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Dortmund, Emscherallee

Road subsidence on Emscherallee in Dortmund’s Huckarde district.
Facts and Figures
Company Stump-Franki Spezialtiefbau GmbH
PrincipalBatteux Bauunternehmung GmbH & Co. KG
LocationDortmund - Germany
Type Specialist civil engineering
Runtime01.2019 - 12.2020

Jet-grouted sewer rehabilitation after a surface fracture.

At the beginning of October 2018, noticeable deformation of the asphalt was detected on the north side of the intersection of Emscherallee and Lindberghstrasse in Dortmund, causing the closure of the Emscherallee. Within a short time, cracks spread from the settled area across the middle of the road to the east. The resulting surface fractures covered approx. 500m². In searching for the original cause of the subsidence, it was soon discovered that soil had filled the access shaft to a sewer duct (DN 1600).
Plans for this rehabilitation project by Geotechnik-Institut-Dr. Höfer GmbH & Co. KG included a waterproof construction pit. Also included was a pit lining of overlapping bored pile walls and the construction of a waterproof foundation floor slab using jet grouting methods (DSV) and waterproof DSV sealing walls, some of them with a static function. Stump-Franki Spezialtiefbau GmbH was contracted to complete the necessary jet grouting works.

Precise execution

The jet grouted elements were manufactured with diameters of 2m and depths of up to 18m, as per the execution planning.

Extreme precision was required as a result of the depth of the DSV elements. All the drilled hole positions were surveyed and adapted to the reference position of the adjacent columns as needed.
The sealing walls were manufactured around the existing sewer channel with an external diameter of 2m. The logistical organisation of the construction site posed another considerable challenge owing to the sheer volume of cement required and the correspondingly large cubage of backflow, which then required disposal.
The construction method of “stump jetting”, introduced by the building authorities, enabled the construction pit to be promptly completed with open dewatering in December 2019, after a construction period of a mere four months.

Technical data / quantities

Trough construction pit

2.214,00m3

Unit diameter

2m

Cubage of jet grouting

1.957m3

Jet length

up to 12.64m