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Liu M.-H.,North China University of Water Conservancy and Electric Power | Yin A.-G.,China Railway Seventh Group Co. | Guo W.,China Railway Seventh Group Co.
Journal of Railway Engineering Society | Year: 2014

Research purposes: The existing civil air defense tunnel reconstruction gets few examples in China. This paper relies on monitoring measurement technology and the theory of finite element analysis, studies the displacement, deformation, and stress characteristics on different stages of dynamic tunneling during the single and bilateral excavation. We improved construction plan, strengthened the construction process control, and compared the numerical simulation results with site measures to ensure the safety of tunnel reconstruction.Research conclusions: (1) The main parameters such as the maximum ground settlement caused by unilateral and bilateral excavation and the stress of surrounding rock meet the code and design requirements. This shows that the construction scheme is reasonable. (2) The rock structure experiences a trend of decreasing tensile stress and increasing compressive stress with the excavation. The maximum tensile stress of the rock structure drops dramatically as the initial support and temporary support. The maximum compressive stress increases dramatically when the top structure is excavated. (3) A two-meter single side excavation of the existing structure is followed by a ground surface sedimentation of 15.10 mm while a one-meter bilateral excavation expects a ground surface sedimentation of 23.67 mm, which is very close to the designed warning value (24 mm) and shall be strictly controlled during the construction. (4) This paper presents the construction methods and measures such as temporary vertical advance reinforcement, side wall and invert, radial grouting, supported by pipe shed, excavation and so on, which can make the internal force change under control, control the displacement of vault, the inverted arch and surface effectively, and ensure the safe of structure and construction. (5) This paper summarizes the deformation rules of surrounding rock, surface, liner structure and so on, which can provide references for the design and construction of similar projects. ©, 2014, Journal of Railway Engineering Society. All right reserved.

Liu M.-H.,North China University of Water Conservancy and Electric Power | Ping S.-L.,China Railway Seventh Group Co. | Yin A.-G.,China Railway Seventh Group Co.
Journal of Railway Engineering Society | Year: 2015

Research purposes: The experimental study aims to promote the application of cold recycling technology in road reconstruction and improve design indexes of cold recycled mixture and construction standards. Comparative analysis about the performance of existing pavement mixture and cold recycled mixture, and design of cold recycled base material are carried out. Finally this paper puts forward the quality control points in construction about cold recycling technology. Research conclusions: (1) The result of the tests shows that types and dose of additive are determined through compaction test, unconfined compression test and engineering characteristics; grain composition, strength and stability of old road mixture are compared with cement-stabilized recycled mixture. And optimum water content on 5% cement-stabilized sandy soil mixture was respectively 12.1% which shows that intensity and stability of cement-stabilized recycled mixture is better, and can meet the requirement on pavement base. (2) Engineering evaluation projects is established in detail. It mainly includes present situation, structural bearing capacity and the performance of old mixture, etc. (3) Through engineering practice, it points out the method of equipment matching on cold in-place recycling units and adding method of cement and water, and integrative operation method of milling-planing and compacting in cold in-place recycling technology is proposed. (4) Detection results of cold-recycled base show that various indexes of base can meet pavement operating requirements, and regeneration effect is good, which is provided for references to the design and construction of similar cold regenerative base. ©, 2015, Editorial Department of Journal of Railway Engineering Society. All right reserved.

Weng C.C.,Wuhan University of Technology | Wu H.,Wuhan University of Technology | Liu X.D.,China Trans Geometrics Co. | Du Z.Y.,Fifth Survey and Design Institute Group Co. | And 4 more authors.
Advanced Materials Research | Year: 2012

From the quality of foundation roller compaction perspective in large civil engineering, this paper integrated the high precision real-time position technology of GNSS and the spatial analysis function of GIS, constructed a foundation roller compaction quality monitoring system to realize the real-time monitoring of foundation roller compacted construction process, which can ensure the quality of this process. At the same time, based on expounding the rolling system structure and working principle, it is detailed introduce the system module and the key algorithms. © (2012) Trans Tech Publications.

Liu Z.,Beijing Jiaotong University | Wang Y.,China Railway Seventh Group Co. | Sun J.,Beijing Jiaotong University | Jia Y.,Beijing Jiaotong University | Gao R.,Beijing Jiaotong University
Beijing Jiaotong Daxue Xuebao/Journal of Beijing Jiaotong University | Year: 2015

The application research of BIM technology on designing stage of a bridge located in Sierra Leone is present, including project modeling, design checking, project quantity counting, 2D design drawing and construction process simulation. Bridge model constructing, design drawing configuration and 4D simulation of construction process are researched, and the data inter face for application stage is developed. The research results show that the BIM technology is effective for visualized design result demonstration, design quality improving, efficiency elevation, cost controlling and construction period shorten. The research practice can provide referential experience on BIM technology, especially in the area of bridge engineering design and lifecycle maintenance. © 2015, Journal Northern Jiaotong University. All right reserved.

Wu J.-G.,China Railway Seventh Group Co.
Journal of Railway Engineering Society | Year: 2013

Research purposes: It had important significance for the deep excavation engineering design and construction to understand the influence factors on mechanical and deformation of retaining structure. Using Hangzhou Metro Line 1 Qiutao Road station deep excavation engineering as an example, design and construction factors such as the first support position, support stiffness, excavation depth and reinforcement space position of the soil in passive area were discussed, which could affect mechanical and deformation of retaining structure so as to provide the reference to the similar metro station construction. Research conclusions: (1) Moving the first support position up was conducive not only to control the pile deformation, but also to control strength of the pile body. (2) It was effective to reduce deformation of the retaining structure by increasing the support stiffness when the support stiffness was smaller. (3) It was not economical to control the deformation of the retaining structure by increasing the support stiffness when the support stiffness was larger. When it was the same reinforcement thickness in passive area, it could better control the deformation of the retaining structure and improve the stress of the retaining structure selecting the reinforcement below the bottom excavation surface than selecting the reinforcement above the bottom excavation surface. (4) As the excavation depth increased, the maximum displacement of the pile body gradually moved downward, and the producing maximum displacement position would change by the difference of the support stiffness and the support prestressing.

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