نتایج جستجو برای: underground tunnel

تعداد نتایج: 49716  

Hossein Entezari Zarch Kazem Barkhordari,

During wars and crises, the underground tunnels are used as a safe space. Therefore, the stability and safety of them under a blast is of particular importance. In this paper, the Finite Difference Method has been used to study the influence of the change in geotechnical parameters and depth on surface blasting on subway tunnels. Results showed that increasing the internal friction angle, modul...

Journal: :The Annals of occupational hygiene 2016
Karen S Galea Craig Mair Carla Alexander Frank de Vocht Martie van Tongeren

Personal 8-h shift exposure to respirable dust, diesel engine exhaust emissions (DEEE) (as respirable elemental carbon), and respirable crystalline silica of workers involved in constructing an underground metro railway tunnel was assessed. Black carbon (BC) concentrations were also assessed using a MicroAeth AE51. During sprayed concrete lining (SCL) activities in the tunnel, the geometric mea...

2014
R. Heikkilä

The present development situation of 3D and BIM based process model for tunnel design and construction methods has been studied. Tunnel design is generally done using traditional 2D drawing based working methods. As a basement for the research, the new specifications developed in Finland for national BIM requirements for infra sector were used. However, underground tunnels are not yet considere...

2013
Matthew Loxham Matthew J. Cooper Miriam E. Gerlofs-Nijland Flemming R. Cassee Donna E. Davies Martin R. Palmer Damon A. H. Teagle

Underground railway stations are known to have elevated particulate matter (PM) loads compared to ambient air. As these particles are derived from metal-rich sources and transition metals may pose a risk to health by virtue of their ability to catalyze generation of reactive oxygen species (ROS), their potential enrichment in underground environments is a source of concern. Compared to coarse (...

Journal: :مهندسی تونل و فضاهای زیر زمینی 0

energy-based optimized design of polymer fiber-reinforced tunnel lining mohammad safi                   analysis of underwater tunnels considering strain-softening behavior in plastic zone ahmad fahimifar; hamed ghadami; masoud ahmadvand; arvin abdolmaleki                                 the effect of operational parameters on penetration rate of a tbm using artificial neural networks- a case s...

Having knowledge of stability of an underground space depends on stresses and strains around it. Creating underground tunnels leads to significant changes in the rock mass stress. Therefore, to achieve the necessary stability, stresses and deformations around the tunnel must be examined carefully. Usually, stress-strain behavior analysis is conducted in two-dimensional mode. This paper was cond...

2011
Jun Sun

Durability problem of reinforced concrete for underground structures is a hot issue in the field of structural engineering. For underground structures, the prediction of structural service life and methodology for durability design are needed to estimate structural durability. Taking the case of Xiamen Xiang’an subsea tunnel as background, which is designed to meet the requirement of 100-year s...

Journal: :Occupational and environmental medicine 2001
B Ulvestad B Bakke W Eduard J Kongerud M B Lund

OBJECTIVES To examine whether underground construction workers exposed to tunnelling pollutants over a follow up period of 8 years have an increased risk of decline in lung function and respiratory symptoms compared with reference subjects working outside the tunnel atmosphere, and relate the findings to job groups and cumulative exposure to dust and gases. METHODS 96 Tunnel workers and a ref...

Various structural discontinuities, which form a discrete fracture network, play a significant role in the failure conditions and stability of the rock masses around underground excavations. Several continuum numerical methods have been used to study the stability of underground excavations in jointed rock masses but only few of them can take into account the influence of the pre-existing natur...

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