Micropiles, also called mini piles, are often used for underpinning. They are also used to create foundations for a variety of project types, including highway, bridge and transmission tower projects. They are especially useful at sites with difficult or restricted access, or with environmental sensitivity. Micropiles are made of hollow bars or steel rebars with diameters of 60 to 200 mm. Installation of micropiles through top soil, sand and cobblestones overburden and into soil rock can be achieved using Air Rotary or Mud Rotary drilling, impact driving, jacking, vibrating or screwing machinery.
Advantages of Hollow Bar Micropiles
Fast one-step installation
Simultaneous drilling and grouting
Allows the use of smaller equipment at lower cost
Allows low overhead, limited access installation
Improves the ground (densification)
Offers higher skin friction
Where can a micropile be utilised?
Micropiles have the advantage of quick construction, small-sized equipment required and economy, etc. It can be used in every kind of construction in basic foundation, retaining wall and water-proof wall. The unique characteristics of micropiles and the equipment that installs them means there is more flexibility than all other type of foundation system. Micropiles can be installed in all conventional applications in addition to numerous other locations where conventional equipment would make the project impossible, some of these are;
Limited access situations
Difficult access situations
Environmentally sensitive projects
Resisting Uplift and Dynamic Loads
Upgrading or increasing the capacity of existing foundations
Structures affected by adjacent excavation, tunneling or dewatering activities
Slope stabilisation and land/rock falls
To provide a fast, effective alternative to more traditional methods
Are micropiles suitable for all geotechnical conditions?
Micropiles can be utilized in more geotechnical conditions than any other type of pile. This can achieved through the application of different drill bits for different soil or rock profiles that are encountered. If the geotechnical conditions vary from conditions anticipated via testing, you just need to change the drill bit, not the installation procedure or design ensuring the project maintains momentum.