Small
diameter drilled and grouted friction piles are Micropiles. 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. These steel piles have
working capacities up to 250 tons.
Usually foundation engineers use micropiles (minipiles) as
an economical alternative to large diameter drilled shaft foundations,
especially in difficult ground conditions, karst geology, or restricted access
situations.
-Drilled into bedrock, micropiles or
minipiles bond to the rock socket wall for load transfer.
-The casings of the minipiles are
advanced as piles are drilled into site's bedrock.-Drill pipe is removed, which leaves casing for mini or micro piles setting in bedrock.
-A reinforcement load bar is lowered into casings of the micro piles, for added capacity.
-Cementitious grout is pumped or
pressure feed into the minipiles casings, bottom up.
-The casings for the micro piles are
lifted
to top of bedrock, allows bonding to the bar.
to top of bedrock, allows bonding to the bar.
-Excess steel is cut from the tops of
micropiles; piles are capped to engineer's design.
-A select number of piles are load tested to prove the engineering load design.
Thanks for this post. I've been looking into micropiles and what they actually are. I've always been interested in things like this and this blog helps me understand it better.
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