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Nie J.,Tsinghua University | Wang Y.,Tsinghua University | Fan J.,Tsinghua University | Zhang X.,Guangzhou Metro Design and Research Institute Co.
Tumu Gongcheng Xuebao/China Civil Engineering Journal | Year: 2012

In old concrete bridges widened with steel-concrete composite beams, the connection is accomplished by using a composite cross beam. There has been no experimental study on the mechanical behavior of such composite cross beams. Six specimens were tested and based on existing methods, the shear strength of interface of old and new concrete was calculated. The results showed that shear failure of the interface of old and new concrete is the cause of failure of composite cross beam in old concrete bridges widened with steel-concrete composite beams. There was nearly no slip between old and new concrete before bonding failure of the interface. The interface of old and new concrete had good ductility and high strength. Based on the constitutive law of the materials, a three-stage mechanical model was proposed for the interface of old and new concrete. The load-slip relationship was also predicted. Comparison between analytical and experimental results showed that the analytical method has enough precision. The ultimate shear strength of the interface was determined by strength of concrete, rough degree of interface, and friction coefficient. The normal stress could increase the ultimate shear strength of the interface. The residual shear strength of the interface was determined by the embedded bars, and the ratio and yielding strength of the embedded bars were the main influence factors. The design method was proposed.

Shen Y.,Southwest Jiaotong University | Zou C.,Guangzhou Metro Design and Research Institute Co. | Jin Z.,Fujian University of Technology | Wang J.,Southwest Jiaotong University
Modern Tunnelling Technology | Year: 2015

Tunnel portal sections passing through an interface of hard and soft rock are vulnerable to severe damage at this high intensity seismic area. Based on the Longxi tunnelon the Chengdu-Wenchuan expressway, the earthquake dynamic response of a tunnel portal structure was analyzed using the numerical simulation method for various inclination angles of the soft/hard rock interface. The results show that; 1) the relative displacement of the tunnel lining structure increases obviously during a strong earthquake when the tunnel structure passes through the interface between soft and hard rock, and the relative displacement of the tunnel lining in the diagonal direction is higher than the relative horizontal displacement at the tunnel crown and invert; 2) the relative displacement of the tunnel structure at the soft-rock side of the interface increases with the decrease of the inclination angle, while the earthquake motion has little influence on the tunnel structure deformation at the hard-rock side; and 3) under an inclination angle <45°, the earthquake motion has a crucial influence on the safety of the upper tunnel structures (crown and spandrel) with some safety factors being less than 1, and under an inclination angle >45°, the seismic motion has a significant effect on the lower part of the tunnel structure(invert and arch springing). ©, 2015, Editorial Office of "Modern Tunnelling Technology". All right reserved.

Yu M.,5th Electronics Research Institute | Yang C.,5th Electronics Research Institute | Zhang S.,Guangzhou Metro Design and Research Institute Co.
Proceedings - 2013 4th International Conference on Digital Manufacturing and Automation, ICDMA 2013 | Year: 2013

Among the subsystems of railway, signalling system is the most important and key equipment of the automation system. Railway signalling system is responsible for directing and used to ensure the safety of train operation, to improve the efficiency of transport and other important tasks, thus the system has an irreplaceable role and high requirements of reliability. The graphical modeling ability of Stochastic Reward Net (SRN) for system reliability analysis can make the model intuitively described, at the same time, SRN can automatically generate a continuous time Markov chain, which has strong ability in mathematics. In this paper, firstly, the function and equipment structure of the railway signalling system is carried out, and then the reliability model of the system is established based on SRN to provide a reliable basis for the design and analysis of railway signalling system. © 2013 IEEE.

Zhao Q.-J.,Guangzhou Metro Design and Research Institute Co. | Liu Z.-G.,Shenzhen Metro Group Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

The anchor cable, as a mature technology, is widely applied in support of excavations and slopes in geotechnical engineering. But the cables with obvious length often bring great influence on the urban underground space after project completion, which is obvious obstruction in urban metro tunneling. The studies on the recycling pre-stressed anchor cables can provide reference for case under restricted conditions. The mechanism, technical maturity, safety reliability and economic benefits are discussed in adaptability and generalization of the recycling anchor cables. A deep excavation project of metro Line 9 in Shenzhen and other two cases are given for examples.

