Kuzey Marmara Otoyolu Garipçe yarmasının mühendislik jeolojisi ve kazı şevlerinin analizi
North Marmara Highway engineering geology and excavation cut slopes analysis of Garipce  slope
Yazar: GİZEM ŞENOL
Danışman: DOÇ. DR. YILMAZ MAHMUTOĞLU
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Jeoloji Mühendisliği Ana Bilim Dalı / Uygulamalı Jeoloji Bilim Dalı
Derece: Yüksek Lisans, 2015
Konu: Jeoloji Mühendisliği = Geological Engineering

Özet:
Kuzey Marmara Otoyolu kapsamında yapılacak olan güzergah çalışmaları Asya yakasında Poyraz-Paşaköy otoyolu ile Çamlık-Reşadiye bağlantı yolu, Avrupa yakasında ise Odayeri-Garipçe otoyolu ile İstoç-Odayeri Bağlantı yollarından oluşmaktadır. Bu projenin Odayeri-Paşaköy bölümünde yaklaşık 115 km uzunluğa sahip Kuzey Marmara Otoyolu yer almaktadır. Karayolu güzergahının amacı mevcut olan trafiği azaltmak ve ulaşım problemini giderebilmektir. 
Bu tez kapsamında Kuzey Marmara Otoyolu Garipçe yarmasının mühendislik jeolojisi ve kazı şevlerinin analizi değerlendirilmiştir. Garipçe yarmasının bulunduğu zemin ve kaya birimlerinin mühendislik jeolojisi özellikleri incelenmiştir. Inceleme alanının veri tabanlarının olşturulması amacıyla 9 adet mekanik sondaj, sismik çalışmalar  ile saha çalışmaları ve laboratuvar deneyleri yapılmıştır.  Sondajlar ile korele edilen jeofizik çalışmalar ışığında inceleme alanının jeolojisi yorumlanmıştır. Mühendislik jeolojisi çalışmaları sonucu şev duraylılığı açısından meydana gelebilecek sorunlar üzerinde durulmuştur. 
Kinematik analiz çalışmaları ile andezit birimlerinin düzlemsel kayma, kama kayması ve devrilme durumları sağ ve sol şevler için ayrı ayrı incelenmiştir. Yarma içerisinde kritik olarak belirlenen kesitlerde zemin ve kaya birimleri için hesaplanmış olan parametreler ile Plaxis programı yardımıyla stabilite analiz çalışmaları yapılmıştır. Analizler statik ve dinamik (depremli) durum için ayrı ayrı incelenmiştir. Kesit üzerinde en büyük kayma çemberi çizdirilerek kritik olan bölge belirlenmiş ve o noktalardaki güvenlik sayıları elde edilmiştir. Yarmalarda uzun dönemde duraylılığı sağlayacak koşullar göz önüne alınmıştır. Araştırma Mühendislik Hizmetleri Teknik Şartnamesine göre uzun dönem (statik) için güvenlik sayısı 1.5'den büyük, uzun dönem (dinamik) için güvenlik sayısı ise 1.1'dem büyük olmalıdır.Bu değerlere uygun olmayan güvenlik sayıları değerleri ile karşılaşıldığında iyileştirme yollarına başvurulmuştur. 
Garipçe yarması için belirlenen şev oranları 1. palyeden önce 2Y/3D, 1. palye ile 2. palye arası 3Y/2D, 2 palyeden sonra 2Y/1D olarak belirlenmiştir. Km:86+330 kesitinde yapılan stabilite analiz çalışması sonucunda statik ve dinamik durumlarda yarmanın güvenlik sayısının uygun değere sahip olmadığı tespit edilmiştir. Zemin çivisi ve püskürtme beton ile iyileştirme yapılan yarmanın statik durumda 1.74, dinamik durumda 1.37 değerleri elde edilmiş ve güvenli olduğu belirlenmiştir. 
