Back Wall in Construction, Demolition & Tunnels

In building construction, industry, and geotechnical engineering, the back wall is a commonly used term for the rear wall of a structure, a room, a pit, a shaft, a support structure, or a container. It can be load-bearing, bracing, or merely space-enclosing. In demolition, special demolition, strip-out, rock breakout, and tunnel construction, the position of the back wall influences the choice of working method: limited access, adjacent use, and the risk of vibrations require controlled, precise methods. This knowledge article by Darda GmbH explains the properties, risks, and proven practices regarding back walls and relates them to tools such as concrete demolition shear as well as rock and concrete splitters.

Definition: What is meant by back wall

A back wall is understood to be the wall facing away from the observer or the rear wall of a building or plant component. Depending on the context, this can be the rear-side exterior basement wall, the rear wall of a shaft, the rear stringer of a staircase, the inner lining of a tunnel, the back of a retaining wall, the rear masonry lining of a plant room, or the closed end of a tank. Back walls can be made of reinforced concrete, masonry, natural stone, shotcrete on rock, metal sheets, or composite constructions. Their processing requires particular care because behind the back wall there are often sensitive areas, soil, voids, utility lines, or neighboring structures.

Structural particularities and typical materials

Back walls perform different functions: They transfer earth and water pressure, secure rock, form the enclosing surface behind installations, or accommodate embedded components. Frequent construction types are reinforced concrete walls with reinforcement, masonry walls made of solid or hollow units, reinforced shotcrete shells, natural stone masonry, as well as metallic back walls on containers. In tunnel construction and rock breakout, back walls appear as stabilized rock faces or as the inner lining. Waterproofing, drainage, anchors, and joints significantly influence load-bearing behavior and workability.

Load-bearing behavior and load transfer

Back walls are subjected to constant or variable earth pressure, groundwater, surcharge loads, self-weight, thermal and shrinkage restraints, and vibrations. Joints, crack inducers, construction and expansion joints, anchor layers, connection details to base slabs and floors, as well as rear backfills require particular attention during interventions. Knowledge of the load paths determines the safe sequence of cuts, splitting operations, and crushing steps.

Preparation: investigation, exposure, and protection

Before working on a back wall, systematic preparation lays the foundation for safety and quality. This includes investigation, documentation, and protective measures on the object and in the surroundings.

Check existing documentation: drawings, structural analysis, waterproofing, anchor layouts, any prestressing, embedded components.
Site inspections: visual inspection of both sides of the wall, if accessible; identify cracks, moisture, voids, underpinning.
Detection: locate reinforcement and utility lines, use drilling scanners; for containers, clarify contents and any residual media.
Expose: remove surface coatings and attachments; strip-out using combination shears or multi cutters.
Protection: shoring, catch scaffolds, coverings; protective separations to adjacent areas; dust and water management.
Emission requirements: noise, vibrations, dust, media; selection of low-vibration methods such as rock and concrete splitters.

Methods for processing and deconstruction of back walls

The choice of method depends on material, wall thickness, reinforcement ratio, accessibility, and environmental conditions. Hydraulic, low-vibration tools have proven effective for controlled separating and breaking.

Controlled splitting and breaking

Rock and concrete splitters as well as rock splitting cylinders enable targeted widening of drill holes and controlled separation of concrete and rock. They develop high splitting forces with minimal vibration and low noise emission. This allows segmenting back walls, creating openings, or gently releasing rock back walls in tunnel heading. Hydraulic power packs supply the tools with the required pressure and flow rate. Advantageous on back walls: splitting generates no uncontrolled lever forces on adjacent components and preserves waterproofing and backfill.

Crushing reinforced concrete

Concrete demolition shear grip, crush, and size-reduce reinforced concrete directly at the back wall. The reinforcement remains accessible and can be cut with steel shears. This approach is common in concrete demolition and special demolition when openings must be produced precisely and without excessive vibrations. In areas with restricted space, such as shafts or basements, compact tools with a short build length and high efficiency are advantageous.

Strip-out and preliminary works

Combination shears and multi cutters support the removal of installations, mounting rails, suspended substructures, and light partition walls attached to the back wall. Clean strip-out improves accessibility for the actual separating, splitting, or crushing.

Metal back walls and tanks

If it is the back wall of a tank or a metallic enclosure, steel shears for sections, beams, and reinforcing steel as well as tank cutters for plate segments are suitable. When working on containers, pay attention to residual media, explosion protection, and degassing; cutting sequences must be chosen so that no uncontrolled stresses are relieved.

