# Presentation: 159116

## The Deep Underground Science and Engineering Laboratory (DUSEL) -------------Challenges and Opportunities for the Rock Engineering Community

- Chris Laughton
- Fermi National Accelerator Laboratory
- Universities Research Association
- United States Department of Energy

## Large-Deep ExcavationsA Research Proposal

- Large-Deep _Permanent_ Cavern
- 1 km + is deep
- 50 m + span is large
**ZERO PRECEDENTS**
- Not such a trivial engineering exercise..
- Merits the consideration of an Engineering R&D package – working with H&H engineers
- Deep & High Stress Mining Workshop Abstract...

## DUSEL - A Basic Research Facility

- Multidisciplinary Program..
- “Pure” Research - no specific end-use targets (e.g. military, nuclear waste..) that could limit research scope
- Wide-ranging expertise and cross-cutting ideas for the “next” generation” of underground experiments
- Many research proposals already submitted....
- Large, Diverse Research Platform..
- Multi-level Campuses
- Laboratory Clusters
- Self-Contained (Workshops, Offices..)
- Isolated Research Stations
- Alcoves for Geo-Bio Drilling/Probing
- _Engineering_ Research Sites, etc...
- Small to Large Scale studies all possible
- Methods, Machines, Materials Proving Ground
- Keystone Research Program - partnering makes it work
- Expensive - partners share the costs = economy of scale
- Shared ideas too.. synergy is already taking place..
- DUSEL Research >> Sum of its parts..
- Exciting “Frontier Research”
- Good “Research Value”

- “Four-in-One”

## Not Just Sciences, Engineering too..

- DUSEL offers opportunities to advance the state-of-the-art in underground engineering;
- _Not only_ to meet science needs...
- Excavations
- spans up to 60 m
- _under high stresses_ (2km + deep)
- Liquid Argon containment in a “warm rock” environment
- Accelerator stability requirements
- Clean-Dry environments
- Etc..
- _But also_ for engineering research..
- Fundamental Studies in
- _Rock Mass under Stress_ (Pre-Failure & Post-Failure...)
- Water in Fractured Rock (Flow, Pressure etc..)
- Technical Innovation..
- Education and Training
- Etc..

## Proposed Sites - Hard-Blocky Rocks

- Located in the Black Hills ~ 60km N-W of Rapid City, SD.
- Housed in footprint of recently closed Homestake Mine.
- In meta-sedimentary and meta-volcanic rock mass.

- Located in front range of the Rocky Mountains, ~ 80 km W of Denver, CO.
- Adjacent to and accessed from the operating Henderson mine.
- In a granitic rock mass.

- Homestake Mine

- Henderson Mine

## Large-Deep Cavern Challenging Design Criteria..

- State-of-the-industry design-construction format adequate for most early design/construction work (~small, ~shallow excavations adjacent to/within previously mined volumes), but...
- Later excavation may “push the envelope” notably for permanent _Large-Deep_ cavern construction. Research may be of value*..
- Consider research – potential value to the project
- Incorporate and perform research tasking as part of  the overall program – > ensure _shared research ownership by academia and industry_
- Ideally maximize excavation research performed _during the earliest phases of construction_ so that recommendations can be incorporated in to subsequent design work

- ~1.2 to 1.5 km

- 60 m

- 180 m

- Physics Detector Needs
- Proton Decay - UNO)

- 60 m

## Larger Physics Caverns

- Physics Laboratories
- Accelerator Detectors ~ 0.1 to 0.2 km
- Large Electron Positron
- Large Hadron Collider
- Shielded Detector ~ 0.5 to 2 km
- Kamioka, Japan
- Gran Sasso, Italy
- Korean Invisible Mass Search
- Sudbury, Canada
- Civil-Mining “Limits” for Large _Permanent_ Excavations (>15m span)
- Span Limit ~ Gjovik
- Depth Limit ~ Western Deep Mine
- Larger, “Self-Supported” Cavities...
- Standing Stopes - 50 m+ span
- Natural Caverns - 200 m+ span

- No _intrinsic_ reason why the Large-Deep Cavern requirements cannot be met at site

