Anadolu otoyolu Bolu Dağı tünelleri elmalık sol tüp 64+150 ile 64+290 kilometreler arasının mühendislik jeolojisi

Abstract

Anadolu Otoyolu Bolu dağı tünelleri, uzunluğu ve kesit alanı itibariyle dünyanın sayılı tünellerinden birisidir. Hizmete girmesiyle hem ülke ekonomisine çok olumlu bir katkı yapack; hem de, bölgede özellikle kışın yaşanan trafik sorununu da çözüme kavuşturmuş olacaktır. Bolu dağı tünelleri, herbiri 3' er şeritten oluşan 2 tüpten oluşur. Tüplerden kilometre artış yönüne göre (istanbul' dan Ankara istikametine doğru) sol tarafta bulunan 3287 m., sağ taraftaki de 3236 m. uzunluktadır. Sol tünelde kazı halen devam ediyor olmasına rağmen, diğer 3 aynada kazı uzun zamandır yapılmamaktadır. Tüneller Yeni Avusturya Tünel Açma Yöntemi (NATM) prensiplerine göre açılmaktadır. Bu yöntemin amacı, tüneli oluşturan kayacın bir miktar deforme olmasına izin vererek, gerilme kemerlerinin oluşumunu sağlamak ve tüneli mümkün olan en esnek iksa sistemiyle kendi kendine taşıtmaktır. Tünellerde kullanılan kaya sınıflama sistemi, Ö NORM B 2203' ün Yeni Avusturya Tünel Açma yöntemi için revize edilmiş halidir. Tünellerde kullanılan iksa yöntemleri de, bu kaya sınıflama sisteminin gerektirdiği şekilde projelendirilmiştir. Tünel güzergahında yer alan kayaçlar, mekanik özellikleri açısından oldukça zayıftır. Bu kayaçların, Ö NORM B 2203' ü oluşturan A1, A2, B1, B2, C1, C2, L1 ve L2 şeklinde düzenlenmiş 8 ana sınıfın dışında olduğu kabul edildiği için, CM (C Modifiye) adında yeni bir sınıfa ihtiyaç duyulmuştur. Daha fazla destekleme gerektiren CM sınıfı uygulamalarında, NATM gereği, tünelde görülen deformasyonlara göre projede değişiklik yapılabilmektedir. Tünellerde, ilk kaplamayla bütün deformasyonların kontrol altına alınabileceği düşünüldüğünden, son kaplama yük taşıyacak nitelikte (donatılı veya çelik fiberii gibi bir başka tipte) projelendirilmemektedir.

The main purpose of thesis is to define the reason of deformations in Anatolian Motorway, Bolu mountain tunnels, especially in left tube between the chainage 64+150 and chainage 64+290. In the first section, studying area and its climate conditions, population density were introduced briefly. In addition, previous studies about the area are given. Studying area is between Bolu and Düzce and in Bolu city borders. Tunnels are placed approximately 20 km. north-west of Bolu. Gümüşova-Gerede Motorway is a part of 114 km. of Anatolian Motorway. These tunnels are the only way connecting Istanbul to Ankara by highway, therefore transportation is extremely easy to these cities. Around the studying area, Düzce and Bolu are important centers considering population density. Elmalık village is just near the south-east portal of tunnels and gives its name to this portal. There are very deep valleys and small plains, and many small streams near the studying area. Although the average elevation is 850 m; the highest point is Köroğlu mount which is about 2370 m. Bolu is located in the inner part of West Blacksea region, summers are hot and drought, winters are cold and rainy. The maximum and minimum temperature determined in the area is 39,5 °C and -40 °C. The annual average temperature the region is 8,5 °C. According to the meteorology data, the minimum and maximum precipitation are 35 mm. in July and 185 mm. in December. The annual average precipitation is 750 mm. The most important studies were done by Latterman (1911), Blumenthal (1948), Abdüsselamoğlu (1959), Yılmaz (1981), Şengör (1985), Yılmaz (1995), in the area. Latterman 1911, was detected the coal that occurred in Tertiary between Bolu and Mengen. The first geological map of Bolu area was done by Blumenthal in 1948. Paleozoic and older aged basin were called as "Bolu massive" by him. Abdüsselamoğlu 1959, determined the "Yedigöller formation", "ikizoluk formation", "Fındıcak formation", "Bayramışlar formation". Yedigöller formation is older than Devonian. Ikizoluk is a sedimentary origined Devonian aged forrmation. Fındıcak and Bayramışlar formations are flishoid series and aged in Upper Cretaceous. Yılmaz 1981, studied on Abant (Bolu) and Dokurcun (Sakarya) area and examined the relations of metamorphic rocks and ophiolitic rocks. Şengör 1985, mentioned that North Anatolian Fault is separated into two arms near the west of Bolu, in 1985. The "southern arm" passes