Detail eines modernen Bürogebäudes in Hamburg. (Foto: © Fabian Wentzel/Getty Images)

Kubische Stadtarchitektur. In Langenau hat Architekt Ralf Kauer ein altersgerechtes Mehrfamilienhaus in moderner kubischer Architektur realisiert. Mit dem Baustoff Ziegel konnte trotz des Verzichts auf einen Vollwärmeschutz der KfW-Effizienzhaus 55 erreicht werden. (Foto: © tdx/Mein Ziegelhaus)

In Memmingen hat die Rohrbeck-Bentivoglio GbR ein durch einen Brand stark beschädigtes Gebäude aus dem historischen Ensemble “Südlicher Schrannenplatz” akribisch nach seinem klassizistischen Vorbild rekonstruiert. Für das vorbildliche Engagement und die überzeugende Rekonstruktion vergab der Bausenat der Stadt Memmingen 2016 einen Fassadenpreis. (Foto: © tdx/Mein Ziegelhaus)

Projekt “Ocean Reef Islands”: Rütteldruckverdichtung für die neuen künstlichen Inseln vor der Küste von Panama-Stadt. Bauer blickt in Lateinamerika auf eine mehr als zehnjährige Erfolgsgeschichte zurück. (Foto: © BAUER Group)

Seit Frühjahr 2015 entschärft eine neuartige, innovative Segmentbrücke eine zuvor gefährliche Straßenkreuzung im Landkreis Neumarkt in der Oberpfalz. Im Zuge des Neubaus der Staatsstraße gelang ein Brückenschlag der innovativen Art - ohne Belag und Abdichtung. (s. auch Beitrag S. 3 ff) (Foto: Firmengruppe Max Bögl, Reinhard Mederer)

SKAIO, Heilbronn
, mit zehn Geschossen das höchste Holzhaus Deutschlands. Im Auftrag der Stadtsiedlung Heilbronn GmbH realisieren das Berliner Architekturbüro Kaden+Lager, Pionier auf dem Gebiet des innerstädtischen, mehrgeschossigen Holzbaus, und die Firma Züblin Timber GmbH den Neubau zur Stadtausstellung im Rahmen der Bundesgartenschau Heilbronn 2019. (Visualisierung: JSB Stuttgart)

Steigerwaldstadion, Multifunktionsarena für Erfurt.
2015 wurde das traditionsreiche Steigerwaldstadion nach einem Entwurf der HPP Architekten Düsseldorf bei laufendem Betrieb erneuert und erweitert. Pünktlich zum Auftakt der Saison 2016/2017 wurde die neue Multifunktionsarena im Sommer 2016 fertiggestellt. Im Bild: gut erkennbar der segmentierte Verlauf der Tribünenelemente während der Bauphase. (Foto: OPTERRA/Sven-Erik Tornow)

Ausbau Grand Paris Express, Paris.
Bis 2030 will die französische Hauptstadt ihr berühmtes U-Bahn-Netz um 200 Kilometer erweitern, vor allem unterirdisch. “Grand Paris Express” lautet der Name dieses gigantischen und größten Infrastrukturprojekts in Europa, bei dem aktuell schon sechs Bauer-Schlitzwandfräsen im Einsatz sind - weitere sollen in diesem Jahr folgen.
(Foto: © BAUER Gruppe)

“Grüner Bahnhof”
, Wittenberg. Im Dezember 2016 wurde der klimafreundlichste Bahnhof Deutschlands in der Lutherstadt Wittenberg eröffnet. Dahinter steckt das Baukonzept “Grüner Bahnhof”. Es sieht zum einen vor, Bahnhöfe klimaneutral zu betreiben, zum anderen steht der Komfort für die Reisenden und Besucher des Bahnhofs im Fokus. Das begrünte Flachdach wirkt der Flächenentsiegelung entgegen, gleichzeitig versorgt eine Photovoltaik-Anlage auf dem Dach das Gebäude CO2-frei mit Strom (siehe auch Beitrag S. 9). (Foto: OPTERRA/Sven-Erik Tornow)

