During the final grouting of the rear truck park, we started to notice that the 8 foot tall site wall on the east side of the property. The automatic rolling gates ceased to function. The walls had moved considerably. In some places they had dropped up to 10” vertically and laterally up to 8” out of plumb. No wonder that gates quick working! The walls had been repaired by a mason already one time while we were working on the site and since then, the wall was cracking upward.
Once again we, in conjunction with the Geotech on the project, put on our thinking caps to find the best solution. Pre drilling push piles like we had installed on the building itself would not work since the wall itself did not weigh enough to serve as a reaction to drive push piles. In addition we needed to raise the wall, but to bring it back into plumb. We still had the same concrete rubble to a 60 foot depth, however the area was outside of the area that was deep dynamic compacted. This area was contiguous to the compaction grouting.
We decided to install hollow bar micro piles. However we were concerned that the loose concrete rubble would prove to be too loose for thin grout….. it might just run between all the concrete chunks and not form an encasement around the hollow bar. We decided to compaction grout first to densify the soil and rubble. We then followed up with the micro piles that were attached to the footings with Supportworks side loading brackets. We staggered the piles on both sides of the wall without notching the footings to give us maximum leverage to lift one side or the other back into plumb. 97 piles in all.
Complicating this work were the small planters in some areas. We purchased an MME mast from TEI for our Drifter so that the job could be installed with an excavator instead of a skid steer. It proved to be a wonderful $50,000 investment. We already have more jobs that it will be used on!
Click HERE to read the last blog in this series.
Click HERE to return to part VI.
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