HPHA School Street Senior Housing
Soil Nails, Probe & Grouting and Micropile Installations
PROBE & GROUT: Kelikai teamed up with Hawaiian Dredging for the construction of the new HPHA School Street Affordable Senior Housing project on Oahu. This project was multi faceted for us, in that first we were tasked with performing probe and grouting at over 300 locations. When the soils contain voids potentially, geotechnical engineers will call for a plan of drilling 3” probe holes along the footings and/or grade beams, in an effort to search and fill any of those potentially cavities/voids. We will typically drill down anywhere from 10’ to 25’ below the new footing elevation and from there, fill each location with a thick sandy grout in an effort improve the overall subgrade to get ready for the new structure/building.
Here you see the grout tubes placed within each probe hole after drilling has been completed, ready for the grout crew to come and fill up each location. If significant voids are encountered, and holes are not able to be filled up, the geotechnical engineer may add new probe and grout locations around the sensitive or porous zones within the site.
SOIL NAIL INSTALLATIONS: Eighty-seven soil nails were targeted for installation along the perimeter of the project to help stabilize the adjacent slope after excavation was completed.
The first step involved drilling through the soil and weathered rock slope surface with our air powered down the hole hammer system. Down the hole hammers make easy work of most rock types that are encountered here in Hawaii.
From there, the multi-corrosion protection (MCP) reinforcing bar is placed within the hole to the specified depths. The MCP bars not only have an epoxy layer protecting the steel, there is also a cementitous grout layer that is encapsulated by a corrugated PVC plastic sleeve.
The grout is then mixed and pumped into the hole, from the bottom up, to make sure we have flushed out any cuttings or fines from within the drill hole annulus.
MICROPILE INSTALLATIONS: The last phase of the project was to install 7-5/8” diameter micropiles down to the bearing material/rock, to provide a deep foundation system for the project’s tower crane.
