A micropile is a small diameter (<300mm) friction pile that is bored or drilled and can be installed at an angle to accommodate axial and lateral loads. They are connected via couplings to achieve the desired pile length, which can vary from 6 to 20m depending on soil/rock type and strength. Once installed, central reinforcement bar and cementitious grout allow for load transfer into the bearing soil or rock.
For subsea applications, a robotic seabed drill is used to install and grout micropile anchor foundations. Mimicking the root piles of trees, the group response of multiple piles represents a highly efficient distributed anchor solution, capable of withstanding large loads.
First use of micropiles dates back to the early 1950’s in Italy, where new methods of underpinning were needed to restore historic monuments and structures damaged during the 2nd World War. Dr. Fernando Lizzi is commonly recognized as the inventor of micropiles in the form of the tree root pile or “palo-radice”. Inspired by nature, his aim was to mimic the ability of tree root structures to modify the engineering properties of soil with great efficiency.
Micropiles have grown to become the dominant foundation and anchor solution for onshore infrastructure and are widely specified throughout the construction industry today.
Background image: Tower of Burano / Il Campanile Storto (Venice) supported by reticulated micropile structure.
For subsea applications, a robotic seabed drill is used to install and grout micropile anchor foundations. Mimicking the root piles of trees, the group response of multiple piles represents a highly efficient distributed anchor solution, capable of withstanding significant axial and horizontal loads.
Under its Ocean Thermal Energy Conversion program, Lockheed Martin first led research for the adaptation of terrestrial micropiles to the marine environment, using remote seabed drilling and grouting systems. Similar to challenges in the offshore industry today, the primary research objective was to explore alternative approaches to anchoring large floating platforms in deep water with extreme seabed topographies.
Research and development has been carried out to advance designs and key operational concepts to include testing of optimal grout formulations and injection systems.
The development of robotic seabed drilling systems over the past decade represent a key enabling technology which supports the installation of micropiled anchors and foundations.
Subsea Micropiles is working with clients, leading research institutions and class bodies to advance design concepts and demonstrate the first commercial applications of micropile technology in the offshore environment.