through Abant lake and meets Mudurnu valley with 11° anti-clock wise. The "northern arm" produces the south border of "Düzce basin" as if changing to north by clock wise. Then this fault called "Düzce Faulf. Yılmaz 1995, according to them, Precambrian basin are consist of two different rocks. The lower rocks are amphibolite, hornblend schist, and metamorphised leuko-granitic structure. The upper rocks are exposed to lower graded metamorphism. Second section is about the formations and evolution of the studying area. In the tunnel, we can observe Yedigöller formation (Pzy), ikizoluk formation (Di) and its Çatak member (Die), Elmalık granitoid (Ke), Atyayla formation (Kat), Bayramışlar formation (Kb), Fındıcak formation (Ktf), Apalar formation (Ta) and its Açma member (Taa), Asarsuyu formation (Qa) and sediments of Quaternary. Yedigöller Formation is Devonian aged and contains metadiorite, metagranite and amphibolites. Ikizoluk Formation is above Yedigöller Formation, consists of slate, phyllite, shale, quartzite and Çatak member comprised of recrystaliized limestone and dolomitic limestone. The contact between Yedigöller and ikizoluk formations is tectonic. Abant complex is above ikizoluk Formation in the sequence. The Elmalık granitoid is at the same age or younger than Abant complex. Overlying this, Atyayla Formation contains upper Cretaceous age brecciated marble and Bayramışlar Formation formed by sandy limestone and carbonate-containing- sandstone. Upper Cretaceous-Lower Paleocene in the area is represented by Fındıcak Formation which consists of alterated and brecciated pebblestone, siltstone, claystone, marl and limestone. Apalar formation composed of clay, claystone and limestone, and the Açma member contains of clayey limestone. Plio-quaternary is represented by clayey silt, clayey sand and pebblysand. Technical information about tunnels, description and types of tunnels, some tunnel driving methods like English, Austria, German and Belgium methods were introduced in the third section. In the fourth section, topography and lithology of the tunnels alignment were explained. Moreover, rock classification, application and design methods of NATM were introduced. XI The beginning of the tunnels starts at Istanbul side, so we can call the tunnels "left tunnel" and "right tunnel". The length of the right tube is approximately 3236 m. and the length of the left tube is approximately 3287 m. The distance between the tubes is minimum at the beginning and changes 30 to 60 m. Along the tunnel alignment, from the Elmalık portal to Asarsuyu portal Yedigöller Formation, Ikizoluk Formation, Elmalık Granitoid, Apalar Formation, Findicak Formation, Atyayla Formation, Asarsuyu Formation are expected to be seen respectively. Approximately 400 m. of tunnels will be passed in Yedigöller Formation (%12,26); 1440 m. in Ikizoluk Formation (% 44,15); 270 m. in Çatak member (% 8,27); 160 m. in Atyayla Formation (% 4,9); 120 m. in Elmalık Granitoid (3,67); 230 m. in Findicak Formation (% 7,05); 640 m. in Apalar Formation (% 19,65). Excavation width and height of the tunnels (without any reinforcement) are 16 m. and 1 1,5 m. Required usable width and height (after every kind of reinforcement) are 14 m. and 8,60 m. The groundwater in tunnels causes some undesirable problems like swelling, squeezing, decreasing in advance speed of driving. In Bolu tunnels, there is only 4 It/sec. groundwater flow in Asarsuyu left tube. This water comes from a drainage hole which is about 15° clock-wise with tunnel alignment in horizontal plane. Although 4 It/sec. of groundwater flow causes considerable problems in future, drainage of this water by a pilot-tunnel or to reduce undesirable effects are proposed. Except this water flow, there is no any kind of water in the tunnels. There were 29 drill holes over the tunnel alignment, and groundwater level was encountered in 22 holes. In recent years, different type of rock classification systems are used for different type of projects. The most common of them are Ö Norm B 2203, Q System (by Barton), RMR System (by Bieniawski), Terzaghi Classification System, RQD System (by Deer). Ö NORM B 2203 rock classification system which is used in Bolu tunnels project, is revised type of Rabcewicz and Pacher (1974) system for necessities of New Austria