Τεχνικογεωλογική και γεωτεχνική θεώρηση για την διάνοιξη σηράγγων σε περιβάλλον γνευσιακών βραχομαζών. Συγκριτική αξιολόγηση δεδομένων μελέτης και κατασκευής.

Γιαννάκου, Νίκη; Giannakou, Niki

dc.contributor.author	Γιαννάκου, Νίκη	el
dc.contributor.author	Giannakou, Niki	en
dc.date.accessioned	2026-01-08T13:38:49Z
dc.date.available	2026-01-08T13:38:49Z
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/63131
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.30826
dc.description	Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Σχεδιασμός και Κατασκευή Υπόγειων Έργων”	el
dc.rights	Αναφορά Δημιουργού-Μη Εμπορική Χρήση-Όχι Παράγωγα Έργα 3.0 Ελλάδα	*
dc.rights.uri	http://creativecommons.org/licenses/by-nc-nd/3.0/gr/	*
dc.subject	Σήραγγες	el
dc.subject	Γνεύσιος	el
dc.subject	Υποστήριξη	el
dc.subject	Γεωτεχνική αξιολόγηση	el
dc.subject	Διάνοιξη	el
dc.subject	Tunnels	en
dc.subject	Support	en
dc.subject	Gneiss	en
dc.subject	Geotechnical evaluation	en
dc.subject	Construction	en
dc.title	Τεχνικογεωλογική και γεωτεχνική θεώρηση για την διάνοιξη σηράγγων σε περιβάλλον γνευσιακών βραχομαζών. Συγκριτική αξιολόγηση δεδομένων μελέτης και κατασκευής.	el
dc.title	Engineering geological and geotechnical evaluation for tunnelling in gneissic rock masses. Comparative evaluation of design and construction data.	en
heal.type	masterThesis
heal.classification	Σήραγγες	el
heal.language	el
heal.access	free
heal.recordProvider	ntua	el
heal.publicationDate	2025-02-12
heal.abstract	Το αντικείμενο διερεύνησης της μεταπτυχιακής εργασίας είναι η τεχνικογεωλογική και γεωτεχνική θεώρηση για την διάνοιξη σηράγγων σε περιβάλλον γνευσιακών βραχομαζών, με συγκριτική αξιολόγηση δεδομένων μελέτης και κατασκευής. Αρχικά αναλύεται το τεχνικογεωλογικό πρότυπο των γνευσιακών πετρωμάτων με σκοπό τον διαχωρισμό της ποιότητας των γνευσιακών βραχομαζών σε τεχνικογεωλογικούς τύπους. Παρατίθενται κάποιες γενικές πληροφορίες για τα γνευσιακά πετρώματα οι οποίες αφορούν τον τρόπο σχηματισμού τους, την λιθολογία τους, τον τεκτονισμό τους, τον τρόπο αποσάθρωσης τους και την συμπεριφορά του νερού σε αυτά. Οι γνεύσιοι, με χαρακτηριστικό γνώρισμα την ταινιωτή τους υφή, είναι γενικά υψηλής αντοχής πετρώματα με πολύ καλή συμπεριφορά όταν είναι υγιείς. Όμως με την εξέλιξη της αποσάθρωσης η ποιότητα τους υποβαθμίζεται. Στα εν λόγω πετρώματα η αποσάθρωση ξεκινά από την επιφάνεια και προχωράει σε βάθος ανάλογα με τον βαθμό και τον τρόπο τεκτονισμού της βραχόμαζας. Είναι ένας από τους κύριους παράγοντες που καθορίζουν την ποιότητας των γνευσίων, σε συνδυασμό φυσικά με τον βαθμό κερματισμού. Γι αυτό ο διαχωρισμός τους σε οκτώ βασικούς τεχνικογεωλογικούς τύπους γίνεται λαμβάνοντας υπόψιν τον βαθμό αποσάθρωσης, τον βαθμό σχιστοποίησης τους και τον βαθμό κερματισμούς τους. Για την καλύτερη κατανόηση της συμπεριφοράς των γνευσιακών βραχομαζών κατά την διάνοιξη σηράγγων ανάλογα με την ποιότητα τους, παρουσιάζονται πιο περιληπτικά ορισμένα έργα σηράγγων που έχουν διανοιχθεί σε περιβάλλον γνευσίων ανά τον κόσμο, αλλά και αναλυτικότερα από τον ελλαδικό χώρο. Όσον αφορά τα έργα στην Ελλάδα, παρατίθενται στοιχεία από δυο περιπτώσεις διάνοιξης σηράγγων σε περιβάλλον γνευσιακών πετρωμάτων στην περιοχή της Μακεδονίας. Η πρώτη περίπτωση αφορά την διάνοιξη της σήραγγας Κλεισούρας στην επαρχιακή οδό Καστοριάς – Πτολεμαΐδας και η δεύτερη αφορά την διάνοιξη τεσσάρων σηράγγων στην Εγνατία Οδό. Για κάθε έργο αρχικά αναφέρονται ο σκοπός και τα βασικά τεχνικά χαρακτηριστικά του έργου, στην συνέχεια περιγράφονται οι γεωλογικές και γεωτεχνικές συνθήκες που επικρατούν κατα μήκος της χάραξης της σήραγγας και τέλος δίνονται η μέθοδος εκσκαφής και οι κατηγορίες άμεσης υποστήριξης. Στην συνέχεια με βάση όλη την εμπειρία από έργα σηράγγων σε γνεύσιο, παρουσιάζεται η αναμενόμενη συμπεριφορά κάθε τεχνικογεωλογικού τύπου γνευσιακής βραχόμαζας κατά την διάνοιξη σηράγγων και γίνεται η ποιοτική επιλογή των μέτρων άμεσης υποστήριξης για κάθε τύπο. Οι εν λόγω επιλογές ελέγχονται με μια σειρά από προσομοιώσεις που πραγματοποιούνται στο λογισμικό πεπερασμένων στοιχείων RS2, για βάθος σήραγγας 200 m για τις υγιείς και ελάχιστα έως αποσαθρωμένες βραχόμαζες (τύποι Ι, II, III, IV, V και VIII) και 50 m για τις πολύ έως πλήρως αποσαθρωμένες ποιότητες (τύπος VI και VII). Με βάση τα αποτελέσματα των εν λόγω αναλύσεων γίνεται η τελική επιλογή των μέτρων άμεσης υποστήριξης για κάθε τεχνικογεωλογικό τύπο με βάση τις επιλεγμένες συνθήκες. Τέλος, παρουσιάζονται τα συμπεράσματα της τεχνικογεωλογικής και γεωτεχνικής θεώρησης για την διάνοιξη σηράγγων σε περιβάλλον γνευσιακών βραχομαζών και δίνεται ένας συγκεντρωτικός πίνακας με τα ενδεικτικά μέτρα υποστήριξης για κάθε τεχνικογεωλογικό τύπο γνεύσιου.	el
