Tunnel tool

Tunnel tool encompasses all equipment, attachments and hydraulic systems used in underground construction and deconstruction to dislodge, remove, cut or split rock, concrete and steel in a controlled manner. In Darda GmbH’s knowledge base, the emphasis is on practical, workable application: tools must act precisely in the tunnel, cause low emissions and operate reliably under confined, often ventilation-critical conditions.

Definition: What is meant by tunnel tool

By tunnel tool one means specialized, often hydraulically powered tools for tunnel heading, lining and deconstruction underground. These include cutting, gripping, separating and splitting systems that are operated on carrier machines or by hand. Typical tasks include opening the tunnel face and crown, adjusting cross-sections, demolishing inner concrete linings, removing reinforcement as well as the gentle release of natural stone. In the context of Darda GmbH, concrete demolition shear as well as stone and concrete splitters play a central role because they act with low vibration, precisely and in a controlled manner—an essential prerequisite in sensitive tunnel environments.

Tool groups and operating principles in tunnel construction

Tunnel tools can be categorized by their operating principle: splitting (stone and concrete splitters, stone splitting cylinders), cutting/gripping (concrete demolition shear, combi shears, multi cutters), steel-severing (steel shears, tank cutters) as well as the supplying units (hydraulic power packs). Splitting tools use hydraulics to generate controlled wedge or cylinder pressure in the borehole and develop high splitting forces with minimal vibration. Crusher and shear tools break concrete, cut reinforcing steel and enable selective removal. Steel shears and tank cutters are intended for load-bearing steel components, pipelines or vessels—underground, for example, during strip-out, special operations or in the deconstruction of technical installations. Hydraulic power packs supply the required pressure and flow rate, matched to hose lengths, ambient temperature and the permissible emission limits underground.

Application areas underground

The application fields of tunnel tool are diverse and range from heading to special deconstruction. Typical areas considered in Darda GmbH’s knowledge base include:

• Rock demolition and tunnel construction: Widening cross-sections, releasing disturbed zones, precise removal at the tunnel face.
• Concrete demolition and special deconstruction: Removing inner linings, foundations and anchor blocks; selective deconstruction near sensitive infrastructure.
• Strip-out and cutting: Deconstruction of installations, shafts, cable trays; cutting reinforcement, structural steel and pipes.
• Natural stone extraction: Gentle winning and shaping of rock underground using splitting methods.
• Special operations: Work in potentially explosive atmospheres and in areas with strict vibration or noise limits.

Stone and concrete splitters: blast-free precision in the tunnel

Hydraulic rock and concrete splitters act via boreholes into which splitting cylinders or wedge systems are inserted. The hydraulic pressure builds a directed tensile stress until material contours open in a controlled way. In tunnel construction this method is especially suitable where vibrations, flyrock and ignition processes must be avoided. It enables staged release of rock or the deconstruction of concrete components—plannable, reproducible and with limited impact on the surroundings.

Methods and parameters

• Borehole diameter and depth are adapted to rock strength, reinforcement ratio and the desired block size.
• Splitting cycles are performed sequentially to control crack propagation and secure the stability of the tunnel face.
• In interbedded rocks, bedding influences the splitting direction; here an adapted drilling pattern is crucial.

Concrete demolition shear: selective removal in confined environments

Concrete demolition shear combines gripping and crushing functions to efficiently downsize concrete and expose reinforcement. In tunnels, they are ideal for removing linings, correcting edges, adjusting cross-sections and deconstructing foundations. The powerful yet controlled action enables work close to sensitive components, cable and ventilation systems. In conjunction with suitable hydraulic power packs, use is also possible in areas with strict emission limits.

Typical tasks

• Demolition of shotcrete or cast-in-place concrete linings without excessive vibration.
• Exposing and separating reinforcing steel in combination with shear functions.
• Preparation for subsequent sealing or strengthening works.

Hydraulic power packs: energy supply underground

Hydraulic power packs provide flow and pressure for shears and splitting devices. Underground, reliability, heat dissipation and safe hose management are paramount. The coordination of pressure levels, oil quality and filtration directly influences tool service life. For longer lines, pressure losses must be considered; throttling and return concepts ensure consistent tool performance. Selecting matched hydraulic power units helps align output with hose lengths, ambient temperature and permissible emission limits underground.

