Micro piles are essentially small diameter piles that have the ability to be installed in any type of ground. They can be installed quickly in practically any type of environment, particularly in restricted or hard to reach areas with low headroom, becuase of the adaptive drilling equipment. Micro piles do not rely on end-bearing capacity, with design loads as small as three tons and as high as 500 tons.
The successful construction of a micro pile, involves a number of steps:
- Drilling, placing reinforcing steel and grouting, which bonds to the soil.
- One of the latest developments is a system and method, which combines all of these steps in a sigle step installation. This new method uses hollow bars
- The pile integrates completely with the soil. It forms a foundation system of reinforced soil mass, in particular if placed in groups. The piles are drilled-grout-injected in one step, using the hollow bars as drill rods and grouting ducts with disposable special drill bits and rotary drilling methods. The drill bits have jet openings allowing for pressure grout penetration while drilling into the soil. During drill advancement and grout injection through the hollow bars, with the aid of a flushing head, the drill cuttings are continuously flushed by the cement grout. This method has a clear advantage because while the drill hole is stabilized, the ground cannot relax or cave around the drill location the soil around the area is being penetrated by the grout causing it to densify.
- The basic idea is that this method produces a pile with a very high capacity but still can operate in tight areas with limited overhead space. It can operate inside buildings to underpin foundations and even upgrade exisiting foundations. If using helical or push piers does not work because of space lilitations, this new method proves to be very adaptable.
Micro Pile Applications
- Supporting new loads in congested areas
- Seismic Retrofit
- Foundation Repair in confined areas
- Excavation Support in confined areas