Süreksizlikler arası mesafe ve süreksizlik kutupsal yöneliminin açık işletme kaya şevlerinde yer değiştirme davranışına etkisinin araştırılması
Investigation of the effect of the discontinuity space and the discontinuity orientation on the amount of displacement in open pit rock slopes
Yazar: HACER BÜŞRA ÇOŞKUN
Danışman: DOÇ. DR. HAKAN TUNÇDEMİR
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Maden Mühendisliği Ana Bilim Dalı / Maden Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2022
Konu: Maden Mühendisliği ve Madencilik = Mining Engineering and Mining
Dizin: Madencilik = Mining ; Süreksizlik = Discontinuity ; Şev kararlılığı = Slope stability

Özet:
Bir kaya şevinin stabilite analizi geoteknik mühendisliğinin en önemli problemlerinden birisidir. Stabiliteyi ve yenilmeyi etkileyen en önemli parametrelerden birisi de kaya kütlesindeki süreksizliklerdir. Bu tez çalışmasında süreksizlik özelliklerinden; süreksizlikler arasındaki mesafe ve süreksizlik yönelimleri üzerinde durulmuş ve bunların şev stabilitesine ne oranda etkisinin olduğu sayısal çözümleme ile irdelenmiştir. 
Ilk olarak süreksizliklerin geometrileri belirlenmiştir. Süreksizlikler arasındaki mesafeler 400cm, 200cm, 130cm, 60cm, 40cm ve 20 cm olarak belirlenmiştir. Bu mesafeler, kaya kütle siniflandirma sistemlerinden birisi olan RMR'de süreksizlikler arası mesafelere atanan puanlama aralığına denk gelecek şekilde belirlenmiştir.  20cm süreksizlik aralığında süreksizlikler arası mesafeler daraldığı için sayısal çözümlemeleri yapılamamıştır. Bu sebeple 5 süreksizlik aralığında çalışmalar tamamlanmıştır. 
Süreksizlik yönelimleri için 0 ile 180 derece arasında belirli bir algoritmaya göre 12 adet farklı açı kuramsal olarak belirlenmiştir. Bu açılar 0, 22.5, 30, 45, 60, 67.5, 90, 112.5, 120, 135, 150 ve 157.5 derecedir. 40 cm süreksizlik aralığı için 135 derece süreksizlik yöneliminde maksimum iterasyon sayısı aşıldığı için çözümleme yapılamamıştır. Toplamda 59 adet ortam için çözümleme yapılmıştır. 5 süreksizlik aralığından her birisi için bu 12 adet süreksizlik yönelimlerinin sırası ile RS2 programında sayısal çözümlemeleri yapılmıştır. Bu sayede şev üzerinde ve gerisinde ne oranlarda yer değiştirme miktarının gerçekleşeceğini belirlemek hedeflenmiştir. 
Süreksizliklerin her bir geometrik durumunda yer değiştirme miktarlarının hesaplanabilmesi için sonlu elemanlar yöntemi ile hesaplamalar yapan RocScience RS2 programında çözümlemeler yapılmıştır. Bununla beraber güvenlik faktörünün de belirlenmesi için kayma mukavemeti indirgeme (SSR) analizleri de yapılmıştır. Bu analizler sonucunda, program kritik SRF olarak adlandırılan mukavemet indirgeme faktörü belirler ve bu faktör şevin güvenlik faktörü ile eşdeğer bir sonuç verir. Yapılan toplam 59 adet durum analizinin her birinde kritik SRF (güvenlik katsayısı) 1.29'un altına düşmemektedir.
Bu ortamların analizleri yapılırken şev geometrisi, kaya kütlesinin jeomekanik parametreleri ve arazi gerilmesi sabit tutulmuştur. Süreksizlik aralıkları ve yönelimleri ikili kombinasyonlar halinde değişmiştir.  
RS2 programında tüm ortamların çözümleme işlemleri tamamlanıp, yer değiştirme verileri elde edildiğinde, şev aynasından içeriye doğru ve paralel olacak şekilde iki metre aralıklarla (0m, 2m, 4m, 6m, 8m ve 10m) sorgu noktaları belirlenir. Yer değiştirme miktarları ve yenilme yüzeyi bu etkilenme bölgelerine göre değerlendirilmiştir. 
Elde edilen sonuçlara göre; en yüksek yer değiştirme miktarı 400cm süreksizlik aralıklarında, 90 derece süreksizlik yöneliminin bulunduğu ortamlarda ve 6 metre den sonraki etkilenme bölgeleri üzerinde olduğu ortaya konulmuştur.

Abstract:
Stability analysis of a rock slope is one of the most important problems in geotechnical engineering. One of the most important parameters affecting stability and failure is the discontinuities in the rock mass. In this thesis, the discontinuity features; the distance among the discontinuities and the discontinuity orientations as well as the effect of them on the slope stability was examined by numerical analysis.
In the thesis, the slope geometry and rock mass strength parameters determined by Shashenko et al. (2014) were used for a case study. The results of changing the discontinuity spacing and discontinuity orientation in the slope, which were handled with the finite element method using RocScience's RS2 software, and the displacement amounts were examined and interpreted.
