GeoPrac.net turns two! Geology cake stratigraphy by Khol-y (Flickr) after original design by Tim Babb.
Rockman's Ramblings

GeoPrac Turns Two!

GeoPrac.net is now well into its toddler years! Today marks the second anniversary of the site. The past year has seen a major upgrade to the content management system, a new design, Geothreads, Delicious geotech, […]

Completed side-hill retaining wall for the SR 264 Second Mesa project in Arizona. Photo by Bharat Khandel, ADOT by way of NCS Consultants, LLC
Articles

Side Hill Retaining Walls – Part 2

Completed side-hill retaining wall for the SR 264 Second Mesa project in Arizona. Photo by Bharat Khandel, ADOT by way of NCS Consultants, LLCIn this part 2 of 2, various types of retaining walls are examined as possible alternatives in a side-hill retaining wall situation. These include conventional wall types such as CIP walls, MSE walls, gravity walls and soldier pile walls and some less conventional approaches such as lighweight concrete fill, hybrid soil-nail and geofoam wall systems, ground improvement and micropile walls.

Part 1 of this Side Hill Retaining Wall article covered the definition, significance, problems and failure modes, investigation techniques, analysis, and construction considerations of side hill walls. A PDF version is now available for download as well. Click through for the article and the download link!

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Rockfall on I-70
Geologic Hazards

Rockfall Hazards Overview by Colorado Geologic Survey

Rockfall on I-70The Colorado Geologic Survey has a very comprehensive overview of the geologic hazard of rockfall in all its many forms in their latest issue of RockTalk newsletter. The entire 24-page newsletter is devoted to various aspects of the problem, mitigation options and case studies all with excellent photos. I highly recommend that you check it out. Click through for the link. (Photo by CGS)

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American Society of Testing Materials Logo - ASTM
Standards and Codes

ASTM Updates March 2009

American Society of Testing Materials Logo - ASTMOur monthly update on new and revised ASTM standards that relate to geotechnical engineering, materials testing, hydrogeology, geosynthetics and related disciplines. This month there are a few notable revisions, including D1452 for Auger Borings, D3385 for Double-Ring Infiltrometer and D4595 for determining tensile properties of geotextiles by the wide-width strip method. There are also a few other geotextile, groundwater, lime, masonry and terminology standards that were added or updated. Click through for the full list.

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Rockman's Ramblings

There and Back Again…Ed Medley

imageIts been a while since I’ve posted in Rockman’s ramblings. But tonight as I try to wind down from a stressful drive back to Tucson from Phoenix on a very windy night, I feel the muse at work. Maybe the martini is helping too! Tonight was a meeting of the Arizona Section of the Association of Engineering and Environmental Geologists (AEG). The speaker was the 2009 AEG Jahns Distinguished  Lecturer, Dr. Edmund Medley of Geosyntec Consultants.

He’s perhaps best known for coining the phrase “bimrocks” for block-in-matrix-rock. He’s also written and presented some stuff on terrestrial 3d photogrammetry for geological engineering.  He’s an incredibly colorful, energetic, and genuine man who is a very entertaining and gifted writer and presenter. I was glad to meet him after trading a few emails previously. I’m not sure how he would feel about this comparison, but for some reason he reminded me of Bilbo Baggins. (Photo from EdMedley.com)

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Failures

Cologne Tunnel Collapse: Investigations Focus on Tiebacks and Groundwater

image The latest information to come out of the collapse of a subway tunnel excavation in Cologne, Germany is that investigators are evaluating the ground anchors or tiebacks that were holding open the subway tunnel excavation. There doesn’t appear to be much information available to the public yet, and the New Civil Engineer article mostly quoted academics saying an anchor failure “could” have caused the collapse. Apparently at the time of the collapse, the excavation had reached the bottom depth after the slurry walls had been constructed along with the ground anchor system. Crews were supposedly working on the base slab which would have undoubtedly stiffened up the whole system. For what its worth, an anonymous comment left at the bottom of that article indicated that after half of the debris had been excavated, the diaphragm walls were still intact and without apparent displacement. So what other theories have been floated? Read on for more info.  (Image Credit: New Civil Engineer)

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Failures

Video: Freeport Maine Culvert Failure and Road Collapse

imageA colleague of mine sent me an amazing video of a culvert failure and subsequent road collapse in Freeport Maine during a storm. The culvert was unable to accommodate the high volume of water, and it was backing up behind the roadway embankment like a dam, and spilling out onto the roadway. In a span of about 3 minutes, the entire section of road collapsed and was washed downstream. I don’t know the exact date the video was taken, but it appears to be in August of 2008. Click through for the video.

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Image of a sandhog inside the new water supply tunnel number 3 for the City of New York. Photo by History.com.
Project Related

New Water Supply Tunnels Underneath New York City

Image of a sandhog inside the new water supply tunnel number 3 for the City of New York. Photo by History.com. Urban miners have been busy constructing a new water supply tunnel underneath New York City to supply the megalopolis with the water it needs. The miners, or sandhogs as they are known, are about halfway complete with the new tunnel which is expected to be in service by the year 2020. Work on the 60-mile tunnel began in 1970 and the total projected cost is $6 billion and is widely regarded as one of the most complex public works projects in the western hemisphere. When complete, it will help deliver 1.2 billion gallons DAILY to 8 million New Yorkers. The city currently gets its drinking water from two water supply tunnels that were constructed in the early 20th century and have not been inspected or repaired since then. More after the break. (Image credit History.com)

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