural viscosity has increased the soil settlements compared to the other settlements that occurred by usingelasto-plastic soil model – where part of the pile induced by negative skin friction becomes greater.