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This article aims to present structural and geotechnical design challenges of the flood relief project "Segundo Emisario del Arroyo Vega", part of Buenos Aires city hydraulic master plan. Works comprised the execution of an 8.4 km‐long tunnel for relief of the existing sewer network. Tunnel alignment develops in a highly populated area, with important interferences such as two metro lines, three railway lines and a main potable water tunnel. All tunnel sections extend mostly within firm, silty soils. Overburden varies between 15 and 25 m. The downstream section was executed with a 6.1 m‐diameter Earth pressure Balance Tunnel Boring Machine (EPB TBM) launched from a 35 m‐diameter shaft with water table pressures up to 200 kPa. Break‐in was performed across a watertight, plastic diaphragm wall cell, which allowed safe shaft wall manual demolition, resulting in a very safe TBM launch. The tunnel upstream section, 2.85 m in diameter, was executed using pipe jacking technology, with the peculiarity of using bidirectional launch shafts along its alignment. To allow water entrance from existing system – through flow diversion chambers – into the new relief tunnel, openings were made in the TBM tunnel, with connection areas of 4 to 7 m2. Its design was particularly challenging, given that unbolted segmental lining was used. [ABSTRACT FROM AUTHOR]

The complex and dynamic nature of shield‐driven tunnel excavation, staged construction, segmental lining installation process, and tail‐void grouting necessitate using detailed numerical modeling for predicting ground behavior and response of segmental lining. In this article, results of three‐dimensional advanced finite element modeling are presented for one of the major ongoing construction projects in the North America. Different segment joint models, i.e., rigid joints, perfect hinge joints, Janssen joints, and rigid joints with reduced lining thickness, are used in the analysis. Critical responses such as ground deformation, settlement trough, crown deformation, and the internal forces in the linings considering different segment joint modeling are discussed. [ABSTRACT FROM AUTHOR]

Pre‐excavation grouting (PEG) is essential for mitigating groundwater inflow to unlined tunnel structures. Prevention of initial water inflow proved best practice to balance groundwater conditions throughout the utilisation of a tunnel. The grouted rock mass acts as a circumferential sealing barrier instead of a secondary lining to minimise groundwater inflow to an acceptable level over the structure's lifetime. The construction of unlined tunnels relies on existing favourable in‐situ rock mass conditions with an overall low hydraulic head, mainly to keep the effort of grouting inferior and avoid an unbalanced proportion of pre‐excavation grouting during the tunnel construction works. From the operational perspective of tunnelling works, pre‐excavation grouting delineates the continuous excavation process of a TBM and represents a discontinuative work process. In addition, grouting includes an exploration process ahead of the cutterhead to predict the ground conditions to align the sealing demand of the rock mass. Generally, pre‐excavation grouting foresees the drilling of mainly open boreholes with a considerable length of 20 m to 25 m ahead of the tunnel boring machine (TBM). Establishing a continuous grouted zone around the tunnel demands an overlapping of the grouting rings ranging from 2 m to 10 m. The overlapping decreases the excavation length of the TBM adequately. The repetitive grouting process interfering with the excavation consists of various processes such as exploration including water loss measuring (WLM), the drilling and grouting of boreholes and the hardening time. TBM tunnelling depends on the systematic and continuous implementation of construction procedures. Therefore, based on current static pre‐excavation grouting, an agile combined grouting and excavation approach is presented, incorporating a reliable pre‐excavation grouting, a systematic TBM excavation and a specific balance of long‐term sealing and high utilisation rates for TBM excavation. [ABSTRACT FROM AUTHOR]

Geological models are commonly used to predict the position of relevant geological features, such as rock types or faults in the subsurface. These models can contain significant uncertainties, as the geological input parameters are often not perfectly known. Predictions of geological features, for example, on the level of a tunnel during an excavation process, are therefore uncertain. This work shows how these uncertainties can be estimated using probabilistic concepts. Furthermore, an approach is presented to automatically adjust the geological model predictions using measurements of the tunnel boring machine (TBM) operation. To this aim, the geological forward model is combined with a measurement model and both are integrated in a probabilistic machine learning framework. This integration enables a Bayesian inference process using computational methods, enabling an update of the parameters of the geological and measurement models. Based on the inferred parameter distributions, the model predictions on the tunnel level are subsequently updated. The application of the concept in a simple schematic application shows that such a combination can accurately and precisely predict features ahead of the operation within the limits of the model capabilities. In future work, the methods need to be tested with a real case study to evaluate the accuracy of predictions using real‐world TBM data and more complex geological models. The framework presented here could directly be extended to this purpose. [ABSTRACT FROM AUTHOR]

