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full-scale multi-functional test platform for investigating mechanical performance of track–subgrade systems of high-speed railways

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Railway Engineering Science 2020年第3期28卷 213-231页

作者： Wanming Zhai Kaiyun Wang Zhaowei Chen Shengyang Zhu Chengbiao Cai Gang Liu Train and Track Research Institute State Key Laboratory of Traction PowerSouthwest Jiaotong UniversityChengdu 610031China MOE Key Laboratory of High-speed Railway Engineering Southwest Jiaotong UniversityChengdu 610031China

Motivated by the huge practical engineering demand for the fundamental understanding of mechanical characteristics of high-speed railway infrastructure,a fullscale multi-functional test platform for high-speed railway track–subgrade system is developed in this paper,and its main functions for investigating the mechanical performance of track–subgrade systems are elaborated with three typical experimental examples.Comprising the full-scale subgrade structure and all the five types of track structures adopted in Chinese high-speed railways,namely the CRTS I,the CRTS II and the CRTS III ballastless tracks,the double-block ballastless track and the ballasted track,the test platform is established strictly according to the construction standard of Chinese high-speed railways.Three kinds of effective loading methods are employed,including the real bogie loading,multi-point loading and the impact loading.Various types of sensors are adopted in different components of the five types of track–subgrade systems to measure the displacement,acceleration,pressure,structural strain and deformation,etc.Utilizing this test platform,both dynamic characteristics and long-term performance evolution of high-speed railway track–subgrade systems can be investigated,being able to satisfy the actual demand for large-scale operation of Chinese high-speed railways.As examples,three typical experimental studies are presented to elucidate the comprehensive functionalities of the full-scale multi-functional test platform for exploring the dynamic performance and its long-term evolution of ballastless track systems and for studying the long-term accumulative settlement of the ballasted track–subgrade system in high-speed railways.Some interesting phenomena and meaningful results are captured by the developed test platform,which provide a useful guidance for the scientific operation and maintenance of high-speed railway infrastructure.

关键词： Full-scale test High-speed railway Track–subgrade system Ballastless track Ballasted track Mechanical performance Long-term performance evolution Damage and degradation

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Mechanical performances of shield tunnel segments under asymmetric unloading induced by pit excavation

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第6期15卷 1547-1564页

作者： Gang Wei Feifan Feng Chengbao Hu Jiaxuan Zhu Xiao Wang Department of Civil Engineering Hangzhou City UniversityHangzhou310015China Key Laboratory of Safe Construction and Intelligent Maintenance for Urban Shield Tunnels of Zhejiang Province Hangzhou310015China Zhejiang Engineering Research Center of Intelligent Urban Infrastructure Hangzhou310015China College of Civil Engineering and Architecture Zhejiang UniversityHangzhou310058China

To explore the stress and deformation responses,as well as the failure characteristics of the shield tunnel segment of Hangzhou Metro under the influences of pit excavation and other surrounding projects,a self-developed“shield tunnel segment hydraulic loading system”was used to carry out full-scale loading tests on the three-ring staggered assembled segments.The structural performances and failure process of the tunnel segment under step-by-step asymmetric unloading were studied.A safety index was proposed to describe the bearing capacity of the segment.Next,a finite element model(FEM)was established to analyze the bearing capacity of segment using the test results.Finally,the effect of reinforcement with a steel plate on the deformation and bearing capacity of the segment was analyzed.The results showed that under asymmetric unloading,the peak value and amplitude of the bending moment on the near unloading side converged with a greater value than those on the far side.The concrete internal force exhibited a directional transformation at different load stages.Cracks first appeared at the 180inner arc surface of the bottom standard block and then expanded to both sides,while the rate of crack propagation of the outer arc surface was relatively lower.The bearing capacity of the segments can be evaluated by the combination of the factors,e.***.the residual bearing capacity coefficient,moment transfer coefficient,and characterization coefficient.The segments approaching failure can facilitate the increase in the residual bearing capacity coefficient by more than 50%.This can provide guidance for the service assessment of metro tunnel operations.

关键词： Shield tunnel segment Full-scale test Asymmetric unloading Stress and deformation Safety index

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Numerical analysis of tunnel segments strengthened by steel-concrete composites

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Underground Space 2022年第6期7卷 1115-1124页

作者： Jiao-Long Zhang Xian Liu Tian-Yu Ren Yi-Ming Shi Yong Yuan Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China China Railway Design Corporation Tianjin 3000142China

In order to study the feasibility of strengthening of segmental tunnel linings by using steel-concrete composites(SCC),a three-dimensional(3D)finite element(FE)model is proposed in this paper.The nonlinear mechanical behavior of concrete is described by a plastic-damage model.The nonlinearity,resulting from the interface of the SCC and reinforced concrete(RC)segments,is simulated with the help of a system of springs.The analysis results are compared with those obtained from a Full-scale test of a tunnel segment.Their agreement validates the usefulness of the 3D FE model.Numerical re-analysis of the test shows that the interfacial connectors govern both the strengthening effect of SCC and the failure pattern of the strengthened segments.Thus,the force-transmitting capacity of the interfacial connectors should be concerned in design activities.As regards the circular segments,the interfacial connectors refer to both the shearing and the stripping connectors.The composite effect of the SCC and RC segments increases with the increasing number of these connectors.The latter,therefore,results in the increases of the bearing capacities and stiffnesses of the strengthened segments.Those increases become insignificant as the number of these connectors is sufficient to ensure a perfect composite effect of the SCC and RC segments.In addition,the numerical simulations show that using high-performance steel shell(HPS)or/and ultra-high-performance concrete(UHPC)is an effective way to increase the strengthening effect of SCCs.

关键词： Nonlinear analysis Concrete structures Composite structures Shield tunnels Full-scale test

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STRENGTH DESIGN OF PREMIUM THREADED CASING CONNECTION

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Chinese Journal of Mechanical Engineering 2004年第1期17卷 110-113页

作者： GaoLianxin JinYe ZhangYi SchoolofMechanicalEngineering ShanghaiJiaotongUniversityShanghai200030China SteelTubeBranchCo ShanghaiBaosteelGroupCorporationShanghai201900China

Using premium casing connections instead of API ones is one of the mosteffective technique to prevent casing failure. The factors contribute to the strength of premiumcasing connections are studied with FEA and Full-scale test. The criterions are presented thatensure the connection's strength higher than the pipe. At the same time, the method is given todecrease the peak stress of the connection so as to improve its anticorruption property. At last,Full-scale tests are done to test the strength of the connections designed with the methoddescribed, the results show that the connection's strength is higher than the pipe. This indicatedthat the method described is effective in designing premium casing connection.

关键词： Casing connection Premium thread Connecting strength Finite elementmethod Full-scale test

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