What are Micropiles and Why are They Used?
Micropiles for Foundation Stabilization
There is not one foundation retrofit system that can be claimed to be the best
fit for every project or subsurface condition. Certain soil conditions can hinder installation and even prevent advancement of conventional underpinning solutions. Some of the more challenging soil profiles may include uncontrolled fill with construction debris or other large fractions, cobbles and boulders within native soils, extremely dense soil layers over weaker material, or karstic formations. When such conditions exist, drilled and grouted micropiles offer a cost-effective, deep foundation option capable of penetrating obstructions to bear within competent bedrock. In compression applications, capacity is achieved through end bearing and also skin friction along the interface of the grout column and the bedrock. In tension applications, only the skin friction contributes to the micropile capacity
- What is a micropile?
Micropiles are small diameter drilled and grouted friction piles. Each pile includes steel elements that are bonded into the bearing soil or rock – usually with cement grout. The bearing stratum is logged during installation drilling to assure that bearing capacity is adequate. Micropiles do not rely on end-bearing capacity, so there is no need to establish the competency of rock beyond bond-depth. They can be installed quickly in virtually every type of ground using highly adaptable mobile drilling equipment.
- Advantages of Micropiles:
1. Fast one-step installation
2. Simultaneous drilling and grouting
3. Allows the use of smaller equipment at lower cost
4. Allows low overhead, limited access installation
5. Improves the ground (densification)