Zigana Karayolu Tünelinde şaft açma işleminde, kayaç özelliklerinin pilot delgi verimlilik parametrelerine etkisinin incelenmesi
Investigation of rock properties affecting pilot drilling efficiency in Zigana Highway Tunnel shaft openning
Yazar: PELİN KOÇAK
Danışman: DOÇ. DR. ÖMÜR ACAROĞLU ERGÜN
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Maden Mühendisliği Ana Bilim Dalı / Maden Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2019
Konu: Maden Mühendisliği ve Madencilik = Mining Engineering and Mining

Özet:
Günümüzde, maden, inşaat, altyapı, enerji vb. uygulamalarında, birçok farklı ihtiyaçtan dolayı şaft açma operasyonları gerçekleşmektedir. Şaft açma işlemi farklı ihtiyaçlar için, yer üstünden yer altına erişim ya da yer altından katlar arası erişimi sağlamak için açılan genelde silindirik, 90 ile 45 derece arasında açıklıklar yaratılarak gerçekleştirilir. Bu uygulama, birçok parametreye bağlı çok kompleks operasyonlardan biridir. Şaft açma uygulamaları bir seri farklı yöntem ile gerçekleştirilebilir. Gün geçtikte artan güvenlik vurgusu ile, diğer bir çok operasyonda olduğu gibi şaft açma operasyonlarında da mekanize kazının önemi artmaktadır. 
Bu tez çalışması kapsamında, Zigana Karayolu Tüneli inşaatı dahilinde,  baş yukarı delme ve genişletme yöntemi  (raiseboring) ile mekanize olarak açılan havalandırma şaftı incelenmiştir. Şaftın çapı 3.6 m, uzunluğu ise 244 m'dir. Mekanize baş yukarı delme, tamamı yer altında veya yer üstünden yer altına olmak üzere iki kat arası açılacak kuyular için,  delinen bir kılavuz deliğin, alt seviyede bulunan katta delici matkabın genişletme kafası takılarak genişletilmesi ile gerçekleştirilmektedir. Projede Atlas Copco/Epiroc 91RHC baş yukarı delme makinesi kullanılmıştır. Bu makinede bulunan yazılımlardan biri olan delerken ölçme (measure while drilling) sayesinde makine çalışma parametreleri (tork, baskı, rotasyon hızı, ilerleme hızı) tüm şaft operasyonu için kaydedilmiştir. Aynı zamanda bu verilerden spesifik enerji değerleri hesaplanmıştır.
Bu tez çalışmasında odaklanılan pilot delgi,  delik temizliğini hava-su karışımı ile sağlayan döner delgi yöntemi ile yapılmıştır. Döner delgi yönteminin ana prensibi, matkap üzerine yüksek baskı kuvveti uygulayarak, kayacın ezilmesi ve eş zamanlı gerçekleşen rotasyon ile ezilen kayacın koparılarak delik dışına taşınması olarak tanımlanabilir. Bu yöntemde hayli yaygın olarak üç konili matkaplar kullanılmaktadır. Üç konili matkaplar, uluslararası sınıflandırmaya tabi olarak uygulamaya özel olarak tasarlanabilir. İlgili şaftın açılmasında da tungsten karbit dişli 349 mm çapındaki üç konili matkap kullanılmıştır.
Zigana Karayolu Tüneli inşaatı, eski Maçka civarı Trabzon-Gümüşhane'yi bağlayan, 1702 m uzunluğunda Zigana Tüneli'nin yerini alacak, yaklaşık 15 km uzunluğunda hala inşaası devam eden karayolları tünelidir. Tünel projesinde toplamda 6 adet kalıcı havalandırma şaftı açılacaktır. Tünelin açıldığı arazi volkanotortul, volkanik ve intrüzif kayaçlardan oluşmaktadır. Şaftlar için spesifik olarak jeoteknik bir çalışma yapılmamış olsa da, bu çalışma kapsamındaki şaft için karotlu sondaj yapılmıştır. Kayaç deneyleri bu sondaj karotları ile gerçekleştirilmiştir.
