Case study: Music City Center green roof

January 1, 1970

By Allan Wingfield Nashville’s new Music City Center convention facility features a unique sloped green roof design designed to mimic Tennessee’s rolling hills. There is a 65-ft difference in elevation from the northwest corner of the site to the southeast corner. Many challenges needed to be addressed, including keeping the vegetation evenly watered while diverting …

Project Angostura

Geotextile tube coffer dam By Sören Schmidt The problem, the plan… The Angostura project is owned by Colbún, one of the largest energy producers in Chile. Angostura is a hydroelectric dam project with a capacity of 350mw. The dam is situated in the Bio-Bio River, a few kilometers downstream from two other Bio-Bio hydroelectric facilities. …

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Measuring puncture resistance

From the GMA Techline RE: Measuring puncture resistance How can I measure hydrostatic puncture resistance of a geomembrane in the field with different conditions (with or without geotextile)? [My company] uses geomembrane in agricultural pools. (Elham) Reply: The test you are looking for is ASTM D5716. It is a large burst test conducted by air …

Interface behavior under pullout conditions

European experience in pullout tests: Part 2 By Daniele Cazzuffi, Lidia Sarah Calvarano, Giuseppe Cardile, Nicola Moraci, and Piergiorgio Recalcati Introduction Geogrids are one of the most common types of geosynthetic used for soil reinforcement. In particular, the use of geosynthetics has unique advantages over other soil strengthening techniques, because of technical, economic, and sustainability …

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Geotextile puncture resistance

From the GMA Techline RE: Geotextile puncture resistance [I have] a question for you on geotextile puncture resistance. I was looking through your book to refresh my memory on the calculation procedure on geotextile puncture resistance, Section 2.5.4. I saw the scaling factors S2 and S3 and the example calculation reference ASTM D4833, which is …

Redundancy that helped a wall survive an extremely high seismic load

This photo shows a geosynthetic-reinforced soil wall that survived a substantially higher seismic load than its designed seismic load. This resulted from redundancy due to use of soil design Φ value lower than its actual value. Furthermore, the substantial apparent cohesion and toe resistance were also ignored. Such a wall serves as a lifeline and …

Inadequate compaction necessitates massive remedy

These photos show a massive remedy utilizing anchors needed for an initially inexpensive geotextile reinforced wall. One reason that necessitated this remedy is poor compaction. Also, risers collecting surface water were embedded in the reinforced soil zone. These risers were connected sequentially by a 10-in. PVC pipe located in the reinforced soil. Differential settlement of …

Wall failure after a typhoon

This photo shows wall failure during a heavy rainfall caused by a typhoon. There was no adequate internal drainage in the fine-grained backfill although water in front of the wall was collected by a concrete-paved ditch. Redundancy due to apparent cohesion disguised the lack of proper drainage for four years, holding the wall system stable. …

Apparent cohesion leads to eventual failure

These photos show a wall failure next to a corner. This failure occurred in an area where successive triangular sectors of geogrid layers were not installed. Failure is to be expected because reinforced walls without reinforcement should fail. Curiously, this failure occurred about one year after the end of construction. Clearly, failure was delayed because …

In this article…

By Dov Leshchinsky and Fumio Tatsuoka There have been numerous failures of geosynthetic reinforced walls. The majority of these failures occurred in the private sector. This article does not look at the forensic of wall systems that failed due to exploited redundancy combined with ignorance or careless attempts to “economize” the structure. Instead, it explains …