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Piroklastik bir kaya türü olan ignimbirit yüksek derecede gözenekli olmasından dolayı ısı ve ses yalıtımı özelliğine sahiptir. Ayrıca oluşumları esnasında kazandıkları estetik dokusal özellikleri ve hafif oluşları sebebiyle yapıtaşı sektöründe yoğun şekilde tercih edilmektedirler. İgnimbiritlerin oluşum ortamındaki sıcaklık (>500˚C) ve basınç koşulları bu kayaçların fiziksel ve mekanik özellikleri üzerinde doğrudan etkilidir. İgnimbiritlerde kaynaşmayı kontrol eden en önemli faktörler olan yüzeye çıkan piroklastik malzemenin sıcaklığı ve depolanma ortamındaki örtü yükü kalınlığı arttıkça ignimbiritlerdeki kaynaşma derecesi de yükselmektedir. Yüksek sıcaklıklarda ignimbiritlerde meydana gelen plastik deformasyon sonucu camsı minerallerde kaynaşma gözlenir. Bununla birlikte, piroklastik akıntının birikimiyle, alt seviyelerde yer alan ignimbiritlerdeki kül hamuru ve pomza taneleri deformasyona uğrar. Bu deformasyon sonucu pomza taneleri farklı oranlarda yassılaşmış bir şekil alır, yüksek deformasyon etkisiyle merceksi bir yapı kazanır. Bu süreçler ile kayacın kaynaşma derecesi artarken aynı zamanda fiziksel ve mekanik özelliklerinde de iyileşmeler oluşabilmektedir. Bu çalışma kapsamında Kayseri, Nevşehir ve Ahlat yerleşimlerinden elde edilen farklı renk ve doku özellikleri sunan 16 ignimbirit türüne ait örneklerde fiziksel ve mekanik özellikler ortaya konulmuştur. Aynı ignimbirit örneklerindeki pomza tanelerinin uzun ve kısa eksen uzunlukları mikroskop altında ölçülmüş ve farklı şekil parametresi değerlendirme yöntemleri kullanılarak şekil oranları ortaya konmuştur. Tek eksenli basınç deneyleri sonucunda en yüksek dayanıma Kayseri bölgesine ait ignimbiritlerin, en düşük dayanıma ise Nevşehir ignimbiritlerinin sahip olduğu belirlenmiştir. Bunun yanı sıra, Kayseri ve Ahlat ignimbiritlerinde pomza taneleri daha merceksi bir yapı kazanmışken, Nevşehir ignimbiritlerinde pomza taneleri yuvarlağa daha yakındır. Basit regresyon analizleri sonucunda ignimbiritlerin fiziksel ve mekanik özellikleri ile pomza tane şekli arasında en anlamlı ilişkinin en-boy ve basıklık oranı şekil parametreleri ile tek eksenli basınç dayanımı arasında olduğu belirlenmiştir. Bu ilişkiye göre, ignimbiritlerdeki pomza tanelerinin basıklık oranı arttıkça malzeme dayanımı da yükselmektedir.

Funding text Bu çalışma, UDAP-G-16-03numaralı proje ile Afet ve Acil Durum Yönetimi (AFAD) Bakanlığınnca desteklenmiştir. Projeyi destekleyen ilgili kuruma teşekkür ederiz. Bununla birlikte AFAD, Planlama ve Risk Azaltma Dairesi Başkanlığından da H. Gürhan Ülgen ve Ahmet Demire teşekkürlerimizi sunarız. Rockfall ditches or areas can be constructed in order to protect against rockfalls in settlements that are in danger of rockfalls when the population density is not high. Nevertheless, in the design of such protection structures, essential site-specific engineering studies and analyzes are often not carried out appropriately. Therefore, rockfallditches are occasionally not capable of preventing rockfalls. Within the scope of this study, the performance of a 2 m-deep and 1 km-long rockfall ditch excavated at the upper elevation of touristic Akköy (Ürgüp) settlement in 2012 in order to prevent the entrance of falling rocks to the residential area was evaluated on the basis of 3-dimensional rockfall analyses. According to the rockfall risk classification, the settlement is under moderate rockfall risk. The digital surface model used in 3-dimensional rockfall analyses was generated by point cloud data obtained from photogrammetric images taken by unmanned aerial vehicle. During field observations, it was determined that the dimension of the previously fallen ignimbrite blocks could reach up to 2 m. On the other hand, the high persistency of discontinuities in the source zone indicates that the dimensions of the potential rockfall blocks may be large. As a result of the 3-dimensional rockfall analyses carried out in RocPro3D software, it was defined that the falling blocks are generally caught by the ditch excavated between the source zone and the settlement, but in some sections of the ditch those blocks may continue to roll over the rockfall ditch. Eventually, Akköy settlement is still partially under the danger of rockfalls. If the rockfall ditch is not periodically cleaned in the course of time, the extent of danger will enlarge with the decrease in the capacity of the trench. © 2019, TMMOB - Jeoloji Muhendisleri Odasi. All rights reserved.

