Geology and Rock Engineering

In construction projects that involve extensive rock work, it always pays to have professional ground investigations and reliable geotechnical and environmental analyses. Using the information from geological pilot investigations together with geotechnical computations, it is then possible to optimize installations in rock and adapt them to meet the needs and wishes of the client.

Our Geotechnical and Environmental Team is made up of professionals including mining engineers, geologists, environmental engineers and CAD operators. We have experience of the most complicated projects in Scandinavia with regard to large-scale blasting work in close proximity to existing facilities such as tunnels, buildings and other sensitive structures. We work in all phases of the project, from the initial concept, feasibility study and system analysis to the seeking of planning permission, contract organization and detailed planning. Nitro Consult also prepares the construction documentation and is often appointed Construction Manager, whereby we administer all necessary controls and carry out inspections and follow-up of the finished product.

Nitro Consult offers the following consulting services in connection with both existing infrastructure and new construction and civil-engineering projects:

• Investigations and Feasibility Studies
• Field Investigations
• Rock Quality Assessments
• Rock Facility Design and Planning
• Engineering Geology
• Rock Mechanics
• Engineering Geological Risk Analyses
• Structural Surveys
• Construction and Project Management (See Construction Management)
• Vibration Control (See Risk Analysis and Vibration Measuring)

We accept commissions for underground civil-engineering works, cuts and foundations in rock with regard to both new and existing installations. Using previous rock investigations and archive material as a basis, we determine the need for geological ground investigations such as geologic and geotechnical field mapping, seismic investigations, probe drilling, diamond core drilling etc. Analytical results from the ground investigations are then used to determine the facility’s placement, geometry and reinforcement needs. Through sampling and the evaluation of analytical findings, we also carry out investigations into the rock’s suitability as a construction material for facilities such as roads and railways.

Risk analysis and structural surveys
Nitro Consult prepares engineering geological risk analyses that focus on rock mechanical conditions. We survey and map the rock, identify risks in the carrying out of different actional alternatives and dimension the geotechnical measures based on probabilities and the desired final safety margin. Nitro Consult also carries out final- and maintenance surveys of both surface and underground facilities in rock.

Project references
Projects in which our Geotechnical and Environmental Team has worked in recent years include the following:

  • Stockholm Public Transport (SL), Karolinska Branch: Ground investigations and planning for the proposed ‘Karolinskagrenen’, a northern extension of the Stockholm Metro Green Line from Odenplan Station to the Norra Station district and Karolinska University Hospital.
  • Swedish Rail Administration (Banverket), Stockholm City Line (Citybanan): Ground investigations and planning for a 6-km double-track railway tunnel under central Stockholm expressly for commuter trains, currently under construction. In this SEK 16.8 billion (USD 2.4 billion) project, the 65 m2 rock tunnels for (twin) single-track sections and 110 m2 tunnels for double-track sections require over 1 million m3 of hard rock to be excavated sensitively by drill-and-blast. The scheme includes a parallel service tunnel, two 260-m x 220 m2 under-city passenger interchange stations, two underwater concrete tunnels and a 1.5 km railway bridge.
  • Swedish Road Administration (Vägverket), Stockholm Northern Link Expressway (Norra Länken): Planning of the 5-km north-eastern link in the prospective Stockholm Inner Orbital Expressway. Currently under construction, the Northern Link will run through 2 x 2-4 lane tunnels beneath built-up city districts that are extremely sensitive to blast vibrations. All together there will be 9 km of rock tunnels and 2 km of concrete tunnels in the Northern Link.
  • Swedish Power Network (Svenska Kraftnät), CityLink: Feasibility study for a series of 20 m2 tunnels for CityLink , a planned 400-kV power line from the north to the southeast of Stockholm, much of which will run under the city through new and existing tunnels.
  • Swedish Rail Administration (Banverket), Svealand Railway (Svealandsbanan): Ground investigations and planning for the construction of several new double-track sections, overtaking points and sidings on this busy commuter railway, which runs southwest of Stockholm along the southern shore of Lake Mälaren.
  • NCC, Tollare Road Tunnel, Nacka, Stockholm: Ground investigations, pilot study and planning for the construction of a 126-m rock tunnel in a built-up community a few kilometers east of Stockholm.
  • Swedish Road Administration (Vägverket), Stockholm Northern Communities Expressway (Norrortsleden), Törnskogs Road Tunnel: Final survey of twin 100-105 m2, 2-lane road tunnels 2100 m in length, which form part of a newly built 16-km, mostly 4-lane highway that now connects the outer northern communities of Stockholm and the key northern radial freeways, the E4 and E18.
  • Swedish Road Administration (Vägverket), Lindö Tunnel, Ekerö: Maintenance survey of fully lined 180-m road tunnel west of Stockholm.