The discontinuity spaces to be analyzed before the model is created were determined to coincide with the scoring interval assigned to the distances between discontinuities in RMR, which is one of the Rock Mass Classification Systems. For discontinuity spaces, there are six intervals, 400 cm, 200 cm, 130 cm, 60 cm, 40 cm and 20 cm, and for discontinuity orientations, the angles are every 22.5 (0; 22.5; 45; 67.5; 90; 112.5; 135; 157.5) and every 30 (0, 30, 60, 90, 120, 150) degrees, 12 different discontinuity trends were determined. In the 20 cm discontinuity space, only three different degrees of discontinuity orientation could be analyzed, and the remaining nine analyzes could not be made. Therefore, the discontinuity space of 20 cm was not included in this study. While creating the model; all parameters were kept constant and no water income was assumed. Analyzes were made for all discontinuity orientation values determined in each discontinuity space. While one of the five determined discontinuity spaces was kept constant, each of the twelve discontinuity oriantation determined one by one was analyzed one by one in the discontinuity space kept constant. This process continued for all discontinuity spaces and a total of 59 analyzes were made. In this way, it is examined to what extent the displacement amount will be affected by the change of discontinuity orientations.
While making these analyzes, the slope geometry, geomechanical parameters of the rock mass, and field stress were kept constant. The discontinuity spaces and orientations varied in binary combinations.
While the model was created in the RS2 module of the RocScience program, firstly the coordinates of the slope geometry and the outer boundaries were created. Then, the rock mass strength parameters values were entered in the material properties section. Mohr Coulomb was chosen as the failure criterion and geomechanical parameters were used in the RocData module of the RocScience program to calculate the required cohesion and internal friction values for Mohr Coulomb. These calculated values are introduced in the material properties section. Then, the data of the discontinuity properties are defined in the program.
Strength reduction method (SRF) was used for the analysis. The shear strength reduction option in the RS2 module makes it possible to automatically perform slope stability analyzes in the finite element method and calculates a critical strength reduction factor for the model. The critical strength reduction factor is equivalent to the "safety factor" of the slope. 
By using the RS2 module, the displacement amounts of all 35 points in the 6 impact zones were calculated and the graphs of these values were created. Graphics; discontinuity spaces, discontinuity orientations and impact zones were arranged and displacement data were examined. While examining the graphs that we created from the data we obtained, first the discontinuity spaces were kept constant and the displacement amounts according to the discontinuity orientations (degrees) were examined, and then the discontinuity orientations were kept constant and the displacement amounts according to the discontinuity spaces were examined.
When the analysis of all regions is completed and displacement data is obtained in the RS2 program, the impact zones are determined at intervals of two meters (0m, 2m, 4m, 6m, 8m and 10m) inwards and parallel to the slope face. The displacement amounts and the failure surface were evaluated according to these impact zones. According to the results obtained; In the study at the lowest discontinuity interval (40 cm), it is thought that the amount of displacement may be high in this region where there are more frequent discontinuities towards the interior of the slope, while Interestingly, it was observed that more displacement values were encountered in the slope with wider discontinuity values (such as 400 cm, 200 cm); The same behavior was also observed in the queries that  in the two meter spaced impact zones from the slope towards the interior created on the slope.
In the slope section with an angle of 37 degrees, the discontinuity orientations with high displacement results were mostly realized at 90, 112.5, 120 and 150 degrees of the discontinuity orientations, which may be perpendicular or close to perpendicular. There will not be any slippage for this study, but if the analysis is made in the same orientations at the critical slope angle and it is observed that there will be a slip motion, it can be interpreted that there may be a toppling type slip.
The discontinuity orientations with the lowest amount of displacement were mostly observed at 0, 22.5, 30.45 and 157.5 degrees. The displacement values caused by the degree of discontinuity orientations that are lower than or close to the slope angle (such as 0, 22.5, 30, 45) are lower when compared to the displacement values obtained from the region without discontinuity. Discontinuities in these regions have a positive effect on slope stability, especially in narrow discontinuity spaces.
By examining the data in the impact zones, the highest displacement was generally encountered after 6 meters behind the slope face. The displacement amounts reached their maximum value 10 meters behind the slope face. If the geometry is rearranged and analyzed so that the slope angle is greater than 37 degrees, it is thought that there will be toppling failure in the impact zones closer to the slope face.
In summary; In this study, which we discussed, the safety factor increased as the discontinuity spaces increased, but the displacement amounts also increased. A much smaller increase in displacement was observed in discontinuities with narrower intervals such as 60 cm and 40 cm. A region with a wide space of discontinuities and similar to toppling failure motion in perpendicular or near perpendicular discontinuity orientations, based on the failure surface contours in the analysis results; It is thought that there may be similar to the sliding motion in region with a narrow discontinuity space. 
According to the results obtained; it has been revealed that the highest displacement amount is at 400 cm discontinuity intervals, in region with 90 degrees discontinuity orientation and on the impact zones after 6 meters.