Analytical solution for micropile design under tension and compression

摘要

Micropiles are being increasingly utilized in foundation rehabilitation and seismic retrofitting projects. The function of the micropiles in these projects is to enhance the foundation ultimate capacity as well as reduce foundation deflection. This paper focuses on an analytical model for micropile load-displacement behavior subjected to compressive as well as tensile loading. The soil-micropile interaction is considered explicitly in the model development. Furthermore, to keep the model simple and accessible to designers, the micropile-soil interface is assumed to be linearly elastic-perfectly plastic and homogeneous with depth. Closed form expressions of micropile deformation as a function of applied load are presented. These expressions are used to study the effect of model parameters on micropile yield behavior. Micropile strain distribution and the load transfer behavior calculated by the model are discussed. The model calculations are compared with the field measured load-displacement curves. The measured micropile load-displacement data available in the literature are analyzed to evaluate the model parameters.