The Klang Valley Mass Rapid Transit (KVMRT) project involves the construction of an urban passenger transport system, i.e., Mass Rapid Transit (MRT) system, together with the existing urban rail network, will form the backbone of the public transport system in the Greater Kuala Lumpur/Klang Valley region in Malaysia. The first MRT line implemented is the 47 km Kajang Line, of which 9.5 km is underground tunnels with seven underground stations. Construction of the line began on 8 July 2011 and achieved the full line opening on 17 July 2017. The second MRT line-Putrajaya Line-began fully operations on 16 March 2023, stretches from Sungai Buloh to Serdang and ends at Putrajaya for a length of 57.7 km, of which 13.5 km is underground tunnels with 10 new underground stations. Like all other metro underground stations/tunnels designed as part of the urban city, the KVMRT underground construction faces challenges from a technical (engineering design and construction) as well as social (environmental and land related) point of view. Needless to say, underground construction in Klang Valley is intensified with the inherent geotechnical challenges presented by complex ground conditions ranging from hard granite, heterogeneous Kenny Hill formation and extreme karstic limestone with fully developed weathered profiles to soft recent deposits including alluvium and mine tailing that is under-consolidated in places due to past mining activities. The development of this large-scale infrastructure project has not only opened up tremendous works and new frontier for tunnelling and geotechnical engineering in Malaysia, but it also provided a wealth of information of unique geotechnical challenges/accomplishments as well as technology breakthrough and design innovation in underground engineering. This article discusses some aspects of geotechnical challenges and interesting lessons learnt as well as numerous innovations embedded into this highly complex urban underground construction project.

The MRT Orange Line construction works in Bangkok are more complicated than works in earlier projects. As the tunnel alignment passes through the congested urban areas in the city, it either clashes with or passes beneath several existing structures. Underpinning works are then required. Assessment of movement of ground and structure plays an important role in the project. The rebound of piezometric pressure in sand layers that is being developed poses a major point of difficulty in the excavation and underground structure design and construction. Groundwater control measures become a crucial issue in MRT Orange Line project that leads to difficulties in deep MRT station excavations. To control base instability, various methods (e.g., cut-off wall, staged excavation) are introduced and presented in this article.

The Bangkok MRT Orange Line East Project consists of 6 km long twin tunnels and seven stations. The tunnel alignment runs along one of the most congested road corridors of the city. Due to adverse conditions of limited road right of way, obstructions from existing structures such as buildings, infrastructure, tunnels, and other utilities, the design and construction of the tunnel require careful consideration and implementation of excavation works to limit excessive ground movements and mitigate the potential impacts on existing structures. This article presents the concepts and procedures in detail on assessing the impact on each type of adjacent structure due to tunnel construction which contribute to the successful completion of the MRT Orange Line Project. Additionally, some mitigation measures for critical cases are highlighted.

The EPB shield tunnelling for mass rapid transit (MRT) Line 1 of Ho Chi Minh City (HCMC) is the first tunnel excavation in Vietnam to use a tunnel boring machine (TBM). A comprehensive instrumentation programme was developed for safety control and to obtain a better understanding of the characteristics of induced ground movement and the forecasts. The observed ground surface settlement is summarized and interpreted with respect to the tunnelling operation parameters. The settlement trough is compared with the forecast data by applying the empirical Gaussian function and numerical 2D finite-element analysis (FEA). The trough width parameter in the city's sandy subsoil is determined. The relation between the volume loss of the ground surface and that of the tunnel (contraction ratio) is identified. The result of the investigation is useful for future shield tunnel projects in HCMC and elsewhere in Vietnam.

Map Kabao Tunnel is a significant part of the track doubling project for the railway line connecting Bangkok to Northeast Thailand. The 5.2 km-long twin-tube tunnel makes is the longest railway tunnel in Thailand. The conventional tunnelling method was used to excavate the tunnel through complex geological conditions consisting of thrusted and folded carbonate and clastic sedimentary rocks. While encountering a few incidents of tunnelling difficulties caused by the poor quality of the rock mass attributed to weathering, sheared discontinuities, and karst features, the construction of the tunnel was ultimately successful and was completed in 2023. This article provides a comprehensive analysis of the lessons learned from the design and construction of this mountain rail tunnel project.

A huge cavern in a zone of thrusted and sheared clastic sedimentary rocks was encountered during drill and blast (D&B) and tunnel boring machine (TBM) excavation of water transfer tunnel in Thailand. The cavern floor made of thick and loose pile of fallen rock blocks hampered the advance of the TBM through it. Because the size of the cavern was large (50 m × 40 m) and the extent of the thickness of the pile of rock blocks could not be precisely determined, the adopted ramification was to solidify a zone of loose rock fragments around the tunnel alignment. This measure is to allow a safe TBM excavation passing the cavern and ensure the long-term function of the segmented concrete-lined tunnel to convey water without problem of loss from subsidence damage. The scheme of the solidification consisted of staged grouting that began with polyurethane (PU) foam grouting to form a bottom barrier of the intended cement grout zone. It was followed large void filling by flowable concrete and then cement injection for the remaining smaller voids. The work that took 8 months to complete started with the excavation of a bypass adit to the front of TBM cutterhead as an access to the cavern and the installation of dewatering and ventilation systems to the cavern so that the grouting work could be made.

