Micropiles are a fairly recent innovation. They see application often in limited access situations where large axial capacities are desired but room for large drill rigs is not available. Micropiles are drilled and grouted reinforced piles that are relatively small in diameter. They can be used similar to conventional piles or are often times arranged in systems of reticulated root piles which include multiple vertical and inclined micropiles that interlock to form a composite soil/pile mass.
They can resist both axial and lateral loads and have many applications, such as: foundation support, underpinning, earth retention, seismic retrofitting, slope stabilization, ground strengthening, and settlement reduction. Micropile systems can be more costly but come with many advantages. Since the equipment used in installation is relatively small, they can be installed in places with restricted access and low headroom. They are also useful in difficult geologic conditions such as, high ground water, soft clays, and running sands. Also, the installation causes minimal vibration and noise as compared to other piling techniques.