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Title: NAGS
/ GRI-19 Cooperative Conference Review |
|
|
Over 200 designers, engineers, manufacturers, fabricators, students, academics, and association members attended the NAGS / GRI-19 Cooperative Conference held December 14-16, 2005, at the Flamingo Hilton in Las Vegas, Nevada. After a full day of pre-conference gatherings (NAGS and IAGI Board Meetings, IAGI General Assembly, GSI Focus Group Meeting, Geo-Institute Task Force to discuss the developing document, Suggested Practices for Reinforced Walls and Slopes, and Geo-Americas Organizing Committee Meeting), an ice breaker was presented in the exhibit hall on Tuesday evening.
Conference-goers started the morning with GRI's first session, Use of Low Permeability Soils in Geosynthetic Reinforced Walls. Five speakers comprised the session (see speakers and papers below) followed by an enthusiastic panel discussion. There was much cross banter on where the problems lie in relation to failure - an age-old conversation. Dean Sandri caused a murmur in the crowd when he said that there was no shortage of structural engineers in the process, the problem is that "finding a geotechnical engineer is impossible! Structural engineers are designing the walls, but they must have a geotechnical background." He continued, "We aren't doing a good job of policing our industry! It's our own fault that these walls aren't getting built properly." More backing and forthing...the blame, or culpability, then jumped to the field and improper construction. Regarding low permeability soils and failure, Michael Simas argued quite eloquently - complete with slides - that he feels it is not so much an internal drainage design problem, but a construction/mulitple-stacking/compaction problem. While Barry Christopher agreed that yes, it is critical to stack one block at a time, gravel fill, and compact as you go along...he is "not seeing this dictated in the design." Ball in designer's court. Don Armstrong of Anchor Wall Systems took the floor and disagreed strongly. He said, "The specification is there. It is a quality control issue. But just because you write it - which we do - doesn't mean it gets done." Back to the field. Jim Collins, author of NCMA's Design Drainage Manual, stated, "We need to change the contract method. We have to design walls for owners, not contractors." Barry Christopher then noted, "We have to reverse the practice." He is concerned that right now, the situation is "use drains in these instances, and really it should be drains must always be used - always - unless you can prove that you don't need it." Roberto Montalvo implored the audience to go to the source. "We need to talk to the people in the field." Meaning, explain the "where and why of the geosynthetic to the builder in the field. It's our responsibility!" Quality control. Bob Koerner put it succinctly, "Poor construction will defeat even the best of designs." John Paulson got up and spoke on Chip Fuller's behalf (he had lost his speaking voice to one very cold and windy last sailing day of five). He read from Chip's notes,
Bob Koerner mentioned that Home Depot, a company that will be needing SRWs in its geographically diverse potential locations around the country, is taking action in this arena.
After the presentations were made, Thursday's panel discussion focused first on how the engineering of heap leach pads is "pushing the envelope." Rick Theil wanted to commend the forward designs in heap leach pads saying, "it is some of the finest engineering I have seen." He sees more slippage in landfills. There is a lower factor of safety in mining, but there is less slippage, despite the fact that there is no "difference in design philosophy." Charley Cobb, who works in mining and dams, disagreed, "The level of engineering in mining is poor." He commented that because the heap leach pad was not a landfill, the engineers push the envelope more, however he feels that care must be taken into account because "they are still fairly sensitive environments." A query from the audience brought up the question of current monitoring instrumentation. Mauricio Ossa said that "one thing that is not very well known is conductive liners." Rick Theil added that the 'most exciting area is the geoelectric surveys. It is nice to have conductive liners, but you don't need them. With the water lance or dipole methods, you can find defects." One example he used was a case where holes in a liner were found in under six meters of ore in Argentina. Dhani Narejo expressed concern in putting all the proverbial eggs in one basket regarding design and lab tests. "We see more damage in a field test than a lab test. Limitations on punctures depend on the field." He suggests that one should "do a test fill, and see what it takes. Fill material, drain cover, traffic, load - all are different each time. Trial and error is the best design you could possibly have." Getting back to factors of safety for existing and new heap leach pads, Jay