Le 11 mars 2016, 09:38 dans Humeurs • 0
Micropiles systems are preferred supports to stabilize buildings, bridges, highways, towers, other man-made structures and are excellent for underpinnings that are constructed using geotechnical techniques and conventional materials. The names micropile or minipile depict their sizes, i.e., 6"-12" mini, 2"-5" micro. Minipile installations are installed by using drilling and grouting technology. Micro and mini installations can also penetrate to hundreds of feet in depth; each of the piles can support hundreds of tons.
A micropile may be reinforced with large-diameter, threaded bar (75K) to attain the correct design load capacity. Support piles (both mini and micro) are often installed rather than "H" piles because of overhead physical constraints. Rembco uses micropiles (minipiles) as an economical alternative to large diameter drilled shaft foundations, especially in difficult ground conditions, karst geology, or restricted access situations. Construction can be in close quarters under restricted headroom by using simultaneous insertion of casing and drill rod, short casing leng
Micro pile systems 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.