Lei T.,Chang'an University | Qian J.,Tongji University | Tian Q.B.,Guangzhou Metro Design and Research Institute Corporation Ltd
Advanced Materials Research | Year: 2013

Based on the reversed cyclic loading test of three 1:4 high-strength concrete flat columns, the computer program ABAQUS was used to simulate behaviors of the specimens. Concrete in the column was modeled using the damage plasticity material model, and a uniaxial steel model with combined isotropic and kinematic hardening properties was used to simulate the behavior of the reinforcement. The establishment of the finite element model, definition of the material parameters and the influence of diagonal reinforcement were discussed at length. The results show that the concrete damage plasticity model can be well used for hysteretic analysis of reinforced concrete members if the relevant parameters are reasonably defined. Diagonal reinforcements can not significantly improve ductility of the specimens, but can improve their shear capacities. This paper can provide reference for the performance simulation of reinforced concrete members under cyclic loading. © (2013) Trans Tech Publications, Switzerland.

Chen X.,Beijing Jiaotong University | Liu C.-J.,Beijing Jiaotong University | Liu C.-J.,Guangzhou Metro Design and Research Institute Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

The slope failure is a kind of frequently-encountered geotechnical disaster. Many cases of slope failure are induced by the rapid transition between the saturated state and the unsaturated state of soil due to the heavy rainfall or sudden water drawdown. The slope failure induced by these changes can be adequately interpreted by the shear strength theory of unsaturated soil. Three distinct stages are systematically introduced to clearly illustrate the staged development of finite element methods for stability of unsaturated soil slopes, that is, time-independent qualitative analysis, time-dependent analysis with decoupled pore fluid flow and deformation, and fully coupled solid-fluid analysis.

Wang Z.-H.,Guangzhou Metro Design and Research Institute Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

The covering top-down method can be better applied to large urban underground construction in city downtown areas, which is inverse in construction under the covering conditions. The design scheme for deep excavation of Pingleyuan Station of Beijing Metro line No. 14 is introduced. The stress characteristics, selection principles, design points of horizontal and vertical systems of the excavation are discussed. Some key problems are also analyzed. It may provide reference for similar projects.

Zhang Y.-M.,Guangzhou Metro Design and Research Institute Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

According to different surrounding building conditions, the forming process of diaphragm wall trench construction in water-rich sand stratum is analyzed by means of the method of finite element numerical simulation. In the process, the module of simulating mud is used. According to the calculated results, the mutual influence of different buildings and diaphragm wall trench construction is investigated. The effects of reinforcement measures are also analyzed, and the relevant rules are obtained.

Li L.P.,South China University of Technology | Wang L.,Guangzhou Metro Design and Research Institute Co.
Applied Mechanics and Materials | Year: 2014

The tests about elastic properties of a commercial vehicle cab suspension air spring were carried out. And the experimental results show that: the higher the initial pressure of the air bag, the greater its carrying capacity, and the bigger the damping; at the same excitation frequency and the vibration amplitude, the dynamic stiffness of the air spring is gradually increased as the initial pressure is increased; in the low frequency range, at the same vibration amplitude and inside pressure, the dynamic stiffness of the air spring is increased as the increasing of the excitation frequency. © (2014) Trans Tech Publications, Switzerland.

Lin Y.-H.,Guangzhou Metro Design and Research Institute Co.
Journal of Railway Engineering Society | Year: 2013

Research purposes: Taking the tunnel project in the section between the Sajinqiao and North Main Street of the Line 1 of Xi'an metro as an example, in this paper, the numerical analyses are made for the different construction processes by using the MIDAS GTS numerical simulation software to control the ground settlement and deformation and ensure the construction safety when the mine tunneling method is used for the metro interval construction. Thees different construction processes include the construction of no use of the anchor and grouting reinforcement, the construction of no use of the anchor but use of the grouting reinforcement and the construction of use of the anchor and grouting reinforcement. Besides, based on the in-site monitored data, in this paper, the study is done on the regulations of the surrounding rocks' settlement and deformation after the excavation of the large cross-sectional shallow loess tunnel and the analysis is made for the feasibilities of the CRD Method and the corresponding supporting measures. Research conclusions: From the comparison of the numerical simulation results with the in-site monitored data, it is concluded: (1) For the shallow loess tunnel, it is proposed that it is unnecessary to use the arch anchor, and the sidewall anchor should be used according to the actual demand. (2) The grouting reinforcement can effectively control the strata subsidence caused by tunnel excavation for the shallow loess tunnel. (3) This research result can provide the reference the similar projects.

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