Vadistanbul Park 3.etap projesi derin kazısı vaka analizi
Deep excavation systems and a case study of deep excavations : Vadistanbul park 3.stage project
Yazar: MUHAMMET RÜŞTÜ ÖZCAN
Danışman: DOÇ. DR. İSMAİL HAKKI AKSOY
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / İnşaat Mühendisliği Ana Bilim Dalı / Zemin Mekaniği ve Geoteknik Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2018
Konu: İnşaat Mühendisliği = Civil Engineering
Dizin: Derin kazı = Deep excavation ; Temel kazıları = Foundation excavations ; Yatay yüklü kazıklar = Horizontal loaded piles ; Zemin ankrajları = Soil anchors ; İksalı kazı = Braced excavation

Özet:
Büyük şehirlerde gün geçtikte artan nüfusa paralel olarak bu nüfusun ihtiyaçlarına karşılık verecek konut, eğitim-iş merkezi, sanayi yapıları gibi inşaat projelerin hızla artması şehir merkezlerindeki arsa stoklarının azalmasına neden olmuştur. Bu nedenle, mevcut olan arsaların kullanımını optimum şekilde değerlendirme gereği oluşmuş, bunun sonucunda da yerin üstü kadar altını da proje gerekliliğine göre maksimum seviyede kullanması ihtiyacı oluşmuştur. Arsa maliyetlerinin artması ve yerleşim alanlarının daralmasıyla birlikte şehirler düşey olarak genişlemeye başlamıştır. Son yıllarda ülkemizde yapılan yüksek katlı binaların derin kazıları nedeniyle yapılan bu derin kazılardan dolayı mevcut yol ve binalarda yapısal hasar oluşmaması ve temel çukurunu emniyetli bir şekilde tamamlamak amacıyla iksa sistemleri oldukça önem kazanmıştır. Bunun neticesinde; zemin durumuna, arazi çalışma koşullarına, güvenlik faktörü ve bütçe kısıtlamaları doğrultunda çeşitli iksa yöntemleri geliştirilmiştir. Bu tez çalışması kapsamında derin kazılar teori ve uygulama yöntemleri üzerinde çalışılmış ve bir vaka analizi ile örneklendirilmiştir.  
Tez çalışmasının ilk kısmında, derin kazılarda iksa sisteminin önemi, iksa sistem seçimine etki eden faktörler, iksa sistem seçimi öncesinde yapılması gereken geoteknik ve zemin etüdü çalışmaları ve iksa sistemlerinin karşılaştırılması üzerinde durulmuştur.
İkinci kısmında iksa sistemlerine etkiyen toprak basınçlarından bahsedilmiş, çeşitli zemin koşulları için öngörülen toprak basıncı dağılımları incelenmiştir. Sonraki kısımda ise oluşan yüklere karşı uygulamada kullanılan yatay ve düşey destek elemanları detaylı olarak incelenmiştir.
Tez çalışmasının son kısmında ise bir vaka analizi olarak Vadistanbul Park 3.Etap Projesinin kazısı incelenmiştir. Proje sahasında yapılan zemin etüd çalışmalarına göre Cendere Deresi yatağında bulunan, dolgu ve alüvyon birimler ve yer altı su seviyesinin yüksek olduğu inşaat alanında, iksa sistem için seçilen ideal zemin parametreleri, uygulanabilecek alternatif iksa yöntemlerinin karşılaştırılması maliyet ve uygulanabilirlik açısından değerlendirilmiştir. Bunların neticesinde yapımına karar verilen iksa sisteminin uygulama aşamaları anlatılmış, uygulama sırasında yapılan inklinometre ölçümleriyle, her kazı kademesindeki yapılan hesap sonuçları karşılaştırılmıştır ve seçilen tasarım parametrelerinin geçerliliği değerlendirilmiştir. Sonrasında uygulama sırasında karşılan sorunlar ve buna bağlı olarak yapılan proje revizyonları irdelenmiştir. 
Sonuç kısmında ise Vadistanbul Park 3.Etap Projesinin iksa sistem seçimi ve uygulama neticesinde çıkarılan sonuçlar değerlendirilmiş ve tez çalışması tamamlanmıştır.

Abstract:
The rapid increase in construction projects such as housing, education-business center, and industrial structures, which will meet the needs of this population in parallel with the ever-increasing population in big cities, has led to a decrease in land stocks in the city centers. For this reason, the need to optimally assess the use of available lanes has arisen, resulting in the need to use as much under the ground as required by the project. With the increase of the land costs and the narrowing of the settlement areas, the cities started to expand vertically. In recent years, due to these deep excavations of high-rise buildings built in our country, shoring systems have become very important in order not to cause structural damage to existing roads and buildings and safely to complete the foundation pit. As a result of this; many methods have been improved according to the ground conditions, field working conditions, safety factor and budget constraints. In this thesis, deep excavation and application methods have been studied and exemplified by a this study.
In the first section of the thesis study, importance of excavation system in deep excavation, factors affecting excavation system selection, comparison of geotechnical and soil investigation studies and excavation systems which should be done before excavation system selection is emphasized.
