Important news in the latest update of the GeoStru software Retaining walls – MDC, in fact, it is now possible to design and verify retaining walls of the gabion and block type. In this article, we will quickly look at how to set up a gabion and block wall.
Premise on calculations in gabions and blocks
In MDC, Resistance verification is carried out in all sections corresponding to the steps or to the separation between the gabions, as well as for the intermediate ones at the points of discontinuity. The rectangular section press-inflected and shear stressed, consisting of non-tensile reacting material or with weak resistance, is checked. For gabion walls, the tensile strength of the material is always assumed to be nothing.
The reagent section will turn out to be a partialization of the whole one, and only in it will a certain distribution of internal tensions be active. In general, if the section is entirely reactant, the normal stress diagram will be trapezoid, possibly intertwined;
If the section is partialized and the material is a non-tensile reactant, the diagram of the reacting part will be triangular with a point of null at the neutral axis; If the section is partial and the material has a certain tensile strength, the diagram will be butterfly-shaped, with a minimum value equal to the maximum tensile strength and a maximum such that the integral of the pressures balances the stress system.
Text taken from GeoStru software online manual Retaining walls – MDC
How to set up a gabion wall
As soon as you start MDC, in the main bar, in the “Type” section there is the novelty: the Gabions tool (Figure 1).
Fig.1 – MDC “Gabions” button
Pressing the button will disable all other functions that do not come into play with the design of gabions or blocks (Figure 2).
Fig.2 – MDC interface when activating the Gabions tool
Geometric data and loads
As mentioned, as soon as the gabion type has been chosen, the software itself will guide the user to enter the wall data by keeping the “Geometric data and loads” tool active as shown in Figure 2, which once activated will open the window where to set the geometry of the gabion or block wall (Figure 3).
Fig.3 – Geometric data
- Definition of Gabions or Blocks
- Geometry and sizes of the single gabion or block and weights;
- Option for automatic calculation of parameters such as: volumetric capacity, fictitious internal friction angle gabions (ϕ* = 25γgab – 10°) and fictitious cohesion (Cgab = 0.03Pu – 0.05 where Pu is the weight of wire mesh present in a cubic meter of work expressed in Kg/m3 obtainable from tables);
- Technical parameters of the mesh;
- Technical parameters of vertical bars;
- Block arrangement setting window where Nr. is the number of the row starting from the bottom and The number of files is the number of gabions or blocks arranged on that specific number of rows arranged horizontally;
- Geometry and characteristics of the Foundation, Learn Mix and External loads.
From the geometric and load data window, you can use a fill volume weight database (Figure 4) from which you can quickly access the values based on the type of material:
Fig.4 – Filling material type database
In the next figure, the settings are illustrated on the characteristics of the Foundation, Learn mix and External Loads.
Fig.5 – Settings for foundation, learn mix and external loads in MDC software
You can set the geometry of the wall, foundation and ground upstream graphically in real time by moving the nodes with the mouse (Figure 6).
Fig.6 – Real-time wall geometry editing in MDC
Is present in the output calculation, of course, the new section on the results of the Gabions (Figure 7).
Fig.7 – Window results in Gabions in MDC
MDC is a software for the design and analysis of retaining walls in: reinforced concrete, gravity, block, and gabions walls, with direct or pile foundations and with anchors.
The geotechnical computation employs the standard geotechnical methods subject to user choice and carries out the verifications prescribed by the selected standard, amongst which global stability even in seismic conditions. Structural evaluations perform reinforcement sizing and verification with Ultimate Limit State or Allowable Tensions.
MDC is simple and intuitive but with unique features, including pre-design work, easy management of the combinations: GEO, STR, GLOBAL STABILITY, localization and automatic import of seismic parameters, displacements analysis in a dynamic field, reinforcements editor, import and export of works that should fall in stabilization operations.