## Cavern Spans in Industry

- Cavern Span Histogram (>15m) – ’05 literature review of existing data bases

- Engineering R&D

## Cavern Depths in Industry

- Most industrial caverns have drive-in access
- Adequate design cover at depths <0.5km
- Fresh (~unweathered) host rock mass
- Below water table (hydro + oil/gas storage..)
- Within a “Preferred Range” of In Situ Stresses
- High enough to mobilize shear strength, but
- Low enough not to induce zones of overstress
- Horseshoe Cross-section
-  Large-Deep Caverns...
**Fracture +** **Stress Regime**...cost/risk drivers
- Engineering Feasibility vs. _Economic Viability_
- Any engineering feasibility study will not find that the cavern can’t be built! (CL opinion!)
- Ultimately - viability of Large-Deep experiments may be limited by cost/risk - down-size early to avoid spending design $ on unaffordable options..
- “Strategic Research” to reduce costs/risk...maybe good value...

- Cavern Depths Bar Plot

## Large-Deep Physics Caverns in Japan

- At the Kamioka Mine two domed caverns:
- Kamiokande ~ 20m dome
- Super-K ~ 40 m dome

- Twin horseshoe caverns are planned:
- Hyper-K ~ 50m span

## Large-Deep Physics Caverns in Europe

- At Frejus, Franco-Italian Border, 3 Domed Caverns are planned ~ 50m span adjacent to an alpine road tunnel....an early concept

- At Gran Sasso, Italy 3 Horseshoe-Section Caverns ~ 20m span have been constructed adjacent to an Apennines road tunnel.

- Gran Sasso

- Fréjus

## Large-Deep Physics Caverns in North American

- In the United States, various detector options are under consideration, larger ones include:
- MPD ~ 50 m domed cavern
- UNO ~ 60 m horseshoe cavern
- LAr - 70m domed cavern

- In Canada, a ~20 domed cavern was Constructed with the boundaries of the Creighton Mine, adjacent to a deep shaft within the country rock.

- SNO

- UNO

- MPD

- LAr

## A Likely Hard-Blocky Scenario

- Assuming that more marginal conditions (soil-like fracture zones, dikes, heavy water inflows..) can be located by site investigation and avoided. There are still issues...
- Engineering Factors..
- Stress
- Structure
- Water
- (Variability)
- Acting Singly or in Combination

- Both mines have relatively low inflows

## Rock Structure ~ Scale Dependent

- Discontinuity-bound blocks, if unfavorably oriented -> liable to slide or fall-out under the action of gravity

- Fall-Out Considerations
- Impact..._Scale-Dependent_
- Severity (block size)
- Frequency
- Design Mitigation
- Requirements
- Size
- Orientation
- Shape
- Rock Engineering
- Shear strength
- Normal force
- Etc..

- Fewer Potential Blocks/Wedges

- Smaller Span/Diameter

- A modicum of fracture can be a good thing -> reduce ability to store large amount of potential rock burst energy

## Stress ~ Scale Independent

- At Depth In Situ Stress will increase
- Deep campus ~ 2km deep
- Overstress encountered at depth at/adjacent to proposed DUSEL sites and at other Deep Lab sites e.g. Kamioka, SNO, Gran Sasso..at CERN squeezing behavior
- Key engineering research topic at DUSEL too..
- Rock Mass Behavior(s) under stress
- Rock Support System(s) performance

- Overstress Considerations..
- _Impact is Scale Independent _
- Problems in smallest tunnel/largest cavern
- Mitigation more problematic in large openings
- Rock bursting particularly dangerous.. potential MUST be addressed early
- Design Mitigation..
- Requirements
- Shape, Orientation ~ ovaloid
- Align major axis to principal stresses
- Proportion axes to principal stresses
- Rock Engineering
- Treatments - property modifiers &/or standardizers
- Pre-Condition
- De-stress
- Reinforcement
- Bolts, “Ribs”, Dowels
- Liners
- Swimming Pool, Steel Tanks
- Rock-Burst Containment (shotcrete, mineguard..)