Application examples: working on back walls safely

Practice-oriented sequences help reduce risks and achieve high execution quality. The following examples show typical procedures in different materials and environments.

Opening in a basement back wall: locate utilities, set up dust protection, produce a drilling pattern for splitting cylinders, split in a controlled manner, cut reinforcement with steel shears, refine edges with concrete demolition shear, properly restore waterproofing.
Segmental deconstruction of a shaft back wall: work from top to bottom in small fields; shore temporarily; concrete demolition shear for crushing, steel shears for reinforcement, removal via secured chutes.
Rock back wall in a tunnel: pre-drill according to geology, deploy splitters, maintain low vibrations, reapply shotcrete and anchors in time; avoid overbreak.
Natural stone back wall in the quarry: split along natural joints, gently release raw blocks; preserve surface quality.
Tank back wall made of steel plate: check residual substances, properly remove flammable media, use tank cutters and steel shears in a defined sequence, deburr edges.

Back wall in the key application areas

Concrete demolition and special demolition

Back walls made of reinforced concrete are often processed in existing buildings while adjacent areas remain in use. Low-vibration methods are therefore preferred. Concrete demolition shear and rock and concrete splitters enable controlled openings and orderly removal without unacceptably stressing adjacent components.

Strip-out and cutting

In strip-out, attachments, installations, and light components on the back wall are removed first. Combination shears and multi cutters create space for subsequent splitting or crushing of the load-bearing structure. Cut edges remain accessible and clean, which facilitates further processing.

Rock breakout and tunnel construction

In underground works, stabilized rock faces or the inner lining of a tube can be considered a back wall. The use of splitters reduces vibrations and minimizes overbreak in rock demolition and tunnel construction. In cross passages, niches, and caverns, the combination of splitting and localized crushing allows an exact profile.

Natural stone extraction

The back wall of the extraction front is prepared by targeted splitting to release raw blocks along natural separation planes. This preserves the texture and strength of the stones while reducing waste.

Special operations

For time-critical tasks, for example after damage events, openings in back walls may be required. Hydraulic tools with external energy supply via hydraulic power packs enable a controlled, low-emission approach. Legal frameworks and safety requirements must always be observed.

Technical parameters and selection criteria

The choice of tools for work on back walls depends on wall thickness, reinforcement density, material, accessibility, and environmental constraints. Water and earth pressure, waterproofing systems, and anchor layouts also influence the procedure.

Material and build-up: concrete strength, masonry type, rock quality, metallic wall thicknesses.
Reinforcement: position, diameter, possible prestressing; cutting and crushing capability.
Access: working space, component overhang, approachability, position of the hydraulic power packs.
Emission limits: noise, dust, vibration; if applicable, prefer splitting.
Cutting and splitting strategy: drilling pattern, segment sizes, sequence, load transfer.
Occupational safety: shoring, catching devices, media-free condition for containers.

Cut path, demolition sequence, and stability

A safe sequence prevents uncontrolled fractures. Work is often carried out from top to bottom, with small segments and defined tipping or fall directions. For back walls with backfill, a combination of splitting for separation and concrete demolition shear for edge finishing has proven effective. Drill holes for splitting cylinders must be set so that reinforcement is preserved and the desired separation line is achieved. Temporary shoring secures connections to slabs and base slabs.

Risks and protective measures

Particular caution is required with concealed voids, utility lines, prestressing, contaminated areas, and water-bearing layers. The following principles improve the safety and quality of work on back walls.

Hazard assessment: loads, media, emissions, escape routes; generally observe legal requirements.
Securing: shoring, cordoning off, catch scaffolds, protective shields, splash protection.
Investigation: detection of reinforcement and utilities, trial drillings.
Procedure: splitting for separation, crushing and cutting only after load redistribution.
Emission control: dust extraction, water mist, low-vibration methods.
Aftercare: secure edges, protect reinforcement against corrosion, restore waterproofing.

Post-processing and surface qualities

After working on a back wall, surface roughness, edge condition, and exposed reinforcement influence the subsequent steps. For bonding with shotcrete or waterproofing, suitable roughness is required; loose constituents must be removed. Exposed reinforcement must be cleaned and, if necessary, temporarily protected. In water-loaded areas, connections to waterproofing must be executed professionally.

Typical details on back walls

Multiple trades often meet at back walls: waterstops, penetrations, anchor plates, brackets, embedded parts, and drainage. These details determine workability. Penetrations are secured before separation, joint areas are separated with low residual stress, and anchor layouts are documented to enable targeted subsequent repairs.