Before a house is built, the ground must be secure. 799 stakes secure the Charlottenbogen. Concrete and steel. 14 meters deep. A visit to the construction site.
Tirelessly, like a greedy animal, the drill digs itself into the ground. Despite the impressive large drilling technique, the earth remains remarkably calm. Powerful machines are at work here and yet one can almost talk normally, so low is the noise level of these giants. Drillings pile up around the borehole. Occasionally water swells out of the ground. The drill bit pushes deeper. Five, ten, fourteen meters. Suddenly it stops. For a brief moment it is completely quiet on the Charlottenbogen construction site, on this Wednesday in mid-August 2019. You can hear the nearby Spree River, the horn of a pleasure boat, the laughter of children on the playground.
“What we are doing here is called pile foundation,” Georg Jobs now says. Calm voice, hands on his hips, on his head he wears a white helmet, above his chest an orange high-visibility vest. He is young, 28 years old, but he bears part of the responsibility for the construction phase of the special civil engineering works as young construction manager of the company JACBO Pfahlgründungen GmbH.
“We have to make about 800 and we’re almost finished,” he says. 800 piles, about 14 meters deep, there is also a little pride in his voice as he looks at his men scurrying around the construction site, at the drilling rig and the concrete pumping vehicle. They have already been working on this construction site for almost two months. They have placed the piles close together. They have moved from one corner to the other, every movement was the result of precise planning. A precision job that is monitored by JACBO thanks to digital monitoring in the drilling rig and 4G data transfer from the respective locations. Thus, the production of the piles can be optimally adapted to the ground conditions on site, compliance with quality standards is guaranteed and even documentation of all-important parameters is included.
Because: “On these poles are the houses. Without them, the houses would eventually slide into the Spree,” says Jobs. How many piles must carry which weight, how long and thick the piles have to be – all this was calculated beforehand and tested in very extensive dynamic and static test loads before the start of construction and optimized accordingly.
Jobs is a civil engineer. A year ago he got his master’s degree. Since then he has been working for JACBO on construction sites. “I chose this side,” he says. Being outside, not sitting at a desk. See what happens. Working with the men and always in consultation with the other companies and trades. Standing in the middle of the storm of coordination. “I like that,” he says and pushes his back through.
Now the drill slowly withdraws from the ground. At the same time liquid concrete is pressed into the hole. All this takes place in a closed system, precisely coordinated with each other. Not too fast and not too slow. The hole fills up until the drill is completely out. Then comes an excavator, which places a round steel frame, the so-called reinforcement, into the fresh pile. This process takes just under ten minutes. And while you are still amazed, the drill is already heading for the next marker, starts drilling and drilling begins.
When everything is ready, when the houses are standing, Jobs wants to come back and look at everything again. “I’m from Berlin, and I don’t normally do this, but this site is special with the amount of piles alone.”