Geosynthetically Confined Soil (GCS®) -
Our GCS® walls are especially cost effective. Federally-funded research shows these structures have bearing capacities up to 20 times those of traditional Mechanically Stabilized Earth (MSE) walls. State of the art GCS® technology translates to better retaining walls, bridge abutments, box culverts, foundations, rockfall barriers, avalanche/mudflow deflection barriers and more.
The final product can be a split-face block, natural stone, synthetic stone veneer, stained and sculpted shotcrete or a mesh with natural vegetation.
Open Bottom Culverts : Project 1
Open Bottom Box Culverts are in great demand. This is a demand that is easy to meet with boxes built with Soil Nail Launcher's Geosynthetically Confined
Soils™ technologies that last longer, are quicker to construct, incur less collateral damage and are less expensive, when compared with traditional concrete and steel
arches and boxes.
GRS OPEN BOTTOM BOX CULVERT AT TAMARRON GOLF COURSE WETLANDS CROSSING
A Yenter Companies project by Al Ruckman and Bob Barrett
The “secret” to this new culvert concept is based on pioneering research in Geosynthetically Reinforced Soil (GRS) by the U. S. Forest Service (USFS) in the 1970’s.
Researchers at Oregon State University also made significant contributions to this effort. The USFS and the Federal Highway Administration (FHWA) published the first
GRS design/construction manual in 1978, authored by Steward, Mohney and Williamson of the USFS.
USFS research was expanded by many other agencies and private enterprises, the most notable being the Colorado Department of Transportation (CDOT) in
partnership with the University of Colorado/Denver (UC-D). This CDOT/UC-D collaboration continued for many years, with total expenditure in the tens of millions of
dollars. Other partners with this CDOT focus were the Colorado Transportation Institute and FHWA’s Turner Fairbank Highway Research Institute. The USFS provided
funds to CDOT and UC-D in 1996 to rewrite their GRS design and construction manual. This document (Design and Construction of Low Cost Retaining Walls by Dr. J.
T. H. Wu) was published by CDOT and continues to represent state-of-the-art in GRS structural design and construction practice.
USFS research demonstrated that GRS was a viable technology for construction of retaining walls and steep slopes. CDOT/UC-D refined this effort and expanded the
applications of GRS to bridge abutments, bridge piers and rockfall impact barriers. Yenter Companies, a design/build engineering group, implemented these research
findings and expanded the application of GRS technologies to Open Bottom Box Culverts. Al Ruckman, then President of Yenter Companies, has constructed several of
these structures. These GRS Open Bottom Box Culverts are indeed easier, quicker, incur less collateral damage and are less expensive in most locales.
Soil Nail Launcher, Inc under the leadership of Bob Barrett and Al Ruckman has continued to improve GRS technologies. We now have evolved to the next generation
ahead of the pack and call our designs Geosynthetically Confined Soil (TM). SNL, Inc. can provide the world's best abutments, boxes, and walls.
Reinforced Bridge Abutment Research : Project 2
GEOSYNTHETICALLY REINFORCED SOIL BRIDGE ABUTMENT AND PIER DEMONSTRATION -
AL RUCKMAN AND BOB BARRETT OF Soil Nail Launcher, Inc. DESIGNED THIS CDOT-FUNDED RESEARCH
NCHRP Project 12-59 provided comprehensive design and construction guidelines for GRS abutments. Project 12-59 Panel Chairman is Bob Barrett, Dr. J. T. H. Wu of
UC-D is Principal Investigator and TRB Senior Program Engineer, Tim Hess is Project Manager. Some of this work is redundant in that many of these constructions exist
around the world.
The reader may surmise by this point that Yenter’s Fortress Abutments are used for the sidewalls of these modern structures. The opening can be any width. Narrow,
it is an Open Bottom Box Culvert. Wider, and it is a bridge. Height can be designed to accommodate any need.
