Geleneksel yöntemlerle tasarlanan derin temellerinarazi deneyleri ve yükleme deneyleri ile optimizasyonuvaka analizleri
Optimization of classically analyzed deep foundations with help of in-situ tests and load tests-case studies
Yazar: GÖKHAN YILDIZ
Danışman: DOÇ. DR. MUSTAFA TUĞRUL ÖZKAN
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:
Şehirleşmeye devam eden ülkemizde, özellikle büyük şehirlerde büyüme ile yeni alanların oluşturulması ve mevcut yapıların yeniden düzenlenerek kullanılması amacı ile denize komşu alanlar, ovalar vb. yumuşak zemin üzerinde yapılar, özellikle yüksek yapılar planlanıp hayata geçirilmektedir. Bu tip yapıların planlanabilmesi amaçlı yüzeysel temel sistemlerinden derin temel sistemlerine geçiş sağlanmış olup klasik temel mühendisliği teoremleri ile çözümler geliştirilmiştir. Halihazırda temellerin hesap kabulleri çoğunlukla klasik yöntemler ile mukavemet parametreleri ile yapılmaktadır. Dünya genelinde bu tip zeminlerde geliştirilen yöntemlerin Türkiye de kullanılabilmesi ile temel tasarımlarında farklı yaklaşımlar ortaya çıkmıştır. Elde edilen parametreler ile konservatif yaklaşımların yerini artan maliyetleri karşılamak amacı ile yerinde arazi deneyleri yapmak ve bunların imalat öncesi ve sonrasında derin temeller üzerinde yapılacak pilot testler ile doğrulamak Türkiye inşaat ekonomisi açısından farklılık getirmeye devam edecektir. Halihazırda bu yaklaşım artık 2018 Mart ayında yayınlanan ve binalar için hazırlanan Deprem Yönetmeliği'nde de üstü kapalı olarak belirtilmektedir.
Bu tezde, derin alüvyonel zemin profillerinde yüksek yapılar altındaki temel sistemlerinin tasarlanması sürecinde kullanılan yöntemlerin değerlendirilmesi ve güvenilirlik analizleri ile elde edilen taşıma kapasitelerinin karşılaştırılması amaçlanmıştır. Nihai amaç olarak mühendislik ekonomisi ile birlikte güvenilirlik analizleri yardımı ile mevcut yöntemlerin karşılaştırılması ve olası sınırlar içerisinde kalacak şekilde temel tasarımlarının yeniden gözden geçirilmesi hedeflenmiştir. Sahada yerinde yapılan testler sırası ile Standart Penetrasyon Testi SPT, Koni Penetrasyon Testi CPT ve Menard Tipi Presiyometre testi MPT olarak karşılaştırılmış ve enstrümantasyon ile teçhiz edilmiş eksenel kazık yükleme deneyi ile güvenilirlik analizleri yapılarak sonuçları değerlendirilmiştir. Amaç olarak sahada yerinde yapılmış olan testler ile sahada kazık üzerinde yapılmış olan testlerden elde edilmiş taşıma kapasitelerinin karşılaştırılması benimsenmiştir.
Halihazırda kullanılan derin temel analiz yöntemleri, Bursa, İzmir gibi derin alüvyal çökeller içerisinde yüksek yapı altındaki performanslarını değerlendirmek amaçlı örnek çalışma olarak seçilmiştir. Çalışma özeti olarak konvansiyonel metotlar ile hesaplanan kazıkların, yerinde saha testleri yardımı ile yapılanlara göre karşılaştırması yapılmış olup, kazık yükleme testleri ile elde edilen sonuçların geri değerlendirmesi ile hesapları karşılaştırılması sağlanmıştır. Sonuç olarak sahada yapılan testler ile hesaplanan taşıma gücü sonuçlarının, kazık yükleme deneyi sonuçları ile %15 ile %35 mertebesinde farklılaştığı sonucuna ulaşılmıştır.

Abstract:
Foundation types, those are used for transferring the loads from superstructures, varies with the soil conditions. Deep foundations are preffered where the settlement criteria does not meet the expectations and where the loads cannot be carried with shallow foundations. 
Foundation type is generally selected after calculation of bearing capacity with the known soil properties and the loads from superstructure. In case the settlement of the foundation is critical and over the limits or pressures by high rise stuctures, deep foundations need to be selected and executed.
