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SEM and Caverns Chair: V. Gall, Gall Zeidler Consultants, USA Co-chair: M. Cash, Tutor Perini Corp, USA 14:00-14:20 Recent Trends in Conventional Tunneling (SEM/NATM) in the US N. Munfah, HNTB Corporation and V. Gall and S. Matthei, Gall Zeidler Consultants Conventional tunneling also known as the New Austrian Tunneling Method (NATM) or Sequential Excavation Method (SEM) was transformed in the US to deal with challenging tunneling conditions as an alternative to the more traditional tunneling methods. It is being used more often in urban areas, under difﬁcult ground and ground water conditions, and with limited cover. Often the tunnel is of a large and non-uniform cross section in soft soils or weak rocks.
The intent of using this tunneling method is to minimize impact on trafﬁc and utilities and reduce disruption of everyday life of people and businesses. To meet these challenges, the industry developed technical approaches and implementation techniques and established sophisticated contractual relationships and collaboration in the ﬁeld among various parties for successful implementation. This paper examines the development of conventional tunneling (NATM/ SEM) in the US to deal with these challenges using recent examples such as Russia Wharf in Boston, Northern Boulevard Crossing, in New York, and Chinatown Station in San Francisco.
14:20-14:40 Design and Engineering During the Construction of Los Leones Station (Line 6, Santiago Subway, Chile) B. Celada; Geocontrol and J. Adasme and H. González. Metro “Los Leones” Station will be the north end of the new Line 6 of Santiago’s Subway (Chile). This station is already in construction under Providencia Boulevard; it has a length of 120 m, a width of 19 m and 12 m height. Its tunnel section is 185 m2 and its overburden is 19 m. The S·W side of “Los Leones” Station is being constructed under a parking. Because of this, between the crown of the Station and the lower ﬂoor of this parking there are only
7.4 m.The construction of the Station was designed by two methods; at the N·E half part the “self supported vault” method was employed; but due to the presence of the Providencia parking the “Foundation Galleries” method was employed at the S·W half part.
In this paper it is presented the design of “Los Leones” Station and the main activities carried out during its construction.
WTC2016 | SAN FRANCISCO CALIFORNIA, USA MONDAY 25 APRIL 14:40-15:00 Upgrading of City of Genoa railway Junction Under-crossing with Shallow Distance of Existing Tunnels in Urban Environment A. Pigorini, E. Pedone, N. Beltrandi and H. Mohamed Dahir, Italferr S.p.A.
Genoa is a very distinctive city located between mountains and the sea and infrastructural upgrading works often have to deal with the intersection of existing infrastructures. This is the case for the new railway tunnel construction between the stations of Brignole and Principe which under-cross two existing double-track tunnels in operation. The latter have been constructed with masonry bricks and the vertical distance between old and new tunnels is approximately 1m.
Due to rock characteristics and the urban environment, stability and vibrations control are the main issues. Consolidation work with the fore-poling method and a speciﬁc sequence of excavation, primary lining and ﬁnal lining support have been designed to assure stability and settlement control. A hard rock road-header has been used to assure vibration control. Finally, a real time monitoring has been implemented. The article presents monitoring and back-analysis results of the under-crossing of the existing tunnels.
15:00-15:20 The Norsborg Metro Depot – Case Study of a Modern Urban Development in Stockholm H. Hogard and J. Alsén, Skanska Sweden AB Construction of large facilities underground in urban areas has many advantages. In order to show the advantages, a case study of the Norsborg metro depot in Stockholm Sweden has been made. The Norsborg metro depot will be the largest and most modern underground metro depot in northern Europe. The depot has been built in hard rock in an urban area with small impact on the environment and local residents. The paper describes how it is possible to build underground facilities in a cost efﬁcient way and take care of the challenges regarding working environment that comes with locating a permanent working place underground.