Urban tunnel construction is often performed in congested areas with many buildings and historical structures nearby. With respect to developing countries, such as Vietnam, the lack of as-built drawings of existing buildings is a big challenge for urban tunnel development. There are a lot of private buildings in downtown are low rise, with many kinds of shallow foundations (from bamboo bar, brick mat, lean concrete mat, pre-casted concrete piles...) that add to the challenge of finding correct data. Consequently, one must find suitable and reasonable technology for the soil strengthening works in order to prevent the harmful impacts to the third -party properties and the tunnel structure itself. This paper introduces the inclined big-diameter jet-grouted column (iBDJ) technique that was recently applied with success in Hanoi Metro Line No3 project in Vietnam. This technique for protecting historical sensitive buildings that are in fuzzy of foundation information can be extended to urban tunnel projects in Vietnam and other countries which have similar conditions.

This article is a summary of the available research works of cast-in-place deep-seated bored piles in Myanmar. Instrumented static pile load test results are analyzed, discussed, and updated. The information contained in the article is mainly from the construction projects of private sectors constructed in Yangon and extended study of previous work on current practices of deep foundations and deep excavation Works in Myanmar.

The Nant de Drance hydropower plant in the canton of Valais is one of the Swiss energy industry's largest construction projects of recent years. The core component is the underground pumped storage power plant. This pumps water from the existing Emosson reservoir at 1930 m asl to the upper Vieux Emossen reservoir at 2225 m asl, where the surplus energy is stored. When demand exceeds supply, water is released to generate electricity. The head ranges from 290 to 395 m, depending on the water levels. The new power plant, which took 14 years to build, has a pump and turbine capacity of 900 MW.
The most important elements of the project were the access tunnel, pressure tunnels, vertical pressure shafts and underground machine and transformer halls, as well as the various access and service galleries, the intake and discharge structures with cofferdam, and the raising of the Vieux Emosson dam by 20 m. The ecologically sensitive use of resources is essential to ensure the success of a complex, high-altitude construction project of this nature involving enormous quantities of material. Excavated rock, for example, has been processed on site to produce aggregate for concrete. In this case a high-capacity aggregate production plant was installed on site to process the excavated material required for on-site concrete production. This created a closed-loop materials cycle which enabled the construction site to be self-sufficient in terms of concrete production.
The challenges of using excavated tunnel material as a resource are enormous.
Nant de Drance im Kanton Wallis war eines der größten Bauvorhaben der Energiewirtschaft der Schweiz in den letzten Jahren. Das Herzstück ist das unterirdisch angelegte Pumpspeicherkraftwerk. Dieses pumpt Wasser aus dem bestehenden Stausee Emosson auf 1930 m ü.M. in den höher gelegenen Stausee Vieux Emossen auf 2225 m ü.M. und nutzt dieses bei Bedarf wieder zur Stromproduktion, wobei eine Fallhöhe von - je nach Wasserspiegelhöhen - 290 bis 395 m bewirtschaftet wird. Das neue Kraftwerk weist eine Pump- und eine Turbinenleistung von insgesamt 900 MW auf. Die Bauzeit betrug gesamthaft vierzehn Jahre.
Die wichtigsten Projektelemente waren der Zugangstunnel, der Druckstollen, die vertikalen Druckschächte, die Maschinen- und Trafo-Kavernen sowie diverse Zugangs- und Logistikstollen, die Ein- und Auslaufbauwerke mit Fangedamm sowie die Erhöhung der Staumauer Vieux Emosson um 20 m. Eine derart komplexe Bauaufgabe im Hochgebirge mit ihren enormen Volumenströmen ist nur mit einem schonenden Umgang der Ressourcen erfolgreich zu realisieren. Dazu gehört insbesondere das Aufbereiten des ausgebrochenen Gesteins vor Ort zu Gesteinskörnungen für Beton. Auf der Baustelle wurde eine leistungsstarke Kiesaufbereitungsanlage installiert und betrieben, die das Ausbruchmaterial bedarfsgerecht für die eigene Betonproduktion verarbeitet. So wurde ein geschlossener Stoffkreislauf erzeugt, womit die Baustelle autark mit Beton beliefert werden konnte.
Die Herausforderungen bei der Verwendung des Tunnelausbruchs als Rohstoff sind enorm. Noch größer sind aber bei zielorientierter Umsetzung die Vorteile für alle Beteiligten. Dabei werden die umweltrelevanten Aspekte bewusster berücksichtigt und umgesetzt. Dies bedeutet für alle Beteiligten Chancenerhöhung respektive Risikominderung.

