Drilled micropiles are small-diameter, deep foundation elements that allow structural loads to be transferred through unsuitable bearing strata (e.g., fill and organic soils) into more desirable geotechnical strata. Designed as frictional elements (rather than end-bearing), micropiles obtain their capacity through side friction developed between the pile’s grout column and the surrounding soils and/or rock. Micropiles are generally 5 to 12 inches in diameter and can achieve capacities in excess of 300 tons within bedrock. While these elements are largely utilized in compression, they can also be used in a tension application, or a combination of both.
Drilled micropiles are utilized in situations where conventional spread footing and/or driven pile foundation systems are either impractical or infeasible. These versatile deep foundation elements are frequently used in low headroom situations, in areas of tight access, and in vibration-sensitive environments. Micropiles also beneficial where the presence of obstructions and/or rock make the use of driven piles cost-prohibitive. They can be utilized for new construction as well as rehabilitation of old foundations, and are also used in different earth support and underpinning applications.
In addition to micropile design and installation, Phoenix’s staff is also very experienced in micropile testing. Phoenix owns a variety of testing frames which enable us to perform pile testing on a wide range of pile types and capacities, and our experienced crews know how to safety and correctly execute a load test from start to finish. Finally, our ability to generate complete and timely load test reports in real time (often before leaving the site!) helps expedite the project’s schedule by minimizing submission and review time.
Typical Applications for Drilled Micropiles
Retrofit of Existing Structures