15:20-15:40 An Innovative Method of Large Space Underground Construction in Soft and Shallow Ground Using Concrete Arch Pre-supporting System, CAPS Method M. Hossein Sadaghiani, Sharif University of Technology Construction of underground structures in urban areas is a very challenging work. There are generally two methods of construction, an open cut-and-cover and underground method. To eliminate the subsurface and surface disturbance and street trafﬁc problems, underground method is preferred. The stress redistribution caused by underground excavation induces movements and deformation in the earth mass and ultimately at the ground surface. This is more pronounced in large space excavations. Generally pre-supporting system is used to control ground deformation and thus enhance its stability. In this paper an innovative pre-supporting system is presented. Concrete Arch Pre-supporting System (CAPS) is introduced in Tehran Metro in 2002. This method has roots in construction 22 – 28 APRIL | MOSCONE CENTER | WTC2016 method of an Old Iranian small water tunnels, called Quanat. CAPS is an efﬁcient method for stabilizing large span underground spaces constructed in shallow and soft ground. In this technique underground reinforced concrete elements are constructed around the proposed underground space prior to main excavation. This method is used successfully in over 50 large span underground structures in Tehran Metro and road tunnel intersections. CAPS has potential to be used to pre-support the large span underground spaces at any weak ground condition in an urban area.
15:40-16:10 Break 16:10-16:30 Construction of Expressway Branch Junction Structure Using Non-cut-and-cover Enlargement Method to Combine Two Shield Tunnels in Sedimentary Soft Rock K. Namikawa and Y. Terashima, Metropolitan Expressway Company Limited; T. Inoue, Hazama Ando Corporation;
J. Koseki and Y. Miyashita, The University of Tokyo and M. Matsumoto, Nom Company Limited In order to construct an underground two-layer expressway branch junction structure with a height of 14.7 m and a width of 22.3 m, two shield tunnels in each layer were combined by using a non-cutand-cover enlargement method in sedimentary soft rock. Before and during the construction work, preliminary analysis, in-situ investigations and laboratory tests were conducted to ensure the construction safety and to evaluate the deformation characteristics of sedimentary soft rock. The construction project was safely executed without any water leakage or collapse of tunnel working face.
The predicted results from preliminary analysis were almost similar to the measured values. From the detailed investigation of measured results, it was conﬁrmed that the deformation characteristic of the sedimentary soft rock was observed to a small extent as the ground deformation derived from construction work.
16:30-16:50 Technologies on SEM Tunneling in Hazardous Material-bearing Soft Rock with Small Overburden T. Kudo, City of Sapporo and A. Ishikuro, M. Shintaku and F. Kusumoto, Shimizu Corporation The Bankei-Kitanosawa tunnel that is located in Sapporo, Hokkaido, Japan includes a 450m long section near the arrival point where mudstone which can liquate out natural hazardous materials such as arsenic and selenium exceeding the tolerance stipulated by country as well as weathered mudstone and unconsolidated sedimentary rocks with small overburden and the competence factor less than 1.0 are present. The mucks containing hazardous materials were disposed into the waterproof branch tunnels created from the inside of the main tunnel. The full face early ring closure method was employed to ensure the stability of the tunnel in the low strength rock masses having no stand-up time. As a result, the waterproof tunnels branching off the main tunnel can manage watertightness so as to ensure safety and relief against environmental risks of the hazardous materials. It is also demonstrated that the full face early ring closure method enable construction of the tunnel with a small overburden in the low strength rock masses.
WTC2016 | SAN FRANCISCO CALIFORNIA, USA MONDAY 25 APRIL 16:50-17:10 The Effect of Excavation Progress on the Behavior of Hakim Highway Tunnel Using Geotechnical Instrumentation M. Sadeghi and S. Mahdi Pourhashemi, Engineering and Development Organization of Tehran Municipality and A. Naghi Dehghan and K. Ahangari, Islamic Azad University Instrumentation and monitoring of ground deformations in tunneling is a principal means for selecting and controlling the excavation and support methods among those foreseen in the design, for ensuring safety during tunnel construction (including personnel safety inside the tunnel and safety of structures located at ground surface) and, ﬁnally, for ensuring construction quality management. In this paper, the effect of Hakim Tunnel excavation on the behavior of the surrounding ground was investigated based on the geotechnical instrumentation. This tunnel with 1080 m length, 18 m width and 12.6 m height is being constructed using the SEM/NATM along the Hakim Highway in Tehran. The results which are obtained from recorded displacements by geodetic pins (on the tunnel wall and roof), extensometers and settlements pins (at the ground surface) demonstrate the tunnel stability during the various stages of excavation. However, it is concluded that the rate of excavation in different sequences could have a major role on stability of tunnel. In this case the surface and underground openings were monitored as well as needed for controlling the face probably collapse.