Open Bottom Culvert : Project 3
GRS Open Bottom Box at Breckenridge Ski Area
A Yenter companies project by Al Ruckman and Bob Barrett
These versatile structures can accommodate Skylights as shown here. Facing can be native dry stacked rock, concrete blocks, timber
and more. Periodic or permanent inundation is acceptable. Rapid drawdown is not a problem.
Scour Issues : Project 4
Scour, or scour prevention, has been an issue for some Open Bottom Boxes for Fish Passage and Terrestrial Passage. Researchers with Soil Nail Launcher, Inc. have
devised a new solution for scour prevention and mitigation that will allow much wider implementation of these much desired structures.
Launched Scour Micropiles are angled about 60 degrees downstream. Boulders and cobbles can be added in the array or upstream. Headward erosion or scouring
below the array will result in a ramp effect, and not a waterfall, another “fish friendly” feature of these new concepts.
These Launched Scour Micropiles can be installed in an active stream. There are no polluting drill rigs or concrete products involved with any of this work. The
sidewalls of the Open Bottom Boxes
Earthquake Wings : Project 5
THE SHAPE OF THE FUTURE IN BRIDGE ABUTMENTS
EARTHQUAKE WINGS, a concept patented by Bob Barrett and Al Ruckman provide close lateral support to the superstructure during seismic events. These
massive restraints create a pocket, a wrap-around encapsulation, that assists bridge girders of all types to remain on their moorings in seismic events.
EARTHQUAKE
WINGS are ideally suited for integral construction with Geosynthetically Confined Soils™ abutments. Based on our observations of performance of traditional and
reinforced soil structures in earthquakes around the world, we think our Fortress Abutment* will likely be the last structure standing following a major seismic event.
The additional width allows more options for guard rail transition from the bridge. The savings in guard rail could easily offset the additional cost for the Earthquake
Wing. A better system for less cost. These modern marvels can be faced with block, rock, timber, concrete panels - about any facade the owner wants. patent pending
Geosynthetically Confined Soil™ : Project 6
NORTH CAROLINA DEPARTMENT OF TRANSPORTATION solves a major slide and saves over $100,000 with new tools and technologies
NCDOT's Dogwood Drive near Maggie Valley experienced a total failure during a water main break. A fatality resulted from the
debris overtopping a house. The designers looked at several traditional alternatives including rock buttresses, piling, caissons
and a bridge. None of these fit the location, site geometry and access.
Soil Nail Launcher, Inc. and the DOT staff designed a solution that included Super Nails™ and a modern GCS™ wall founded on
Super Micropiles™. This was a first for bringing together all these new tools, concepts and technologies. Savings was estimated
at over $100,000.
Local residents really appreciated that time for this construction was less than half of any of the other choices and that their
access roads were not damaged with heavy traffic.
Contacts:
John Fargher - jfargher@dot.state.nc.us
Jonathan Woodard - jwoodard@dot.state.nc.us
Geosynthetically Confined Soil™ : Project 7
GIANT ROCKFALL INTERCEPTED BY GCS™ WALL
Modern GCS™ Technologies Save the Day Again
Interstate 70 threads through deep, rocky canyons as it traverses western Colorado. Rockfall is a significant hazard on this route. It was during the Glenwood Canyon
I-70 design phase that CDOT's geotech group led by Bob Barrett wrote the Colorado Rockfall Simulation Program, or CRSP, which is used around the world to predict
the behavior of a rock in motion.
One major rockfall hazard site is located in Debeque Canyon and was created when highway construction cut out the colluvial slope at the toe of a major sandstone
cliff section. This cut exposed a soft shale that quickly air slaked and weathered back. This resulted in reduction in foundation support for the sandstone above. Huge
slabs of sandstone would peel away and topple onto I-70.
The other complication was that the original design minimized the roadway ditch section to about 10 feet wide to avoid cutting further into the shale. One result of
this was that there was no storage for the rockfalls. The rockfalls would overwhelm the ditch and fill out to the median barrier and beyond.
