Underground tunneling encompasses the planning, construction, stabilization, outfitting, maintenance, and deconstruction of structures below the ground surface. It ranges from tunnel and gallery construction to shafts, caverns, utility corridors, and underground facilities. Characteristic are confined work spaces, high safety requirements, low vibration levels, and controlled emissions. Therefore, hydraulic tools with precisely metered force are often used, such as rock and concrete splitters for non-explosive removal or concrete demolition shears for selective concrete deconstruction and re-profiling.
Definition: What is meant by underground tunneling
Underground tunneling refers to all construction activities for creating, extending, upgrading, operating, and deconstructing underground voids. This includes tunnels, galleries, shafts, cross passages, caverns, and utility tunnels. The work is performed by mining methods (e.g., shotcrete method, conventional advance), mechanical methods (e.g., cutting head or milling methods), or non-explosive mechanical methods. Core elements are excavation (advance), support and lining, as well as material logistics, dewatering, and ventilation. Depending on the environment, vibration, noise, and dust limitations are particularly important, which is why controlled methods and tools are preferred.
Techniques and process chain in underground tunneling
The process chain begins with investigation (geology, hydrology, as-built analysis) and selection of the excavation method. This is followed by auxiliary structures (accesses, shafts), excavation with simultaneous or subsequent support, lining, outfitting (dewatering, cable trays, ventilation), and, depending on the project, later deconstruction. Tools are selected according to boundary conditions: rock strength, discontinuities, water ingress, access, ventilation capacity, permissible vibrations, and requirements for component separation. In sensitive areas, rock and concrete splitters as well as concrete demolition shears have proven effective due to low-vibration, accurate work.
Excavation methods and removal tools
Drilling and blasting
Conventional advance combines boreholes, charging, detonation, mucking, and support. Its advantage is high performance in hard rock. Limitations arise from vibration and noise thresholds, explosives logistics, and timed lockout periods. In urban environments, near existing structures, or in facilities with sensitive equipment, blasting may be partially or entirely omitted.
Non-explosive demolition with rock and concrete splitters
Hydraulic splitting technology creates a defined split in boreholes. Pressure is introduced into the rock or concrete via wedges or cylinders, and cracks open in a controlled manner along the weakening plane. This method is low-vibration, quiet, and well controllable. It is suitable for re-profiling, cross passages, openings, niches, invert raises, freeing obstructions, and the deconstruction of concrete in existing structures. Rock splitting cylinders and rock and concrete splitters achieve high splitting forces with a compact design, which is crucial in the confined tunnel profile.
Mechanical removal and milling
Cutting heads, mills, and hammer attachments remove material continuously. Performance depends on strength and abrasiveness. They usually produce lower far-field vibrations than blasting, but require sufficient ventilation for dust extraction and consistent tool management.
Support and lining
Immediately after removal, support follows, tailored to geology and intended use. Typical elements are shotcrete, fiber or steel reinforcements, rock bolts and anchor bolts, lattice girder beams, pipe umbrellas, and temporary props. In shield tunneling, segments take over the lining. A precise match to the target geometry succeeds when excavation and fine removal are low-vibration; concrete demolition shears and multi cutters are suitable in the concrete domain to trim edges cleanly or selectively expose reinforcement.
Material logistics, processing, and haulage
Material flow is central to performance and safety: loosening, crushing, loading, and hauling. In tight cross-sections, portable hydraulic power units facilitate energy supply for splitters, concrete demolition shears, or combination shears. An adapted crushing strategy (e.g., splitting instead of hammering) reduces vibrations and equipment load. Haulage is by tracked vehicle, rail, conveyor belt, or hoisting containers via shafts, depending on space, distance, and ventilation.
