Tag Archives: GeoPrac

Geofoam and Slope Stability

A recent TRB E-newsletter (4/2/2013) was spotlighted by Randy Post (aka RockMan) at Geoprac.net.  The newsletter was about the publication in January of Research Results Digest 380: Guidelines for Geofoam Applications in Slope Stability Projects.

TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 380: Guidelines for Geofoam Applications in Slope Stability Projects explores the use of expanded polystyrene-block geofoam for slope stabilization projects. For the purpose of the report, slope stabilization projects include new roadways as well as repair of existing roadways that have been damaged by slope instability or slope movement.

The research was performed by the Department of Civil Engineering at The University of Memphis (UoM). David Arellano, Associate Professor of Civil Engineering at UoM, was the Project Director. The other project investigators were Timothy D. Stark, Professor and Consulting Engineer, Department of Civil and Environmental Engineering at the University of Illinois at Urbana-Champaign; John S. Horvath, Consulting Engineer and Professor, Civil and Environmental Engineering Department at Manhattan College; and Dov Leshchinsky, President of ADAMA Engineering, Inc., and Professor, Department of Civil and Environmental Engineering at the University of Delaware.

The digest is a summary of the NCHRP Project 24-11(02), “Guidelines for Geofoam Applications in Slope Stability Projects.”

This report presents the results of a study performed to develop a comprehensive document that provides both state-of-the-art knowledge and state-of-practice design guidance to facilitate the use of EPS-block geofoam for slope stabilization and repair. This report includes the following five primary research products: (1) summary of relevant engineering properties, (2) a comprehensive design guideline, (3) a material and construction standard, (4) economic data, and (5) a detailed numerical design example.

The project was initiated to develop comprehensive design guidelines for use of geofoam in slope stability applications.  According to the Digest, geofoam use is becoming more widespread in the U.S., but the adoption of it as a routine roadway construction material has been slowed by lack of design guidelines.

Although EPS-block geofoam for road construction is an established technology and despite the more than 30 years of extensive and continuing worldwide use of EPS-block geofoam, it has been underutilized in U.S. practice because a comprehensive design guideline for its use as lightweight fill in roadway embankments has been unavailable. There was, therefore, a need in the United States to develop formal and detailed design documents for use of EPS-block geofoam in roadway applications.

To learn more about the project, go here.  Click this link to download the project report.

And speaking of slopes and slides, RockMan has some posts on a recent slope failure in a copper mine in Utah and one on the WSDOT doing some rock blasting on I-90 (with cool video!).  Check them out:

WSDOT rock blasting on I-90 for Snoqualmie Pass

Bingham Canyon Slide

Calibration of Resistance Factors for Drilled Shafts -A report from the LADOTD

Note: Okay – I’ll admit – I also do a blog for the Geo-Institute Deep Foundations Committee.  as such, there are often things that I feel should be posted at both – to get the widest possible audience! So, if you have already been over there, this post will look very familiar.  It is much easier to reuse a post written by yourself. – Robert

With the adoption of LRFD design methods by the American Association of State Highway and Transportation Officials (AASHTO), the Federal Highway Administration (FHWA), and most state Departments of Transportation,  the big question in the geotechnical world is “What resistance factor should we use for __________?”.  AASHTO LRFD Bridge Design Specifications provide a lot of guidance, but many in the industry are working to calibrate resistance factors to regional or local design methods and soil conditions. Various universities and state DOTs, with assistance from FHWA, National Highway Institute (NHI), and the Transportation Research Board (TRB) are conducting research projects to provide some answers to the big question (there is never just one answer in geotechnical engineering!).

Randy Post over at GeoPrac.net recently blogged about a newly released report from The Louisiana Transportation Research Center and the Louisiana Department of Transportation and Development (LADOTD) on their investigation for calibrating resistance factors for the design of axially loaded drilled shafts.  From the report abstract:

As a continuing effort to implement the LRFD design methodology for deep foundations in Louisiana, this report will present the reliability-based analyses for the calibration of the resistance factor for LRFD design of axially loaded drilled shafts using Brown et al. method (2010 FHWA design method). Twenty-six drilled shaft tests collected from previous research (LTRC Final Report 449) and eight new drilled shaft tests were selected for statistical reliability analysis; the predictions of total, side, and tip resistance versus settlement behavior of drilled shafts were established from soil borings using both 1999 FHWA design method (O’Neill and Reese method) and 2010 FHWA design method (Brown et al. method). The measured drilled shaft axial nominal resistance was determined from either the Osterberg cell (O-cell) test or the conventional top-down static load test.

You can download a PDF of the report here.