Penetration of a single steel foundation pin in a granitic rock
Development of a subsea tidal turbine requires specific research to design the foundation in contact with the seabed. The design stage can be simplified using numerical modelling and more specifically discrete modelling. HydroQuest commissioned Cathie Associates to simulate the behavior of a single foundation pin in a granitic rock mass using Itasca’s discrete numerical approach PFC3D. Itasca France developed the numerical model and routines to track the evolution of the forces applied to the pin as well as the zone of damage around the tip of the foundation during penetration. Two key stages were simulated within the model: the installation phase (vertical penetration) and the operational phase (shearing due to swell).
The model was able to validate theoretical values of the vertical pressure required to penetrate the rock for different sets of material properties and multiple realizations of fracture network. The pre-existing fractures had a major influence on the mechanical behavior and fracture propagation mechanism. The figure below illustrates the evolution of the reaction force on the pin during the horizontal loading, and large variations can be observed due to pre-existing fractures and damage propagation in the rock mass.

Isometric view of the rock sample (colored by ball radius) and the simplified fracture network used for the simulation.

Crack mapping evolution during the operational phase (the first cracks in red, the most recent cracks in blue) and evolution of the horizontal force

Stability calculations for small slopes
ITASCA Consultants GmbH was commissioned to demonstrate the stability of embankments in a stratified soil as part of the expansion of a small shopping center. The embankments concern a slope and a rain retention basin (RRB). An additional traffic load is applied to the left edge of the model. The following figure shows maximum shear strain for a stable factor of safety of 1.42 using the cross section of the RRB as an example. The maximum shear strains show the possible failure mechanisms of the embankment. The simulations were performed with FLAC3D version 6.0.

Cross section of the rain retention basin with maximum shear strain

PFC 6.0 is going to be released soon. Among the new features implemented in version 6.0:

• PFC3D/FLAC3D Interface coupling logic
• 2D and 3D convex rigid blocks
• PFC3D/FLAC3D overlapping-domains coupling logic
• PFC 5.0 to PFC 6.0 save file export

  

Avalanche of rock boulders (PFC3D convex rigid blocks) and interaction with a protective barrier net (FLAC3D structural elements)
Click on the picture to watch the movie

• Discover all the improvements of UDEC 7.0: Factor of safety contours, 3D joint specification, Asymmetric Voronoi generator, Automatic brick generator, Adopt common
  framework base, ...

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