As a basic fraction in which it is soil mechanics lateral breakaway of the bottom denoted by too much pressure. Typically, a ground failure can occur under a foundation of a building, with the ground being displaced along a sliding joint . The cause of the process is the exceeding of the shear strength , which describes the resistance of the soil. As a rule, there is only a risk of ground failure with shallow foundations .
If the ground is broken up by strong groundwater currents, on the other hand, one speaks of a hydraulic ground failure . VJ Kurdjümoff (1889) took the first photograph of a ground failure.
Process and fracture figure
If the soil is overloaded, the shear strength is exceeded, that is, the interlocking of the soil grains, the cohesive forces and the weight of the moving soil are not sufficient to withstand the applied load. If the foundation breaks under a foundation, it sinks into the ground and tilts. A shift can also be the result. A ground failure can seriously damage the entire structure or even collapse.
The soil body known as a fracture figure or ground fracture figure, which moves in the event of a ground fracture, is circumscribed by a curved sliding surface. In the vertical section this line consists of straight lines and logarithmic spirals as a transition between them. The sliding surface begins at the edge of the foundation and ends, depending on the type of soil, several meters from the foundation.
Standardization and verification
The proof of the ground fracture safety of a foundation is carried out with the methods of earth statics and is regulated in Europe in Eurocode 7 . An additional German standard is DIN 4017, which contains verification options for important standard cases. The evidence is based partly on calculations with the theory of plasticity and partly on experimental investigations.
Important parameters in the verification are the angle of friction and the cohesion of the soil. The proximity to sloping embankments, non-vertical load introduction and a very low embedment depth of a foundation also favor a ground failure. These factors must therefore also be taken into account when examining the resistance to ground failure.
- 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 (Ed.): DIN 4017: 2006-03: Subsoil - Calculation of the ground failure resistance of shallow foundations . Beuth Verlag, March 2006.
- ^ Karl-Eugen Kurrer , History of Structural Analysis. In search of balance . Ernst & Sohn , Berlin 2016, ISBN 978-3-433-03134-6 , pp. 338f
- ↑ Goris, A. (Ed.): Schneider building tables for engineers . 20th edition. Werner Verlag, Cologne 2012, ISBN 978-3-8041-5251-9 , pp. 11.45 ff .