Tunnel wall convergences should be predicted before the excavation and should be determined accurately in order to ensure safe and economic tunnel excavation media. For this to be possible, rock mass behaviors in the tunnel should also be estimated prior to excavation. This could be ensured by site investigation studies, numerical models and predictive statistics. In this study, the development of convergences during a tunnel excavation in Turkey, excavated by NATM technique, was evaluated by using statistical prediction techniques for weak-to-fair-quality rock masses. For this aim, actual tunnel wall convergence data and rock mass strength parameters were used. For prediction of tunnel wall convergence, multivariable regression analysis, artificial neural networks (ANNs), classification and regression tree (CHAID) and Chisquare automatic interaction detection (C&RT) methods were used and prediction results were compared to each other in terms of superiority and practicality. For this aim, 112 tunnel sections were used for prediction model and 30 different tunnel sections were used for validation. According to the obtained statistical prediction findings, it is seen that C&RT and ANN methods provide good prediction of tunnel wall convergences. However, C&RT method was found more practical in field use when compared to ANN. The results have shown that overburden thickness is the most effective parameter on tunnel convergence when compared to C rm , Φ rm , E rm , RMR and Q. However, the best way for determination of tunnel wall convergences is to use in situ measurements, but in case of the lack of in situ measurement instruments, the suggested probability-based statistical approach is proven to be very effective and practical. Ultimate convergence level for any cross section with similar geological and geotechnical parameters to those analyzed before can be predicted by using the suggested method in this study. Yet, it should be kept in mind that the findings of this study are limited with the data used in this study. Although the aim of this study is to ensure a different point of view for determination of convergences in case of lack of convergence measurements and field data, by adding up more convergence measurements and rock mass strength data to the proposed statistical method, prediction power of this method can be improved and then this method can be used as a practical tool for the prediction of tunnel convergences. Besides, the user-friendly and opento-development structure of this study can be a very useful tool for the geotechnical engineers, engineering geologist and mining engineers, if it can be developed by more field data.
Bu çalışmada mühendislik jeolojisi uygulamalarının tünel açma yöntemleri ile ilişkisi anlatılmaktadır. Geçmişten bugüne çeşitli tünel açma yöntemleri ortaya çıkmış ancak bunların büyük çoğunluğu aşamalı kazı ve tam ayna kazılarının çeşitli türevleri şeklinde olmuştur. Uluslararası alanda yaygın bilinen tünel açma yöntemleri, kaya kütlelerinin davranışlarını sınıflandırmaya çalışmakta, ancak bu sınıflandırmaya sayısal bir altlık oluşturamamaktadır. Bu nedenle bu yöntemlerin uygulanması sırasında sayısal ve objektif değerlendirmelere ihtiyaç duyulmakta, bu eksiklikse kaya kütle sınıflamaları kullanılarak kapatılmaya çalışılmaktadır. Günümüz tünelciliğinde yaygın olarak NATM ve ADECO-RS adı verilen iki yöntem kullanılmaktadır. Her iki yöntem de kaya kütle davranışını çeşitli şekillerde kategorize etmiş ancak bunun için değerlendirmeye esas objektif bir altlık oluşturamamıştır. Bu çalışmada, tünel tasarımında yaygın olarak kullanılan tünel açma yöntemlerinin, uluslararası kabul görmüş kaya kütle sınıflama sistemleri ve sayısal modeller ile olan ilişkisi ve uygulamada yaşanan sorunlar anlatılmaya çalışılmıştır. Uygulamada; kaya kütle sınıflamalarından tünel kazı ve destek sınıflarına geçiş, bunların sayısal modellere yansıtılması, yapılan kabuller ve özellikle sayısal modelleme sırasında yazılımların dayandığı kabullerden kaynaklanan mühendislik jeolojisi modelleme hataları ve doğru tasarım için yapılması gerekenler birer örnek ile açıklanmaya çalışılmıştır.
Usage of underground space is an old habit for human beings since ancient era. Our ancestors have used caves as a shelter for protection from the wild life and nature, and they excavated caves to extract valuable minerals. They also used them as sanctuaries, tombs or for storage of goods. In addition, they built tunnels to be used as assault systems or to underpass fortifications during ancient warfare. Later on, tunnels were driven to supply water to the towns or to protect the towns from floods. They also built them for communication purposes. Though not knowing the exact time when they were first used, natural underground structures which have several interconnections were also built for underground dwelling purposes through the human history. In the following centuries, due to the need of transportation facilities, transportation tunnels were constructed where new excavation techniques were also used. Navigation canal tunnels, railway tunnels and road tunnels were constructed during that period. All these structures were mostly excavated in rocks. The first excavations were performed manually. Later on, fire technique had been used to excavate more easily. This was followed by the methods in which gunpowder, explosives and tunneling machinery were used. By some means or other, ancient civilizations had used fundamental principles of rock mechanics and applied these principles in the construction of the underground structures. Principles of rock mechanics are the sine qua non for all of these structures and facilities. In this review paper, the history and evaluation of rock mechanics will be given briefly and some examples of historical and monumental underground and rock structures will be presented. Keywords
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