1,721,075 research outputs found
Monitoring and displacements at Heathrow Express Terminal 4 station tunnels
No full textA wide variety of instrumentation was deployed during the construction of the sprayed-concrete lined tunnels at Heathrow Express Terminal 4 station. This paper presents data from the in-tunnel displacement monitoring system and for settlements above the tunnels, providing data on instrument survival and performance, and an overall summary of the displacements arising from tunnel excavation
Displacements ahead of an advancing NATM tunnel in the London clay
No full textThis paper reports the results of monitoring carried out to study the patterns of ground displacement that develop ahead of an advancing sprayed concrete lined tunnel in soft ground. Extensive instrumentation was installed and monitored during the construction of the Heathrow Express platform tunnels forming part of the underground station at London Heathrow's Terminal 4. The construction of the concourse tunnel, built between the two completed platform tunnels, provided the opportunity to install additional instrumentation ahead of the tunnel drive, and to measure ground movements as the tunnel approached the instrumented sections. The paper describes the ground conditions at Heathrow, and the method of construction used for the concourse tunnel. The performance of the instrumentation and the pattern of ground displacements measured are reported. Finally, a synthesis of ground displacements measured is given, and the results are compared with the volume loss recorded during the concourse tunnel construction
An evaluation of the role of monitoring during the construction of shallow NATM tunnels in urban areas
No full textMonitoring forms an essential part of the construction of New Austrian Tunnelling Method (NATM) tunnels. After the collapse of two platform tunnels and the concourse tunnel at the Central Terminal Area, Heathrow Airport, in October 1994, an extensive evaluation of NATM tunnelling, including the role of instrumentation, followed. The paper critically evaluates the purpose of monitoring during the construction of NATM tunnels, with specific reference to shallow tunnels in soft soils in urban areas. The instrumentation used during the construction of the station tunnels at Terminal 4 is evaluated with regard to its purpose and performance during construction. (As part of the Heathrow Express rail link between central London and Heathrow Airport, two underground stations are being constructed at Central Terminal Area and Terminal 4 respectively.
Monitoring of the concourse tunnel at Heathrow express terminal 4 station constructed using the NATM
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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