Killi zeminlerde NATM ile açılan tünellerin deformasyon tahmini
Estimation of surface deformations of tunnels opened with NATM in clay soils
Yazar: MEHMET AKIN
Danışman: PROF. DR. RECEP İYİSAN ; DOÇ. DR. MEHMET ŞÜKRÜ ÖZÇOBAN
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / İnşaat Mühendisliği Ana Bilim Dalı / Zemin Mekaniği ve Geoteknik Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2019
Konu: İnşaat Mühendisliği = Civil Engineering

Özet:
Günümüzde; nüfus artışının neden olduğu şehir içi alanlarının daralması ve yeni yerleşim yerlerinin hız kesmeden inşa edilmesi, yer üstünün olduğu kadar yeraltınında kullanımını kaçınılmaz kılmaktadır. Teknolojide meydana gelen hızlı gelişmeler, inşaat sektöründe uygulanan yöntemlerin ve çözüm yollarının da gelişmesini sağlamıştır. Bu gelişmelerin en etkili olduğu alanlardan birisi de yeraltı yapıları ve tünelcilik çözümleri olmaktadır. Ulaşım sektöründe karayolu ve demiryolu güzergâhlarının bir kısmının, metro projelerinin ise büyük bir bölümünün tüneller ile yeraltından geçirilmesi bu çözümler içerisinde yer almaktadır. Kaya mekaniğinde ve zemin mekaniğinde yapılan araştırmalar klasik tünelcilik anlayışını değiştirmiş, yaklaşık yetmiş yıldır birçok projede başarılı bir şekilde uygulanmış olan Yeni Avusturya Tünel Açma Yönteminin (NATM) doğmasını ve sürekli gelişmesini sağlamıştır. Eski sistemlere göre daha uygulanabilir ve denetlenebilir olan bu sistemlerin modellenmesinde ve çözümlenmesinde çeşitli bilgisayar programlarından yararlanılmakta, böylelikle sonuçlara daha hızlı ve doğru şekilde ulaşılmaktadır.  
Bu çalışmada, İstanbul'da Çekmeköy ile Üsküdar arasında yapımı tamamlanan tünel güzergahı üzerinde, kil zeminde Yeni Avusturya Tünel Açma Yöntemi - NATM ile inşa edilen makas ve peron tünelleri incelenmiştir. Çalışma kapsamında, öncelikle tünel güzergâhının ilgili kesimleri jeolojik ve geoteknik açıdan değerlendirilmiştir. Yapılan sondajlar ve laboratuvar deneyleri sonuçlarına göre makas ve peron tüneli yerleşim alanında yer alan jeolojik birimler tanımlanmış, bu birimlere ait yerinde zeminlerin geoteknik parametreleri belirlenmiştir. NATM esasları gözetilerek inşa edilen bu tünellerin yapımı sırasında geoteknik ölçümlerle yapılmış, tünel içinde ve zemin yüzeyinde oluşan hareketler incelenmiştir. Analizler sonucunda, tünelin yapımı sırasında yüzeyde meydana gelebilecek oturmaların pratik amaçlar doğrultusunda tahmini için bir bağıntı elde edilmiş, önceki çalışmalarla karşılaştırılmıştır. Kontrol ölçümlerinden yola çıkarak yüzeyde meydana gelebilecek oturmaların tahmini için yeni bağıntılar oluşturulmaya çalışılmıştır.

Abstract:
Today; The contraction of urban areas caused by population growth and the construction of new settlements without slowing down makes it inevitable to use underground as well as above ground. The rapid developments in technology have led to the development of methods and solutions applied in the construction sector. One of the most effective areas of these developments is underground structures and tunneling solutions. In the transportation sector, tunneling of some of the highway and railway routes and most of the underground projects through tunnels are among these solutions. Research in rock mechanics and soil mechanics has changed the understanding of classical tunneling and has led to the emergence and continuous development of the New Austrian Tunneling Method (NATM), which has been successfully applied in many projects for nearly seventy years. In the modelling and analysis of new methods of construction the use of computer aided design methods enabled to reach rapid and accurate solutions which made these new technologies more easily applicable and monitorable. 

One of the major problems in developing and developed cities in the world and in our country is transportation problems in those cities. The construction of metro lines, which is one of the most effective solutions to these problems, has been continuing in recent years with an increasing acceleration in our country even though it is late. With the introduction of Taksim - 4.Levent metro in late 2000, the importance of the metro in public transportation was understood and in the following years, tram lines, which are referred to as light rail subway systems, were put into service.