Tunnelling Method (NATM). Bolu mountain tunnels are driven and constructed by NATM. The properties and differences of this method from the classical methods are explained by Leopold Muller in 21 item. (Der Felsbau, 3. band, Tunneibau, Enke Verlag, Stuttgart, 1978). There are eight type of rock class in Ö NORM B 2203. These are A1, A2, B1, B2, C1, C2, L1, L2. In addition to them a new classification produced to the project by constructor which called CM (C-Modified). The driving method in the tunnels is excavation of the face in three step by an excavator. The face divided into three part as "top heading", "bench" and "invert". The distance between top heading and bench changes 20 to 30 m; and the distance between bench and invert changes 15 to 25 m. (These distances especially are being followed when the rock type is CM or C2 classifications). XII The tunnels are being constructed as "double tube". Gabarites in the tunnels are 5 m. There are 3 lined roads in the tunnels and every line is 3,75 m. Concerning the flowing of traffic, free spaces were projected 0,50 m. at the right, 0,25 m. at the left as a security line. Tunnels are not permitted to pedestrian traffic. Pavements are over 30 cm. of the road surface. 0,75 cm. width; 2,00 m. heigth gabarites were projected for the pavements. In the tunnels, excavation was started at the four face at the same time in the beginning of the project. Due to excessive deformations, only Elmalık left tube excavation is carried up to now. Excavations at other faces will be started as soon as new project prepared. Traffic values given below, were used for the calculation airing system capacity in the tunnels. These are projection values of 2010 yean Total 23313 per day Fifth section is about engineering geological and geotechnicai studies during application step. Face cross sections, geomechanical properties of 8ie samples that were taken from boreholes or excavations, supporting and excavation types and their elements, deformations (between chainage 64+150 and chainage 64+290) were described. The tests about water, Atterberg limits, sieve analysis, soil classification test (USCS) were carried out, but uniaxial test, triaxial test, consolidation test were carried out on the samples which were taken from boreholes or excavation areas time to time. Sixth section consists of results and interpretations about observations. To obtain sensitive results about parameters in order to explain reason of deformations, observational and experimental systems should be used in the tunnels. In the Bolu mountain tunnels, undefined high stress values observed as excessive deformations make calculations and interpretations unrealistic. Using water, during drilling of rock bolts, will affect negatively confined rocks. Especially, test results held on clay samples shows that giving up water use will be so useful to prevent deformations. In squeezing rocks, after some tolerable deformations passive support systems must be fixed. Without final lining fin place casted concrete) deformations (convergence) will increase. XIII Steel fiber added or reinforced final lining will be very useful. Deformations will be controlled with less cost when compared with unreinforced linings which is more expensive. In the tunnels, controlling the deformations which occurred by the 3rd dimension effect, ring closure distance has an important role. Not exceeding 35 m. ring closure distance, supplies advantages to control deformations. Using the time in the tunnels is extremely important factor both economy of the project and convergence. On the other hand continuity driving of tunnel is important for the tunnel cost. With the new projects demands, cost-benefit-time analysis must be carried out. It is possible, if the measurements, researches and observations are being interpreted correctly. Steel fiber added shotcrete will supply more powerful initial lining. Moreover it will decrease the thickness of shotcrete and amount of using wire mesh. If there is no any movements on the rock bolts' plates, rod extensometer measurements must be examined so sensitively. The definition of elastic-plastic zone borders exactly, is very important both cost economy and convergence. The axial sliding of the tunnel should be examined according to the movements on the rock bolts' plates.