Nicholson installed a total of 433 micropiles for new bridge foundations. Due to the voids in the shale and gypsum bedrock formation, 252 of the micropiles were installed using low-mobility grout to protect the structure from future settlement. One of the advantages that low mobility grouted micropiles have over other available foundation systems is their ability to be installed through difficult ground conditions not suitable for other techniques.
Using specialized drilling methods, the drill casing can be advanced through man-made obstructions, cobbles, boulders, and deep into rock formations, which is typical of Western Michigan. Where some projects may require the use of low-mobility grout to fill these voids, micropiles can serve a dual purpose by providing a structural deep foundation element as well as a mechanism for delivering ground treatment.
In addition to the micropiles, 52,000 square feet of vibro-compaction was completed to densify backfill to a depth of 15 feet.
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