Drilling and ramming for the tunnel

Created: 2022-10-02 09:02

By: Peter Schiebel

The workers used this equipment to examine the subsoil at six locations in the Gautinger Strasse, Petersbrunner Strasse and Leutstettener Strasse areas.

©Fibinger

The Starnberger See Wastewater Association is currently having the building site in the commercial area north of Münchner Straße (B 2) examined.

The background to the measure is the relocation of canals when the B 2 tunnel is built.

Starnberg

– residents of Gautinger Straße, Petersbrunner Straße and Leutstettener Straße have noticed the mobile construction site with the drilling and piling equipment in several places in the past few days.

With great force, workers drove equipment into the ground to take samples and collect data.

The client is the Starnberger See sewage association.

Its construction manager and deputy managing director Michael Friedrich spoke to Starnberger Merkur about "extensive preliminary investigations" in connection with the construction of the B 2 tunnel.

In the area of ​​the planned northern portal at the level of McDonald's there are main sewers for waste water and rainwater.

Friedrich explains that they would literally be cut through by the access to the tunnel.

So they have to be relocated.

Where exactly the reason is best suited for this is to be found out with the help of the investigations.

"Civil engineering measures are always expensive," says Friedrich.

Therefore, a preliminary investigation that is as accurate as possible is essential.

In Seeton, for example, the sewage association definitely does not want to build.

Areas that may have been contaminated from earlier decades should also be excluded as far as possible.

Why is the association already having the investigations carried out even though the planning change procedure for the tunnel has still not been completed?

"We had recently received favorable offers," explains Friedrich.

However, it is still completely open when the channels will be laid.

"We don't know whether in one, two, three or four years." However, the more precise the preliminary investigation, the better you can plan.

The channels of the sewage association in Starnberg are usually 1.50 to three meters deep in the ground.

Main lines for dirty water have a diameter of 300 millimeters, those for rainwater have a diameter of 500 to 600 millimeters.

Our own investigations in the area of ​​the north portal are also necessary because the area is densely built-up and a larger arch may be required for the new canals.

Some of the investigation sites are 350 meters away from the main road.

The commissioned company Blasy and Mader from Eching am Ammersee has the soil examined at a total of six locations.

Soil samples are taken with exploratory drilling, which are then analyzed in the laboratory.

Dynamic probing is used to check the strength of the soil, explains one of the company's managing directors, Stephan Bourauel.

The workers drove the equipment into the ground to a depth of 15 meters, he says.

Normally, such a depth is not necessary for the planned construction work.

However, the ground in Starnberg is rather poor, which is why a greater depth is being investigated.

Based on the data obtained and the results of the laboratory tests that will follow, he will then calculate how stable the ground is at the respective points and whether more complex foundations may be necessary, says Bourauel.

After two weeks, the work in Starnberg should be completed on Friday.