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Wang X.-F.,China Railway 12th Bureau Group CO.
Journal of Railway Engineering Society | Year: 2013

Research purposes: Combined with construction of the Tiantaisi Tunnel of the Dazhou-Chengdu Railway, the experimental study was done on the air tightness of the concrete used for the high gas tunnel to find the influence factors and influence law on the concrete gas tightness for providing the technical parameters for making up the gas-tightness concrete and its appliable control in high gas tunnel construction. Research conclusions: (1)The water-binder ratio of the air-tightness concrete should be less than 0.4, no bigger than 0.45. (2)The silt content of the fine aggregate should be not more than 2.5%. The silt content of the coarse aggregate should not be more than 40 mm, with maximum grain size of no more than 40 mm. (3)The elongated flaky particle content of the coarse aggregate should be strictly controlled, and the ratio of the sand and the aggregate should be more than 36%, and the ratio of the sand and the aggregate should be big as much as possible if allowable. (4)The binder content of the air-tightness concrete should be more than 380 kg for 1 m3 concrete. (5)The silica fume and fly ash are good for improving the air tightness of the concrete. (6)The water reducer and compacting agent are able to improve the air tightness of concrete. When many additives have to be used, their adaptabilities should be tested to make them adaptable each other for obtaining the best air tightness. (7)The C-S-H alkalinity of the cement hydration product can be decreased and compactness can be increased by using silica fume and fly ash. In this way, the directional arrangement of Ca(OH)2 at the aggregate interface can be improved, the production of ettringite can be reduced and the air tightness of concrete can be enhanced. (8)The research results can be used in preparation and construction of air tightness of concrete for the gas tunnel.

Zhao N.-Q.,China Railway 12th Bureau Group CO.
Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology | Year: 2010

Based on the engineering background of Jing-Hu high speed railway and the actual situation of natural sand shortage, artificial sand high performance concrete was prepared. The effects of mud content, water consumption and sand ratio on the properties of concrete were investigated. The mix proportion of C30 and C35 artificial sand high performance concrete were obtained, which provide a reference for the application of artificial sand in railway project concrete.

Yang X.,Tongji University | Yao Y.,China Railway 12th Bureau Group CO. | Zhang Y.,Tongji University | Ye P.,Tongji University
Geotechnical Special Publication | Year: 2010

The Shiziyang tunnel is in passenger dedicated rail line connecting Guangzhou, Shenzhen and Hong Kong. It will be the longest underwater tunnel and have the highest technical level in China. This article describes the tunnel's design and construction schemes, analyzes and summarizes the characteristics of this tunnel, in terms of its geological and hydro geological formations; and defines the strata graphic classification. According to sub-formation and characteristics of the tunnel, this article discusses the problems that may arise in the construction of the tunnel in sub-strata, declares the key points in technology of shield tunneling in three major aspects: soft ground, the upper-soft and lower-hard mixed ground and hard rock (medium hard rock) ground.

Zhang M.-J.,Beijing University of Technology | Zhao M.,Beijing University of Technology | Wang P.-C.,China Railway 12th Bureau Group CO. | Jia D.-P.,China Railway 12th Bureau Group CO. | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

The change rules of the secondary stresses of advanced tunnel segment induced by parallel shield tunnels dirving in close proximity are studied by field tests. The layout of the measured points and the field test methods are introduced, and the change rules of the secondary stresses are analyzed. Furthermore, the relationship between the secondary stresses and the distance of the shield driving face to the measured section are studied. Statistical analyses of the maximum and the stabilized magnitudes of the secondary stresses are carried out. The results of the field tests show that there will be sharp change of the secondary stresses when the hind shield is driven to the measured section, the circumferential secondary stresses in the intersection of horizontal diameter with circumference of the tunnel will be laid, and the magnitudes of the circumferential secondary stresses will be greater than those of the longitudinal secondary stresses. The results may be applied to the quantitative assessment of the construction interaction of shield tunnels in close proximity and is regarded as references to the design and construction of this kind of shield tunnels.

Xu Z.-L.,The Third Railway Survey and Design Institute Group Corporation | Zhang N.-L.,China Railway 12th Bureau Group CO. | Zhou Z.-C.,Shanghai Kunming Railway Passenger Dedicated Line Hunan Ltd Liability Company | Xu Y.-M.,The Third Railway Survey and Design Institute Group Corporation
Journal of Railway Engineering Society | Year: 2014

Research purposes: Railway tunnel construction process, due to the complex geological conditions, tunnel construction faces more insecurity factors , especially long tunnel. Xuefeng Mountain Tunnel No. 1 of Changsha to Kunming Passenger Dedicated Line faces many high risk factors, such as landslides, sudden inrush of water and mud, large deformation of surrounding rock. According to gradeIrisk management, the specific risk control measures and risk management basic system are proposed for the tunnel surrounding rock deformation, landslides, sudden inrush of water, mud and other risks , in order to achieve quality, investment, construction period and other development goals. Research conclusions: (1) Accurate and complete information is an important basis for the geological survey to identify the risk factors. With the continuous improvement of the tunnel geological survey data, the risk factor identification is gradually deepened, to form a comprehensive, sophisticated risk control measures. (2) Risk assessment of construction drawing stage and construction phase is an important stage of the risk assessment. (3) Risk management of tunnel is a system engineering, organization guarantee is the foundation of risk management success, which depends on the organization and management of design, construction, and construction units. (4) Effective implementation of the risk management system will make sure the tunnel safety, quality, investment, construction period and other ground targets of construction projects met successfully. (5) The research results can provide a good reference for the risk control and management of high speed railway tunnel.

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