Abstract: Rain-induced slope instability is a significant natural hazard in Switzerland, Slovenia and elsewhere in Europe. This contribution was prepared especially for the 12th Šuklje Symposium, and recognises that landslides occur both in mountain regions as well as in lowland regions during and following extreme-rainfall conditions. The Institute (and Professorship) for Geotechnical Engineering at the Swiss Federal Institute of Technology (ETH Zürich) has been engaged over several years in projects concerned with the characterisation, monitoring and modelling behaviour of slopes in mainly granular porous media across the full range of altitudes in Switzerland. A link is made to the doyen of the Šuklje day and then three case histories are presented and discussed to demonstrate the principal reactions to seasonal rainfall. A small slip was released in two of these cases and the “triggering” factors have been investigated and are discussed in this contribution. It transpires that the mode of inslope drainage influences the way in which the ground saturates and hence the volume of the potentially unstable ground. Simple stability analyses using limit equilibrium and soil parameters that have been amended to account for unsaturated soil behaviour were found to function well for slopes in largely granular media.Keywords: rain-induced landslides, slope stability, case histories, monitoring, characterisation, modellingPublished in DKUM: 13.06.2018; Views: 630; Downloads: 50 Full text (1,79 MB)This document has many files! More...
Abstract: This thesis deals with factor of safety calculations on geogrid reinforced embankments carried out by commonly used limit equilibrium (LEM) and finite element methods (FEM). The study utilize LEM based software SLIDE and FEM based software PHASE2. The main difference between these two approaches is that the LEM methods are based on the static of equilibrium whereas FEM methods utilise the stress strain relationship. Unlike to LEM, numerical analysis also computes displacements.
For practical example of a geogrid reinforced embankment the factor of safeta (FoS) is calculated. Reinforced soil structures are nowadays utilized for a lot of civil engineering applications. Traditionally, the design of geogrid reinforced soil is performed using analytical methods (LEM). Unfortunately, these methods missing the fundamental physics of stress-strain relationship and are therefore not able to compute a realistic stress distribution.
In first step of the analysis the FoS is carried out with analytical approach. The most rigorous LEM methods, Bishop’s, Spencer’s and Morgenstern-Price are selected and the FoS for circular and polygonal slip surface is calculated.
In second step of the analysis the FoS is carried out with numerical approach. Shear strength reduction (SSR) procedure was performed to determine the critical strength reduction factor (SRF) which represents the FoS of slope.Keywords: civil engineering, finite element method (FEM), limit equilibrium method (LEM), embankments, slope stability, bearing capacity failure, geosynthetics, geogrids, shear strainsPublished in DKUM: 27.09.2017; Views: 879; Downloads: 165 Full text (17,05 MB)