Micropiles technique is used in vertical or inclined drilling having a diameter from 90 mm to 300 mm.
Engineers set up the tubes dimension according to the project, establishing diameter, wall thickness, steel grade, length, type of threading for the junctions and type/number of valves for the injection of cement grout.
The team, after the drilling of the ground, inserts the pipe and injects cement grout to fill the hole. This foundation technology is mainly used in civil constructions (underpinning of existing buildings or new ones in narrow spaces) and roads (foundations of bridges and consolidation of steep terrain).
Micropiles with steel pipe.
– Why micropiles in foundations are used?
The reasons for using pipes in micropiles technique are the following:
1.Eease of junction (with threadings) in order to reach the desired depth;
2. Possibility to use the tube as self-drilling pipe: the pipe is first used as drill pipe and then, once arrived at the desired depth, is left in the hole; the hole is then filled with cement grout and the tube can be used as a definitive reinforcement;
3. Pipe can be valved with button or manchette valves (the pipe itself is used to pump the grout of cement and water) to set up the micropile;
4. Micropiles are used when spaces in the construction site are limited and there is the need of high loads for foundations on loose terrains;
Another advantage of micropile technique is the versatility: micropiles can be used to solve environmental and restoration problems. In case of brackish/acid land and water, galvanized pipes can be used.
The micropiles can be used both in compression than in tension.