1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) ALAN AULD GROUP THE LAGUNA PROJECT Excavation and Support of Large Underground Excavations at Depth John Elliott Managing Director Alan Auld Engineering Ltd

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Chamber Excavation and Support The Laguna project requires the construction of state of the art scientific detection equipment to be housed in chambers deep underground and will involve the excavation of very large chambers, for whichever type of detector is eventually chosen. All three types of detector involve the construction of domed chambers of large diameter For the purpose of the talk we have based the details on the Glacier liquid argon type detector

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) What is Laguna A complex/mining/civil engineering/process engineering/science project involving many disciplines. There will be many challenges to overcome to ensure a successful project built on time and on budget.

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Laguna- The Challenges Safety - Very large chamber excavation to support Safety - Large tank containing liquid argon at very low temperatures Safety – Safe operation and maintenance for workforce & technicians Safety/Cost – Needs to be operational for many years with safety backups Cost – Dependant on many factors, including site specifics and logistics Site Selection - Fair and open decision process to select the best site based on all relevant factors Project Management- Ensure smooth communication between all specialists

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Laguna Next phase Development of Underground Construction Plan & Costing Operation Strategy- Costing & Risk Analysis This work will include planning the chamber construction, costing and interface with the tank construction in greater detail, to gain greater certainty of outcome.

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Proposed Areas of AAG Support for Next Phase Technical appraisal of suitability of each site Independent commercial appraisal of each site proposal Independent vetting of overall project costs and programme Independent design check on local engineering for each proposal Assistance in identifying & resolving technical issues and problems Construction project management services to science team acting as an interface resource in planning the project and coordinating the work of other technical specialists. Management of the construction process leaving the science team to concentrate on science

Alan Auld Engineering Ltd Specialists in underground engineering design for mines and civil engineering projects in rock and soft ground. Worldwide presence and work load in a variety of specialist areas, including mine shaft and decline access design in UK, Europe, North & South America and Asia Underground chambers & excavations for civil and mine projects Deep underground nuclear waste repository design work Specialist engineering for materials handling and construction logistics 1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0)

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Alan Auld Engineering Areas of Expertise Underground engineering in both superficial deposits and rock Specialists in ground support in difficult ground at all depths Geotechnical processes including artificial ground freeze design Problem solving, construction sequencing & methodology Design of temporary & permanent excavation support Design & detailing of steelwork and materials handling 3D modelling & finite element analysis General underground contractor’s technical support services from tender to project completion.

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Laguna Site Characteristics The site chosen must be suitable in terms of its geology. The rock must be strong and essentially self supporting. Three sites have been chosen for further study. Frejus, France – Mountain site utilizing exiting road tunnel for access. Umbria, Italy – Greenfield mountain site with tunnel access. Pyhasalmi, Finland– Deepest mine in Europe – shaft access Support systems installed will mobilize the inherent strength of the rock to make it self supporting. The overall macro behaviour of the rock can be predicted reasonably accurately. At a micro level the rock behaviour is more difficult to predict due to localised rock fractures and minor changes in rock parameters.

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Design Before construction is commenced complex design analysis will be required using state of the art computer software to ensure the excavation and tank structures remain stable. This is important as the tank will house 100kt of liquid argon at -180 degrees Celsius. A failure of the excavation roof would have a catastrophic impact on the tank and its contents. The consequences of an event such as this could easily lead to loss of life and the end of the project and therefore all risk scenarios must be planned for and designed out. For this reason the design shall be rigorously independently peer review checked using modern software.

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Design- Modern Finite Element (FE) analysis software will be used to check overall stability and define excavation support requirements.

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Things can go wrong when the geology is variable, or not fully understood, or where the support system is not designed correctly Safety on the Project is Paramount

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Roof and side wall support will be provided by both steel rod type rock bolts and multi strand cable bolts. These are installed into predrilled holes and grouted in place. Cable bolts are often pre-tensioned. These systems work by assisting the rock to support itself like a voussoir arch Excavation Support

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) The rock bolts and cable bolts act to tie the rock elements together in the elastic zone around the excavation, allowing the freestanding arch segments or ‘Voussoirs’ to support the ground above it. Roof Support

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Construction Sequence

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0)

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0)

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Safety of the excavation is paramount and the roof will be monitored for convergence using a variety of instrumentation systems. Monitoring of the Chamber Excavation

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Excavation will be by drill and blast using automated computer controlled drilling equipment known as a ‘ Drilling Jumbo’ Excavation & Support Equipment

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Loading out the blasted rock will be by diesel powered front end loading equipment and load haul dump (LHD) mine trucks.

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Roof supports will be installed from the working area using mechanised drilling and installation equipment

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Access tunnels and laboratories areas will be driven full face

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Typical top heading excavation completed for a metro station. Once the roof is secure the excavation continues downwards, blasting and loading out the floor.

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) ROAD Hydro-electric schemes typically involve the construction of large underground turbine halls. Whilst Laguna is unusual in terms of depth and span there are precedents.

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) ROAD Large excavations in the Slanic salt mine in Romania

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) ROAD Caverns at Slanic These very large caverns are self supporting and are excavated in halite (rock salt)

1 South Parade, Doncaster, South Yorkshire, DN1 2DY, UK Tel: +44 (0) Fax: +44 (0) Thank you