The planned Brescia–Verona high‐speed/high‐capacity railway line is a key project of the Milan–Verona railway link. Between Brescia and Verona, the new line is about 48 km long, running mostly alongside the A4 highway. Near Lonato (south of Garda Lake), the line goes under A4 and other buildings and structures, through twin tunnels bored by the tunnel boring machine (TBM). The soil consolidation project is deemed necessary to protect the road from subsidence before the TBM is deployed. On site, the soil is extremely heterogeneous but always characterized by a silty sand matrix. The poor capacity of the soil to be permeated led to reshaping the borehole mesh and selecting both cementitious and silicate‐based grout mixes designed to obtain rheological features leading to better permeation capability. The operation to prevent subsidence involved injecting some 10,000 m3 of grout mixture, through about 90,000 m of sleeved pipes, in multi‐directional geometries. [ABSTRACT FROM AUTHOR]

The practical application of accurate design and coordination in Building Information Modeling (BIM) environment for precast rings in Tunnel Boring Machine (TBM)‐bored tunnels is becoming more achievable. These rings, made up of individual segments, are subject to many constraints which include: 1) deviations from theoretical alignment, as modeling the straight centerline of a ring into a curved alignment naturally produces minor deviations in line and grade, 2) avoiding crucifix joints when the joints between segments align in the longitudinal direction, reducing sealing performance, 3) and TBM shield design by minimizing the diameter of the TBM to reduce overcut and required backfill. This article describes the automated procedures for developing our design intent in the BIM environment with consideration for ring length optimization in tunnel curves, geometrical analyses of the staggered pattern of joints, and the minimum diameter and overcut envelope of the TBM shield. This procedure is demonstrated in multiple light‐rail transit lines in Montréal including the Réseau Express Métropolitain (REM) airport link tunnel and the expansion of the Montreal Blue Line Metro. Virtual build of these segmentally lined tunnels negotiating all straight and curved drives of the alignment with BIM modeling is realized and summarized in this article. [ABSTRACT FROM AUTHOR]

Tunnels are significant in shaping our future infrastructure. Increasing limitations of the available ground require underground solutions for future infrastructure projects. Due to various reasons, boundary conditions for project realization are becoming more and more substantial, and the parties involved have to tackle a wide range of stakeholders' interests. Digitization may be able to handle some of these challenges and is one of the most relevant topics in the near future of the construction industry. First approaches of digital data capturing in different activity fields of project execution, such as geological and geotechnical conditions, survey, and reporting, are launched within Implenia's initiative. This article discusses essential aspects of data capturing, particularly in the light of the vast data volumes generated throughout tunnel construction in Europe and gives an insight into the various activities of Implenia on how to tackle these problems. The various TBM and drill‐and‐blast excavated tunnel projects illustrate the variability of data management and implemented solutions to work with the tremendous amount of data. In each case, one can clearly state that construction teams involved in digital data management highly appreciated the merits for their daily business: saving time, gaining transparent information, controlling processes, and more. The beneficial capability of appropriate data management in project execution is evident and will be carried out within Implenia's projects. [ABSTRACT FROM AUTHOR]

In the past decades, Norwegian tunnelling has undertaken a major digital development in all operations from planning to the excavation phase. The breakthrough is driven by digital contract requirements from forward‐leaning clients and innovative industrial stakeholders, aiming for ever more efficient, quality‐oriented and risk‐reducing operations. A formal milestone documenting this development was the publication of Digitalisation in Norwegian Tunnelling in 2019. From 2019, most contracts of new infrastructure tunnels must deliver a level 3 Building Information Modeling (BIM) model. Control systems for drilling jumbos are fully digitalised. All drilling must be monitored and documented with Measurement While Drilling techniques. Via cloud servers, the drilling information is interpreted and delivered live to face engineers for decision support. Sensors are used to monitor rock grouting flow and pressure in each drill hole. Digital electronic detonators with exact delay time are used for blasting. Geotechnical mapping is carried out on field tablets. High‐resolution scans with RGB imaging must be carried out on the exposed rock surface and after rock support/linings. The next step is to utilise all the collected data to a higher degree by advanced analysis with machine learning (ML) and similar techniques for automation and optimisation. This study reviews and exemplifies the digital focus and achievements in core operations in Norwegian tunnel excavation. [ABSTRACT FROM AUTHOR]

