Foundation Below Sea Level in Karaköy: Eren Holding Office Building

Project summary

For Eren Holding’s office building in Karaköy, we carried out the excavation support and ground improvement works for the main contractor Sam İnşaat. The plot was right on the waterfront and the foundation level was about 4 m below sea level.

We formed the retaining wall around the excavation with 100 secant bored piles of Ø65 cm. Below the foundation, 800 tangent jet grout columns of Ø80 and Ø100 cm created a base sealed against groundwater and improved the ground.

Challenge: a foundation below sea level

Because the foundation level was about 4 m below sea level, we carried out jet grouting from the surface before excavation, forming the columns only within the target depth below the foundation and drilling empty through the ground above. When the excavation was opened, the ground below the foundation was already sealed and the formation stayed dry.

Challenge: narrow streets and limited working hours

The streets leading to the site were narrow, so work was only possible between 10:00 and 17:00, which reduced daily output. We planned the concrete pours with the necessary permits and, thanks to our crew’s dedication, delivered on schedule.

Outcome

The client thanked us in person. The diaphragm wall crew that came on site after us broke through the jet grout columns to build their wall, and their foreman’s words were the best feedback we could get:

“I have been doing this for a long time and have never seen such good jet grouting. After this jet grout work our job was very easy.”

Foreman of the diaphragm wall crew that followed us, translated from Turkish

We worked with the main contractor Sam İnşaat as true solution partners on this project.