İTÜ  Maden Mühendisliği Bölümü, Kaya Mekaniği laboratuvarında, seçilen ve gerektiği şekilde boyutlandırılan numunelere, tek eksenli basma dayanımı, dolaylı çekme dayanımı ve Pundit akustik hız testleri yapılmıştır. 
Bu deney sonuçları, makine tarafından kaydedilen makine parametreleri ile ilişkilerinin incelenmesi adına, veri setleri oluşturulmuştur. Bu veri setleri kayaç davranışlarına ve uygulama gerekliliklerine göre normalleştirilmiştir. Sonrasında her bir makine parametresi ile ölçülen  kayaç parametresinin grafikleri çizilerek, bire bir iki değişken arasındaki ve iki bağımlı bir bağımsız parametre grupları için eğilimler araştırılmıştır.  Elde edilen sonuçlar ile, kayaç parametreleri ve makine parametreleri arasındaki ilişkiyi temsil eden R2 determinasyon katsayıları sunulmuştur.

Abstract:
Based on many different needs, shaft drivage operations have been carried out all around the world in mining, foundation, construction, energy industries.  A shaft drivage may be defined as creating an access structure among levels in underground or simply the access from surface to underground. Mostly, it is cylindrical shaped openning with 45 to 90 degrees from horizontal line. As all the mining operations tend to go deeper by the increased raw material demand from industries, or by the increased population creating a need for higher buildings which will have deeper foundation excavations, or deeper transportation options, shaft sinking will become even more of a common operation. Since it is one of the most complex applications, emphasis on safety is also increasing. Like any other operation related to underground, mechanical excavation of the shaft are making the operation safer. 
Mechanized shaft openning, has many versions due to dimensions and methods. The principle of raiseboring method is drilling a pilot hole between two levels, and ream the pilot hole upwards with a reaming head which can be designed specific to the operation needs. The pilot hole is a hole with much smaller diameter than the required final one. This pilot hole must be reaching an underlying mining space where the full diameter reamer bit is mounted. The raiseboring method can be used for different dimentions with a mandatory condition to have access of the two levels beforehand. 
This master thesis includes studies on a ventilation shaft´s pilot hole which is opened by a mechanized raiseboring method in Zigana Highway Tunnel construction. The tunnel is a new version of the same passage on Pondic mountains in North-East Turkey. The 1702 m length old tunnel which is open for the traffic, connecting the cities Trabzon to Gumushane. The new one will be connecting the same cities with a length of 15 km, with twice more lanes, and  shorthening the distance. The project consists of 6 permanent ventilation shafts. So far, there is only one of the planned shafts opened, which makes this study possible but not compareable. The shaft in question has a 3.6 m diameter 244 m depth. The machine model is Atlas Copco/Epiroc 91RHC which has a capacity to create shaft opennings with 5 m diameter and 1000 m depth. 
In order to evaluate the performance of a raiseboring operation, number of factors were governed to fracture and cut the rock using mechanical means. Some of these are related to the rock formation, others to the forces applied by the machine, and working process including operations, maintenance so on. Within this study, the rock properties´ effects in drilling efficiency, were investigated.
The geology around the construction area varies from volcanic, volcanic sedimentary and intrusive rock formations. Unfortuantely, there is no specific geotechnical studies done for the shafts.There have only one core drilling done for sampling, for the shaft in question. The rock properties taken into consideration for this study, were the results of the laboratory testing of those core samples. The selected core samples were sized as needed and tested in  ITU Mining Enginnering Department, Rock Mechanics laboratory. The tests run with the samples are like following: uniaxial compressive strength, indirect tensile strength and Pundit ultrasonic wave velocity testing.