When tunnelling with a TBM (Tunnel Boring Machine) in rock and soil, mostly the machine is described and often reduced to a slogan. Such descriptions say little about geotechnical processes at the tunnel face that are key to the success of tunnel driving and must be considered when selecting a tunnelling system. In soil tunnels the tunnel face must be safely supported and extracting material must be possible. For a slurry shield the slurry must not escape and pressure must act on the face. In the literature mostly bentonite content is considered. With an Earth‐Pressure balance machine the soil has to have characteristics that it can be remoulded and transformed in a mass of adequate consistency with mechanical means, adding water and additives such that this mass can support the face and be extracted. Long‐term experience shows that the fine content and polymers are also important factors. Flow channels (pores) in open gravel may be clogged, and the face supported by seepage forces. Also, the drag forces in the slurry circuit are increased and the operation of the slurry circuit became more stable. Rates of advance exceeding 10 m/day were achieved with a 11.6 m slurry shield. The limited depth of penetration of the slurry could be determined in‐situ. For fine‐grained soils the characteristics of the fines are crucial and are described by the Atterberg limits. Soil mechanics strength properties may be vastly different. [ABSTRACT FROM AUTHOR]

Both conventional and mechanized tunnelling have a fantastic tradition. The technical progress of the industry moved in step with social developments, characterized by crises and leaps in innovation. In the field of mechanized tunnelling, the driving force for some years now has been the desire to excavate heterogeneous construction sites with changes in tunnelling modes without the need for costly conversions underground. In addition, two innovation surges are currently discernible. On the one hand, the demands on innovation and technology management again follow a societal challenge, namely the goal of climate neutrality. On the other hand, digital processes and tools are changing all areas of our lives at an enormous speed, which means that the construction industry will also undergo a transformation in the coming years. Automation, robotics, the Internet of Things, machine learning, or artificial intelligence are all gradually encroaching on current processes and methods. Tunnelling jobsites in general, and largescale construction projects in particular, are inherently complex in their operation and are subject to major challenges. Current and future developments will add another necessity, namely the integration of digital applications into an overall system consisting of people and machines while enabling high‐performance construction processes. This calls for intelligent systems. [ABSTRACT FROM AUTHOR]

Globalisation and advancing urbanisation around the globe have a significant influence on market dynamics in tunnelling. The expansion of infrastructures in urban and regional centres calls for the construction of new transport, supply, and disposal systems to link individual economic centres. Innovative technologies in mechanised tunnelling, such as the now well‐established Variable Density TBM, are making a significant contribution to the safe and low‐settlement construction of sustainable tunnel infrastructure projects in extremely challenging and variable ground conditions. In this publication, the current developments and design features as well as the application areas of the Variable Density Technology are addressed, based on one of the first project experiences in Europe, in Lyon. [ABSTRACT FROM AUTHOR]

