Scholarship win for former student Joel Lewis

17 December 2008

The Association of Consulting Engineers Australia (ACEA) has just announced that the winner of the ACSE 2007 Student Scholarship, is Mr Joel Lewis, a final year student from last year, based his thesis, "Failure Mechanisms of Crushed Shale in Reinforced Earth Walls". The thesis was supervised by Associate Professor David Airey.

Each university in NSW was asked to put forward its best thesis in the civil or environmental engineering field, and Joel's was judged the (equal) best by a panel of leading practitioners.

The Scholarship comprises work experience in three different overseasconsulting engineering firms over a six week period with airfares paid and living expenses provided.

Joel says "My trip begins in March when I depart for South-East Asia to work on a Boxing Day Tsunami relief project with ACEA member firm Cardno.The next destination is the United Arab Emirates where I will spend two weeks working for Hyder consulting, designers of the tallest building in the world the Burj Dubai. I also plan to visit several other famous projects currently under construction such as the World Islands and the Mall of Arabia. My last destination is Los Angeles, California where I will work in the global HQ of my current employer, Maunsell | Aecom."

For the last five years, both the ACEA and ACSE (Association of Consulting Structural Engineers) have together awarded scholarships for the best civil/environmental and structural engineering theses. Previous winners of this prestigious award include David Keast (2006), Paul Williams (2005) and Dan Cook (2003) who also did their theses within the School.

The School congratulates Joel on his great achievement.

Abstract of Joel Lewis' Thesis

Several failures of reinforced earth walls in Sydney have been attributed to the use of crushed Ashfield Shale as the fill material. The walls all experienced frictional failure where the reinforcement pulled out of the soil. This has caused the NSW Roads and Traffic Authority to ban the use of Ashfield shale in these structures even though the mechanism by which the failures have occurred is unknown. This thesis investigated the possible causes of the failures by testing samples of crushed Ashfield Shale and a synthetic reinforcing material, ParawebTM. These materials were subjected to three types of frictional interactions to observe differences in behaviour and identify possible causes for the failures. A durability test was also undertaken to simulate material handling procedures during construction. It was found that Ashfield Shale is a durable material and would not break down during construction. It was also found that the friction generated between the soil and reinforcement in REW conditions is far less than the theoretical values obtained from conventional testing techniques and used in design. The failures were most likely caused by a combination of factors including soil arching and compressibility of the reinforcement. Ashfield shale can be used in REWs but the friction parameters used in design must be determined using pull-out tests.