Deep foundations or piles-drilled shafts are obligatory when the loads that shall be transferred from heavy structures or highrise buildings. Despite the fact that this solution is more expensive compared to shallow foundations, the performance of the structure need to be maintained.  With developing technology in this area, the loads that shall be transferred from the structure can be monitored.
The priority in deep foundation design is that the geotechnical-structural designer has to evaluate the pyhsical conditions of the pile (diameter, length etc.) with respect to in-situ test results and the pressures that shall be transferred from super structure. Lots of researchers worked with the problem and developed solutions for evaluating the bearing capacity of deep foundations. The design of foundations can be analyzed by means of these solutions.
In our country Turkey, where infrastructure and urbanization progress is rapidly increasing, especially in large cities with the motivation of developing new areas with growth and reuse of existing areas, neighboring areas, plains, soft soils, especially high structures are planned and realized. In order to be able to plan such structures, the transition to the deep foundations from the superficial foundations is provided and solutions are developed with classical fundamental engineering theorems. At present, design criteria of the foundations are mostly made by classical methods and strength parameters. The methods developed in this type of soil, Turkey has emerged with different approaches to the basic design. The parameters obtained and conservative approaches are replaced by on-site field experiments to meet increasing costs and verify them with pilot tests on deep foundations before and after manufacturing will continue to make a difference in terms of economy. Currently, this approach is now implicit in the Earthquake Code for Buildings published in March 2018.
In this thesis, it is aimed to evaluate the methods used in the design of the foundation systems under high structures in deep alluvial soil profiles and to compare the reliability capacities and the carrying capacities. The final objective is to compare the existing methods with the help of reliability analysis together with the engineering economy and to review the basic designs to remain within the limits. The summary of each chapter is given as a brief as follows;
In chapter one, the main goal and the secondary inference of the thesis are given in the light of previous studies. Hypothesis is given additionally in his chapter. 
In chapter two, types of piles and the advantages/disadvantages of the pile types are summarized where the installation of the piles are given as a side note. Additionally, pile calculations for cohesive and cohesionless soil are stated with laboratory test results. The methods for pile bearing capacity analysis are given as a literature study.
In chapter three, the bearing calculations are summarized by means of in-situ tests. Standard Penetrations Test, Cone Penetration Test and Menard Type Pressuremeter Test are given for bearing capacity analysis. The genaral methods those are given in worldwide standards are briefly explained. The input and the output of the calculations are summarized.
In chapter four, in-situ pile load tests and the back analysis methods are stated. Standard loading pattern and cyclic loading pattern tyoes were given where graphical and mathematical methods for evaluating the pile capacity are also summarized. A brief information and the methods for evaluating pile capacities are given when the piles cannot be loaded to failure state. The mathematical and graphical methods are given in detail those also used for the recent thesis study.
In chapter five, the comparison of case studies and optimization of pile capacities are studied. Bursa and Izmir case studies are selected for the thesis. The general geology of two sites, laboratory and in-situ tests of the cases, regional geology are summarized. The pile capacities of both two sites are calculated with the given data by means of standard penetration test, cone penetration test and pressuremeter tests data. There is only one pile load test in Izmir where four tests were studied for Bursa case. All tests were with strian-gauge instrumentation where the skin friction values were determined precisely. The graphical presentation of load versus deformation, load versus time are given for each case anf test.
In chapter six, the results and the  evaluations are made for the two cases. The comparison of pile capacities for both Bursa and Izmir case studies are given with respect to insitu tests and pile load test results.     
Standard Penetration Test SPT, Cone Penetration Test CPT and Menard Type Pressometer Test were compared and the results were evaluated by axial pile loading test equipped with instrumentation and reliability analyzes were performed. The aim is to compare the carrying capacities obtained from the tests carried out on site and the tests performed on the pile.
Deep analysis methods, which are currently used, have been evaluated in order to evaluate their performances under high altitudes in deep alluvial deposits such as Bursa and İzmir. As a summary of the study, the piles calculated by conventional methods were compared according to the field tests and the results of the pile loading tests were compared with the back evaluation and the calculations. As a result, it has been concluded that the reliability of the field tests and pile transportation capsules differed by 15-35%.