The Bolu Tunnels lie along Trans European Motorway (TEM) which is connecting Eastern Europe with the Middle East. The tunnels are approximately 3.0 km long, 40 m apart and have excavated cross sections more than 200 m2. In construction, New Austrian Tunneling Method (NATM) was used in soft ground. Due to the challenging ground conditions, many problems have been encountered during tunnelling. To solve these problems special construction techniques were adapted. To simulate and demonstrate the effectiveness of these construction techniques, 2D and 3D Finite Element Methods are utilized in this study. Through comparison between 2D and 3D modelling of advance of Bolu Tunnels, respective merits of these two approaches are investigated and the conditions under which shortcomings of the 2D approach become serious are identified.

The influence of the surface excavation and loading on the existing tunnels has been investigated using a Finite Element Method program, Plaxis 3D Tunnel. A parametric study has been carried out where the parameters were the depth of the surface excavation, the eccentricity of the excavation with respect to the tunnel axis, the height of the embankment fill and the stiffness of the soil. It is found that, excavations over the existing tunnels have a negative effect on the tunnel lining capacity since the unloading due the excavation reduces the normal forces and increases the bending moments. On the other hand, it is found that surface loading within the limits considered in this study is not critical in terms of the tunnel stability due to the increase in normal forces and decrease in bending moments.

O crescente aumento de acidentes em obras subterrâneas, sobretudo em meios urbanos, fez com que aumentasse a preocupação mundial com a segurança destas obras. Portanto, ressalta-se a importância da análise dos deslocamentos no maciço em obras de túneis em solo executados pelo método NATM (New Austrian Tunneling Method), visando à segurança da obra, das estruturas vizinhas a obra e, principalmente, das vidas humanas envolvidas. A instrumentação geotécnica é apenas uma ferramenta, e não uma solução. Ela não pode ser limitada à locação de vários pontos de medidas em um gráfico. É necessária a especificação de critérios para a análise e avaliação dos resultados e a formulação de procedimentos para a interpretação de dados. Com isso, a presente dissertação tem como objetivo estudar os deslocamentos do maciço no decorrer da execução de um túnel em solo. Propõem-se analisar os dados do túnel em solo executado pelo método NATM, pertencente à obra do Lote 1 da Linha 5 (Lilás) do Metrô de São Paulo. Esse túnel foi instrumentado na fase de execução da obra e acompanhado tecnicamente pelo autor deste trabalho, junto à equipe da Maffei Engenharia. Ao final deste trabalho, pretende-se tecer comentários sobre a importância de uma adequada análise dos deslocamentos no maciço em obras de túneis em solos executados pelo método NATM. / The increasing growth of accidents in underground works, especially in urban areas, caused a magnification in the worldwide concern about the safety of these works. Therefore, it must be emphasized the importance of the ground displacements analysis in ground tunnels constructed by the NATM method (New Austrian Tunneling Method), aiming the safety of the work, of neighboring structures and mainly of the human lives involved. Geotechnical instrumentation is just a tool, and not a solution. It can not be limited to the placement of several measurement points on a graph. A criteria must be specified for the analysis and evaluation of results and for the formulation of procedures for data interpretation. This thesis objective is to study the ground displacements during the execution of a ground tunnel. It is proposed to analyze the data of the tunnel executed by NATM, belonging to the Lote 1, Line 5 (purple) of São Paulo subway. This tunnel was instrumented during the execution phase of the construction and technically monitored by the author of this thesis, with Maffei Engenharia team. At the end of this paper it is intended to make comments about the importance of adequate displacements analysis in ground tunnels constructed by NATM method.

O crescente aumento de acidentes em obras subterrâneas, sobretudo em meios urbanos, fez com que aumentasse a preocupação mundial com a segurança destas obras. Portanto, ressalta-se a importância da análise dos deslocamentos no maciço em obras de túneis em solo executados pelo método NATM (New Austrian Tunneling Method), visando à segurança da obra, das estruturas vizinhas a obra e, principalmente, das vidas humanas envolvidas. A instrumentação geotécnica é apenas uma ferramenta, e não uma solução. Ela não pode ser limitada à locação de vários pontos de medidas em um gráfico. É necessária a especificação de critérios para a análise e avaliação dos resultados e a formulação de procedimentos para a interpretação de dados. Com isso, a presente dissertação tem como objetivo estudar os deslocamentos do maciço no decorrer da execução de um túnel em solo. Propõem-se analisar os dados do túnel em solo executado pelo método NATM, pertencente à obra do Lote 1 da Linha 5 (Lilás) do Metrô de São Paulo. Esse túnel foi instrumentado na fase de execução da obra e acompanhado tecnicamente pelo autor deste trabalho, junto à equipe da Maffei Engenharia. Ao final deste trabalho, pretende-se tecer comentários sobre a importância de uma adequada análise dos deslocamentos no maciço em obras de túneis em solos executados pelo método NATM. / The increasing growth of accidents in underground works, especially in urban areas, caused a magnification in the worldwide concern about the safety of these works. Therefore, it must be emphasized the importance of the ground displacements analysis in ground tunnels constructed by the NATM method (New Austrian Tunneling Method), aiming the safety of the work, of neighboring structures and mainly of the human lives involved. Geotechnical instrumentation is just a tool, and not a solution. It can not be limited to the placement of several measurement points on a graph. A criteria must be specified for the analysis and evaluation of results and for the formulation of procedures for data interpretation. This thesis objective is to study the ground displacements during the execution of a ground tunnel. It is proposed to analyze the data of the tunnel executed by NATM, belonging to the Lote 1, Line 5 (purple) of São Paulo subway. This tunnel was instrumented during the execution phase of the construction and technically monitored by the author of this thesis, with Maffei Engenharia team. At the end of this paper it is intended to make comments about the importance of adequate displacements analysis in ground tunnels constructed by NATM method.