- A modicum of stress can be a good thing – normal stress mobilizes shear force against gravity sliding or fall-out

## Spatial Variabilitylarger volume - > more variability

- Geo-Variability: a fact of geo-engineering life..
- Classically-trained engineers beware
- Rock properties and loading vary spatially more than is soils..
- In a hard rock setting, one can find significant volumes of..
- Fresh intact rock many times stronger than concrete
- Residual clay or running sand..

- Change itself is a challenge!
- Site condition changes require methods/means responses

- concrete

- rock

## Engineering Factors in Combinations

- In addition to stress and fracture..
- Water Pressure and Flow
- Long-Term Creep or Deterioration
- Etc..
- Site Investigation only gets you so far..
- Every site is somewhat unique, but most issues can be mitigated/managed using established technologies.. the challenge is to predict/identify all the problems (severity, locations and extents) and address them before excavation begins..
- Avoidance...ideal
- Mitigation
- through “negotiated” adjustment in end-user requirements
- Use cost-effective engineering technology (mitigate short and long-term problems most cost-effectively)
- Manage!
- In all but the most uniform of rock masses one generally needs to plan to address a variety of problems...

## Large-Deep Research Program

- Current Status
- Several concepts and solutions (detectors/sites in combination)
- Significant divergence in costs/durations...decision drivers
- Minimal discussion of the nature, frequency and size of risks
- Need engineering framework to optimize/compare experiments..
- Proposal - to support a Large-Deep Cavern Design
- Build “engineering consensus” between the various proposals (initially generic hard rock setting.. site-specific after down-select)
- Develop self-consistent engineering models that provides for a “first look” at cost, schedule, and risk - _experiment viability maybe a direct function of construction cost, schedule and risk_
- Identify, detail and schedule-out an engineering research roadmap to support the design and construction of Large-Deep Cavern(s).
- Provide design feedback/interact with to end-user WG

## Proposed Tasking (a work-in-progress*)..

**1)** **Identify and Document Core End-User Requirements & Site Constraints**
- Requirements - Identify Main Options and Establish Requirement Lists
- Best Guess Site Constraints - Host Rock Mass at depth in a Hard-Blocky Rock
- Develop a short-list of key early site investigation activities (_STRESS & FRACTURE.._)
**2)** **Develop Excavation and Support Concept(s**)
-  End-user/geo-parameters driving design
**3)** **Baseline Schedule and Parametric Cost Model(s)**
-  Parameters driving cost/duration
- Bottoms-up approach with simplification for key “what if” parameters ($ & t sensitivity)
**4)** **Risk Analyses**
- Comprehensive Risk Analysis..major multi-year undertaking - credibility on the line!
- Highlight dependence on rock mass...
**5)** **Research Roadmap ~ “VE-style”**
- a) Identify and prioritize “worthwhile” research opportunities that could be incorporated in to the design and construction of DUSEL (faster, cheaper, better, more reliable) with additional emphasis on the value of research to the underground industry-at-large
- b) Integrate research activities in to the Baseline Schedule - if it isn’t planned it will not get done!
- c) Develop a detailed research “roadmap” and scope for more promising ideas

- * Coordination with Henderson & Homestake

## Task 1 - Requirements & Constraints

- Space - Size, Shape, Orientation, Volume, Connections..
- Structures (end-user driven)
- Anchors, partitions, rails, cranes, trays, racks, shields..
- Short and long-term movements.. vibrations, de-stress, overstress, swell..
- Services (ideally some reuse of construction utilities)
- HVAC, Water, Power, Communication, Data Acquisition..
- ES&H (on-site and off-site)
- Egress, access, air quality, noise, groundwater, lighting etc..
- Optimize engineering aspects of design
- _enhance self-supporting ability of rock and_
- _ __improve practicality and _
- _safety of construction _
- _while respecting core functions_

## Task 2 - Excavation & Support Concepts

- Likely Adverse Behaviors..
- Fall-Out under Gravity
- Burst &/or Squeeze under Stress
- Just add water......?
- Extents and severities?
- Ground Treatment
- Pre- and Post-systems to alter strength, permeability..
- Excavation Sizing/Phasing
- Blasting techniques..cautious? Pre-, post split etc..
- Avoid overstressing etc..
- Reinforcement Systems
- Pre- and post-systems –active/passive (Cables, bolts dowels, ribs, etc..)
- Liner Systems
- Pop Rock Containment – shotcrete, mineguard..
- Watertight “overlap, wallpaper-lining swimming pool