India is well on its way to create a world-class Mass Rapid Transport system environment as an integral part of community infrastructure development. Mumbai Metro Line 3 is one such project being constructed in Mumbai city. It comprises 33.5 km-long underground metro corridor running along Colaba to Bandra to Santacruz Electronic Export Processing Zone. It includes 27 stations (26 underground and 1 at grade), depot and associated twin-tube tunnel. Mumbai Metro Rail Corporation Ltd., an affiliate organisation of Mumbai Metropolitan Region Development Authority, is responsible for the implementation of the project. Excavation and tunnelling works posed significant challenges as they cross densely inhabited zones of Mumbai. There were several buildings which were old and in delicate condition, many of which were heritage structures. In Mumbai - being a coastal city - the water table is almost at ground level which added to complications. There were several utilities, many of which were lifeline utilities, which could not be diverted or even closed, thus requiring support during excavation. Likewise, ensuring traffic movement with minimal disruptions with enormous excavation works for the project required several innovative solutions. Other criticalities included low overburden to the existing flyovers and to the air traffic control tower as well as saving a 100 year-old banyan tree.

The new Ontario Line is one of four priority transit projects announced by the province of Ontario in 2019 for the Greater Toronto Area (GTA). It will be a 15.6 km stand-alone rapid transit line that will run through the city from Exhibition/Ontario Place in the southwest, through the heart of downtown Toronto, all the way to the Ontario Science Centre in the northeast. Over half of the route (9 km) is planned to run underground through new tunnels, with the remainder running along elevated and at-grade rail corridor sections of track. Fifteen new stations are proposed, whereby eight are planned as deep underground structures. Most of these underground stations will be built in the downtown core, with numerous connections to the broader transit network of the GTA, including GO Transit rail services, the Toronto Transit Commission's (TTC) existing subway Lines 1 and 2, the Line 5 (Eglinton Crosstown LRT) currently under construction, as well as numerous bus and streetcar routes. The expected project benefits of Ontario Line are as follows:
- A faster and more reliable access to rapid transit system with more than 227,500 people living within walking distance to the new line.
- Reduction in crowding of existing Line 1 subway.
- Up to 47,000 jobs accessible by transit in 45 min or less for Toronto residents.
- Economic and community growth along the future transit line and significant reduction in traffic congestion and greenhouse gases by providing alternative transportation options.
The Ontario Line is currently being delivered through a number of contracts with different procurement approaches.

Developing large-scale tunnelling projects in orogenic regions implies enormous technical challenges. Las Leñas International Tunnel Project through the Andes Main Cordillera of Chile and Argentina has been a long-awaited infrastructure project, whose geological and topographic settings suggest several complex singularities to be considered, analyzed, and assessed during its development. Throughout the course of this feasibility study, the complex geological subsurface interpretation offers a broad spectrum of technical demands to be fulfilled. The overburden conditions, the presence of certain lithologies such as expansive clays or soluble evaporitic sequences, along with regional stress assessment, are major technical challenges. Through extensive geological, geotechnical, and hydrogeological mapping, subsurface 3D modelling interpretation, along with numerical analysis and its relationship with similar projects in the region, brittle, and plastic behaviour are analyzed. A wide range of modern techniques are used to assess those mentioned tasks, which enable an extensive comprehension of the geological and geotechnical conditions of the area. The purpose of this contribution is to enrich the knowledge on geological and geomechanical challenges faced in large tunnelling infrastructure projects in high-mountain environments and what specific lessons may arise from them for similar future projects.
Las Leñas International Tunnel - Geomechanische Herausforderungen bei großen Tunnelbauprojekten in den Anden
Die Entwicklung groß angelegter Tunnelbauprojekte in orogenen Regionen impliziert enorme technische Herausforderungen. Der internationale Tunnel Las Leñas durch die zentralen Anden in Chile und Argentinien ist ein lang erwartetes Infrastrukturprojekt. Seine geologischen und topografischen Rahmenbedingungen zeigen komplexe Singularitäten auf, die während der Projektierung berücksichtigt, analysiert und bewertet werden müssen. Die Interpretation des komplexen geologischen Aufbaus bot im Zuge dieser Machbarkeitsstudie ein Spektrum an technischen Anforderungen: Die Überlagerungshöhe, Lithologien wie expansive Tone oder Evaporitgesteine sowie der regionale Spannungszustand führten zu technischen Herausforderungen. Auf Basis umfangreicher geologischer, geotechnischer und hydrogeologischer Kartierungen, Erstellung und Interpretation des Untergrunds in 3D-Modellen sowie numerischer Analysen wurde unter Einbeziehung ähnlicher Projekte in der Region sprödes und plastisches Verhalten analysiert. Dabei wurden moderne Techniken eingesetzt, die ein umfassendes Verständnis der geologischen und geotechnischen Bedingungen des Gebiets ermöglichen. Ziel dieses Beitrags ist, Kenntnisse über die geologischen und geomechanischen Herausforderungen bei großen Tunnelbau-Infrastrukturprojekten im Hochgebirge zu erweitern und konkrete Lehren daraus für ähnliche zukünftige Projekte zu ziehen.

