Analysis of Shaft Resistance Setup of Driven Piles in Soft Sensitive Clays Considering Soil Consolidation and Creep
Liang Li, Jingpei Li
Abstract
Soft sensitive clays around a pile shaft experience destructuration during pile installation, excess pore pressure (u) dissipation, and creep after pile installation, but their influence on pile shaft resistance is difficult to assess quantitatively. This paper will present a semianalytical approach to evaluate the shaft resistance setup by considering soil destructuration, consolidation, and creep. Pile installation effects will be captured using the cavity expansion method. The dissipation of u will be modeled using linear radial consolidation theory, and the corresponding radial effective stress increase will be estimated by considering the stress relaxation effects. The changes in soil state after installation will be obtained by solving a system of ordinary differential equations with the initial conditions representing the pile installation effects. The limiting skin friction (τf,i) will be calculated by applying an interface reduction factor to the ultimate shear stress under simple shear conditions. Analysis of the results shows that the shaft resistance increases rapidly during the first few days after installation and continues to increase approximately linearly with the logarithm of time (t) after pore pressure equalization. The initial bonding (χ0) and overconsolidation ratio (OCR) have a marked influence on the time-dependent shaft resistance.