In the second part, the soil pressures affecting the excavation systems are mentioned and soil pressure distributions for various soil conditions are investigated. In the next section, horizontal and vertical support elements used in practice against the loads that have occurred are examined in depth. The lateral soil pressure, which is the most important load acting on the excavation system, depends on the shear strength parameters of the soil, the unit volume of the soil, the excavation depth, the displacement rate of the excavation and the groundwater level. The lateral earth pressure is generally defined as the applied effective pressure applied at the desired depth while limiting the horizontal movement of the ground mass behind the bulk support method. The Rankine Theorem or the Wedge Theorem, which was discovered by Coulomb and later developed as the Wedge Theory, is used to calculate the soil pressures that affect the support systems. In addition, when calculating lateral pressures caused by other loads, there are also formulas found using elasticity theory. A Passive Earth Pressure occurs when the Active Earth Pressure advances towards the side of the excavation structure floor, when a backing structure with a soil on its back moves forward. When the retaining structure does not move, the pressure is defined as the Soil Pressure.
In the last section of this study, the excavation of Vadistanbul Park 3rd Stage Project was examined as a case study. In the area of construction, where the filling and alluvial units and alluvial units in the Cendere Creek bed and the groundwater level are high according to the ground survey studies carried out on the project site, the ideal soil parameters selected for the shoring system have been evaluated in terms of cost and applicability of the alternative shoring methods that can be applied. At the end of thesis, the application phases of the system were determined and the results of calculations made at each excavation stage were compared with the inclinometer measurements made during the application and the validity of selected design parameters was evaluated. Afterwards, the problems encountered during the implementation and the project revisions which are made accordingly have been examined. In the construction area where the filling and alluvial units and alluvial units and the groundwater level are high in the Cendere Creek bed according to the project ground survey studies, the ideal ground parameters selected for the excavation system are evaluated in terms of cost and applicability of alternative excavation methods that can be applied. At the end of these, the application phases of the system were determined and the results of calculations made at each excavation stage were compared with the inlinometer measurements made during the application and the validity of selected design parameters was evaluated. Afterwards, the problems encountered during the implementation and the project revisions which are made accordingly have been examined.
In the conclusion, the results of the selection and application of the vix system of Vadistanbul Park 3rd Stage Project were evaluated.
In this study, the analysis of the excavation system made within the scope of Vadistanbul Park Phase 3 Project, the comparison of displaced values measured at the site during the application, the cost and duration comparison of alternative excavation systems were made and the following results were obtained. It is important that the selection of the soil parameters reflects the facts in the analyzes made by the finite element method in the determination of the temporary excavation system. The use of the Hardening Soil Model in the analyzes was deemed appropriate for this project, given that the results obtained reflect the facts. In four different inlinometer measurements examined, the positive displacement effect of jet grout column in the heel area of excavation is observed in horizontal displacements. In addition, the inclination of the inclination with the inclination of the Plaxis analysis curve is parallel to the excavation upper edge and the excavation elevation, but does not appear to be below the excavation height. In the four examined inclinometer wells, the graphs show that the displacement values in the analysis are larger than the measured displacement values in the field. Six rows of jet grout columns were produced in this area. It can be said that the jet grout columns manufactured on the alluvial soil have improved the healing and soil rigidity in a wider area than the design. It has been seen that the water-impermeability with the jet grout columns to be manufactured between the fore piles can be successfully achieved with the piles made of Fore piles. It has been understood that a safe and economical excavation system can be created by the limited amount of pile length under the excavation floor level and by the improvement of the jet grout columns in the heel area. The effect of jet grout columns manufactured in the heel area on the buckling columns formed by Fore piles was found to be positively affected by inlinometer measurements.
As a general approach, in such projects, if the vertical component is close to the surface, it is expected to be plugged into this layer. However, despite the fact that the main house is about 30m deep in this project, alternative solutions have been aimed at because of the high cost and applicability of the system. A pit jet grout column system was created on the heel to limit lateral displacements in the excavation ball by choosing a pile length of approx. The project has been made according to these principles, and as a result the cost system has been completed safely by reducing the cost.
Deep excavation support systems use a variety of different methods such as bored piles, secant piles, diaphragm wall, ground anchors, struts. Cost, duration and safety criteria should be considered together with the optimum solution for each project according to the site and ground conditions. Three different shoring systems have been dealt with in the light of these criteria for deep excavation of 3rd stage in Vadistanbul Park. The first of these is the system consisting of the bored pile, the prestressed anchor, the jet grouting between the piles to ensure water impermeability, and the jet grout application in order to increase the passive resistance in the heel area. The second system consists of a diaphragm wall and an anchor system. The third system consists of secant piles and and prestressed anchorages. Within the scope of this thesis study, these three alternative systems were compared in terms of cost, duration and safety. In practice, according to these criteria, it was decided and applied that the pile system consisting of bored pile, prestressed anchorages and jet grout is the most appropriate solution.
In the conclusion, the results of the selection and application of the shoring system of Vadistanbul Park 3rd Stage Project were examined and this study is completed.