Deep drilling is a central method in concrete demolition and rock excavation as well as in selective dismantling when components are to be deliberately weakened, separated, or prepared. In combination with hydraulic tools such as rock and concrete splitters or concrete demolition shears, precise cut and separation lines are created that minimize vibrations and protect adjacent structures. In tunnel construction, during building gutting, in special demolition, or in natural stone extraction, the borehole serves as a defined access and initiation point to purposefully manage material stresses and safely release components.
Definition: What is meant by deep drilling
Deep drilling refers to producing boreholes with greater depth and defined geometry in concrete, reinforced concrete, masonry, or rock to enable a technical function. This includes inserting splitting cylinders, installing anchors, relief and dewatering purposes, investigations, as well as creating breakout and separation joints. In demolition and special demolition, deep drilling is usually executed in a borehole grid to pre-weaken components and then separate them in a controlled manner using hydraulic tools. Key quality characteristics are positional accuracy, diameter, depth, inclination, and the surface finish of the borehole wall.
Applications of deep drilling in concrete demolition and rock excavation
Deep drilling is a universal starting point for demolition and geotechnical measures. Typical applications are:
- Preparation for rock and concrete splitters: Boreholes define splitting lines; inserted splitting wedges or splitting cylinders are used to break the concrete or rock cross-section in a targeted manner.
- Preparation for concrete demolition shears: Borehole weakening reduces cross-sections and exposes reinforcement so mechanical cutting and shearing operations require less force.
- Relief and dewatering boreholes: Discharging pressure and water for stabilization, especially in tunneling and rock engineering, to control loads and keep the work area dry.
- Anchor drilling and injection drilling: Temporary stabilization prior to deconstruction or for auxiliary structures, such as shoring and support scaffold.
- Separation joints: Series drilling with close spacing creates intended fracture planes as an alternative to sawing when access, noise, or vibration limits require it.
- Test drilling: Locating reinforcement, voids, and layer sequences for planning demolition or extraction measures.
Drilling methods and tool selection
The choice of drilling method depends on material, depth, diameter, and objective. For concrete and rock, the following methods have proven effective:
Rotary and rotary-percussive drilling
Rotary percussion combines impact energy and rotation. It is suitable for reinforced concrete and massive natural stone when rapid advance with medium diameters is required. Hard, wear-resistant bits are used in rock; in concrete, reinforcement-capable bit geometries are selected.
Core drilling (wet/dry)
Diamond core drilling produces highly accurate, smooth borehole walls with minimal edge spalling. It is often used in sensitive areas, such as during building gutting in existing structures, to limit noise and dust emissions. Wet core drilling binds drilling slurry; dry core drilling requires effective dust extraction.
Down-the-Hole Hammer (DTH)
For greater depths and diameters in rock or very dense concrete, the in-the-hole hammer is a robust option. The impact energy acts directly at the drill bit, increasing directional stability and penetration rate. Compressed air handles cuttings transport.
Flushing, extraction, and cooling
Water, air, or combined media transport cuttings and cool the tools. The choice influences cutting speed, tool life, and cleanliness of the workspace. In interior areas, low-dust methods take priority; wastewater must be properly captured and disposed of.
Planning, drilling pattern, and parameters
Careful planning of the drilling is crucial so that subsequent work steps with rock and concrete splitters or concrete demolition shears proceed efficiently and safely. Relevant parameters are:
- Diameter: determined by the tool to be used (e.g., splitting cylinder) and the required splitting energy.
- Depth: must fully intercept the planned separation line; for massive components, staged depths are advisable.
- Inclination and direction: control crack propagation and ease the removal of cuttings and water.
- Edge distances: prevent breakout at visible edges and protect adjacent components.
- Spacing (pattern): tighter for tough, highly reinforced concrete; wider for brittle natural stone.
Sequence and pacing
The drilling sequence follows the structural logic of the component: relieve first, then close the separation lines. During splitting, work from the free edge into the component to keep stress redistribution controlled.
