The construction industry has the capacity to turn out products that solve specific construction challenges. And micropile is no exception. Micropiles are piles that are between 100 to 300 mm in diameter. They are some time known as mini piles. But unlike other mini piles, the installation of micropile involved drilling a hole into the ground using specialized machines. They are normally reinforced with steel reinforcement and the drilled pile is grouted with cement mixture.
Micro piles are used in many areas. but primary they are used in foundations for many types of structures. They are also used in soil stabilization in stabilizing hill sites rocky in nature. Micropile is used in underpinning work too. This is where existing foundation need to be strengthened for building renovation or to arrest building settlement problems.
As micropiles are much smaller compared to bored piles, the installation equipment will be smaller compared to bored piles and most micropile installation machines can customized to the specific site working conditions eg limited head rooms and confined working space.
The drilling of micropile can make use of rotary drilling in normal soil and to pneumatic hammers in rocky conditions. Thus this make the use of micropiles advantages in rocky areas compared to bored piles where the augers are unable to drill through rocks.
As micropiles equipment are much smaller than bored piles and other heavy foundation equipment, the cost of mobilization of micropiling equipment is cheaper. They (micropiles) equipment are more maneuverable too. Thus they make the prefer choices of foundation works for areas that are hard to reach or off roads sites.
Then when it comes to installation works, the number of supporting equipment is less too. Drilling will includes a minimum of 1 rig operator and 2 helpers. The drilling rig has build in capacity to raise and lower the drilling rods and as well the steel reinforcement if so required. Grouting mix can be done on site and once mixed can be pumped directly into the drilled micropile holes.
The picture below shows a completed group of micropiles with the reinforcement exposed. They do look like mini bored piles isn’t.
A Group of Micropiles
The picture shows a group of micropiles that had been exposed and the cement grout above ground removed to exposed the reinforcement bars. Most likely this is to get this group of micropiles ready for the pilecap works.