Research on the Influence of Vertical Deformation of Bridge on the Track RegularityEI北大核心

Research purposes: The vertical deformation of high-speed railway (HSR) bridge will cause the track irregularity, which threatens the safe and efficient operation of the HSR. Taking the 32 m simple supported beam bridge as the research object, based on the existing mapping analytical model for bridge vertical deformation and rail geometry, the influence of the track regularity of the CRTS Ⅰ slab ballastless track structure caused by the key parameters such as the bridge vertical deformation amplitude, the hanging length of the beam end and the vertical stiffness of mortar layer were studied, and the corresponding measures to control the rail deformation were proposed, to provide theoretical reference for comprehensive treatment of rail deformation of HSR bridge. Research conclusions:(1) The pier settlement, the vertical rotation of the beam end and the beam fault will cause the rail to follow the beam deformation, and "up-warping" of the rail on the vertical deformation boundary will appear. (2) The rail deformation is directly proportional to the vertical deformation amplitude of the bridge and the key to control the rail deformation is to reduce the vertical deformation of the bridge. (3) The rail deformation can be controlled by reducing the hanging length of beam and vertical stiffness of mortar layer. (4) The research results can provide a theoretical reference for controlling the vertical rail deformation of high-speed railway bridges. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

Research on the Mechanical Properties of Transparent Sand Based on Triaxial TestEI北大核心

Research purposes: Transparent sand is a new type of geotechnical engineering material, which is made of fused silica sand and porous liquid with the same refractive index. In order to understand its mechanical properties, the CU and CD tests of fused silica sand with a particle size of 0.5~1.0 mm and 1.0~3.0 mm are carried out by triaxial apparatus, and the stress-strain curves, pore water pressure changes and effective stress ratio of the two are compared and analyzed. In addition, E-μ model parameters of coarse and fine sand are calculated respectively, which provide corresponding parameters for further numerical calculations. Research conclusions:(1) The loose sample's stress-strain curve shows hardening characteristics. (2) The coarse particle specimen with steeper stress-strain curve comes to the peak at faster velocity than fine particle specimen. (3)The pore pressure value of the coarse particle specimen is greater than the fine particle, the pore water pressure coefficient of the two shows a decreasing trend with the increase of the confining pressure. (4) Transparent sand can be used to simulate natural sand and the change of diameter can represent different soils. (5) The research results can provide reference for model tests based on transparent soil technique. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

Research on the CTCS-4 Train Control System Based on Track Circuit Information FusionEI北大核心

Research purposes: CTCS-3 train control system is adopted in Chinese high-speed railway with speed of 300 km/h or higher. It is based on track circuit to check train occupancy and adopt quasi-moving block. In recent years, rapid development of national economy has put forward higher requirements for the capacity of high-speed railway. As a higher level train control system, CTCS-4 train control system can realize virtual block or moving block, and further shorten headway, but it is still in the stage of theoretical research. So this paper aims to analyze the characteristics of high-speed railway, and to propose a scheme for the implementation of CTCS-4 train control system based on track circuit fusion. Research conclusions:(1)When the wireless communication between vehicle and ground is interrupted, transport efficiency of CTCS-4 train control system can not meet the transport demand of high-speed railway.(2)CTCS-4 train control system should have the CTCS-2 backup function, which can make non-communication trains run normally and ensure the transport efficiency.(3)CTCS-4 train control system should integrate track circuit information, which can make RBC obtain position information of non-communication trains, improve the availability of the system and avoid complicated operational rules.(4)Due to complexity of high-speed railway and change of existing equipment, virtual block can be used in early stage of CTCS-4 train control system.(5)The research results can provide some references for CTCS-4 train control system in high-speed railway. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

Research on the high-speed railway catenary systems online real-time testingEI北大核心

Research purposes: Some catenary system vibrated largely after the train since Chinese high-speed railway running, which came from an oral report of one rail worker on duty. Its accurate displacement must be measured in order to solve the problem. The measurement technique based on image has the advantages of non-contact and dynamic which is suitable for unique structure such as catenary system. The computer gets displacement value through analyzing image which may ensure train's safety when on-line test is carrying out. The research not only can be used to analyze the cause of abnormal existing catenary shaking and swaying amplitude, but also can provide the technical support for catenary of electrified railway online real-time test. Research conclusions: (1) The measured amplitude of cantilever, shoulder brace of positive feeder and carrier cable was small relatively and consistent with other normal sections of the whole line. (2) The interaction between catenary and pantograph was the main reason for its vibration, without the coupling effect between up-bound and down-bound. (3) The accurate value of test result indicated that the amplitude of catenary is under the range allowably, which verified the uncertainty of human sense and further clarified the safety hazard. (4) The non-contact measurement technique based on image can get the dynamic real time test data and have simple and convenient operation, which supplies subtle and suitable way for high-speed railway catenary systems real-time on-line test.     