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Deep drilling creates the prerequisite for material-appropriate separation using hydraulic tools:
- Rock splitting cylinders and rock and concrete splitters: They require boreholes with matching diameter and sufficient depth so the splitting body can safely introduce force. A clean borehole wall promotes load transfer.
- Hydraulic power units: supply the necessary energy for splitting or cutting operations. Short hose runs and clear setup areas result from forward-looking drilling planning.
- Concrete demolition shears, combination shears, multi cutters: benefit from pre-drilled weakening, enabling cuts at strong nodes with reduced reaction forces.
- Steel shears: Drilling can expose reinforcement bundles so steel can be cut precisely.
- Tank cutters: In specialized deconstruction concepts, drilling enables venting, measurement, or flushing openings prior to safe separation.
Fields of application at a glance
Concrete demolition and special demolition
For foundations, bridges, or massive columns, deep drilling creates defined separation joints. In combination with concrete demolition shears, it enables controlled piece sizes for handling. Low-vibration methods are advantageous in inner-city locations.
Building gutting and cutting
In existing buildings, core drilling creates openings for utilities, auxiliary support structures, or as starting points for further separation work. Dust and noise control take precedence; extraction and water management are integral.
Rock excavation and tunnel construction
Series drilling defines excavation contours. In fractured rock, relief boreholes reduce stresses; in competent rock, deep drilling supports controlled splitting and guides breakouts, especially in tunnel construction.
Natural stone extraction
Vertical and horizontal drilling patterns define the splitting direction along bedding and joint planes. Mechanical splitting via splitting cylinders reduces blasting vibrations and protects the block.
Special applications
For hard-to-access components, contaminated areas, or underwater, methods and drilling technology adapt to the boundary conditions. Mobility, remote operability, and media management are decisive.
Safety, emissions, and environment
Dust, noise, vibrations, and water must be actively controlled. Appropriate personal protective equipment, extraction systems, and low-splash cooling reduce exposures. Legal requirements regarding emissions, wastewater, and occupational safety depend on the location and activity and should be considered early. Low-vibration combinations of deep drilling and mechanical splitting help protect sensitive neighborhoods.
Quality assurance and documentation
- Pre-check: Material investigation, rebar detection, location of utilities.
- Verification: Record diameter, depth, inclination, and position of each borehole.
- Borehole conditioning: Flush, blow out, or vacuum until fully clean.
- Logging: Document pattern, parameters, media consumption, and special occurrences.
Typical failure patterns
- Hole drifting due to incorrect starting technique or unsuitable bit.
- Edge breakout caused by insufficient edge distance or excessive feed forces.
- Insufficiently cleaned boreholes with residual cuttings that impair force transfer during splitting.
Practical guide: From idea to borehole
- Define the objective: splitting, separating, relieving, investigation.
- Analyze the component: material, reinforcement, load paths, adjacent use.
- Select the method: rotary-percussive, core drilling, DTH—adapted to depth and diameter.
- Plan the drilling pattern: define spacing, edge distances, inclination, and depth.
- Create an emissions plan: extraction, cooling/flushing, wastewater and slurry handling.
- Execute the drilling: control starting technique, feed, rpm/impact rate.
- Clean and check the borehole: dimensional accuracy, free of cuttings.
- Continue processing: insert splitting cylinders, separate with concrete demolition shears and shears, secure and remove pieces.
Key parameters and guidance
The decisive parameters arise from material strength, degree of reinforcement, the desired splitting or cutting effect, and the tool used. In practice, coordinating borehole diameter and pattern with the available splitting cylinders and the component thickness has proven effective. Greater component depths often require staged borehole depths or multi-row patterns to separate homogeneously. All values must be verified for the specific project.
Combinations and alternatives
Depending on the objective, deep drilling is combined with wire sawing, joint cutters, controlled chiseling, or high-pressure water jetting. The right sequence reduces forces, material losses, and emissions. Where explosive methods are excluded, the combination of drilling and mechanical splitting offers a low-vibration alternative with high dimensional accuracy.