Km:86+590 kesitinde yapılan stabilite analiz sonucunda statik ve dinamik durumlardaki güvenlik sayıları açısından herhangi bir problemin olmadığı görülmektedir. Ancak yarmada Garipçe formasyonuna ait ayrışmış andezit birimlerine rastlanılan aralıkta destek sisteminin kullanılması şevin duraylılığı açısından yararlı olacaktır.

Abstract:
Works regarding highway course to be carried out within the scope of the North Marmara Highway comprise of Poyraz-Paşaköy motorway and Çamlık-Reşadiye access road in the Asian side and Odayeri-Garipçe motorway and İstoç-Odayeri access road in the European side. North Marmara Highway having approximately 115 km length takes place in the Odayeri-Paşaköy section of this project. Objective of such highway route is to ensure passing the strait of İstanbul within the shortest time in a comfortable way as well as to mitigate the traffic load of hazardous pollutants on the urban roads and existing suspension bridges over Bosphorus, and as a result of this, ensure fuel savings, and reduce the effects of contaminated air resulting from the transportation inside the city. Transportation system on rails will also benefit from the suspension bridge planned to be constructed over the strait with high standard for passing Bosphorus.
Engineering geology and excavation slopes analysis of road cuts in Garipçe of the North Marmara Highway have been evaluated within the scope of this thesis. Studies related to the engineering geology in order to determine engineering properties, state of underground water and the rock quality of the environment with regard to Garipçe earth work place in the project scope, have been evaluated within the scope of this thesis. In the area where the road cutting is taken place, it changes into totally decomposed, extremely decomposed andesite and levels of agglomerate andesite locally available comprising the Garipçe formation when going down to lower layers, whilst Meşetepe formation is taken place at the upper part. It caused subsurface water to be present in the Andesite-volcanic tuff bodies, and locally formed small spring waters unearthing such subsurface water. Although these bodies usually seem to be stable in the nature, they may also exhibit other behaviors than stable state when they are subjected to engineering processes.
Geological map-cross section with 1/1000 scale and geotechnical data table of the Garipçe earth work covering the area under examination have been prepared. Cross-sectional studies have been carried out at the certain kilometers specified as critical.
General geology and hydrogeology of the route have been outlined within the scope of the report, engineering geology properties of the formations have been described, drilling and geophysical studies have been carried out in the field and laboratory experiments have been evaluated. Laboratory experiments have been performed on the soil and rock using analyses to determine the stability of slopes that will be built up during the construction of Garipçe earth work within the area under examination, and samples taken for the purposes of determining index properties of the material in order to evaluate the geomechanical behaviors of the material in this area. Data related to consistency limits, sieve analysis and water content have been determined with the experiments on samples taken from the soil. On the samples obtained from the rocks experiments such as physical properties, mechanical properties, erosion index in water and triaxial pressure test have been performed. In addition to that geophysical (MASW) studies were carried out in order to determine the border between soil and rock in detail. Geological state of the area under examination have been interpreted in the light of drillings and correlated geophysical studies. Emphasis has been put on the problems that may arise in terms of slope stability and be identified as a result of engineering study.
Positions of their joints were determined from the andesite exposure constituting the rock bodies through which road cut slopes are formed. Contour diagrams and kinematic analysis have been carried out with such mesurements taken by using the Dips software program of the RocScience company. With the aid of kinematic analysis studies, planar sliding, wedge sliding and toppling situations of the andesite bodies have been examined for right and left  slopes separately.
Determination of the slope ratios capable of keeping their stability under the conditions in the long run, has been intended in the road cutting known as Garipçe earth work, exhibiting a feature of through road cut, having a length of 800 meters and a height of 40 meters. In this regard, drilling operations and geophysical measurement (MASW) works have been carried out together with the  studies on surface geology in the field, and laboratory tests with regard to soil and rock mechanics have been performed on the samples taken. All of these data have been evaluated in the office environment and stability analysis works have been carried out along with the engineering parameter calculations. Hoek-Brown Criterion Generalized by Hoek et al. (2002) has been proposed in order to estimate the strength of rock mass from the properties of rock material with the most correct approach. In this respect, a software known as RocLab which is based on Hoek-Brown failure criterion and determines the strength parameters of a rock mass, has been employed for the rock classification in the cross sections specified as critical within the road cut. 