Discussion on the assessment of initial stress field of railway rock massEI北大核心

Research purposes: In actual work, according to the ground stress data for assessment, most railway tunnels are under very high ground stress and high ground stress state, which causes adjustment of surrounding rock and engineering measures to strengthen, thus these will cause large increased investment, even cause large dispute and chaos in analysis causes of tunnel lining cracking and deformation, but the engineering case that rock burst and large deformation occurred in actual excavation of tunnel is very rare. In this paper, according to rock mass mechanical theory, the ground stress information and engineering case, combined the relevant provisions of similar industry, the assessment of initial stress fields of rock mass in railway specification is discussed. Research conclusions: (1) The assessment of railway specification to initial ground stress field is not realistic and should be revised, preliminary judgment when the measured in-situ stress >30 MPa, the possibility of rockburst is increased. (2) Assessment conclusion of initial ground stress field should be discreet, the increased investment should be incorporated into the dynamic design. (3) The stress tests of survey design stage should be reasonable and appropriate. (4) The research results can be applied to the modification of railway norms and tunnel exploration.     

Research on the relationship among subgrade bearing capacity,embankment stability and settlementEI北大核心

Research purposes: In order to ensure the safety of railway or highway subgrade, subgrade bearing capacity, embankment stability and settlement which are the three main control indexes of subgrade design should be analyzed and checked in theory. However, many railway and highway designers still have differences on whether subgrade bearing capacity should be calculated in our country. Through analyzing the relationship among subgrade bearing capacity, embankment stability and settlement, the necessity of checking subgrade bearing capacity is discussed in this paper. Research conclusions: (1) It is unsafe that circular arc method is used to check the embankment stability, in the case that subgrade bearing capacity does not meet the requirements, the conclusion that embankment is stable can be also drawn. (2) The lateral displacement of subgrade will increase sharply when the load approaches or exceeds subgrade ultimate load, and the existing settlement calculation methods are no longer applicable. The application condition of settlement calculation methods is that the requirement of subgrade bearing capacity is met. (3) In order to ensure the stability of the embankment and control the settlement of it, the subgrade bearing capacity should be checked in the design of subgrade. (4) In this paper, the research conclusion can provide a theoretical basis for the further improvement of subgrade design method.     

Research on the thrust output of a long primary double-sided linear induction motorEI北大核心

Research purposes: Based on Maxwell equations and T-type equivalent circuit of linear induction motor, we analyze the electromagnetic thrust output of a double-sided linear induction motor in the case of edge effect, and use the finite element method and simulation to test the effectiveness of the theoretical calculation. We further derivate the mathematical expressions of a double-sided linear induction motor, build the simulation model by parameter design, and experimentally analyze the slip frequency control thrust output in conditions of different operating. Through analysis of the output characteristics of the electromagnetic force, optimal control of constant current slip frequency is achieved. Research conclusions: (1) We calculate various mechanical properties of a bilateral linear induction motor through its mathematical model and equivalent circuit, and derive the corrected coefficients of the horizontal and vertical edge effect. When the motor runs at a high speed, the edge effect has little influence on the output of the electromagnetic force. (2) We use the finite element computer software to establish the simulation model of a bilateral linear induction motor, and compare the theoretical calculation and simulation data: the simulation results are consistent with theoretical calculation, thus ensuring the validity of the mathematical model. (3) We simulate and analyze the influence of slip frequency, speed, suspension air gap, and length of the mover on electromagnetic force. At different speeds, properly adjusting the slip frequency can increase the output of electromagnetic force. For low speed, the optimal slip frequency is near 2 Hz; for high speed, the optimal slip frequency is between 4.0 Hz and 6.0 Hz. When satisfying the motor's rated condition, the optimal control of electromagnetic force is achieved. (4) The research result of double-sided linear induction motor can provide important implications for the electromagnetic launch system of an aircraft carrier.     

Research on the management innovation and practice of construction for Beijing-Shanghai high speed railwayEI北大核心

Construction of Beijing-Shanghai high speed railway is unprecedented great feat. Around the construction goal of "world class", a series innovation and practice measures are taken in the construction ideas, organization and management, technology research, investment financing, quality, safety, investment, construction period, environmental protection, stability, and so on, to lay a solid foundation of completing Beijing-Shanghai high speed railway construction efficiently. In the current new situation of speeding up railway construction, systematically summarizing the results of management innovation and practice for Beijing-Shanghai high speed railway has very important practical significance to improve the level of railway construction project management in our country.     