- Pre-Support Concepts

## Task 3 – Schedule & Cost Models

- Even if it is technically-viable can we afford it?
- Large Span requirement may be a major cost/risk driver..
- Understand cost drivers and their influence on costs
- Technical trade-offs first
- Involve an experienced cost estimator - viability probably more likely to be deciding factor than feasibility - feasibility study = self-fulfilling prophesy (avoid engineers’ “can-do” response! – get a hard dollar estimators perspective)
- Address these hard questions first.. research needs &/or scope reduction?

- Cost-Effective Layout -> for Volume

- Long-Section

- Cross-Section

- Stability
- Costs

## Theta 13 Scope Underground Construction(Cal Poly Workshop March 2004)

- Braidwood
- 2 Vertical Shafts - 10m Ø & 120m deep
- 1 Tunnel - 300m long 8m span horseshoe tunnel. Uniform 1% tunnel gradient to shaft.
- Firewall-Isolated Excavations accessed from the Running Tunnel/Shafts
- 3 Detector Rooms
- 1 x Near Detector Room - 32 m long 12 m span
- 2 x Far Detector Rooms with 8 m span access tunnels - 16 m long x 12 m span
- 1 Underground Emergency Refuge (at end of tunnel)
- 6 m long 4m span
- separately ventilation 2-hour fire rated wall
- Utility/Sump Room 4 m horseshoe
- nominal 8m length

- Diablo Canyon
- 1 Portal Entrance  -10 m long
- 1 Tunnel - 850m long 6m span horseshoe tunnel. Uniform 1% tunnel gradient to portal.
- Firewall-Isolated Excavations accessed from the Running Tunnel
- 2 Detector Rooms
- 2 x 40m long 10m span chambers
- 1 Underground Emergency Refuge
- Nominal 6 m long 4m span
- Equipped with 2-hour fire rated wall and self-rescuers

- http://theta13.lbl.gov/calpoly04/talks/Laughton

## Cost & Schedule - The Estimating Process (Cal-Poly Workshop March 2004)

- Proposal should be based on a reliable cost estimate.
- “The only kind of estimate that is worth anything is the one that is clearly defined on paper and bears the signature of the author.” J.S.Redpath, (1980). Theta 13 has underground estimates that are:
- Well-documented and  site-specific - developed “from the bottom up”
- Estimated independently by an experienced, tunneling professional.
- Reviewed independently by experienced, tunneling professionals.
- Underground estimate scopes include:
- Underground Structural Shell and Utilities
- Utilities left in place (power, ventilation, water, air lines, communication..).
- Permanent facilities installed (groundwater pumps, elevators and refuge firewall, surface water treatment facilities).
- Estimates exclude:
- Engineering, Design, Inspection and Administration (EDIA), Surface Buildings, Technical Installations, Life Cycle Costs

## Cost & ScheduleBottoms-up Estimates’ Bottom-lines

- Braidwood
- Duration 39 months
- “First” detector site delivered in17 or 20 months (far or near)
- Cost $34.6M
- General Mobilization ~3.3M
- Shafts ~ 15.9M
- Tunnel ~ $9.1M
- Detector Rooms ~ $6.0M
- Refuge ~$0.3M
- 40% contingency.
- Initial  comments: equipment selection, crew sizing and productivity OK. Shorter shafts could use cranes.

- Diablo Canyon
- Duration 24 months
- Cost $23 M
- General Mobilization ~$2.9M
- Portal Cost ~$0.3M
- Tunnel ~ 16.5M
- Detector Rooms ~$3.2M
- Refuge ~$0.1M
- 30% contingency.
- Initial  comments: equipment selection, crew sizing and productivity OK. Some relatively conservative production factors - mucking might be done more quickly.

