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San Pasquale Station of Line 6 in Naples: Measurements and Numerical Analyses
No full textThe paper reports some geotechnical aspects of the design and construction of the San Pasquale
Station, intermediate along Line 6 and located close to the sea and at the same time within one of the
most fascinating district of the city known as Chiaia borough. The station required an excavation
deeper than 25 m, almost entirely located in pyroclastic sand below the groundwater table. The main
shaft is 85.5 m long and 24.1 m large, containing also the whole length of the pedestrian platform
while a single large section tunnel, built before the excavation of the station shaft, accommodates the
two operating rail tracks. In the paper monitoring data will be presented and discussed. Settlements
and horizontal displacements represent certainly very significant outcomes among the observed data.
Their variations along with time and main construction steps are first of all presented in the paper. The
monitoring data have also been submitted to a process of careful interpretation based on the use of
numerical analyses to better understand the interaction of deep excavation with urban area. The FEM
code Plaxis has been adopted for such a purpose adopting advanced constitutive soil models which are
available in the code library
San Pasquale station of line 6 in Napoli
No full textThe paper reports some geotechnical aspects of the design and construction of the San Pasquale Station, intermediate along the stretch of Line 6, which walks across the coastline named Riviera di Chiaia. The station required an excavation deeper 27 m, almost entirely located in pyroclastic sand below the groundwater table. The main shaft is 85.5 m long and 24.1 m large, containing the whole length of the pedestrian platform while a single large section tunnel, built before the excavation of the station shaft, accommodates the two operating rail tracks. Monitoring data will be presented and discussed. Settlements and horizontal displacements represent certainly very significant outcomes among the observed data. Their variations along with time and main construction steps are presented in the paper. The monitoring data have also been submitted to a process of careful interpretation based on the use of numerical analyses to better understand the interaction of deep excavation in a crowded urban area. The FEM code Plaxis has been adopted for such a purpose. Advanced constitutive soil models are available in the software library; however the best compromise between available models and the concrete possibility of properly calibrating their parameters on the basis of the site and laboratory geotechnical investigations was made
Three-Dimensional Performance of a Deep Excavation in Sand
No full textA 27 m deep excavation in a pyroclastic sand has been constructed in the urban area of Napoli (Italy). The main excavation is supported by T-section reinforced concrete (RC) diaphragm walls. The presence of valuable historical edifices on one side of the excavations suggested the selection of a top-down construction procedure. Maximum settlement recorded at the building façade was about 25 mm [i.e., 0.09% of the free excavation depth (He)]. Full settlement troughs were observed along three different alignments. As a matter of fact none of the monitored alignments could be interpreted exactly as a normal or a parallel settlement trough. A shape function based on the complementary error function was thus proposed to fit the observed settlement data in the plane considering both the distances x and y respectively parallel and normal to the excavation. This approach is actually a combination of existing independent methods
Cedimenti indotti da grandi scavi in ambiente urbano: il caso della stazione san Pasquale a Napoli
No full textArtificial Ground Freezing to excavate a tunnel in sandy soil. Measurements and back analysis
No full textThe paper is dedicated to the case history of a 13 m wide, 17 m high and 40 m long service tunnel at Toledo Station, previously constructed in a deep open shaft and belonging to the Line 1 of the Napoli underground network. The existing Line 1 has been recently extended with a new stretch consisting of five new stations connected by twin rail tunnels for a total length of about 5 km. Toledo Station main shaft is located by a side of the line and it is connected to the pedestrian platforms by the above mentioned large size service tunnel. The station is situated in the historical center of the city of Napoli, under a deeply urbanized area. In Fig. 1 a longitudinal section of the main shaft of the station and of the large service tunnel with the above and surrounding buildings is sketched. The focus of this paper is on the settlement caused by the tunnel excavation and on the use of the Artificial Ground Freezing (AGF) technique to allow the safe excavation of the large crown of the service tunnel, located about one half in a silty sand layer and one half in yellow tuff, well below the groundwater table
San Pasquale station of the Linea 6 in Napoli: dewatering field tests, measurements and back-analyses
No full text
The Naples metro Line 1: the service tunnel at Toledo station
No full textAbstract
This paper is concerned with the analysis of a 13 m wide, 17 m high and 40 m long service tunnel execution at Toledo Station within the Metro Line 1 extension project in Naples (Italy). From the terminal of Dante Station, the new stretch of the underground is composed of five new stations and two twin rail tunnels with a length of 5 km. Four stations out of five have the access shaft centered with the twin rail tunnels. On the contrary, Toledo Station, situated in the deeply urbanized historical centre of the city, has the shaft located laterally and a large size service tunnel connects it to the rail and pedestrian access tunnels, starting from the access shaft. The subsoil concerned can be divided schematically into two main layers: a top loose silty sand overlying the soft and sometimes fractured Neapolitan Yellow Tuff, with a hydrostatic head of 27 m above the tunnel invert. In this work, a more refined and thorough back analysis of the full construction process of the service tunnel was implemented starting from the drift construction and passing through the freezing process of the soil with the pore water, the excavation with the soil removal and the final thawing step. To this purpose a 3D model was built into the general purpose DFM software package named Flac3
Excavations in the Neapolitan Subsoil: the experience of the Toledo Station service tunnel
No full textABSTRACT: A Metro Line 1 extension is being executed in Naples from the terminal of Dante Station. The new underground section is composed of five new stations and two twin rail tunnels with a length of 5 km. Toledo Station has the shaft located laterally and a large size service tunnel (13 m wide, 17 m high and 40 m long) connects it to the rail and pedestrian access tunnels, starting from the access shaft. The tunnel is located in the historical centre, under a deeply urbanized area in volcanic soil (loose pozzolana silty sand and tuff) with a hydrostatic head of 27 m. For stabilizing the tunnel crown in loose volcanic soil, it was decided to adopt the Artificial Ground Freezing method among the various options of ground improvement techniques. In this paper, the observed behaviour is presented and discussed, allowing to throw a light on the effects of the rather complex execution steps of the underground excavation
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