Research on the Mechanical Characteristics of Primary Supporting in Deep Buried Large-section Red Clay TunnelEI北大核心

Research purposes: In the New Austrian Tunneling Method, the primary supporting has the vital function as the main structure of taking the pressure of surrounding rock. In order to study the force characteristics of primary supporting in the composite lining of deep buried large section tunnel, this paper is based on Qingyang tunnel engineering in Yinchuan-Xi'an High-speed Railway. After the on-site monitoring of the process, we can find the variation law of surrounding rock pressure on the deep buried large section red clay tunnel, steel arch internal force and concrete internal force, and analyze the internal forces and distribution characteristics of the primary supporting structure. Research conclusions:(1) The pressure of surrounding rock on both sides of the large section tunnel of red clay is greater than that in the vault and the inverted arch. (2) The internal force of primary supporting structure shows a distribution pattern of big top and small bottom, and the steel arch bears most of the surrounding rock pressure. (3) It can be considered to increase the marking of steel arch frame on the side wall and vault roof, and reduce the section area of arch frame in inverted arch, so as to make full use of materials, reduce the cost and improve the reliability of lining structure. (4) This research conclusion can provide reference for the optimization of lining design and construction organization of tunnel primary support under similar geological conditions. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

Research on the Design of Career Development Channel for Employees in Large State-owned Construction EnterprisesEI北大核心

Research purposes: From the factors and the principles the enterprise employees' career development design should consider, this paper studied and further discussed channel setting, the division of hierarchy and width, positions or proportional control of all levels, qualification criteria of all levels to determine, career development path management, to solve the problems of the large state-owned construction enterprise, such as narrow development channel, less promotion platform, and insufficient continuous motivation of professionals, technical operators, and general management personnel, resulting in employees no passion, no fighting will, not dedicated, difficult to bring in talents and high attrition rates of talents. Research conclusions:(1) The design of employees' career development should consider four aspects: attractiveness, operability, practicality and pertinence. (2) The design of employees' career development should follow the principles of systematic, overall and long-term development. (3) The design of career development channel should be mainly considered from the aspects of post setting, channel hierarchy and width division, and job qualification criteria. (4) The research results can provide a reference for the design and research of career development channels for employees in state-owned construction enterprises. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

Research on the Influence of Small Distance Subway Tunnel Passing through Buildings at Short DistanceEI北大核心

Research purposes: At present, the urban subway is developing rapidly in our country, among which there are many problems. This paper takes a seven-story frame structure office building as research object. In view of the phenomenon that the dome subsidence and the land subsidence rate exceed the early warning in the field construction of the left line tunnel, combing theoretical analysis with the MIDAS-GTS numerical simulation, we took the "building-stratum-tunnel" as the research object, analyzed the influence of small distance tunnel construction process of mine method on the adjacent buildings, and analyzed the influence difference of the construction sequence of the left and right lines. Finally we put forward the relevant engineering technical measures. Research conclusions:(1) The tunnel construction makes the building in the tensile zone, and the structure is easy to be damaged. When the structure is far away from the influence of the excavation, the order of tunnel excavation is not significant. (2) When the surrounding rock is broken and close to the building, it is better to excavate the tunnel far away from the side of the building. At the same time, we should pay attention to taking the reinforcement measures near the side of the building and the intermediate rock column. (3) The research results can be applied to the field of shield construction in subway, and have a good guiding effect on the shield tunnel passing through buildings at close distance. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

Research on the Cause and Influential Factors of Tunnel Lining Cracking of Side Wall in Seasonally-frozen RegionsEI北大核心

Research purposes: In recent years, tunnel diseases like lining cracking and water leaking during spring thawing period, caused by frost heaving of surrounding rock, have occasionally occurred in high-latitude seasonally-frozen regions of northwest China and northeast China, which has seriously affected the tunnel structure and operation safety. Taking several railway tunnels in northwest China as an example, this paper investigates the cause and main influencing factors of longitudinal cracking of side wall in winter in seasonal frozen soil area by means of field test, laboratory experiment and numerical simulation. Research conclusions:(1) When the water content of surrounding rock of tunnel built in strongly-weathered sandstone is 12.3% and the frozen depth of surrounding rock is up to 60 cm, the maximum tensile stress of side walls is 2.28 MPa, which is larger than the ultimate tensile strength of C30 concrete, then the horizontal lining cracking will appear on side walls under the effect of continuous negative temperature in winter. If the lining bears part of the surrounding rock load, the longitudinal cracking degree of the side wall will increase. (2) Under the effect of frost heaving loads, the cracking of tunnel lining has its own characteristics of symmetry, seasonality and accumulation, etc. The cracks appear in winter and distribute in the middle of side walls. As the temperature is rising, the crack begins to shrink. (3) The frozen circle thickness and water content of surrounding rock should be used as main indicators during the process of calculation of frost heaving loads of surrounding rock in seasonally-frozen regions. (4) The research results can be used for reference in tunnel design, operation and maintenance in seasonal frozen soil area. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