17:10-17:30 The Hirschhagen Highway Tunnel (BAB 44) in Germany: Pre-Support in Extremely Difﬁcult and Inhomogeneous Ground Conditions G. M. Volkmann, DSI – DYWIDAG-Systems International GmbH The construction of the BAB 44 motorway between Kassel and Herleshausen (both Germany) is an important part of the trans-European road network. After its completion, the A 44 will permit an efﬁcient connection of the Benelux States in the West and Poland in the East. In the section between Eschenstruth and Hessisch Lichtenau the Hirschhagen Tunnel is constructed with a length of 4.1km.
Most sections of the tunnel are situated in weak ground conditions.
Hence a combination of face bolts with spiles (short forepoling) or pipe umbrellas (long forepoling) additionally support the tunnel heading on a regular basis. This article will focus on the application of a newly developed method to connect the pipe umbrella support, which is mostly installed by conventional drilling machines nowadays. The installation method limits the outer diameter to a maximum of 168mm and a pipe wall thickness of 12.5mm because workers must be able to handle pipes and its drill steel. Typically these pipes are connected with threads that create a weak link in the support system so during the last decade alternative connection systems were developed to overcome this disadvantage. One of these alternative coupling systems is the so called Squeezed Connection, which will be explained in this article followed by a discussion of its advantages and disadvantages regarding technical speciﬁcations, construction time, and safety issues.
22 – 28 APRIL | MOSCONE CENTER | WTC2016 Posters (On display in the exhibit hall during exhibit hours. Authors will be at their poster from 13:00-14:00 for discussion.) Underground Car Park in the Ancient “Morelli” Cavern in Naples M. Bringiotti, A. Bellone and F. Rossano, CIPA S.p.A.
In 2004 works started for the now completed seven-level automated car park accommodating 480 parking spaces inside the pre-existent “Morelli cave”, located in a strategic area in Naples. Since 470 BC Greeks initiated the growth of the fascinating world of the underground Naples, of which this cave belongs. It seems that once here the god Mithras was worshiped. it’s also became a quarry for tuff extraction and in 1600s it became an aqueduct serving the area. In 1853 the Bourbon Tunnel, a project commissioned by King Ferdinand II of Bourbon to allow easy escape from the Royal Palace in case of riots, was connected to this network of tunnels. The cavern became an air raid shelter during the Second World War, then a deposit of cars and motorcycles in the ‘50s and’ 60s, a disposal area and it has been abandoned in the last 40 years before it’s new utilization.
Performance Requirement of Immediate Ring Closure Method for Difﬁcult Ground Conditions in Conventional Tunneling D. Awaji, N. Isago, A. Kusaka, and K. Kawata, Public Work Research Institute The immediate ring closure method, in which the entire periphery of the excavation area is closed immediately with an initial support within a short distance from the excavation face, has been increasingly used in Japan, especially, as one of the most effective countermeasures against difﬁcult ground conditions in conventional tunneling. For reasonable design of this method, the performance requirements for the initial support should be clearly stated. The analysis of construction data of 30 road tunnels and the three-dimensional numerical modeling based on real data suggest that the immediate ring closure stabilizes the tunnel structure and the ground around it because of the inner pressure effect of the initial support, especially, for low ground competence factor and small internal friction angle. Finally, the bending compressive strength and the cross-sectional geometry of the initial support have to be considered in the tunnel design while considering the earth pressure and ground properties.