Group and network effect in micropile design practice

Facing the difficulties in evaluating the group and network effects for different types of micropiles, soils and site conditions and in the absence of sufficient field data, no specifications have yet been established to take into account the group and network effects which are commonly neglected in micropile design practice. This paper summarizes the micropile state of practice assessment (D. A. Bruce and I. Juran, 1995) conducted for the Federal Highway Administration in order to evaluate current design guidelines, quality control, and construction practices of micropile group systems. Available analysis approaches are presented and evaluated through comparisons with experimental data obtained by different investigators on the engineering behavior of micropile group systems and reticulated micropile networks under different loading conditions. Preliminary conclusions are presented along with proposed design guidelines for micropile group systems.