Research on the law and controlled limit value of transverse deformation for shield tunnel in soft clayEI北大核心

Research purposes: The transverse deformation of shield tunnel may deeply threaten the safety of tunnel structure. Excessive deformation may lead segment joints to open and leak and segments to craze. The deformation may even cause insufficient cross-section limit and the missing of structural-load-carrying capacity of the tunnel. On the other hand, it costs a lot to repair and reinforce the shield tunnel. In order to determine the proper moment to repair segments and ensure the safety of tunnel structure as well as economical efficiency, it is necessary to study the deformation law and limit value of the transverse section of the tunnel. Research conclusions: Based on the analysis of the influencing factors to causing the transverse deformation, the following conclusions was proposed: (1) The root of transverst deformation is increase of vertical and horizontal load ratio. (2)The shield tunnel properties of Nanjing Metro Line 2 was adapted to analyze the relationship between the variation of tunnel horizontal diameter andmaximum rate of joint opening, tress rate of both bolt and concrete using numerical simulation, furthermore the controlled limit value of transverse deformationwas got, the bolt tress achieve maximal strength when the variation of tunnel horizontal diameter reach 123 mm for sequential segment seams, and 127 mm for staggeredsegment seams, which means severely threaten to the safety of shield tunnel. Finally the precontrol and governance methodswere delivered to different influencing factors. (3)The research results can provide references to determine the controlling methods and restoration moment of the transverse deformation.     

The Methodology Research on the Test and Evaluation of Static Stiffness of Elastic Pads in Elastic Separated FastenerEI北大核心

Research purposes: In order to explore the reasonable test and evaluation methods of the static stiffness of the elastic pads in elastic separated fastener, the influences of various factors on the static stiffness of the elastic pads were tested and analyzed by single factor test, a reasonable static stiffness test plan for the elastic pads was proposed. Besides, the evaluation suggestions for static stiffness of rail pad and baseplate pad were analyzed in terms of the installation state of the elastic separated fastener. Research conclusions:(1) The test of the static stiffness of elastic pad should include two stages: preloading stage and formal loading stage. Firstly, the elastic pad shall be preloaded with no less than 2 times at a loading rate of 3-5 kN/s, and the preloaded maximum load shall be at least 10 kN higher than the static stiffness test load range of the elastic pad. Then, formal loading is supposed to be carried out at least 3 times with a loading rate of 1~2 kN/s, and at both ends of the load range the load should be maintained for 90 s, which could be shortened to 60 s in special case when the load is less than 100 kN. Finally, the static stiffness of the elastic pad is calculated by the average value of the three test results. (2) The evaluation methods of static stiffness of rail pad and baseplate pad are dissimilar. The static stiffness of the rail pad could be evaluated by the secant stiffness in the range of 20~70 kN, while the evaluation of static stiffness of baseplate pad should be processed in terms of the reasonable static stiffness test load range of baseplate pad determined by the installation torque of anchored bolt. (3) This research results can be applied in the test and evaluation of static stiffness of rail pad and baseplate pad in elastic separated fastener. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

Study on horizontal and vertical temperature gradient of ballastless track on curve lineEI北大核心

Research purposes: In order to get the time-varying rules of temperature field distribution in the track structure with superelevation and build the horizontal and vertical temperature gradient of ballastless track, a continuous observation of CRTS II; by using temperature sensors on curve segment of a passenger dedicated line was held. Research conclusions: (1) The temperature change of ballastless track between daytime and nighttime is big, the temperature changing value of surface was 24.7℃ in maximum, 19℃ in average. (2) The temperature changing value became small and the time of maximum temperature come late with the increase of distance to surface. (3) At the bottom of the track structure, the temperature changing value was 6.1℃ in maximum, 5.0℃ in average. (4) Fitting curve of vertical temperature gradient of longitudinally connected ballastless track on curve line can be exponential curve, and the curve sharp can match the distribution about the vertical temperature gradient of the code for design of bridge and culvert in China. (5) The horizontal temperature gradient of the CRTS II; longitudinally connected ballastless track included the track slab and support layer, temperature gradient of track slab could be fitted by using quadratic function, temperature gradient of support layer could be fitted by using piecewise linear function. (6) This study can provide guidance for the temperature load model in the design of high speed railway in central China.     

