1 Scope
This European Standard specifies the execution of diaphragm walls and the practical aspects which must be taken into account in the production of the working drawings. Diaphragm walls can be permanent or temporary structures. The following types are concerned:
a) retaining walls: usually made to support the sides of an excavation in the ground. They include:
- 1) cast in situ concrete diaphragm walls;
- 2) precast concrete diaphragm walls;
- 3) reinforced slurry walls;
b) cut-off diaphragm walls: usually made to prevent migration of groundwater, clear or polluted, or of other liquids present in the ground. They include:
- 1) slurry walls (possibly with membranes or sheetpiles);
- 2) plastic concrete walls.
The design, planning and execution of diaphragm walls call for experience and knowledge in this specialized field. The execution phase requires skilled and qualified personnel and this document cannot replace the know-how of specialist personnel and the expertise of experienced contractors.
2 Normative references
This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication referred to applies.
EN 10080, Steel for the reinforcement of concrete, weldable ribbed reinforcing steel B500 —Technical delivery conditions for bars, coils and welded fabric.
ENV 197, Cement —Composition, specifications and conformity criteria.
ENV 206:1990, Concrete —Performance, production, placing and compliance criteria.
ENV 1991, Eurocode 1: Basis of Design and Actions on Structures.
ENV 1992, Eurocode 2: Design of Concrete Structures.
ENV 1994, Eurocode 4: Design of Composite Steel and Concrete Structures.
ENV 1997, Eurocode 7: Geotechnical Design.
ENV 1998, Eurocode 8: Earthquake Resistant Design of Structures.
ISO 9690, Production and control of concrete —Classification of environmental exposure conditions for concrete and reinforced concrete structures.
3 Terms and definitions
For the purposes of this European Standard, the following terms and definitions apply.
3.1
cast in situ concrete diaphragm wall
fr: paroi moulée EN béton
de: Ortbetonschlitzwand
wall made of plain concrete or reinforced concrete, which is constructed in a trench excavated in the ground. The concrete is placed through concreting pipes, beneath the supporting fluid in the case of liquid-supported trenches or in some cases, in dry conditions
3.2
precast concrete diaphragm wall
fr: paroi préfabriquee EN béton
de: Fertigteilschlitzwand
wall made of precast elements which are lowered into a trench containing a self-hardening slurry
3.3
reinforced slurry wall
fr: paroi moulée EN coulis armé
de: Bewehrte Einphasenschlitzwand
wall made from a self-hardening slurry reinforced by steel beams, steel mesh or other suitable means
3.4
slurry wall
fr: paroi moulée EN coulis
de: Einphasenschlitzwand
wall made from a self-hardening slurry. In most cases, the excavation is carried out using a self-hardening slurry as the supporting fluid. Sealing elements such as membranes or sheetpiles may be inserted
3.5
plastic concrete wall
fr: paroi moulée EN béton plastique
de: Tonbetonschlitzwand
wall made of plastic concrete, which is constructed in a trench in the ground. The concrete is placed beneath the supporting fluid using concreting pipes in liquid-supported trenches, or in some cases, in dry conditions
3.6
panel
fr: panneau
de: Schlitzwandelement
section of a diaphragm wall which is concreted as a single unit. A diaphragm panel may be linear, T-shaped, L-shaped, or of other configuration
3.7
guide-walls
fr: murettes-guides
de: Leitwände
small, parallel temporary walls which are used to provide a guide for the excavating tool and to secure the sides of the trench against collapse in the vicinity of the fluctuating level of the supporting fluid
3.8
concreting pipe
fr: tube plongeur
de: Betonierrohr
pipe used for placing concrete beneath the supporting fluid, to avoid contamination and segregation
3.9
supporting fluid
fr: fluide d'excavation
de: Stützende Flüssigkeit
fluid used during excavation to support the sides of the trench. It is usually a bentonite suspension, a polymer solution or a self-hardening slurry
3.10
self-hardening slurry
fr: coulis autodurcissant
de: Selbsterhärtende Suspension
slurry which hardens with time. The slurry is a suspension which contains cement or another binder, and additional materials such as clay (bentonite) , ground granulated blast furnace slag (GGBFS) or pulverized fuel ash (PFA) , fillers, and admixtures
3.11
plastic concrete
fr: béton plastique
de:Tonbeton
a low strength, high plasticity concrete. Here, high plasticity means the ability to sustain larger strains than normal concrete. It is usually made with a low cement content, containing bentonite and/or other clay materials. It may also include other materials such as PFA and admixtures
