Introdution
Micropiles, sometime are called as minipiles, anchor piles or root piles, are widely used in foundations constructions.
Especially for underpinning or emergency repairs, it is an effective method to provide reinforcement.
Micropiles normally consist of high-strength, small-diameter threaded steel bar. After the injection of cement, micropiles can supply 1,000 tons strength and more.Meanwhile, the rough and profiled surface of the grout anchor bar also transfer tension loads to the deep ground.
Larger diameters of all thread solid rebar are most popular in the applications of micropile reinforcement. Meanwhile, hollow bars are also increasingly used since its rapid installation and adaptability of collapsing soil conditions.
ONTON hollow bar micropiles comply in Europe with DIN 1054:2010-12 (Subsoil-Verification of the safety of earthworks and foundations), Eurocode 2 and EN14199/10080 standards and in America with FHWA-NHI-14-007(2015). The steel material of the hollow bar, as well as the thread deformations comply with ASTM F432 and A615.
Basic Technique of Hollow Bar Micropiles
The piles are formed from a fully threaded steel bar with a hollow core which is drilled and simultaneously grouted into soils without a casing, typically employing rotary percussive skills.
How to Install Micropile
The installation procedure for mircropile is similar to bored piling it’s using drilling method.
- Drilling and Flushing
- Withdrawing Drilling String
- Inserting Steel Reinforcement and Grouting
- Completed Micropile
- Reinforcement Result Test
Advantages
- Small lightweight equipment
- Low noise and vibration
- Suitable for tension loads
- Minimal site preparation
- Rapid & efficient installation, high output
- High capacity capabilities in limited access areas
- Works in all soil types, ideal for collapsible soils
- Cased or uncased
