Cut-off walls

Cut-off walls reliably seal construction pits and structures against groundwater. They are constructed using a single- or two-phase system, can serve temporary or permanent purposes, and, when combined with structural elements, can also provide structural support. Cut-off walls are regarded as a cost-effective, low-deformation and low-noise solution for construction pits, dams, landfills and the containment of contaminated sites.

Glossary: Cut-off walls

Cut-off walls
in accordance with DIN EN 1538

The cut-off walls are constructed using both single-phase and two-phase systems. They serve to provide waterproofing and/or shielding and can be used for temporary or permanent applications.

In conjunction with installed load-bearing elements, cut-off walls can also provide structural support and, depending on the project, be used as a shoring solution for construction pits.

To seal construction pits horizontally against groundwater, cut-off walls are integrated into existing soil layers with low water permeability or into artificially constructed sealing slabs.

Areas of application include:

Construction pit shoring with installed load-bearing elements
Transverse bulkheads for subdividing large construction pits
Dam sealing
Landfill enclosures
Enclosures for contaminated sites on industrial brownfield sites and similar locations

Bild einer Dichtwand; Fotografiert aus der Baugrube

Technical brochure
Construction pits

Construction pit walls (only available in German)

PDF

Benefits / Features
of cut-off walls

Waterproofing: Cut-off walls can be used to provide a waterproof barrier against groundwater.
Deformation behaviour: In combination with load-bearing elements and back anchors, minimal deformation can be achieved.
Shoring function: It is possible to separate the structural and waterproofing functions.
Construction depth: Construction using the grab method is possible at depths of approximately 20 to 40 m.
Construction process: The shorter runtime compared to bored pile walls saves both time and money.
Surface finish: Smooth surfaces can offer benefits for subsequent work stages.
Construction: Low-noise construction with minimal vibrations is possible.
Application conditions: Can also be used where headroom is limited (e.g. under bridges).

Basic facts

Standards and rules

Cut-off walls are designed and manufactured in accordance with DIN EN 1538 and the recommendations of the “Construction Pits” Working Group (Empfehlungen des Arbeitskreises “Baugrube”, EAB). Verification of the stability of the open diaphragm is carried out in accordance with DIN 4126.

Production

Cut-off walls are produced along the same lines as diaphragm walls, using the grab method. Guide walls are built along the route where the cut-off wall will stand beforehand to guide the grab.

A cut-off wall compound is used to stabilise the earth walls. This does not have to be replaced in the single-phase system; instead, its high cement content means that it sets in place. Precast concrete elements, HEB profiles and sheet pile profiles are used as structural load-bearing elements.

Cut-off wall thicknesses typically range between 0.45m and 1.0m, with typical depths ranging from 15m to 40m.

Design variants
Cut-off wall

The following variants are available:

Cut-off wall with sheet-pile wall
Cut-off wall with prefabricated concrete elements
Cut-off wall with HEB profiles
Cut-off wall without load-bearing elements, for sealing purposes only

Bild zeigt eine Skizze einer Dichtwand mit Trageelement — © PORR

Quality assurance
Cut-off walls

Cut-off walls are constructed in accordance with the applicable standards, technical regulations as well as project-specific requirements.

Principles of construction:

Project-specific procedural instructions
Requirements in accordance with DIN EN 1538
Verification of the position, rotation and verticality of the slotted lamellae using modern measurement technology such as inclinometers
Quality management system in accordance with DIN EN ISO 9001:2015