The pilot hole was drilled by rotary drilling method with a flushing by water and air. Rotary drilling is one of the most common drilling methods whose basic brinciple is to crush the rock by the weight on the bit, and simultaneously to cut the chips and remove them out of the hole by rotation. It is of importance to remove material being cut from the bottom of the pilot hole immediately to receive a clean efficient drilling process. Indwelling material will lead to lower penetration rate and rougher drilling operation. By sending bailing medium, like compressed air and water, through drill pipe cut material is removed. 
The bit used in rotary drilling may come in different shapes and properties, designed specifically for the operation. As a rotary drilling bit, tricone bits highly preferable in many rotary drilling applications which has an international  classification system. This system enables improved drilling efficiency by monitoring within standards. For example, the spacing of inserts of teeth is greatest for the softer or weaker formations and decreases as the formation hardness increases. The pilot bit which was used in Zigana has 349 mm diameter, is equipped with hard, round top inserts, low offset and full bottom hole coverage combine for long hours of drilling in hard rock, high weight on bit applications. Nose and inner row teeth are round top and are positioned for bottom hole coverage. 
Not only the drill bit and reamer but also the selection of other drill string elements is highly important for raiseboring applications. As in every rock advancing method, the power must be transmitted as efficiently as possible. The purpose of the drill string here is to transmit the torque and weight from the head assembly to the drill bit for the whole depth during the pilot drilling.
As a safety factor, increased automation is also continuous trend for shaft openning applications for reduced labor; faster and smoother operation; data logging and diagnostics. Computerized control systems ensure that the operating parameters can be selected as the optimal to get the most out of the raiseboring, both in performance and economy. The machine before mentioned has a computerized control system which has many different software options.  One of these software is called as Measure While Drilling (MWD), which reads sensor data and records the machine operating parameters like, net force, torque, rotation speed, rate of penetration, flushing pressure, power used and so on for both pilot drilling and reaming for requested length or time interval. Measure While Drilling allows drilling parameters to be reviewed for optimization and safety. As the focus of this study is the pilot drilling, and the pilot drilling data was recorded by MWD. The data was utilized in order to contribute the investigation in question. The data was recorded for each 5 cm of the shaft opening in Zigana Highway Tunnel.
The MWD data was firstly prepared in order to be utilized for the investigation. An unusual behaviour was recognized as a significant and instant change in bit force and velocity in stage change in the telescopic thrust cylinder. The problem defined as; penetration velocity decrease in first stage and change significantly in transition between the two stages, also pressure indicators at displays showing that force between pilot bit and rock increases in transition between the two stages. By the light of previous studies about the machine 91RHC, net bit force data was normalized.  Then the preparation was completed to calculate the spesific energy which can be defined the work done to drill/break/excavate one unit volume of rock. Specific energy is proposed to be accepted as a function of machine parameters as torque, penetration rate, weight on bit and rotation speed, and in order to investigate and define the correlations further, it was proposed as a function of rock properties as axial stress and axial strain.
In conclusion, in order to investigate and evaluate rock properties affecting pilot drilling efficiency, the results of laboratory testing for uniaxial compressive strength, indirect tensile strength and Pundit ultrasonic wave velocity, MWD data for net force, torque, rotation speed, rate of penetration and specific energy values were listed by the  depth. As a combination of the rock behaviour, core logs and machine parameters, 244 m pilot hole was divided into 39 zones, and 1 zone was omitted from the investigation.The graphs for torque, weight on the bit, rotation speed, specific energy were generated with the rock properties test results within the zones in order to monitor the trends among the parameters. For further investigation, a secondary data set was created for the drilling and rock parameters in line at the exact same depth. The correlation analysis were run again and R2 determination coeffients were also presented for the new data set. The R2 determination coeffients were obtained low too. Moreover, 2 variant regression analysis was run, and as a significance of correlation between each drilling parameters and multiple rock properties, R2 determination coeffients were presented.