Trench excavation refers to the targeted creation of narrow, elongated excavations for utilities, cables, drainage systems, and foundations. The scope ranges from small inner-city cross-sections to deep utility corridors in transport construction. Decisive factors include the stability of trench walls, controlled dewatering, and safe routing for pipes or protective conduits. Whenever firm subsoil, boulders, or existing structural elements obstruct the excavation, controlled removal techniques are used. In this context, concrete demolition shears as well as rock and concrete splitters are important, as they operate with low vibration in confined work areas and have proven themselves in utility construction as well as in concrete demolition and special demolition.
Definition: What is meant by trench excavation
Trench excavation is the creation of a linear earth excavation with a width often small relative to its depth in order to install utilities, channels, media pipes, cable routes, or strip foundations. The process includes route investigation and staking, securing with side slopes or shoring, dewatering, removal of obstacles, construction of the pipe bedding, installation, and layer-by-layer reinstatement of the excavated material or suitable backfill. The goal is a stable, durable route with defined elevation, slope, and bearing capacity. Depending on subsoil, groundwater, traffic loads, and surrounding development, the trench is constructed open with side slopes or using shoring systems. In rock or highly consolidated ground, mechanical or hydraulic methods for rock and concrete disintegration are used, including splitting techniques and shear tools.
Workflow, construction methods, and typical equipment in trench excavation
Trench excavation follows a structured sequence from route planning through execution to compaction. In practice, a section-by-section approach with manageable daily outputs proves effective, coordinated with traffic control, shoring, material logistics, and dewatering. Obstacles such as concrete foundations, legacy utilities, or rock are handled in a controlled manner using suitable tools. Hydraulic power packs supply mobile attachment and handheld tools, increasing flexibility in confined spaces.
Typical sequence at a glance
- Investigation and preparation: utility locating, subsoil investigation, staking, traffic management, and, where applicable, ordnance clearance checks.
- Constructing the trench: excavating with bucket or grading bucket, setting side slopes or installing shoring, establishing dewatering.
- Obstacle management: breaking rock, selectively removing concrete elements, cutting reinforcement; in confined conditions using splitting techniques and shear tools.
- Bedding and pipe installation: preparing the subgrade, placing a sand or gravel layer, installing the pipe or protective pipe, sidefill and cover.
- Backfill and compaction: layerwise placement, compaction to specification, restoration of the surface.
Tools and methods in hard ground
- Rock and concrete splitters as well as rock splitting cylinders apply controlled splitting forces in the borehole to loosen rock, boulders, or massive concrete with low vibration and minimal dust.
- Concrete demolition shears grip, break, and downsize concrete elements within the trench cross-section; in combination with steel shears, reinforcement steel is cut.
- Combination shears and multi cutters accommodate material changes, for example at crossings involving different materials.
- Hydraulic power packs provide the energy needed for mobile shear and splitting tools—independent of carrier size.
Handling obstacles: rock, concrete, and reinforcement along the route
In the utility route, teams frequently encounter concrete remnants, old foundations, pile heads, manholes, duct banks, or bedrock. The choice of method affects safety, quality, and environmental emissions.
Rock and boulders in the trench
Where blasting is not an option for legal or neighbor-related reasons, splitting techniques enable targeted reduction of the rock. After drilling to defined depths, splitting wedges or cylinders are applied to open the rock in a controlled manner. Block sizes can thus be tailored to haulage and subsequent backfilling. This approach is particularly useful in rock demolition and tunnel construction and in sensitive areas with vibration limits.
Concrete elements in the trench cross-section
If the route intersects existing foundations, cover slabs, or old channels, concrete demolition shears are the method of choice for precise layer-by-layer removal. The selective approach supports accurate deconstruction to defined edges, for example at connection details. Reinforcement is cut cleanly with steel shears, facilitating source-separated haulage and recycling of materials.
Utility crossings and material changes
At crossings of existing utilities, controlled, material-friendly opening is crucial. Combination shears or multi cutters allow quick switching between concrete, metal, and plastic components. This reduces rework and shortens intervention times in existing structures, which is relevant in concrete demolition and special demolition as well as during special operations under live traffic.
