Values of interface friction angle and adhesion are generally not the same as the friction angle and cohesion of the surrounding soil.Д®lastoplastic spring elements are used to model anchors and struts. For example, these elements may be used to simulate the thin zone of intensely shearing material at the contact between a tunnel lining and the surrounding soil. Joint elements are available to model soilstructure interaction.

Hinges may be introduced to create joints where plate ends can rotate freely, or with rotation springs for connections that are neither pinned nor fully fixed. Plates with interfaces may be used to perform realistic analyses of geotechnical structures.ДЄ hinge is a connection that allows for a discontinuous rotation in the point of connection (joint).

A plastic hinge may develop for elastoplastic plates, as soon as the ultimate moment is mobilised. The behaviour of these elements is defined using a flexural rigidity, an axial stiffness and an ultimate bending moment. Special plate elements are used to model the bending of retaining walls, tunnel linings, shells, and other slender structures. Quadratic 6-node and 4th order 15-node triangular elements are available to model the deformations and stresses in the soil. The mesh may contain thousands of elements. Plaxis allows for fully automatic generation of unstructured finite element meshes with options for global and local mesh refinement. From this geometry model, a 2D finite element mesh is easily generated. View of the excavation layers: Steel mesh, shotcrete, geotextile and geomembranes.The input of soil layers, structures, construction stages, loads and boundary conditions is based on convenient CAD drawing procedures, which allows for a detailed modelling of the geometry cross-section. Steel mesh ready for shotcrete and anchors ready for tension.ДЄnother view of the first level of the excavation. Steel mesh is placed ready for shotcrete placement. Placement of steel mesh in the interval between the piles. The figure illustrates the two portions of the anchor: The one that is to be cemented (fixed) and the one that is not.ДЄnchor tension. Pumping grout into the hole using a 20 mm diameter plastic pipe.ДЄnchor placement. Three or four tendons were used according to the required strength. Predrilling for anchor installation in the appropriate inclination.ДЄnchor preparation and end product. View of the first level of the excavation.ДЇull view and excavation works (first level -3,5 m approximately). The part that does not have concrete will be concreted later to connect the pile cap with the parking ceiling. View of the pile heads (front) and pile cap reinforcement (back). The spacing of the excavated holes ranged between 1,20 and 1,50 m. The spacing of the excavated holes ranged between 1,20 and 1,50 m.Placement of the steel cage.

The spacing of two couples of th 20 bars is larger on the two opposite sides (see photo) to facilitate the drilling for the anchors that will pass through the pile body. Each cage consists of 20 bars (20 mm diameter) and spirals (10 mm diameter) in a 100 mm distance one from the other. Steel cage construction: Automated steel cage construction facilitates the construction process and reduces the construction time. In the photo the hole where the pile will be placed is being drilled using a bucket. The excavation was supported by reinforced concrete piles having a diameter of 800 mm and a length that ranged between 21 and 23 m. The photos were taken by Dionisis Kolotouros as part of his diploma thesis at the University of Patras, Greece under the supervision of Professor G.

The groundwater table was located 4.5 m below the surface. The soil profile generally consisted of clayey gravels with sand overlaying the 'Athenian schist' formation, which is the predominant bedrock material in Athens Greece. The photos shown below illustrate some construction phases of a 5-story underground parking located in Aigiptou square, in the vicinity of the Pedion tou Areos area, in the center of Athens, Greece.

Steel excavation in plaxis 2d