## Task 4: Risks - Threats & Opportunities

- For such an unprecedented combination of depth and span, it will be critical to establish a disciplined approach to risk identification, mitigation and management form the start:
- Complement design team expertise – look for broadest technical-geotechnical perspective.  Underground there is a room for difference_s_ in opinion.. (like a horse race...so many expert...so little consensus)
- Select those who have been _responsible_ for similar work
- Nothing wrong with optimism but, the more realistic the Baseline....the lower the contingency...
- Cost + Contingency may be prohibitive...Some _research_ seed money invested early-on as part of the design effort may help address issues of cost and/or risk:
- Site investigation and characterization
- Design and construction

## Task 5 - Research “Metro” Map

- Be selective..not all engineering research appropriate for DUSEL..
- Resources are limited
- Best performed elsewhere by others
- Generally, not enough reward..too risky, too long, too costly..
- DUSEL Research Shortlist
- Hand-picked review team
- Expertise + “opinion-diversity”
- Brainstorm ideas first
- More than one route..
- Consider relative merits..
- all ideas worthy - not an academic exercise or productivity issue
- Risk versus reward...
- Intrinsic value to Industry too
- Achieve strong shortlist consensus
- Integrate in to the Plan..

- Potential Engineering Research Areas

## Cavern Research in Design e.g. Exploration

-  Designers need better data in order to produce better designs and contracts..
- Key Questions..partially answered
- Rock Structure
- Stress Regime

- Too many surprises...

- Cross-Hole Tomography

- Engineering Press - Headlines

## Cavern Research in Construction e.g. Design as you Go

- Office designs ~ at best, only as “good” as ground predictions are accurate...
- Discrepancies between the “as-predicted” and “as-found” are commonplace...
- There is a need to adjust methods/means to as-found conditions in _Real-Time_...
- Real-Time design feedback at the heading
- Map/Photogrammetry/models/images...geologic/technical conditions at the heading
- What lies beyond the rock walls and heading?....Monitor rock drills, geophysics etc..
- _Monitor Deformation and Stress.. (before, during after...long-term creep too)_
- Adjust rock treatment, excavation, reinforcement and lining system(s)
- Update predictions of “what’s ahead”..probing, geophysics, monitoring of the drill rig etc..
- Model versus Reality “Instant Interface”.. ”Design-as-you-go”..

- Design as you Go

- What miners do at the heading - absent designer feedback!

## Cavern Research During Early Operatione.g. Rock Mass under Stress

- Rock blocks dedicated to rock engineering research...
- Site Preparation
- Site Investigation..boreholes, geophysics
- Pre-Instrumentation
- Stress Measurements
- Main Variables
- Multi-Pass Reaming Processes
- Stresses - pillar thickness
- Pre-Treatments (conditioning..)
- Support Systems - types and timing
- Potential measures/observations
- “Ground Truthing” (“mine-backs”)
- Pre-’ & Post-Failure Phenomena
- Load Transfer rock->supports
- Hard Rock Creep

- “Organ Pipe”
- Configuration

## Technical Innovation During Operation Too..e.g. Mechanized Excavation

- ...some ideas for rapid tunneling research, Laughton ‘02

- DUSEL offers many techno-opportunities too..
- Instrumentation
- Equipment
- Materials
- Methods
- Training
- Etc..

- Other engineering disciplines too: Safety, Environment, Elec-Mech, Aquifer, Geothermal..

## Conclusions

- In general, DUSEL research can contribute towards a better understanding of the _rock mass as an engineering material_ and promote _innovation underground_.
- In particular, research targeted at delivering a safe, cost-effective Large-Deep Cavern facility can contribute significantly to the viability of “frontier _physics._”
- Key (Engineering) People - Charles Fairhurst (PI), Mark Kuchta (CSM & Henderson Mine), Bill Roggenthen (SDSMT &  Homestake Mine).. all to be involved with the program once the Site CDR’s are delivered to NSF (June 23rd)....
- Key Web Sites (program TBD..proposals welcome..)..
- _[General Site - http://www.dusel.org/](http://www.dusel.org/)_
- Henderson - http://nngroup.physics.sunysb.edu/husep/
- Homestake - _[http://www.lbl.gov/nsd/homestake/](http://www.lbl.gov/nsd/homestake/)_