Research on minimum headway between EMU and common passenger train on passenger dedicated lineEI北大核心

Research purposes: The minimum headway of trains is an important technical standard in the railway survey and design. The common passenger train running on passenger dedicated line (PDL) has big influence on the headway between trains. This paper mainly analyzes the type of coach, passenger train composition and train operation control system, and presents the calculation method and model for the headway between the EMU and common passenger train for providing the reference to the survey and design of passenger dedicated line. Research conclusions: Based on the technologies of the train control system level 2 (CTCS-2), the train running monitor and record device (LKJ) and the ground signals, the analyses and calculations were made for the minimum headways between trains into the Yuncheng North Station of Datong-Xi'an PDL by using the calculation model. The calculations show the 3 minutes headway of the arrival-running through, the 3 minutes headway of the arrival-arrival and the 3 minutes headway of the running through-departure between the common passenger train and the EMU can be realized. And the 5 minutes headway of the departure-departure between the EMU and the common passenger train can be realized.     

ces for the Cenozoic evoluti

day. Base on the new field works in Shuanghu and Tuotuohe regions of central Tibet by us and the datum have been obtained by other researches on the grabens. We proposed that, the graben structures are distributed in the most part of plateau; including Himalayan, Gangdese and Qian     

Discussion on retaining structure limit state classificationEI北大核心

Research purposes: Retaining structure belongs to the geotechnical engineering structure, the limit state classification of geotechnical engineering is more difficult than the structure projects. Based on the limit state concept at home and abroad, this paper makes a comparison and analysis of the common and difference of geotechnical engineering and structural engineering limit state, teases the retaining structure limit state and focuses on limit state of open-cut foundation and pile foundation, proposes the recommendation of limit state classification of retaining structure. Research conclusions: (1) The generalized limit state can be considered as a function which can achieve the expected requirements, the limit state is not limited to the concept of damage and failure, and its extension has been expanded to the requirements of that the goal of expected design cannot be achieved-a prescribed limit. (2) Retaining structure belongs to the category of geotechnical engineering, its limit state includes structure overall stability limit states and the structural stability limit state which includes the bearing capacity limit state and serviceability limit state and limit state between them, the state needs to be studied further. (3) In general area, the compressive stress limit state of open-cut foundation and lateral pressure limit state of rock foundation anchor pile foundation can be considered as the serviceability limit state. (4) The research conclusion is useful for guiding the design research of retaining structure limit state.     

Test Analysis of the Vibration Response of Trough Girder Bridge in the Small Radius CurveEI北大核心

Research purposes: The bridge in circinate line of Hefei Railway Hub was built in the curve with radius of 300 m. In order to reduce structural height of the bridge across the Huainan railway, the single-line simple trough girder bridge with 32 m span was applied. The lateral vibration of the vehicle and bridge is intensified under the action of centrifugal force, and the torsion effect is obvious when the train running on the bridge in the small radius curve. On the other hand, the torsional rigidity of the trough girder with open section is lower than that of the closed box girder. Moreover, the wheel lateral force and the derailment coefficient is increased, and the reduction rate of wheel load is also increased owing to centrifugal force caused by unbalanced superelevation. In order to ensure the safe and smooth operation of the train and reveal the dynamic performance of the trough girder bridge in the small radius curve, the vibration response of the single-line trough girder bridge is tested and analyzed. Research conclusions:(1) The measured vertical and horizontal fundamental frequencies of the trough girder bridge are obviously larger than the vertical self-vibration frequency limit given by the relevant specification and the normal value of the measured transverse minimum natural vibration frequency. The lateral stiffness of the bridge is mainly controlled by its foundation stiffness. (2) The stiffness of the bridge can meet the requirements of C62 freight train safe running on the trough girder bridge in the curve with radius of 300 m at a speed of not more than 40 km/h. (3) The transverse vibration response of the bridge consists of the transverse static response of the structure caused by the centrifugal force and the lateral dynamic response caused by the coupling vibration of the vehicle-bridge system. (4) The research results can be referenced in the design of the railway bridge in the curve and coupled vibration analysis of trains and bridge in the small radius curve. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

Study on Process Re-engineering,ProjectPlanand Process Integration in Electric-Mechanical Product Development Process

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