Description
Stability analysis of embedded cantilever retaining walls in the seismic area is generally carried out by calculating a factor of safety against a possible collapse mechanism. However, a more rational approach assesses the structure’s performance in terms of accumulated permanent displacement. Indeed, this approach is required by many national standards as well as Eurocode 8 Part 5 (§7.1(1)P; §7.1(2)). In this context, DReW Seismic allows predicting the earthquake-induced permanent displacements of embedded cantilever retaining walls (diaphragms and sheet-pile walls). DReW Seismic is developed based on the method recently published by Conte, Pugliese and Troncone (2022) in the journal Géotechnique.
GENERAL FEATURES
The main features of the software are listed below:
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- The redistribution of the soil pressure on the wall as a function of the wall displacement is accounted for, as required by Eurocode 7 Part 1 at §9.7.1(5)
- Different typology of structures: diaphragm and sheet-pile walls
- Cohesionless soil
- Layered soil
- Presence of surcharge
For the sake of completeness, a pseudo-static analysis can also be performed. This latter refers to the method developed by Conte, Troncone and Vena (2017).
REQUIRED INPUT
DReW Seismic is very easy to be used and requires a limited number of input parameters. In particular, the following data is required:
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- Excavation height;
- Embedment depth;
- Soil unit weight;
- The angle of shearing resistance;
- Friction angle at the soil-wall interface;
- Unit weight of the wall;
- Wall thickness (in case of diaphragm wall);
- Pile diameter and spacing between piles (in case of sheet-pile wall);
- Surcharge intensity.
Moreover, since a seismic analysis is performed, an acceleration time history representative of the wall-soil system is required. A database of earthquakes recorded in different parts of the world is available on this website.
If a pseudo-static analysis is performed, the horizontal and vertical seismic coefficients, kh and kv, are required.
OUTPUT
DReW Seismic provides the outputs listed below when a seismic analysis is performed:
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- displacement time-history owing to a given earthquake. The displacement is calculated for the top of the wall;
- comparison between the ground acceleration time history and the corresponding critical threshold, which is also updated during the earthquake;
- evolution with time of the angular acceleration of the wall;
- evolution with time of the angular velocity of the wall;
- evolution with time of the rotation of the wall;
- evolution with time of the net pressure at the wall end and comparison of this latter with the corresponding limit value;
- evolution with time of the depth in which the passive resistance is completely mobilized;
- evolution with time of the centre of rotation of the wall;
- evolution with time and depth of the net pressure acting on the wall.
When a pseudo-static analysis is performed, the following outcomes are provided:
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- net pressure acting on the wall;
- shear force;
- bending moment.