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- Exhibition “Geotechnics and Tunnelling” at University of Leoben Closed its Doors
- University Certificate Programme - NATM Engineer

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.