Landslides Flashcards
What is the difference between long term and shirt term analysis?
Short term is run before any consolidation takes place (undrained). If the pore pressure is unknown then the analysis will be carried out in terms of total stresses.
Long term is run at the end of the consolidation process in terms of effective stress.
What are the pros of DEM
Simulations are dynamic and implicit over time.
Method is becoming increasingly popular
Info about the evolution of the landslide is obtained at the same cost as the analysis of slope stability.
An assembly of blocks of any shape can be investigated having prescribed the joint and intact block properties.
What are the cons of DEM
3D analysis involves a large number of blocks so in most cases simplifications need to be used
Engineers aren’t as educated in it as other methods.
Limited user friendly software
Indirect calibration of parameters (dissipation coefficient can’t be obtained directly from experiments
What is soft particle approach?
A particle and deform during a contact
Assumptions made in DEM
Contact modelled using the linear theory of elastic.
Dimensions if contact area are much smaller bbz the dimensions of the whole contacting bodies.
Contacting surfaces are frictionless.
What are the different methods of failure analysis?
Continuum models: Wedge analysis (hand calculations) FEM- strength reduction technique - reduction of strength characteristic - uses mesh and boundary conditions. - homogeneous slope conditions. - clear presence of a shear band - uncertainties in material properties and applied loads -Well established -results are mesh dependant LEM - failure surface is assumed - shape - location - failure only on certain predefined surfaces. There is no check on yielding else where - kinematics not considered - deformation isn't considered - only satisfied for slices Discontinuous model: -wedge analysis for joints daylighting on the surface - Distinct element method - discontinuous deformation analysis