Dubai Municipality awarded to Porr Besix JV the Project for the Main Tunnel component of the Deep Storm Water System. The tunnel will collect both rainwater and groundwater from approximately 500 sq. km and transfer the captured flow to the sea. The Design Builder JV selected COWI as Designer of the entire Project and IC Consultant as Design Checker for the Tunnels. The Project includes approximately 10.3 km of 10‐meter‐inside diameter tunnel in rock, three construction shafts and one drop shaft. The main tunnel will convey stormwater and groundwater flows from the EXPO 2020 area near the intersection of Sheikh Mohammed Bin Zayed Road and Jebal Ali Lehbab Road to the sea close to the EGA facility. The tunnel will follow beneath the road easement along Jebal Ali Lehbab Road and along Sheikh Zayed Road and continue to the pumping station. The tunnel traversed through the Barzaman and Fars formation with an overburden of 33 m with maximum water pressure of 4.4 bar and was excavated by EPB TBMs. This project is characterized by its dimensions with an internal diameter of 10 m and 350 mm of segment thickness, and by the use of steel fibre reinforced concrete in the precast segmental lining. The use of fibres aims to reduce the CO2 footprint obtaining an optimized design from the environmental point of view. These facts are associated to a complex design of precast segments, in order to ensure their structural competence and their integrity according to the durability requirements, under large thrust forces (temporary loads) and permanent load. Hence, considering such complexities, the structural design has been carried out producing a 3D structural model by means of a sophisticated FEM structural software. Results of the model allow to identify areas of the segment where spalling and bursting stresses are generated along circumferential joints and maximum value of those stresses in the temporary load cases. Moreover, a structural design verification of the segment has been undertaken considering the contribution of steel fibres class 4c, as it is set up in the FIB model code, aiming to ensure that the precast segments are structurally competent and fulfil the durability requirements of the Project. The article details the design approach and the independent checker design verification approach. The experience gained during construction is also reported, describing challenging aspects of the Tunnel execution and an analysis of the lining damages. [ABSTRACT FROM AUTHOR]

The Tulfes‐Pfons construction section of the Brenner Base Tunnel includes a 16.6 km long tunnel section excavated with an open gripper TBM. Due to the very difficult logistic conditions (steep access tunnel with 10 % gradient and a 90° bend at the transition to the exploratory tunnel as well as a limited clearance profile with 8 m diameter), the contractor and client decided on an alternative supply of the TBM – the 'multi‐service vehicle' (MSV). This laser‐controlled train on rubber wheels without rails is able to handle both the steep access and the 90° bend. After 16 km of excavated tunnel with a top performance of 61 m/d and top monthly performance of up to 800 m in hard rock conditions with 1000 m overburden, the decision to use the MSV has proved to be a complete success. In addition to the logistics and safety advantages, a cost reduction has also been achieved compared to the planned conventional system. MSV are a cost‐effective and technically proven alternative to conventional track‐bound TBM supply equipment. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the pre‐construction evaluation of the ground for the Lake Mead Intake No 3 Tunnel and the experience gained from the project, which had the aim of maintaining water supplies for the Las Vegas greater metropolitan area. The construction of this tunnel using a dual‐mode slurry shield represents a major engineering achievement, which pushed back the boundaries of closed shield tunnelling: Overcoming an extended fault zone under high hydrostatic pressure in the metamorphic rocks and mucking‐out difficulties associated with high rates of water inflow in the sedimentary rocks necessitated closed‐mode operation over about 2 km at unprecedentedly high face pressures of up to 14 bar. [ABSTRACT FROM AUTHOR]

The Brenner Base Tunnel (BBT) is a straight, flat railway tunnel between Austria and Italy. It runs from Innsbruck to Fortezza (55 km), crossing the main Alpine crest with an overburden up to 1.7 km. Including the connection to the line around Innsbruck, which has already been built and which is the endpoint for the BBT, the total length of the tunnel will be about 64 km. Once finished, the BBT will be the longest underground rail link in the world. A peculiar feature of the BBT is the exploratory tunnel running from one end to the other. This tunnel lies between the two main tunnels and about 12 m below them and is noticeably smaller than the main tubes. So far, a total of 60 km of tunnels have already been excavated in Austria and Italy (access tunnels, exploratory tunnel, main tubes and chambers), driven both by blasting and by TBM. Crossing fault zones is a geological and geomechanical challenge, both for TBM and conventional excavation methods. The Periadriatic fault zone, with a total length of 1 km, has already been driven through. This first step of the project provides an interesting look at the comparison of the predicted rock mass conditions with those that were actually encountered, the rock mass behaviour in fault zones and investigation measures ahead of the tunnel face. [ABSTRACT FROM AUTHOR]