Cette publication collective est la deuxième d’une série de travaux qui s’appuient sur un programme de recherches AMIDA - relevant lui-même des programmes MISTRALS/ENVI-Med/CNRS – auquel participent de nombreux partenaires, issus des universités, du monde de la recherche, des institutions ou associations de la société civile, et qui s’est tenu les 26 et 27 octobre 2015 à Montpellier. Ont été cette année entendues différentes communications qui cherchaient à mettre en évidence, par des voies et des méthodes diverses, les traces et signes que les jardins de l’Hevsel avaient légués à la postérité ; nous avons également cherché à consolider les espérances et les dynamiques que porte pour le futur leur classement au Patrimoine Mondial de l’UNESCO et les projets de réhabilitation qui lui sont associés.

The Diyarbakır City Walls is a significant historical and cultural example of common human design. It was constructed by using natural stones. Although the City Walls were subjected to numerous past interventions and scientific studies, studies on long-term activity of stone material and its deterioration mechanisms have yet to be launched. The Diyarbakır City Walls reveal some forms of weathering, including cracks, detachments, material losses, discoloration, and deposits. Such weathering forms are affecting the durability of the material used in the Diyarbakır City Walls.

All types of stones have been used as building stones, depending on their durability, visual harmony with the intended construction and availability. In the Hellenistic period, as in other periods, tuff was preferred as a building stone due to its convenience – it was easy to extract, transport and use for building. In the present study, three ancient quarries that were the possible tuff sources for the Apollon Smintheus Temple in C¸ anakkale are investigated by comparing the durability properties of stones in the temple and in the quarries. These properties are determined using physical and physico-mechanical tests, comparing fresh and artificially weathered samples. Microstructural and elemental correlations were found using optical microscopy, stereomicroscopy, X-ray diffraction, scanning electron microscopy, methylene blue adsorption and X-ray fluorescence analyses. The results indicate that temple tuffs and two of three quarries have similar geological engineering and microstructural properties with the strong claim that those two quarries could have been the source of building stone for the temple.

The study area, which will be open to tourism in Kusadasi (Aydin), has steep and high cliffs on the Aegean coast in Turkey. Flysch is the main lithological unit and consists of alternating sandstone–claystone–marl sequences. Some sliding and rockfall problems have occurred in the area in the past, so potential geological hazards need to be investigated to ensure the safety of tourists. The aim of this study is to mitigate geological hazards by recommending engineering solutions, which will ensure the continuation of the nature-friendly appearance of the slopes. To accomplish these tasks, a geological survey was performed. It involved gathering information on rock discontinuities by means of scan-line surveys and collection of rock samples. Furthermore, in situ and laboratory tests were also carried out. The data collected from the field and laboratory test results were used to perform slope stability and rockfall (2-D and 3-D) analyses for different slope conditions along 43 profiles. Based on the analyses, rockfall was found to be the main slope instability problem in the study area. Under the light of these studies, rock removal, drainage, greening (vegetation), filling of caverns, protective wall building and erosion prevention are offered as remedial measures.