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.

Since ancient times, rocks and their geomechanical and mineralogical properties have played a fundamental role for realising construction and infrastructure projects. Workability and excavability of the material itself are still decisive factors controlling tool wear and advancement rates. In engineering geology, standardised tests and analyses related to the strength, hardness, abrasivity and mineralogical composition are commonly conducted in this context. The uniaxial compressive strength (UCS), CERCHAR Abrasivity Index (CAI) and equivalent quartz content are widely used parameters for such an assessment, in order to estimate and predict drillability and associated wear of drill bits, cutting discs or chisels. In this article, the correlations between strength, abrasivity and mineral content of various rock types are investigated. The concept of hardness in geotechnics and engineering geology is elaborated in greater detail, shedding light on hardness definitions, testing methods and how hardness parameters are interrelated. Under the aspect that the CAI shows a good correlation with the Mohs hardness commonly used in mineralogy, a novel approach for estimating the CAI is presented. It is suggested that the CAI of a rock can be estimated within 50 % of the actual value, if its UCS exceeds »60 MPa. On the data basis of various rock types analysed from national and international construction projects, the potential and limitations of this method are discussed.

Liquefaction is a vital issue for the tunnel-sand pile interaction (TSPI) system under seismic excitation. Therefore the present study proposed a TSPI model for the liquefaction analysis numerically using the numerical code of Plaxis 3D under local seismic excitation. Validation results of the numerical code inform a convincing level of accuracy to ensure the analysis of the TSPI model using this code. In this research, the geometry of the TSPI model is considered smaller compared to the tunnel diameter to influence the probability of the liquefaction occurrence, and the only variable geometric dimension is the tunnel pile clear distance of the interaction zone while other geometric and material properties are considered to be the standard value. UBC3D-PLM (two yield surfaces consisting of kinematic hardening rules) constitutive model is used to ensure the liquefaction effect in the TSPI model; however, the excess pore pressure ratio exceeds the limiting value of 1 to inform the existence of liquefaction in the TSPI model. In addition, the uplift of sand is exceeded from the settlement due to liquefaction. However, further investigations such as experimental and analytical studies may have to be performed in the future to enhance the present study.

In the construction industry, increased efforts are being made to automate production processes using industrial robots in order to increase efficiency, improve quality and optimize the use of materials. Tunnel construction is particularly suitable for the use of modern production methods, as the increased use of machines and the high repetition factor of the components used make it possible to scale production technology across project boundaries. This paper provides examples of current developments in segment production, in particular the use of industrial robots in the prefabrication of reinforcement cages and subsequent concreting. Necessary adaptations in segment design are pointed out when welded reinforcement is used, and conceivable further developments are shown. The medium-term goal is a continuous IT-based production control system that allows short-term adjustments to segment production, logistics and subsequent installation in the tunnel.
In der Bauindustrie werden verstärkte Anstrengungen unternommen Produktionsprozesse durch den Einsatz von Industrierobotern zu automatisieren, um die Effizienz zu steigern, die Qualität zu verbessern sowie den Materialeinsatz zu optimieren. Besonders geeignet für den Einsatz moderner Fertigungsmethoden ist der Tunnelbau, da insbesondere durch den verstärkten Maschineneinsatz und hohen Wiederholungsfaktor der eingesetzten Bauteile eine Skalierung der Produktionstechnik über Projektgrenzen hinweg möglich ist. Der vorliegende Aufsatz erläutert exemplarisch die aktuellen Entwicklungen im Bereich der Tübbingproduktion, insbesondere den Einsatz von Industrierobotern in der Vorfertigung der Bewehrungskörbe bzw. der anschließenden Betonage. Auf notwendige Anpassungen im Tübbingdesign wird bei Einsatz von geschweißter Bewehrung hingewiesen sowie denkbare Weiterentwicklungen aufgezeigt. Mittelfristiges Ziel ist eine durchgehende IT-basierte Produktionssteuerung, die kurzfristige Anpassungen in der Produktion, aber auch in der Logistik und dem anschließenden Einbau im Tunnel ermöglicht.