The Prague Metro today forms a very reliable backbone of the Prague mass transit system. The network consisting of three radial lines (A, B and C) with interchanges in the city centre developed gradually. The paper is devoted to engineering solutions for tunnels and tunnel construction methods. The first section describes the origins of the system in the 1970s and its history through the 1970s, 1980s and 1990s. The New Austrian Tunnelling Method arrived in the modern era. The first applications of the method were primarily associated with the construction of the fourth extension of Line B (Metro Line IV.B, followed by the 4th operating section of Line C (Line IV.C). The design work for this part of the metro network was probably the longest and most difficult and it resulted in extremely interesting technical solutions. The main part of the paper is dedicated to the current development of operating section V.A, which commenced in the autumn of 2009. The section is 6,134 m long and contains four stations, of which three are being built by mining methods. Die Prager Metro stellt heute ein sehr verlässliches Rückgrat des Prager Personennahverkehrs dar. Das U-Bahn-Netz, bestehend aus drei Linien (A, B und C) mit Umsteigestationen in der Innenstadt, hat sich fortlaufend entwickelt. Dieser Beitrag widmet sich den dabei verwendeten verfahrenstechnischen Lösungen für den Tunnelbau und unterschiedlichen Tunnelbaumethoden. Im ersten Abschnitt werden die Ursprünge des Systems in den 1970er-Jahren und seine historische Entwicklung während der 1970er-, 1980er- und 1990er-Jahre beschrieben. Die Neue Österreichische Tunnelbaumethode erreichte die Neuzeit. Eine der ersten Anwendungen dieser Methode stellte der Bau der vierten Erweiterung der Linie B (Metro Linie IV.B) dar, gefolgt vom vierten Bauabschnitt der Linie C (Linie IV.C). Die Planungsarbeiten für diesen Bauabschnitt der Metro waren wohl die Längsten und Schwierigsten und resultierten in einer höchst interessanten, technischen Lösung. Der Hauptteil des Beitrags widmet sich den derzeitigen Baumaßnahmen am Bauabschnitt V.A, welche im Herbst 2009 begonnen wurden. Dieser Abschnitt ist 6.134 m lang und beinhaltet vier Stationen, von denen drei bergmännisch hergestellt werden. [ABSTRACT FROM AUTHOR]

Characterizing performance of tunnel boring machines (TBM) is important for numerous contractual and technical reasons. A common tool to determine machine performance in the field is the penetration test. The purpose of the penetration test is to operate the TBM for a defined period of time under normalized conditions that allow for interpretation and comparison between tests. The result of a penetration test is a thrust-penetration curve that reflects the excavatability of the rock mass. Prediction models use thrust-penetration curves to calculate the expected performance of a TBM in specific ground conditions. This paper provides a review of recent practice including testing at the Norwegian University of Science and Technology (NTNU) along with research by Villeneuve and Käsling. Each of these methods includes excavation at certain thrust levels and rotational speeds for a certain distance. These existing methods have a number of disadvantages that lead to fairly slow tests, which the proposed methodology aims to eliminate. Für eine Reihe von technischen und vertraglichen Fragestellungen ist die Charakterisierung der Leistung von Tunnelbohrmaschinen (TBM) von Bedeutung. Ein häufig genutztes Werkzeug, um die Bohrleistung einer TBM zu bestimmen, ist der Penetrationstest. Der Zweck eines solchen Tests ist, die TBM für eine gewisse Zeitdauer unter definierten Bedingungen zu betreiben, um so die Vergleichbarkeit zwischen verschiedenen Ergebnissen zu ermöglichen. Das Ergebnis eines Penetrationstests ist eine Penetrations-Kraft-Kurve, die es erlaubt, die Vortriebsleistung einer TBM unter bestimmten Gebirgseigenschaften zu prognostizieren. In diesem Beitrag werden die bisherigen Ansätze der Norwegischen Technischen Universität in Trondheim und Forschungsarbeiten von Villeneuve und Käsling beschrieben. Diesen Ansätzen ist gemein, dass die TBM über eine kleine Vortriebsstrecke bei verschiedenen Vortriebskräften und Bohrkopfdrehzahlen betrieben wird. Die beschriebenen Methoden haben aber auch eine Reihe von Nachteilen, die zu einer relativ langen Testdauer führen. Die hier vorgeschlagene Methode verkürzt die Testdauer bei gleichzeitiger Erzielung höherer Genauigkeit der Ergebnisse. [ABSTRACT FROM AUTHOR]