Subsoil, stability, and dewatering
The stability of trench walls depends on soil type, moisture content, stratification, slope angle, and traffic loads. In cohesive soils, steeper walls may be temporarily stable, whereas non-cohesive sands ravel quickly. With groundwater or perched horizons, dewatering is required to construct the subgrade and bedding.
Shoring and side slopes
- Side-sloped trenches: suitable when space is available and no adjacent loads act.
- Shoring systems: required in confined conditions, under traffic, near structures, or at greater depths.
The choice of system is based on a geotechnical assessment. In areas with vibration constraints, low-vibration methods are advantageous, giving splitting techniques and shear tools a tactical edge over impact or driving methods.
Dewatering and subgrade
Lowering the water level should only go as far as necessary to safely construct bedding and pipe alignment. Filter stability, settlement sensitivity, and neighboring buildings must be considered. The subgrade is prepared to be load-bearing and even; local irregularities (e.g., rock noses) can be selectively removed with rock and concrete splitters without widening the entire trench.
Quality assurance: bedding, installation, and compaction
The durability of a pipeline largely depends on the bedding and uniform support of the pipe. A fine-grained, compactable material forms the pipe bedding; sidefill prevents displacement, and cover protects against point loads. Compaction is carried out in layers to the required degrees of compaction. Measurements of elevation and slope ensure proper drainage—especially for foul and stormwater sewers.
Material separation and processing
Selective deconstruction in the trench reduces disposal costs. Concrete demolition shears produce well-sortable fragments; steel shears cut reinforcement steel for separate haulage. Splitting techniques minimize fines and dust, which benefits the reuse of excavated material (where permitted).
Emission, vibration, and noise control in sensitive environments
In densely built-up areas, near sensitive facilities, or when working under traffic, minimizing vibration, noise, and dust is paramount. Low-vibration methods such as splitting rock and downsizing concrete with shear tools reduce risks to existing utilities and structures. Water mist and controlled cutting sequences reduce dust peaks. This is particularly relevant in the context of building gutting and cutting as well as concrete demolition and special demolition.
Safety and legal framework (general)
Work in trenches is subject to strict safety requirements. These include protection against slipping and collapse, gas monitoring, safe dewatering, lifting and securing loads, and safe access. Carrier machines and hydraulic attachments must be operated within their operating limits. Legal requirements, technical rules, and local directives must be observed; in case of doubt, qualified specialist contractors should be involved. When working on or near existing utilities, close coordination with network operators is required.
Sustainability, resource conservation, and disposal
Careful handling of materials begins with on-site separation in the trench: soil, concrete, asphalt, steel, and rock are collected separately. Concrete demolition shears and steel shears support source-separated recovery. Where geotechnically permissible, the excavated material can be processed and reused; otherwise, orderly disposal is carried out. Splitting techniques generate few fines and reduce transport volume through targeted fragmentation. This reduces trips and conserves resources.
Special operations in trench excavation
Special situations require special technology. These include deep shafts for drives, launch and reception pits, crossings at critical points, or exposing utilities in contaminated areas. In such cases, tools are needed that work precisely and in a controlled manner in tight spaces. Rock and concrete splitters, concrete demolition shears, combination shears, multi cutters, and steel shears are proven for this purpose. Tank cutters are used as a special solution when containers or tank bodies must be properly segmented along the route—always with appropriate protective measures and only by suitably qualified personnel.
Planning, sectioning, and hydraulic power packs in the site workflow
For a smooth process, sectioning is crucial: short open times, coordinated shoring and backfilling cycles, and continuous material logistics. compact hydraulic power units supply shear and splitting equipment independently of the carrier, speeding up the changeover between excavation, obstacle removal, and backfilling. By combining excavator performance with hydraulic handheld or attachment tools, the trench cross-section is produced precisely, without unnecessary overwidth and without unduly burdening the neighborhood.