Landslide

A landslide is a gravitational mass movement of soil, loose rock, or weathered rock on natural or artificial slopes. It affects structures, transport routes, and open excavations and thus shapes planning and execution in concrete demolition, rock excavation, tunnel construction, and natural stone extraction. In such situations, controlled material removal, low vibrations, and safe working distances are crucial. Depending on the situation, products from Darda GmbH are used within the application areas mentioned, such as concrete demolition shears for dismantling damaged support structures or stone and concrete splitters for low-vibration removal of unstable rock sections.

Definition: What is a landslide

A landslide is understood as the downslope movement of soil or loose-rock masses along a slip surface. It is triggered when downslope-directed shear forces exceed the material’s shear strength. Typical forms are rotational and translational slides; transitions to debris flows (stream-like movements) or creep processes are possible. Relevant geotechnical parameters include cohesion, internal friction, pore water pressure, grain structure, and the slope angle. Landslides differ from rockfall (freely falling or bouncing blocks) and from settlements (slow subsidence), but they can occur in combination in natural and infrastructure environments.

Causes, triggers, and geotechnical framework conditions

Landslides arise from an interplay of geological structure, water regime, and external loads. Common triggers are heavy rainfall and thaw, which increase pore water pressure and reduce shear strength. Construction activities can also destabilize slopes, for example, through steep cut faces, additional superimposed loads, or interventions in drainage.

• Slope geometry: slope angle, height zoning, cuts and fills.
• Material properties: grain size distribution, plasticity/bonding, weathered layers, layer boundaries.
• Water: saturation, perched and groundwater, inadequate drainage, capillary rise.
• Dynamics: earthquakes, vibrations, freeze–thaw cycles, vegetation change.
• Construction operations: load redistribution, effects of excavation and deconstruction, traffic loads.

In construction and deconstruction contexts, the combination of softened soils, steep cuts, and construction loads is particularly critical. This requires methods that release material in a controlled manner, make removal stackable, and minimize additional vibrations.

Landslide in construction and deconstruction contexts

Landslides endanger work areas, equipment, and adjacent structures. Areas prone to sliding require a sequence of securing, draining, and careful removal. In concrete demolition and special deconstruction as well as in strip-out and cutting, a gentle approach to existing structures and subsoil is essential to avoid secondary slides.

Concrete demolition and special deconstruction on landslide-prone slopes

Damaged retaining walls, abutments, or shotcrete shells are preferably dismantled with low vibration. Concrete demolition shears allow concrete to be nibbled off in partial quantities, reducing masses in a controlled way and shedding loads step by step. Reinforcement can then be cut with steel shears or multi cutters. Such methods help maintain stable construction states when structural stability has already been reduced by a landslide.

Rock excavation and tunnel construction in unstable zones

In rocky slope sections, blocks are often detached not by blasting but by controlled splitting. Stone and concrete splitters as well as rock splitting cylinders generate tensile stresses in the rock and separate along natural weakness zones. This approach reduces vibration inputs into sensitive areas, for example, on existing tunnel tubes or near loose slope packages.

Natural stone extraction and special applications

In natural stone extraction and in special applications, blocks must be detached in a defined manner and handled safely. Splitters help keep the breakout moment low, while combination shears and multi cutters support work on inserts, nets, or anchors. In special scenarios—such as at landslide-prone facilities—tank cutters can be used to remove vessels or steel components and reduce superimposed loads—always following prior expert assessment and with appropriate protective measures.

Investigation, monitoring, and early warning signs

Systematic investigation forms the basis for planned measures. Geological logging, soundings, laboratory shear tests, and hydrogeological analyses clarify the conditions. In parallel, monitoring helps detect changes in good time.

Typical early indicators on the slope

• New cracks in soil, asphalt, or walls; offsets at joints and edges.
• Bulging at the slope toe, steps at the slope crest.
• Spring outflows, turbid water, waterlogging after rainfall.
• Tilting of poles, trees, fences, or facades.

Pragmatic steps during ongoing operations

1. Close off the hazard zone and reroute traffic and equipment flows.
2. Control water: temporary channels, gravity drainage, filter gravel.
3. Reduce loads: remove material in small batches; avoid large-area superimposed loads.
4. Stabilize: temporary support bodies, nailing, shotcrete after structural verification.
5. Further measurements: continuously check settlement markers, inclination, and water levels.

Prevention, stabilization, and structural measures

Effective strategies combine drainage, geometric adjustments, and structural securing. The aim is to reduce pore water pressure, improve shear strength, and achieve a more favorable load distribution. In all phases, appropriate removal techniques are advisable to minimize additional risks.

Drainage and terrain modeling

• Divert surface water: swales, berms, channels with erosion protection.
• Subsurface drainage: drain lines, filter bodies, localized relief wells.
• Optimize slope angle: flatten, add steps or berms.
• Use vegetation: root reinforcement, erosion control mats, site-appropriate species.

Material removal and relief cuts

If slope loads are locally too high, stepwise removal reduces the driving forces. Stone and concrete splitters make it possible to detach blocks and concrete components along defined lines. Concrete demolition shears subdivide massive elements without impact. Steel shears and multi cutters cut reinforcement and embedded parts. This creates a controlled tactic: small-scale, with short lifting paths and manageable intermediate states.

• Advance securing: nets, catch ditches, temporary supports as planned.
• Sequencing: from crest to toe only after release; often the reverse is sensible—from the toe upward to strengthen the slope toe.
• Continuous control: after each lot, check stability and adjust water routing.
• Drive and energy: size hydraulic power packs appropriately and protect hose routing against tearing.

Safety, organization, and legal aspects

When working in landslide-prone terrain, occupational safety and third-party protection take priority. Clear exclusion zones, spotter-based communication, redundant escape routes, and a weather-dependent operating regime are recommended. Measures for protection against rockfall, dust, and noise must be defined for the specific site. Legal requirements can vary by country and project; they should be considered at an early stage. Binding statements cannot be made here. In general, a geotechnical expert plan, a documented risk assessment, and coordination with the competent authorities are advisable.

Workflows for deconstruction and removal on landslide-prone sites

1. Analysis: survey of terrain and structures, water pathways, potential slip surfaces.
2. Concept: securing and drainage strategy, lot sizes, equipment selection.
3. Pre-securing: catch and guide structures, temporary supports, traffic management.
4. Controlled removal: use of concrete demolition shears in concrete demolition and stone and concrete splitters in rock—each section by section.
5. Cutting and clearing: reinforcement with steel shears or multi cutters; special components with tank cutters if needed.
6. Aftercare: complete drainage, regrade the slope, establish erosion protection.
7. Monitoring: observe crack widths, settlements, and water levels beyond the construction period.

Selection of materials and methods in Darda GmbH’s application areas

Depending on project phase and geology, the suitable combination of tools and methods varies. In concrete demolition and special deconstruction, concrete demolition shears support low-vibration partial deconstruction of unstable support bodies. In rock excavation and tunnel construction and in natural stone extraction, stone and concrete splitters and rock splitting cylinders enable precise, controlled detachment of rock without blasting vibrations. In strip-out and cutting, combination shears, multi cutters, and steel shears are added to cut metallic inserts. For special applications, specialized cutting methods—such as with tank cutters—are available, always aligned with stability, environmental conditions, and the protection objective of the intervention.