Creating a wider ditch was not practical. The rockfall events were larger than steel draperies could retain. Bolting the sandstone cliffs would cost millions. So would a
wider cut. The Colorado River on the other side was already too confined to move the roadway in that direction. CDOT was seemingly at an impasse.
Bob Barrett and Al Ruckman developed a novel solution with a modern application of Geosynthetically Confined Soil™. They designed a 26 foot high GCS™ wall with a
level top that effectively provided the wide ditch and protected the soft shale layer as well. Yenter Companies and CDOT District 3 Maintenance built the rockfall
catchment.
The plan worked. The elevated storage area was built in 1995 and the first rockfall of consequence happened in the fall of 2005. As you can see in the photos, the
volume and energies were enormous, yet the GCS™ wall remains intact.
About the GCS™ design
CDOT along with the US Forest Service and the Federal Highway Administration spent perhaps 25 million dollars in research and demonstration in GCS™ technologies.
In fact, this 26 foot high, 800 foot long Debeque Canyon I-70 wall continues to be the largest wall built with this modern design. Reinforcements are 200 pound per
inch woven polypropylene fabrics. The lower most fabric is only 3 feet wide. Fabric width increases upward on a 45 degree angle in this truncated design to a width of
16 feet and continues upward to the top with 16 foot wide sheets. Primary reinforcement fabrics are placed every other block, or about 15 inches apart.
CTI Tails were used alternatively between every other block. These new "Tails" are sheets of the same fabric that are 3 feet wide. They were placed to the full height
of the fall. These produce a stiff face. As you can see in the first photo below, the wall was carefully instrumented and monitored. CDOT enlisted the assistance of Dr.
Jonathan Wu and Dr. Ketchart of the University of Colorado/Denver. It was observed that the total deformation from start of construction to 6 months after
completion averaged less than half an inch. That is revolutionary. A concrete cantilever wall built to that height and then backfilled would have deflected outward
more that that.
The facing is ordinary CMUs. They are dry stacked and without mortar. Research by the FHWA since has shown that from the 3rd row down, these blocks cannot be
plucked. These standard concrete blocks would have to be broken to be removed from the stack.
This wall and others like it are bringing about improvements in design criteria for GCS™ features. The new NCHRP 12-59 project document, NCHRP Report 556 will
add significantly to the updating of current practice.
Al and Bob have been involved in perhaps 300 million dollars worth of these modern GCS™ features. Al has his stamp on more of these than anyone in the world. As
a result of all these field constructions, university professors, state and FHWA employees and contractors are revisiting outdated teachings about creep, embedment,
leveling pads, spacing, fabric/grid spacing, truncated bases, backfill quality and more. Geotechnical engineers are replacing structural engineers as lead designers of
reinforced soil walls and abutments. The result of improvements in our practice will be billions of dollars a year.
Strain Gauge Monitoring. Strains in the reinforcements in this GCS™ wall were below one half percent. This illustrates
that very weak reinforcements can be used as long as the spacing is around 8 to 12 inches. The vertical steel posts are
founded in bedrock and were used to measure outward deformation. This was unexpectedly stiff, with total deflections
less than one half inch. The lowermost reinforcements in this tall wall are only 3 feet wide.
This photo shows the extent of the massive rockfall. Note that only a minor fraction of the rock reached the
east bound lanes, and none made to the west bound.
The photo to the right shows the largest cliff section that remained intact. Much of the massive cliff section broke apart
on impact. The energy that the GRS wall absorbed is just phenomenal by any expectation.
Here you can see the extent of the damage. There is no fence to our knowledge that would have withstood this impact.
Once the rockfall is removed, the wall can be repaired by removing the blocks, trimming the slope back to original slope
and then replacing the blocks. This could be done in a day. Certainly the field performance of this modern design will be
noted and discussed by our international experts in the GRS arena.
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