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Page 1 2016
Analysis of retaining walls (simple or double)
using the subgrade reaction coefficient method
Interface and features
Page 2 2016
Plan
• Overview of K-Réa v4 features and capabilities
• Subgrade reaction method
• Project's definition
• Construction stages
• Results
• ULS checks
• Print of stages and main results
Page 3 2016
Introduction
• K-Réa v4 is a user-friendly and interactive program for the analysis of
retaining wall solutions (diaphragm walls, sheet-pile walls, soldier-pile
walls).
• New calculation kernel developed in 2014/2015 by the scientific
department of Terrasol.
• K-Réa handles 2 walls in interaction without limitation in the number
of links and without iterations (direct calculation)
• Takes into account all Eurocode 7 approaches:
• Approach 1
• Approach 2/2*
• Approach 3
• Automatic checks in conformity with French norm NF P 94-282
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Introduction
• Takes into account the embankments and berms.
• Active and passive earth pressure and pore pressure may defined throughout the stages.
• Several supports conditions : struts, anchors, rotation springs, surface struts, circular lierne, linking anchor, slab…
• Takes into account earthquake conditions
• It’s also possible to define load combinations
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The calculation method
Subgrade reaction method (beam on elasto-plastic supports)
Soil layers are modelled as springs reaction linearly until the reach a plastification stress (either on active or passive pressure side).
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Project definition
• Calculation options
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Project definition
• Soil layers definition
Take into account a minimal coefficient of
active pressure (for each soil layer)
Take into account a maximal passive pressure
(for each soil layer)
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Project definition
• Soil’s behaviour : automatic wizards
Page 9 2016
Project definition
• Soil’s behaviour : automatic wizards
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Project definition
• Soil’s behaviour : automatic wizards
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Project definition
• Soil’s behaviour : automatic wizards
3 methods are proposed to define the
subgrade reaction coefficient (Kh) :
• Balay
• Schmitt
• Chadeisson
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Project definition
• Wall definition: automatic wizards
Possibility to define circular walls
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Staged construction
• Main window of K-Réa v4
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Initial phase
• Take into account a non horizontal ground level
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Initial phase
• Take into account existing loads
Existing building
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Initial phase
• Take into account initial groundwater flow
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« Excavation / Fill » action
• Take into account the embankments and berms
a
b
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a
b
« Excavation / Fill » action
• Take into account the embankments and berms
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« Hydraulic » action
• Take into account hydraulic gradient set point by point : [z, h(z)]
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« Hydraulic » action
• Take into account hydraulic gradient set point by point : [z, u(z)]
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Soil parameters
• We may define the active and passive earth pressure throughout the stages (set point by point)
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Supports
• Anchors: we may modify prestress force throughout the stages
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Supports
• Surface strut
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Supports
• Circular lierne
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Supports
• We may prestress all support (including linking anchors)
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Supports
• We may handle gap and plastification for all types of supports
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Loads
• We may modify/deactivate the loads throughout the stages
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Loads
• Boussinesq load: take into account the “wall effect”
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Loads
• Automatic management of loads combinations (loads cases)
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Loads
• Automatic management of loads combinations (loads cases)
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Loads
• Automatic management of loads combinations (loads cases)
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Loads
• Automatic management of loads combinations (loads cases)
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Loads
• Automatic management of loads combinations (loads cases)
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Force diagrams
• Determination of the axial (normal) forces
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Force diagrams
• Determination of the vault pressure (orthoradial)
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ULS calculation approaches (EC7)
• Approach 2/2*
(NF P 94 282 – french application norm)
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ULS calculation approaches (EC7)
• Approach 3 (EC7)
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ULS calculation approaches (EC7)
• Approach 1 (EC7)
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ULS calculation
• LEM calculations: automatic correction of the counter passive earth pressure inclination value
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ULS calculation
• Automatic management of over-excavation Δa
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Double wall projects
• No limitation in the number or inclination of linking anchors
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Double wall projects
• No limitation in the number or inclination of linking anchors
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Double wall projects
• "Surface links" can be defined through specific anchor actions (slabs)
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Seismic conditions management
• Using the seismic coefficients of the pseudo static method
kH.g
(1±kV).g
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Seismic conditions management
• Includes the Mononobé-Okabé pseudo static method
Cas d’un sol frottant
Case of a frictional soil
α so that P is maximized
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Seismic conditions management
• Ré-intégration du modèle de Mononobé-Okabé
Prise en compte de la cohésion
α so that P is maximized
Cohesion is taken into account
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ULS checks
• Failure in the passive side of the wall (MEL for cantilever walls)
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ULS checks
• Failure in the passive side of the wall (SSIM for anchored walls)
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ULS checks
• Resultant of vertical forces : validation of the active and passive earth pressure angles
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ULS checks
• ULS check are available for double wall projects (including the validation of the free length of anchors – Kranz’ method)
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ULS checks
• ULS check are available for double wall projects (including the validation of the free length of anchors – Kranz’ method)
Possible with logarithmic spiral as failing surfaces
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Printing of results
• Project stages synthesis
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Prints
• Printing of wizards data
Page 54 2016
Prints
• Graphical printing of results
Page 55 2016
Thank you for your attention
