Modeling of tunnel excavation deformation

ABSTRACT PhD THESIS MODELLING OF TUNNEL EXCAVATION DEFORMATION Ahmet ÖZBEK DEPARTMENT OF GEOLOGICAL ENGINEERING INSTITUTE OF NATURAL AND APPLIED SCIENCES UNIVERSITY OF ÇUKUROVA Supervisor: Assoc.Prof.Dr. Altay ACAR Year:2004, Page:206 Jury :Assist.Prof.Dr. Altay ACAR Jury :Assoc.Prof.Dr. Hasan ÇETÎN Jury :Assist.Prof.Dr. Sedat TÜRKMEN Jury :Prof.Dr. Aziz ERTUNÇ Jury :Prof.Dr. Ilyas YILMAZER One of the most important application areas of engineering geology is excavating a cavity like a tunnel in underground. Heterogeneity, high deformability and low strength of mass are the most important parameters that affect stability and performance of tunnel excavation in weak rocks. Rock mass structure and good- short term prediction of rock mass quality are necessary for successful tunnelling. Empirical (RMR and Q), analytical (Phases2 2D) and method based on monitoring and observation (NATM) systems were developed for supplying the safety, economical and applicability of tunnel and similar engineering applications. The Diyojen tunnel (Sinop), that approximately 2 km long, has been excavated in sedimentary rocks made up flysch (sandstone-shale alternation), conglomerate and limestone olistoliths. The Kırkgeçit- 1 (Pozantı) tunnel (Pozantı) is 503 m long and it has been excavated in microgabro, basalt, tuffs, aglomerate and biomicritic limestone. The NATM system has been applied for both tunnel excavations. The biggest convergent value was measured as 95 mm at KM.36+651 by using a convergenmeters (only greatness of deformation can be determined) in the Diyojen (Sinop) tunnel. The biggest displacement vector value was measured as 6 mm at 150 m in left tube in the Kırkgeçit- 1 (Pozantı) tunnel, during the displacement that measured by using 3D optical measurement device (both greatness and direction of deformation can be determined). Both tunnels were excavated in generally weak, moderate and locally hard strength rock groups according to the RMR-Q systems. As a result of the analytical solution by means of using the Phases2 2D software programme, prior tunnel supporting maximum displacements in Diyojen tunnel were predicted as 7 mm at the crown and 9 mm at the base corner in between KM.35+400 - KM. 36+040 whereas 13.2 mm for side walls in between Km.36+040 - 36+480. Maximum displacements in Kırkgeçit- 1 tunnel were determined as 1 mm at the crown and 3.5 mm at the base corners in between KM.20+100 - 20+225 whereas 6.9 mm for sidewalls in between KM.20+225 - 20+530. As a result of evaluations for both tunnels, NATM tunnelling system provides good-short term prediction for rock mass quality. Therefore, this system has been utilized as the most applicable system for both tunnels. However, it should be taken into account that application of this system requires experienced technical persons who are eligible for rapid and accurate evaluation. Key words: Tunnel, Convergen Displacement, Rock Mass Classification System n