Insufficient information on the host medium can cause serious problems, even collapse, during construction in a tunnel. This study focuses on understanding the reasons behind the collapse of the Tunnel BT24 to be opened within the framework of Ankara-Istanbul High Speed Railway Project. The tunnel is located near Boz&uuml / y&uuml / k in the Bilecik Province. The collapsed section of the tunnel was driven into a highly weathered, weak to medium rock mass. Unanticipated geological/geotechnical circumstances caused excessive deformations at the section on which the primary support system was applied, leading eventually to collapse. To understand the response of the tunnel and the collapse mechanism, the construction sequence is simulated using two-dimensional plane-strain and axisymmetric finite element models. The analyses were carried out for the section with and without invert closure of the shotcrete liner. To implement the effects of likely unfavorable ground conditions on the tunnel response, a number of fault scenarios and possible creep effects were also considered with those two alternatives. Displacements in the tunnel periphery, forces and moments in the primary liner as well as the plastic deformation zones in the surrounding ground were determined for each case and comprasions were made accordingly. It is concluded that the unforseen ground circumstances might have substantially aggravated the deformations in the section and that the lack of ring closure of the primary liner at invert played the key role in the collapse.

A completed part of the Bolu Tunnel at Elmalik side collapsed during the 1999 D&uuml / zce earthquake. In order to by-pass the collapsed section, a new tunnel route was determined. 474 meters of the new route, including two portals and double tubing, crossed through the weak to very weak rock units with intersecting fault gouge, excavated from Elmalik side. In this study, the characteristics of the rock masses and support classes are determined for new route of the Elmalik Side. Then, during the tunnel excavation, the deformations of temporary and permanent support systems were precisely measured and recorded. The support system properties as determined from NATM were analyzed by two dimensional convergence confinement method using the numerical RocSupport software. As a result of this study, for weak ground tunneling, duration of primary support installation should be kept at minimum. Besides that, temporary support measures such as forepoling, face sealing and temporary invert have an important role in controlling deformations before the primary support installation. With the application of temporary supports, loading on the permanent support, and hence the final deformation of the excavation, was found to be reduced significantly. Application of rigid lining was found to be necessary in order to prevent long-term deformations in weak ground tunnels, even though it is contradictory to the NATM philosophy.

The use of sprayed concrete lining is common in tunneling practice since it allows the application of non-circular tunnel sections and complex tunnel intersections. Low capital cost of construction equipment is also an important factor for the selection of the sprayed concrete lining. In general the use of sprayed concrete lining is referred as New Austrian Tunneling Method (NATM). Depending on the requirements regarding tunnel heading stability and limitations on tunneling induced soil displacements, tunnel cross sections often advanced by different construction sequences and round lengths in NATM. For the purpose of assessing the effects of excavation sequence, round length, soil stiffness and tunnel depth on surface settlements and on tunnel lining forces, a parametric study has been carried out, considering short-term and long-term soil response. Three dimensional finite element analysis are performed to model the excavation sequence and stress distribution around the tunnel lining during excavation. The parameters used in the parametric study can be listed as: tunnel diameter, tunnel depth, round length and soil stiffness. Existing analytical and empirical solutions, which are used for prediction of ground subsidence due to tunneling and forces on tunnel lining, are also reviewed in this study / and their predictions are compared with the results obtained from numerical analysis. This comparison also provides an opportunity to evaluate the performance of the existing efforts. The variations between the results obtained from different methods are discussed and it is concluded that the limitations of the existing methods are the primary reason of the variations between results.

As part of modernization of the Brno-Přerov railway line, is in the section between village Blažovice and town Vyškov desined tunnel composed of two monorail tubes about 640 meters length. Tubes are situated in neogenic clay with an overburden height of 11 meters. This master thesis deals with design suitable tunnel exavation, primary lining with static calculation and geotechnical monitoring.

A parametric study is performed to investigate the parallel tunnel interaction. Three dimensional finite element analyses were performed to determine the effects of soil stiffness, pillar width and advancement level of the second tunnel on the behaviour of displacement, bending moment and shear force of the previously constructed tunnel. In the analysis PLAXIS 3D Tunnel geotechnical finite element package was used. This program allows the user to define the actual construction stages of a NATM tunnel construction. In the analysis, construction stages are defined in such a way that firstly one of the tunnels is constructed and the construction of the second tunnel starts after the construction of the first tunnel. The mid-length section of the first tunnel is investigated in six different locations and at seven different advancement levels in terms of displacement, bending moment and shear forces. It is found that, displacement and bending moment behaviour are more related with soil stiffness and pillar width than the behaviour of shear forces. While the level of advancement of the second tunnel causes different type of responses on the shear force behaviour, level of advancement does not affect the type of behaviour of displacements and bending moments. Another finding of the research is that pillar width has an evident influence on the behaviour of displacements and bending moment than the soil stiffness. It is also found that the interaction effect may be eliminated by increasing the pillar width equal or larger than an approximate value of 2.5 &ndash / 3.0 D (diameter) for an average soil stiffness value.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第14137号 / 工博第2971号 / 新制||工||1441(附属図書館) / 26443 / UT51-2008-N454 / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 朝倉 俊弘, 教授 田村 武, 教授 岡 二三生 / 学位規則第4条第1項該当