Effect of moisture on mechanical characteristic of soil and interaction of soil-pile in integral abutment bridges

Mechanical properties of soil are function of many parameters. Moisture content is one of the key factors that impact the soil’s mechanical properties. Soil-pile interaction and pile displacement in bridges can, therefore, be impacted by the moisture content. In particular, pile displacement in Integral Abutment Bridges (IABs) due to daily and seasonal temperature variations is a problem that has been under investigation. IABs don’t have joint and as a result all the load and deformation in the slab is transferred to piles. If piles are deformed beyond their yield point, plastic deformation can occur. The objective of this study is to evaluate the moisture content effect on the interaction of pile and soil and the resulting pile displacement through computational modeling. An ANSYS Finite Element Model (FEM) is used to repeatedly change the moisture content of the soil and adjust the properties and compute the displacement in the piles. It is shown that increasing the moisture content decreases several key parameters such as bulk density, young’s modulus, cohesion and Poisson’s ratio. The simulation results indicate higher displacements of the piles as the moisture content increases. This behavior can be explained by decreased elastic modulus. As a result, soil behaves more flexible and allows more displacement of the pile.