Analysis of Load Tests on Instrumented Steel Test Piles in Compressible Silty Soil

Abstract

Axial compression and tension tests were performed on two end-bearing piles (one pipe and one H-pile) and two friction piles (one pipe and one H-pile) 3 months after they were driven through a granular test fill into compressible clayey silts. In analyzing the behavior of the piles, skin friction equations were developed based upon effective stresses in the soil, the soil-pile friction factor and the Poisson's ratio of the pile. These equations satisfactorily estimated the distribution of negative skin friction loads mobilized on the piles before they were test loaded and the skin friction mobilized in the axial compression and tension pile tests at failure. The equations were also applied to some well-documented pile tests, and showed that the skin friction that can be mobilized to resist axial compression loading can be estimated from pullout tests. This paper discusses the pile test procedures and the observed relative movements between the pile tips and the surrounding soil at various loads applied to the piles and describes a laboratory test method for measuring the coefficient of friction between the pile and the soil.