PLAXIS is renowned as a robust, reliable and user-friendly finite element software solution. Thanks to its sound computational procedures, PLAXIS provides a comprehensive solution for design and analysis of soils, rocks and associated structures and has been implemented worldwide in industries dealing with embankments, excavations and foundations.
Typical PLAXIS applications include stability analysis of embankments, displacements around an excavation pit, and dam stability during different water levels. The applicability of PLAXIS has been extended to solve problems dealing with excavations in soft soils, piled-raft foundations, embankments or dams with creep behaviour and its interaction with consolidation and large deformation analysis.
Embankments and dams have been built for centuries by civil engineers for different purposes. The design for embankments can be for railways, roadways, water retention, flood controls or airports.
The challenges that remain are the stability of embankments under conditions of drawdown, designing embankments on soft compressible soils with low permeability of the underlying deposit together with low undrained shear strength, dynamic movements of embankments that determine the train speed, and migration of finer materials during the long-term operation of an embankment or a dam.
In the design of high-rise buildings, the combination of deep excavation and foundation design can be found. Raft, pile and combined piled-raft foundations are probably the most considered foundation types. In general, a minimization of the settlements of the foundation is seeked in order to limit the damage of the superstructures. The numerical analysis with PLAXIS can be used to optimise the foundation design and the construction process. Piles can be modelled in PLAXIS as either volume piles (3D) or embedded piles (2D).
The numerical analysis of excavations and building pit support systems and its soil-structure interaction are of great importance in, e.g., high-rise building and tunnel shaft design. Settlements and, hence, damage to surrounding buildings, infrastructure or underlying tunnels have to be minimized. Furthermore, the stability of the excavation pit has to be guaranteed.
A good case that represents the soil-structure interaction is the design of quay walls. The excavation is supported by concrete diaphragm walls and the walls are tied back using prestressed ground anchors. The ground anchors can be modelled by using a combination of node-to-node anchors and embedded beam rows in the a two dimensional model. The behaviour of soil upon removal of its overburden can be best represented with the Hardening Soil model. It takes stress-dependency of stiffness moduli into account. Also, the Hardening Soil model with small-strain stiffness is available to account for the increased stiffness of soils at small strains.