Swihart, mentioned that he is "not seeing any huge factors of safety" and is now "concerned that we are at the limit for the load of the pipe." Rick Theil answered by saying that while "most designs have pipe now, the regulations to have them there don't exist." He wonders if pipes are even needed. "We've probably overkilled the pipe design." He then demonstrated, making a large circle with his index fingers and thumbs, that when a pipe collapses, it makes two smaller pipes (bringing his index fingers and thumbs together in the center). "It's probably going to get crushed, but we design the flow to take that." Below are the presentations made throughout the event. Please click here to order a copy of the proceedings. NAGS 2005 Conference Session #1 - Reinforcement in Static and Seismic Applications Parametric Analysis of Reinforced Soil Walls with
Different Backfill Material Properties Influence of Various Parameters on Seismic-Induced
Permanent Displacement of Geosynthetic Reinforced Segmental Retaining
Walls Experimental Investigation of Geofoam Seismic
Buffers using a Shaking Table Landfill
Construction over Peat Deposits – A Case History Session #2 - Geosynthetics in Based
Reinforcement Approach Embankment Supported by Geotextile
Reinforced Sand Platform over Vibro Concrete Columns- A Case Study Use of Geosynthetics for
Stabilizing Recycled Ballast in Railway Track Substructures Geosynthetic-Reinforced Column-Supported
Embankment Design Guidelines Theoretical Analysis of Bending Stiffness
Test of Geosynthetic-Reinforced Base Layer Interpretations of Behaviors of Reinforced Geotextile
Composites Session #3 - Geosynthetics for
Reinforcement in Pavement Systems and Perspective on Geosynthetic Education Probabilistic Analysis of Geosynthetic-Reinforced
Unpaved Road Subject to Subgrade Comparison of a Mechanistic-Empirical Design Model
to Measured Performance for Base-Reinforced Pavements Design and Build of a Small-Scale MSE Wall:
January 2005 Geo-Challenge Competition Session #4 - Student Papers Full Scale Geosynthetic-Reinforced Column-Supported
Test Embankment The Short and Long Term Compressive Behavior
of HDPE Geonet at Different Inclined Conditions Numerical Investigation of Geofoam Seismic
Buffers Using FLAC Use of GCLs to Control Leakage Through
Geomembrane Defects Under High Hydraulic
Heads Multi-Scale Assessment of Geotextile-Geomembrane
Interaction Geotextile Separators for Dust Suppression
in Gravel Roads Practical Construction Details
Used to Build an Instrumented
Flexible Pavement with Geosynthetics Session #5 - Geosynthetics in
Drainage and Construction Site
Run-off Geotextile Tube: Filtration
Performance of Woven Geotextiles
under Pressure Case History: Failure of
a Geotextile Turbidity
Curtain Geotextile Biofilters for
Wastewater Treatment Geotextiles
for Filtering Water and Oil Fluids An Evaluation of Potential
Clogging of Geonets
and Geocomposites Due to
Suspended Soil Session #6 - Geosynthetics
in Containment
Applications Geosynthetics
Research and Applications
in the Mining
and Mineral Processing
Environment Current
Research on Dynamic Shear
Behavior
of Needle-Punched
Geosynthetic
Clay Liners Investigation
of PVC Liner
Leakage
in a
Very Large
Evaporation
Pond Impacts
and Limitations
of Quality
Assurance
on Geomembrane
Integrity Lessons
Learned
from
a Geomembrane
Liner
Failure
in a
Cold Environment Leachate
Recirculation
and
Potential Concerns
on
Landfill Stability Aluminium
Migration
Through
a
Geosynthetic Clay
Liner GRI-19 Conference Use of Low Permeability Backfill Soils in Geosynthetic Reinforced Walls and Slopes Low Permeable Backfill Soils
in Geosynthetic Reinforced Soil Walls: State-of-the- Geosynthetic Reinforced MSE Walls and Slopes with
Fine Grained Fills: International Full-Scale MSE Test Walls Back Drainage Design and Geocomposite Drainage Materials Drainage Recommendations
for MSE Walls Constructed with Marginal Fills Thursday12/15/05 Morning Session Use and Design of Geosynthetics in Heap Leach Systems Geomembranes Used in Heap Leach SX-EW Mining: A
Manufacturer's Perspective Heap Leach Facility Liner Design A Tale of Two Conditions: Heap Leach Pad versus Landfill
Liner Strengths Designing for Vertical Pipe
Deflection Under High Loads Seismic Design/Analysis of Heap Leach Embankments Friday 12/16/05 Morning Session Continued Hot Topics in Geosynthetics Activites
in GSI-Korea – GCI-PCP of Geogrids Long-Tern Plastic Pipe Stiffness Advances on
the Use of Geosynthetics in Hydraulic Systems Geosynthetic
Engineering Concerns from a Manufacturer’s
Perspective Geosynthetic
Manufacturing Concerns from a Consultant’s
Perspective Design of Pressurized Liquid Distribution System for
Landfill Liquids Addition and Augmentation Geosynthetic Installation
Damage Testing - A Status Report Posters Aluminium
Migration
Through
a
Geosynthetic Clay
Liner Geotextile
Separators for Dust Suppression in Gravel Roads Practical Construction Details Used to Build an Instrumented
Flexible Pavement with Geosynthetics |
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