Concrete demolition and special deconstruction underground
In existing structures, selective, low-vibration methods are in demand. Concrete demolition shears separate concrete components in a controlled manner, protect adjacent structures, and enable sectional removal on slabs, walls, and foundations. Combination shears and multi cutters complement this when cutting reinforcement and structural steel. For massive blocks or foundation remnants, rock and concrete splitters as well as rock splitting cylinders are a proven option to free large cross-sections without blasting. Steel shears are added when girders, rails, or lining elements must be deconstructed.
Rock demolition, tunnel construction, and shaft work
In rock excavation, discontinuities, joints, RQD, and water ingress determine the method, as in rock demolition and tunnel construction. Non-explosive splitting allows pinpoint removal along existing discontinuities. For shafts, splitting cylinders help widen inverts, open channels, or remove embedded components. In tunnel connections and at breakthrough, concrete demolition shears minimize edge spalling on inner linings and component cracking in adjoining structures.
Underground natural stone extraction
In underground quarries, preserving the rock is key. Splitting technology enables block-true extraction with clean separation surfaces and minimal crack propagation. Post-processing is mechanical, while hydraulic power packs supply the tools with the required power. Haulage remains efficient thanks to defined block sizes.
Strip-out and cutting in existing installations
In utility tunnels, cable ducts, or caverns, plant components must be removed. Concrete demolition shears allow removal of foundations and brackets. Steel shears cut trays, girders, and frames. Tank cutters are used for dismantling suitable vessels or pipelines in underground facilities, provided the boundary conditions allow it. A thorough hazard analysis and coordination with ventilation are mandatory.
Special operations with limited vibrations
In sensitive sections (e.g., under buildings, near existing utilities, or during ongoing operations), low vibrations as well as minimal noise and dust are crucial. rock and concrete splitters and concrete demolition shears enable controlled interventions, for example for niches, cross passages, cable penetrations, or repairs on inner linings. The approach is sectional, well documented, and supported by close monitoring.
Geotechnical boundary conditions and monitoring
The choice of methods and tools is guided by rock mechanics, rock pressure, water ingress, gas flow, and temperature. Classification systems support forecasting. Measurement and monitoring systems track convergences, settlements, vibrations, and air quality. Where limits for vibration and airborne dust are tight, projects benefit from non-explosive methods and from crushing strategies using splitting and shear tools.
Occupational safety, health protection, and environment
Safety takes precedence. Measures address ventilation, dust and quartz protection, noise, lighting, escape routes, fire protection, electrical safety, and ergonomic handling. Hydraulic tools should be secured on the pressure side, hoses inspected, and power packs adapted to the ambient airflow. Legal requirements and official conditions must be considered project-specifically; statements here are general and do not replace case-by-case assessment.
Planning, quality, and documentation
Step-by-step planning with a variants comparison (blasting, milling, splitting, shears) provides clarity on performance, emissions, and costs. Quality assurance includes target-actual comparisons of geometry, concrete cover, joints, and fillets. For deconstruction, the separability of construction materials is essential. Tools such as concrete demolition shears and combination shears support single-material removal by selectively separating concrete and steel.
Sustainability and resource efficiency
Underground operations benefit from low-emission, energy-efficient methods. Non-explosive splitting reduces vibrations and secondary damage. Selective deconstruction with concrete demolition shears facilitates recycling, reduces transport volume, and improves reusability of materials. Demand-controlled hydraulic power packs lower energy use and waste heat in the heading.
Application areas at a glance
- Concrete demolition and special deconstruction: Selective removal of inner linings, foundations, and installations with concrete demolition shears, complemented by splitters for massive elements.
- Strip-out and cutting: Removal of brackets, channels, and trays; separation of concrete and steel with combination shears, multi cutters, and steel shears.
- Rock demolition and tunnel construction: Advance, profile correction, and niches using non-explosive splitting or mechanical removal.
- Natural stone extraction: Blockwise extraction using rock splitting cylinders and precise crushing.
- Special operations: Work under strict emission limits, near existing structures, or during ongoing operations with low-vibration methods.