Hydraulic ground break
In soil mechanics, a hydraulic ground failure is a process in which flowing groundwater causes a sudden movement of the soil. This is usually associated with severe impairment or destruction of adjacent structures. There is always the risk of hydraulic ground failure wherever construction work over a short distance leads to very different groundwater levels, such as B. in watertight construction pits or dikes . If, on the other hand, the soil fails only due to excessive loads, it is referred to as a ground failure .
The hydraulic ground failure in Germany became known beyond specialist circles due to the collapse of the Cologne city archive in 2009.
process
For construction sites below the water table, e.g. B. for the creation of foundations and basements, the groundwater in the area of the excavation must be lowered . Often a tight wall, e.g. B. a sheet pile wall , built around the construction pit and the groundwater is lowered within the construction pit by constant pump operation. This creates a large gradient between the water table outside and inside the excavation pit. Following the principle of communicating pipes, the groundwater flows around the base of the retaining wall from the outside. The flow force of the water counteracts the weight of the soil. A hydraulic ground failure occurs when the flow force exceeds the weight force. In this case, the ground is raised by the groundwater and “breaks up”.
Standardization and verification
In Europe, the calculation of safety against hydraulic ground failure is regulated in Eurocode 7 (DIN EN 1997-1). The previously valid German standard DIN 1054 now contains supplementary regulations for this document.
The proof of safety against a hydraulic ground failure is generally carried out by comparing the acting forces, whereby the flow force is mathematically increased for safety and the weight of the soil is mathematically reduced.
literature
- German Institute for Standardization (Ed.): DIN EN 1997-1: 2009-09: Eurocode 7: Design, calculation and dimensioning in geotechnical engineering - Part 1: General rules . Beuth Verlag, September 2009.
- German Institute for Standardization (publisher): DIN 1054: 2010-12: Subsoil - Proof of safety in earthworks and foundations - Supplementary regulations to DIN EN 1997-1 . Beuth Verlag, December 2010.
Web links
- Instructional film hydraulic ground failure. University of Duisburg-Essen, accessed on August 16, 2013 .
Individual evidence
- ↑ a b Martin Ziegler, Benjamin Aulbach: General dimensioning diagrams for the reliable proof against hydraulic ground failure . In: WasserWirtschaft . April 2010 ( talsperrenkomitee.de [PDF; 174 kB ]). PDF; 174 kB ( Memento of the original from March 10, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ B. Schuppener: Floating and hydraulic ground failure. (PDF; 186 kB) In: BAW Colloquium: “New Standardization in Geotechnics”. Bundesanstalt für Wasserbau, Karlsruhe, p. 8 ff. , Accessed on August 16, 2013 .
- ↑ a b Goris, A. (Ed.): Schneider building tables for engineers . 20th edition. Werner Verlag, Cologne 2012, ISBN 978-3-8041-5251-9 , pp. 11.96 .
