Design of Single Piles Using the Mechanics of Unsaturated Soils

Abstract

The load carrying capacity of single piles are commonly estimated using the well known a [1], b [2-3] and l [4] methods. These methods are also used in engineering practice for unsaturated soils even though the a, b and l  methods are based on conventional saturated soil mechanics. In this study, a series of single model pile tests were conducted in a laboratory environment to study the influence of matric suction on the pile shaft capacity in a statically compacted fine-grained soil. The results of the study show that the shaft capacity of single piles is significantly influenced by the contribution of matric suction. Based on the experimental results, the conventional a, b and l methods were modified to estimate the total shaft resistance of piles in unsaturated soils by including the influence of matric suction. The modified methods can also be used for estimating the variation of shaft capacity of single piles with respect to matric suction using the Soil-Water Characteristic Curve (SWCC) and the saturated soil shear strength parameters. The modified a, b and l methods are promising for use in engineering practice to estimate the ultimate shaft bearing capacity of single piles placed in unsaturated soils