Underpinning

In the construction industry, underpinning is the term used to describe the securing of a building against slipping or subsidence during earthworks below its foundations .

application

In the case of excavation pits created directly next to or near an existing structure , it may be necessary to expose foundations to below the lower edge of the foundation. In such cases, or in the case of basements built under a building at a later date, the existing foundations must be underpinned to prevent cracking from subsidence or the building from slipping into the excavation.

If no special civil engineering methods are used, such work may only be carried out in sections on strip foundations according to the specifications of DIN 4123 and require proof of stability for the final state of the underpinning carried out. In individual cases also for intermediate stages.

execution

The excavation is initially only carried out up to the excavation limit according to DIN 4123 at least 50 cm above the foundation. After that, trenches are dug in sections no wider than 1.25 m to the required depth. An underpinning wall will be created immediately afterwards. Only then is the next section exposed. 3 times the section width must always be maintained as the distance between sections that are executed at the same time. After completion of the underpinning, the construction pit can be excavated to the desired depth. The underpinning must be at least 50 cm deeper than the planned new excavation.

literature

Michael Frahm : Geotechnical and civil engineering underpinnings . Grin Verlag, 2008, ISBN 978-3-640-17407-2 ( limited preview in Google book search).
Information center space and construction of the Fraunhofer-Gesellschaft (ed.): Underpinning and underpassing of buildings . IRB-Verlag, 1985 ( limited preview in Google book search).

Web links

Underpinning in the Google book search

Individual evidence

↑ ^a ^b Ulrich Smoltczyk: Grundbau-Taschenbuch, part 2: Geotechnical procedures . 6th edition. John Wiley & Sons, 2001, ISBN 978-3-433-01446-2 , pp. 97 ff . ( limited preview in Google Book search).
↑ ^a ^b ^c Foundations next to foundations underpinning. (PDF) BG BAU - Berufsgenossenschaft der Bauwirtschaft, accessed on July 13, 2017 (4/2016).

[A-1] Ulrich Smoltczyk: Grundbau-Taschenbuch, part 2: Geotechnical procedures . 6th edition. John Wiley & Sons, 2001, ISBN 978-3-433-01446-2 , pp. 97 ff . ( limited preview in Google Book search).

[B-2] Foundations next to foundations underpinning. (PDF) BG BAU - Berufsgenossenschaft der Bauwirtschaft, accessed on July 13, 2017 (4/2016).