Strength parameter calculation related to the soil bodies has been carried out with the empirical calculations at all distances between axis for the clay bodies where pile foundation are located, taking the results obtained from the laboratory experiments into consideration. Soil parameter calculations include cohesion without drainage (cu) and modulus of elasticity (Es) calculations. Soil parameter calculations include such short term parameter calculations as cohesion without drainage (cu) and modulus of elasticity (Es) and such long term parameter calculations as angle of internal friction (ϕ) and drained elastic modulus (Es). Rock quality classifications for Garipçe earth work have been achieved using RQD and RMR methods.
Stability analysis works have been carried out using Plaxis 2D software with the parameters calculated for the soil and rock bodies in the cross-sections specified as critical inside the road cut. Plaxis 2D software is a finite element package specially developed for two dimensional analysis of deformation and stability in the geotechnical projects. Analysis have been carried out for static and dynamic (with earthquake) cases separately. Effective ground acceleration coefficient is A0 = 0,2g since location of road cut in Garipçe under examination falls into the third grade earthquake region according to the seismic hazard map. Critical region was determined drawing the greatest slip circle on the cross-section, and factors of safety at those points were obtained. Long term stability which is the most critical case, must be evaluated using effective sliding resistance parameters when stability of the excavation slopes are of concern. According to the technical specification for surveying engineering services, safety factor for long term (static) must be greater than 1.5 and for long term (dynamic) must be greater than 1.1. Safety factors have been improved using certain ways in case where factors of safety nonconforming to these values were observed.
It was observed that no stability problem will be expected in case of specified slope ratios such as 2Y/3D before the 1st bench, 3Y/2D between 1st bench and 2nd bench and 2Y/1D after 2nd bench for the road cut in Garipçe. At the end of the studies, Km: 86+330 and Km: 86+590 cross sections have been considered to be critical and stability analyses have been carried out. In these cross sections at the 42 meter deep from the land level located are a soil body where andesite was completely decomposed and became soil, together with an andesite body featuring main rock properties with agglomerate interface underneath, and decomposed sections of that body. Parameter calculations have been carried out for sandy elastic silt, slightly sandy low-plastic silt and andesite bodies observed for this section. It was determined that it has a "very weak rock" quality taking the correlation between the RQD defined by Deere (1968) and engineering quality of the rock into consideration. It was determined that the factors of safety under both static and dynamic conditions did not have a proper value at the end of the analysis works performed on the Km: 86+330 cross section. Such factors of safety as 1.31 for the static situation and 1.11 for the dynamic situation have been obtained in the stability analysis study. At this section where there is a expropriation problem, it was recommended that the slope before the 1st bench must be reinforced with  28mm (diameter), 10 meter long soil nails with 2mx3m (Y/D) pattern and 20 cm thick shot concrete. Following values, such as 1.74 for static conditions and 1.37 for dynamic conditions, have been obtained for the road cut reinforced and improved with the soil nails and shot concrete and it was deemed to be reliable.
It is seen that there is no problem in terms of static and dynamic safety factors observed at the end of of stability analysis works carried out in the Km: 86+590 cross section. Parameter calculations have been carried out for elastic silt, sandy clay, decomposed andesite and andesite bodies observed for this section. It was determined that it has a "very weak rock" quality taking the correlation between the RQD defined for andesite and decomposed andesite by Deere (1968) and engineering quality of the rock into consideration. Such factors of safety as 2.30 under static conditions and 1.77 under dynamic conditions have been calculated in the stability analysis study and it was seen that there is no problem with the stability of road cut. Slope before the 1st bench between Km: 86+570 – 86+650 in the section where Km: 86+590 is located, was observed to be reliable. However, in terms of road cut safety in the long run it will be proper to apply the reinforcing system given at the table above to this gap where decomposed andesite body will be interrupted.