By Ian D. Peggs
Can geomembrane stress cracking (SC) be eliminated altogether? Probably not. But it can still surely be reduced if we understand its causes a little better.
Can SC be eliminated altogether? Probably not. But it can still surely be reduced if we understand its causes a little better.
We have made great improvements (specified NCTL times from 200 to 1000 hr) since the 1980s when there were extensive slow crack growth (SCG) and rapid crack propagation (RCP) or “shattering” failures in exposed HDPE geomembranes. However, neither SCG nor RCP have totally gone away.
Recently I have seen SC events that I have never seen before after quite short service periods. For instance, while I have seen many SCs along the peaks of wrinkles I had never seen SCs across wrinkles as shown in Figure 1. It is believed that complex cyclic stresses caused these accelerated breaks after only 2 years in service. Nor had I seen isolated patches of four or five SCs in geomembrane panels with no cracking at adjacent welds, as shown in Figure 2, after only 6 months in service. There has also been an RCP shattering event in Canada this year.
If anyone has seen anything similar to these three SC events, some photographs and background information would be welcomed. We ask you to take part in a brief survey to further the field’s understanding of this subject.
Given sufficient time I hope to submit a paper to the 10th International Geosynthetics Conference in Berlin which will list basic details of SC events that have occurred internationally since the start of 2010. I am asking anyone who knows of a stress cracking event to contact me. You may complete a short questionnaire here in a Word doc version of this article.
We will identify the predominant causes of SC events and define how they may be prevented. We may come back to you for more detailed information which will be treated as confidential.
To be part of these discussions, please contact Ian D. Peggs at firstname.lastname@example.org.
Again, this is a general interest study, not a paid consulting project.
Ian D. Peggs, Ph.D., P.E., P.Eng is President of I-CORP INTERNATIONAL, Inc., www.geosynthetic.com.