Excavation of pit refers to the entirety of earthworks and rock excavation for constructing an excavation pit or a shaft for foundations, basements, utility line construction or special foundation engineering. Depending on the subsoil, tasks range from loosening soft soils to accessing rock. In inner-city locations, low-vibration methods are often used, particularly when existing foundations, pile heads or concrete components are encountered in the ground. In these cases, hydraulic rock and concrete splitters and concrete pulverizers can be professionally integrated into the sequence of operations, as is customary in the application areas of concrete demolition and special demolition, rock breakout and tunnel construction or special operations.
Definition: What is meant by excavation of pit
Excavation of pit means the planned removal and excavation of soil, rock and any existing concrete or masonry remnants to create a stable and operationally safe excavation pit. This includes loosening the material, loading, haulage or interim storage, groundwater control, securing the pit walls and creating working spaces. The choice of method depends on subsoil, groundwater, geometry (depth, slope angle, dimensions), surroundings and the requirements regarding vibrations, noise and dust. For rock or heavily reinforced concrete, hydraulic methods are often used to allow controlled and accurate work.
Methods in excavation of pit: Loosen, load, haul
The execution of excavation of pit follows a methodical chain. First the in-situ ground is loosened, then loaded and hauled away. Depending on the material, different methods are used:
- Soils (loose to semi-firm): loosening with excavators, ripper tooth (excavator), possibly with prior ground improvement; transport with loaders and dump trucks.
- Rock or very hard ground: controlled pre-breaking using rock wedge splitters (low-vibration), alternatively ripper tooth, hydraulic breaker or—if permitted—blasting technology; followed by loading.
- Concrete in the ground (foundations, pile heads, slabs): deconstruction with concrete pulverizers in coordinated cutting and breaking sequences; exposing and cutting the reinforcement with hydraulic shear or steel shear.
Hydraulically powered equipment is supplied by suitable hydraulic power units, which is advantageous especially on confined, emission-sensitive construction sites. This allows low emission limits to be maintained in special operations and components to be released precisely, as required in special demolition.
Planning and subsoil: From investigation to execution
Robust subsoil and groundwater investigations form the basis for selecting the excavation method and the pit shoring. Investigations determine material classes, stratigraphy, bearing capacity, settlement and water conditions. From this follows the technical planning of slope angles or shoring (e.g., soldier pile shoring, sheet pile walls), groundwater lowering and the logistics chain for haulage and interim storage.
Stability and shoring
The excavation pit must be stable and operationally safe during all phases. Slopes are only created where sufficient space is available and the slope remains stable over time. In existing built-up areas or along traffic zones, tie-back anchored shoring systems are used. When working within shoring, coordination of loosening, loading and temporary bracing is crucial to limit deformations.
Groundwater control
Groundwater and stormwater significantly influence the excavation pit. Options include open dewatering, filter wells, underwater concrete or impermeable pit enclosures. Each requires adapted pumping technology, settling or treatment stages and proper discharge. In rock or concreted old foundations, hydraulic splitters can be used to create targeted openings for drainage or filter wells without impacting the surroundings.
Handling rock and concrete remnants in the excavation
If excavation of pit encounters rock, block layers or old concrete, the material must be loosened appropriately. Low-vibration methods are often a prerequisite in densely built areas to avoid cracks, settlements or impairments to neighboring structures.
- Rock removal: Splitting with rock wedge splitters enables controlled fracture lines along boreholes. Advantages include low vibrations, precise piece sizes and reduced noise emissions—relevant in the application areas of rock breakout and tunnel construction.
- Concrete foundations and pile heads: concrete pulverizers break concrete layer by layer and expose the reinforcement, which can then be cut with hydraulic shear or steel shear. This allows components within the pit area to be dimensioned accurately.
- Hydraulic power packs: A demand-appropriate hydraulic fluid volume and a constant working pressure are prerequisites for uniform splitting and cutting operations. In confined workspaces, spatially separating the power pack and the tool is advantageous.
Material management, recycling and disposal
Professional mass management reduces costs, transport effort and environmental impact. Materials should be separated already during excavation: soils by quality, rock and concrete by suitability for reuse.
- Separation: Cleanly separated fractions (soil, rock, concrete, reinforcement) facilitate reuse and disposal.
- Recycling: Concrete debris from deconstruction with concrete pulverizers can be processed as recycled construction material, provided quality requirements are met.
- Disposal: Suitable disposal routes must be provided for non-recyclable materials. Classifications are made in accordance with applicable regulations, to be verified on a project-specific basis.
Urban excavation of pit: Emission control and precision
In city centers, emission limitation, precision and construction sequence take priority. Low-vibration methods avoid impacts on sensitive neighboring structures, utilities or monuments. Hydraulic splitters and concrete pulverizers fit into such concepts because they allow precise control of removal steps.
Construction logistics
Short routes, coordinated time slots and suitable containers or dump trucks minimize downtime. For small-scale demolition within the excavation area, the combination of hand-held hydraulic tools and a central hydraulic power pack has proven effective.
Safety and health protection
Occupational safety starts at the planning stage. Hazards arise from falls, tipping and slipping risks, haul traffic, hydraulic pressure, noise and dust. Protective measures include stable traffic routes, impact protection at the shoring, regular inspections of lifting devices and tools, as well as dust suppression and appropriate safety equipment.
Vibrations, noise, dust
Low-vibration splitting methods and step-by-step removal with concrete pulverizers reduce emissions. Measuring and monitoring measures can be contractually specified to comply with limit values.
Quality assurance, tolerances and documentation
The target geometry of the excavation pit must be checked regularly, for example via survey control points and intermediate inspections. For foundations and blinding layers, flatness and pit depth are decisive. In rock or old concrete in the subground, documented exposure of the founding level is helpful, including photo documentation of removal stages and the methods used.
Interfaces with adjacent trades
Excavation of pit touches numerous trades: special foundation engineering (piles and shoring), concrete demolition and special demolition (old foundations), gutting works and cutting (contact with existing structures), rock breakout and tunnel construction (connection to shafts or galleries) and natural stone extraction (comparable release principles). Hydraulic tools such as concrete pulverizers, Multi Cutters or rock wedge splitters form a technical bridge here, as they can be used in both demolition and excavation.
Typical project sequence in excavation of pit
- Investigation and planning: subsoil, groundwater, excavation pit boundary conditions, logistics.
- Pit shoring and groundwater control: install shoring, prepare water management.
- Loosening the material: soil, rock, concrete—method-appropriate and low-emission.
- Loading and transport: aligned with masses, routes and interim storage.
- Removal of obstructive components: deconstruction of foundations and pile heads with concrete pulverizers, cutting the reinforcement.
- Fine profiling and base: achieve final elevation, inspection and documentation.
- Handover to structural work or special foundation engineering: lean concrete, drainage, protective measures.
Special features in special operations
Under confined or sensitive conditions—such as in plant areas, at protected objects or during night work—processes with a high degree of control are required. hydraulic splitters allow segmented removal; hydraulic power packs can be operated remotely to decouple exhaust and noise sources from the workspace. Where steel components are encountered, steel shear or Multi Cutters can perform the separation.
Economic efficiency and sustainability
Economic and ecological aspects go hand in hand in excavation of pit: short haul distances, material-appropriate methods, source-separated sorting and recycling reduce costs and environmental load. Low-vibration methods prevent damage to neighboring buildings and reduce consequential costs. The targeted interplay of excavator technology and hydraulic tools—such as concrete pulverizers and rock wedge splitters—increases process reliability and the predictability of the construction sequence.