Most likely cause of Segment Crack Established! - Türkiye: Metro tunnel segments crack - "Segments use Fiber Reinforced Polymer and Macro Synthetic Fiber"

Narlıdere kazısı2.jpg

In late August I reported here that segments that used innovative Fiber Reinforced Polymer and Macro Synthetic Fiber in İzmir metro tunnel, Türkiye cracked.

Türkiye: Metro tunnel segments crack - "Segments use Fiber Reinforced Polymer and Macro Synthetic Fiber"

After this news I receive many messages. I was also saddened by some comments here. People hint bad design  bad manufacturing people said RTFM read the f* manual and so on so on. I was sorry that I opened door to such unfaır critisim.

AND I read a article a süperb article about this. The experts say that the most likely cause of cracks is tensions created by stacking of tunnels in tunnel site.

It says that This application in Turkey of hybrid GFRP+MSF reinforced segments is believed to be the first in the world. During fabrication, real scale tests of the segments and the rings were conducted, in addition to all necessary materials tests, and all were positive. Moreoever also after the cracks they performed tests and design reviewed and also positive.

The editor of the article says It takes confidence to be the first to adopt a new method, system or technique and the engineers and contractors in Turkey should be recognised for taking the bold step in the case of the world’s first use of a GFRP+MSF reinforced segmental lining. Also says this setback should not prevent future implementation and progress.

As far as I read and heard in Turkish sources, controller company (and municipality) intervened and forces to use segments with steel instead.

An independent expert referenced in the article Charles Allen says " potential causes for cracks appearing in segmental linings, it might simply be a case of stacking misalignment in the storage yard." and also adds "it is alarmist to start making comments, as people have, regarding poor design, bad concrete or the type of reinforcement"

(Charles Allen also refer to the "reference article" which is certainly my post but unfortunately publication blacked it out :-)  I dont understand why)

I already knew that Gülermak is a süperb engineering company. I was sad that some people just made fun of this setback. Dynamic engineering companies go to uncharted places and that is how engineering goes forward.

Please people be more fair and engineer-like in your comments next time.

And read this süperb article from TunnelTalk (except unnecessary leaving out link to my article)

note:parts of this writing I used help of Google Translate


  • Roberto Calvi
    By Roberto Calvi

    I knew it. Gulermak is no ordinary construction company. I worked with them, They are innovative and very high standard engineering company always try to push construction techniques further. 

  • Roberto Calvi
    By Roberto Calvi

    We should admire and thank Gulermak for pushing the technology envelope further rather than childishly making fun of a problem.

    If indeed they the first to implement this technique in whole world. THANK YOU GULERMAK for trying to improve tunnelling techniques rather than lazily sitting on old techniques like the most of tunnel construction companies.

  • Santiago Morales
    By Santiago Morales

    I already wrote. I am not the one who said they did not study the books. I only translated what was already said into so-called "tunnel talk".

    In my humble opinion, new technology is always risky. Why did they use new tech? What problem was it to solve?

  • Ray M. Morgan
    By Ray M. Morgan

    I searched around for this company. One should applaud Gulermak for taking this initiative.

    No doubt they must be investigating the root cause of the problem. For sure they must have conducted R&D beforehand, though obviously something is wrong, be it the stacking or other.

  • Tim Altman
    By Tim Altman

    after reading this and looking back, I now see that my previous comments on this subject were not fair. My unreserved apologies to gulermak engineers and everybody else who had read my comments.

  • Ercan Başar
    By Ercan Başar

    First Turkish then English

    Az önce şu yazıyı okuduktan sonra olayı anlar gibi oldum.

    Soru: Gülermak İzmir Narlıdere tüneli için Bakaert-Maccaferri fiberlerini mi kullandı o kırılan segmentlerde? Kesin olan, fiber satıcıları Gülermak'ta birilerini kandırıp Türkiye'yi deneme tahtasına çevirmiş. Yok efendim segmentler üst üste konulduğu için olmuşmuş şuymuş buymuş. O segmentler her zaman öyle dizilirler. Neden demirli segmentler çatlamıyor da bu fiber segmentler çatlıyor?

    Eğer Gülermak gerçekten iyi bir şirketse, bu işin üzerine gitmeli. Kim Türkiye'yi neden  Belçikalı İtalyanların deneme tahtası durumuna getirmiş araştırmalı, açıklamalı. Öncelikle İzmir Büyükşehir belediyesi bu işin üzerine gitmeli. Kim daha denenmemiş teknolojileri İzmir'lilerin yaşamlarını riske atarak deniyor araştırıp bulmalı. Bir suç varsa Gülermak'a ağır bir yaptırım uygulamalı, tünel işini Gülermak'tan almalı.

    Gülermak o tünel yapımında, denenmemiş başka uygulamalar kullanıyor olabilir mi?

    Bu olayı öyle fiber üreticisi tekellerin reklam kaygısındaki yabancı dergilerin saçma açıklamaları ile mi geçiştireceğiz? Türkiye'de mühendislik daha ciddiye alınır!

    Türklerin canı Belçikalıların, İtalyanların canlarından daha az değerli değil!

    I read this

    My question= Did Gülermak use fibers of Bakaert-Maccaferri for crack segments in İzmir Narlıdere metro tunnel? It is certain some fiber seller fool some Gülermak people to make Turkey a trial testbed. I don't believe these bullshit explanation "misalignment stacking". Segments always stack that way. Why iron segments not crack?

    Maybe that journal worried about fiber factories advertisements and with so unbelievable explanation but in Turkey we take construction engineering very serious. 

    If serious organization, Gülermak must investigate why this happen. Foremost İzmir Municipality must investigate. If necessary must penalize Gülermak. If necessary take tunnel contraction away from Gülermak. What other untested technology Gülermak may use in İzmir?

    Turkey is not test ground for untested technologies. Lives of Turks as important as lives of Belgium and Italy people.