After the construction of the subway, the Kadıköy-Kartal Metro, Başakşehir-Olympic-Kirazlı Metro, the extension of the existing subway lines and the tender process have been completed and the new subway lines have been rapidly growing.
Construction of metro lines in Istanbul, especially in areas where construction is frequent, requires detailed and qualified research, examination and measurement. During urban tunnel excavations, the behavior of the ground and its effects on the superstructures are the most important issues to be considered in terms of metro constructions.In these studies, these two important issues were emphasized. Generally, Mining and Geological Engineers published studies on soil and rock behavior during tunnel excavations, while Civil Engineers worked on the behavior of superstructures during tunnel excavations. The aim of this study is to prepare two different sources and information that can be used for the next subway and tunnel projects by examining the two important subjects of Üsküdar-Ümraniye-Çekmeköy Metro Construction and Electromechanical Works. The surface displacement values obtained as a result of the geotechnical measurements were compared with the results of the important people who have done studies on this subject, the differences between them were investigated, the factors that caused these differences were investigated and finally, a new surface deformation proposal was proposed as a result of the displacement values obtained.

The aim of the study is to establish analytical and empirical methods for the estimation of surface deformations caused by different types of tunnel sections constructed within the scope of Üsküdar-Ümraniye-Çekmeköy Metro Construction and Electromechanical Works project. As a result of the geotechnical studies, the determination of the engineering properties of the soils is blended with the physical position of the tunnel and to form a correlation as a result of the geotechnical measurements made during the construction.

Within the scope of ÜÇÇ Subway constructions, deformation measurements of T2, T3, P1 A and A2 type subway tunnels to be opened by NATM between S14 Dudullu and S15 Necip Fazıl Stations were examined and analytical and empirical correlations were formed depending on the physical location of the tunnel and the engineering properties of the ground. In the second part of the study, general information about tunnels, terms of tunnels and how to classify tunnels are mentioned. In the third part of the thesis, field and laboratory researches for the construction of tunnel projects are mentioned. In the fourth part of the thesis, rock quality and support classifications and soil classification methods which help in the design of tunnel constructions are summarized. In the classification of rocks, starting from the Terzaghi Rock Classification according to their historical order, the classifications frequently mentioned in the literature are mentioned. RQD, RMR, RSR, Q-Barton, GSI are the most commonly used classifications in Turkey. Information about the Unified Soil Classification System (USCS) and Highways Soil Classification System (AASHTO) is given. In the fifth section, tunneling with TBM and tunneling with NATM are mentioned. TBM and New Austrian Tunneling Method (NATM) are described. Stress conditions occurring in underground rock structures, history of NATM, principles of NATM, determination of NATM classification and support, consolidation and improvement methods in tunnels are explained. In the sixth part of the thesis, the empirical and analytical methods and the development of the geotechnical and mining experts that will be used to calculate the deformations will be mentioned. In the seventh section, surface displacements caused by tunnels opened with NATM on clay soils are mentioned. In this study, general information about Üsküdar-Ümraniye-Çekmeköy Metro construction is given and the geotechnical measurement results are explained. These results are compared with the empirical methods described in the previous section and a new empirical deformation estimation method will be formed in accordance with these results. This method will be compared with the old methods and the differences between them will be examined. In the last chapter, the results are evaluated and discussed in accordance with the information obtained in the seventh chapter.

In this study, switch and platform tunnels constructed with New Austrian Tunneling Method - NATM on clay ground were examined on the tunnel route completed between Çekmeköy and Üsküdar in Istanbul. Within the scope of the study, firstly the relevant sections of the tunnel route were evaluated in terms of geological and geotechnical aspects. According to the results of the boring and laboratory tests, geological units in switch and platform tunnel settlement area were defined and geotechnical parameters of the soils were determined. During the construction of these tunnels, which were built according to NATM principles, geotechnical measurements were carried out and the movements in the tunnel and on the ground surface were examined. As a result of the analysis, a correlation was obtained for the estimation of the settlements that may occur on the surface during the construction of the tunnel for practical purposes and compared with the previous studies. Based on the control measurements, new correlations were tried to be formed for the estimation of possible settlements on the surface.