Combi shears, multi cutters, steel shears and tank cutters in the tunnel

Combi shears and multi cutters combine crushing and cutting tasks, which is efficient during strip-out or mixed deconstruction. Steel shears handle structural steel, sheet piles, rails or heavy reinforcement. Tank cutters are used in special operations for severing vessels and pipelines, particularly where low-spark or cold cutting is required. In tunnel logistics, this range enables a task-adapted, safe approach.

Geology, material and component: influence on the choice of tool

The choice of tunnel tool depends essentially on rock parameters (e.g., compressive strength, bedding, jointing), the reinforcement ratio and the geometry of the components. Brittle, jointed rocks split more readily, while tough concrete with high reinforcement favors cutting and crushing tools. For mixed cross-sections, a combination of splitting and shear work is often expedient.

Key criteria

1. Strength and structure of the material (rock/concrete, reinforcement, inserts).
2. Accessibility and space conditions (overhead, recesses, shaft areas).
3. Permissible emissions (noise, dust, vibration) and the ventilation concept.
4. Hazards in the vicinity (utilities, structural condition, water ingress).
5. Carrier machine, hydraulic output and tool weight.

Workflow in the tunnel: from drilling to removal

A structured workflow increases safety and efficiency. The following has proven effective:

1. Survey of existing conditions and definition of removal boundaries, including assessment of structural stability.
2. Selection of tools according to material, emission limits and accessibility.
3. Set up the energy supply (hydraulic power packs), check hose routes.
4. Preparatory work: marking, and drilling where required for splitting cylinders.
5. Removal with concrete demolition shear, combi shears or splitting devices in coordinated stages.
6. Separation of reinforcement/metal with steel shears or multi cutters.
7. Material logistics: backhauling of debris, interim storage, transport out.
8. Inspection, touch-up and surface preparation for subsequent works.

Safety, health and environmental protection

Work in tunnels requires special care. As a general rule, only work in accordance with recognized best practice, applicable occupational safety regulations and with qualified personnel. The following notes are general and not case-specific:

• Dust and noise reduction through coordinated methods, water mist and suitable extraction.
• Vibration limitation using splitting methods or metered shear work.
• Safe hose routing, regular visual inspection of couplings and pressure lines.
• Check load uptake and standing areas; overhead work only with suitable protective measures.
• Identify hazardous substances and utility lines in advance; secure cutting operations accordingly.

Maintenance and operation in an abrasive environment

Tunnel job sites are exposed to dust and moisture. Consistent care extends tool life and increases operational safety:

• Regular cleaning of shear jaws, splitting wedges and cylinders; protection from mud and splash water.
• Inspection of wear parts (blades, jaws, wedges) and timely replacement.
• Check hydraulic oil quality, filter condition and line tightness.
• Documentation of operating hours and load peaks for preventive maintenance.

Selection and sizing: practical guide

For suitable tool sizing in tunnels, the following points are decisive:

• Required splitting force or shear force relative to material strength.
• Tool geometry suited to the task (narrow jaws for recesses, large opening for massive components).
• Hydraulic parameters (pressure, flow rate) and available power pack capacity.
• Total weight and ergonomic handling in confined spaces.
• Interchangeability of inserts (e.g., cutting, crushing) for changing site conditions.

Execution quality and typical sources of error

Quality in tunnels depends on material knowledge, tool selection and execution. Common mistakes can be avoided:

• Unsuitable borehole geometry during splitting leads to uncontrolled crack patterns.
• Excessive stroke settings on shears increase loads on both carrier and component.
• Insufficient ventilation heightens emission risks; planning and monitoring are essential.
• Lack of interim inspections encourages over-removal and rework.

Role of Darda GmbH in the context of tunnel tool

Darda GmbH approaches tunnel tool with a focus on safe, controlled and efficient removal. Tools such as concrete demolition shear and stone and concrete splitters are central components in many situations—from selective concrete demolition to blast-free rock removal and strip-out. In addition, hydraulic power packs, combi shears, multi cutters, steel shears and tank cutters help to address complex underground tasks appropriately.