heal.abstract	The subject of the postgraduate thesis is the engineering geological and geotechnical evaluation for tunnelling in gneissic rock mass, with comparative evaluation of design and construction data. First, the geotechnical model of the gneissic rocks is presented to separate the quality of gneissic rock masses into geotechnical types. To define and understand the geotechnical model, some general information about the gneissic rocks is necessary, which relates to their mode of formation, their lithology, their tectonism, their weathering and the behavior of water in them. Gneisses belong to the category of metamorphic rocks. They are formed by the metamorphism of either sedimentary or igneous rocks and the main minerals of which they are composed are quartz, feldspar and mica. They are characterized by their banded texture and are generally rocks with high strength and very good behavior when healthy. However, as weathering progresses, their quality deteriorates. Weathering starts at the surface and progresses in depth depending on the degree and mode of tectonisation of the rock mass. More specifically, weathering in the gneisses occurs because of the weathering of the feldspars and is initially manifested at the surface of the unconformities through the formation of low-strength clay materials. As the degree of weathering increases, the thickness of the clay minerals increases, resulting in a decrease in the friction angle of discontinuities. Subsequently, the weathering extends along the length of the gneissic texture, resulting in the degradation of the strength of the unconfined fragments. Finally, at full weathering, the formation becomes soil due to the predominance of clay materials Regarding the presence of water, gneisses are generally low permeability to impermeable formations. However, when they are strongly crenulated, selective water circulation is observed along the discontinuities. Water flow decreases with increasing weathering of these formations as the clay minerals formed on the surfaces of the unconformities are impermeable. Weathering is one of the main factors that determine the quality of the gneiss, in combination of course with the degree of waxing. For this reason, their division into eight main technical-geological types is made taking into account the degree of weathering, the degree of fissuring and the degree of weathering. These types are as follows: ▪ Type I: Fresh gneiss rock mass The rock mass is fresh, compact with light to moderate fragmentation. Its quality is determined by the degree of fragmentation, and the strength of the intact rock is very high but also anisotropic due to the gneissic texture. The discontinuities create large blocks of intact rock, they have a high friction angle and are closed with rough surfaces and considerable persistence. The gneissic texture is a discontinuity but due to the lack of weathering no separation planes are created. ▪ Type II: Slightly weathered gneissic rock mass The rock mass is slightly weathered with moderate to intense fragmentation. Weathering occurs only on the surfaces of the discontinuities with the presence of minimal clay material without affecting the strength of the intact rock, only minimally. The discontinuities have a reduced angle of friction as they are open with moderate to poor surface quality and have significant persistence. The main discontinuity surface is the gneissic texture, and weathering extends only along the foliation and does not create new discontinuities of separation. ▪ Type III: Slightly weathered schistosed gneissic rock mass The rock mass is slightly weathered with moderate to intense fragmentation and has pronounced schistosity, which is the main discontinuity. The discontinuities have a reduced angle of friction as they are open with moderate to poor surface quality and have significant persistence. The weathering is more extensive than Type II due to the more pronounced schistosity. However, it is limited to the surfaces of discontinuities which have been eliminated creating a very thin film of silty sandy material which reduces their friction angle. The fissuring separates the rock mass into thinner, now moderately sized, fragments and creates poorer interlocking. ▪ Type IV: Moderately weathered gneissic rock mass The rock mass is moderately weathered with moderate to very intense fragmentation. The weathering extends throughout the rock mass, determines its quality and has reduced the strength of the intact fragments considerably, resulting in intact rock having moderate to high strength values without being friable. The discontinuities with basic the gneissic texture are open with surfaces of poor to very poor quality and limited persistence due to frequent interruption by the clay weathering material. Weathering has separated the surfaces of the discontinuities into clay zones of small thickness and creates new discontinuities of separation. The rock mass consists of small blocks of low interlocking and reduced friction. ▪ Type V: Moderately weathered schistosed gneissic rock mass The rock mass is moderately weathered with very pronounced fragmentation and intense schistosity. The weathering has created new zones in a frequent arrangement, extending throughout the rock mass, the intact rock has moderate to high strength values without being friable. Discontinuities with basic the gneissic texture