Investigation of the time-dependent bearing capacity of a jacked pile in saturated structured clays

Abstract

Natural clay setup significantly contributes to the improvement of the bearing performance of a jacked pile. This paper presents a semianalytical solution to predict the time-dependent bearing capacity of a single pile in natural clays. The proposed solution properly incorporates the initial structure and stress-induced structure degradation of soils and the subsequent thixotropic and reconsolidation of disturbed soils. Pile penetration is simulated using the cavity expansion method (CEM) based on the Modified Structured Cam Clay (MSCC) model. The governing equations computing stress components during consolidation are established using a variable relaxation gradient function and are numerically solved by combining initial boundary conditions. A functional relationship between the ultimate strength and stress state of soils is presented according to critical state soil mechanics theory. The predicted results are validated against the results from the existing analytical approach, published centrifuge model tests, and laboratory model tests in structured clays. The excellent agreement between the measured and predicted values demonstrates that the method can properly predict the time-dependent bearing capacity of jacked piles in structured clays. Considering the impact of soil structure on soil setup plays a significant role in quantitatively evaluating the time-dependent bearing capacity of piles in natural clays.