are open with surfaces of poor to very poor quality and limited persistence due to frequent interruption by the weathering clay material. Compared to type IV, here the intense schistosity leads to more extensive and easier weathering which separates the surfaces in a dense arrangement with clay zones of small thickness, leading to even poorer interlocking due to reduced friction. ▪ Type VI: Highly weathered gneissic rock mass The rock mass is highly weathered with intense fragmentation. Due to the intense weathering, the strength of the intact blocks, which are partly friable, has been significantly reduced. The structure is very open, and the discontinuities are open with poor to very poor-quality surfaces, weathered with silty sandy weathering material. The gneissic texture is the main discontinuitie surface with high persistence while the discontinuities perpendicular to it are interrupted by clay weathering material and thus have limited persistence. Weathering has detached the surfaces in clay zones thicker than that of type V, which also extends perpendicular to the gneissic texture creating very small fragments with very poor interlocking. ▪ Type VI: Completely weathered gneissic rock mass The rock mass is completely weathered with traces of wedged structures. It is restricted to the category of disorganized structure and at the same time due to the intense weathering the strength of the intact rock is low, and the rock mass is very friable while retaining features from the original structure. The banded texture and the gneissic foliation are preserved but interspersed with a clay zone of considerable thickness. Discontinuities are not clearly discernible as the structure is highly disordered - laminated to disorganized, consisting of small fragments bounded by weathering clay material and having very poor interlocking resulting in easy rotation due to the low friction of the clay materials separating them. ▪ Type VIII: Foliated-sheared schistosed gneissic rock mass The rock mass is strongly foliated and sheared. Due to the intense cleavage caused by shearing, the strength of the unbroken fragments is moderate and is further reduced when the material between the foliations has an increased mica composition and an increased contribution of a fine fraction of low cohesion. The foliation planes have very low shear strength as they have poor to very poor discontinuity quality. The rock mass has poor quality and strong anisotropic behavior due to foliation. In the following, for a better understanding of the behavior of gneissic rock masses during tunnelling depending on their quality, some tunnel projects that have been opened in gneissic environments around the world, but also in more detail from Greece, are presented. As far as the projects in Greece are concerned, data from two cases of tunnelling in a gneissic rock environment in the region of Macedonia are presented. The first case concerns the opening of the Kleisoura tunnel on the Kastoria-Ptolemaida road and the second concerns the opening of four tunnels on the Egnatia High speed Road. For each project, the purpose and the main technical characteristics of the project are first described, then the geological and geotechnical conditions prevailing along the tunnel alignment are described and finally the excavation method and the support categories are given. Then, based on all the experience from tunnelling projects in gneiss, the expected behavior of each geotechnical type of gneiss rock mass during tunnelling is presented and the qualitative selection of support measures for each type is made. These choices are tested by a series of simulations carried out in the finite element software RS2, for a tunnel depth of 200 m for healthy and slightly to fully weathered rock masses (types I, II, III, IV, V and VIII) and 50 m for highly and completely weathered grades (types VI and VII). Based on the results of these analyses, the final selection of support measures for each geotechnical type is made based on the selected conditions. The design parameters for each type, and the selection of support measures are presented in the tables below. Τhe parameters presented are indicative of the qualities analysed in this work. Also, the calculated cohesion and friction angle values are made using the RSdata program for the specific tunnel depths. Indicative design parameters for each geotechnical type: Finally, the conclusions of the engineering geological and geotechnical considerations for tunnelling in a gneissic rock mass environment are presented and a summary table with the indicative support measures for each engineering geological type of gneissic rock mass for the conditions studied is given.	en
heal.advisorName	Μαρίνος, Βασίλειος	el
heal.committeeMemberName	Νομικός, Παύλος	el
heal.committeeMemberName	Μπενάρδος, Ανδρέας	el
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Μηχανικών Μεταλλείων Μεταλλουργών	el
heal.academicPublisherID	ntua
heal.numberOfPages	340 σ.	el
heal.fullTextAvailability	false