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Investigation of cracking mechanism of the first tunnel lining during double-arch tunnel construction

Underground Space 2024年第1期14卷 1-17页

作者： Yi Sui Xiaohui Cheng Zuozhou Zhao Weibin Ma railway engineering research institute China Academy of Railway Sciences Corporation LimitedBeijing 100081China School of Civil engineering Tsinghua UniversityBeijing 100084China

To solve the engineering problem of the first tunnel lining cracking caused by the second tunnel construction of double-arch highway tunnels,a research method combining distributed optical-fibre monitoring,inversion analysis and numerical simulation that can reflect lining cracking was *** fibres were laid on opposite sides of the steel arches inside the first tunnel *** optical-fibre monitoring was conducted continuously during the second tunnel *** on the fibre-optic strain profile,the lining cracking was deduced and warned in *** mechanical behaviour of the steel arch was investigated by the inversion analysis,which took into consideration the integrated impact of axial force and flexural moment.A two-dimensional(2D)load-structure method–based numerical model was established,considering the influence of different load distributions in each construction *** total strain rotating crack constitutive model was applied to reflect the cracking behaviour of concrete lining in the simulation,and the model was calibrated and verified in the *** analysis between the simulated strain distribution and the distributed optical-fibre monitoring results was carried *** deformation mode and crack distribution of the lining were *** cracking mechanism was ***,the second tunnel construction led to the loading at the top of the middle partition wall and the release of rock pressure in the first *** these load changes,the secondary lining of the first tunnel cracked on the inner side of the top of the middle partition wall owing to tension,and compression-bending failure occurred near the right arch ***,the influence of the parameters on the lining force was analysed,and a construction optimisation scheme was proposed.

关键词： Double-arch tunnel Cracking mechanism Distributed optical-fibre sensing Inversion analysis Total strain rotating crack model Loadstructure method

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Damage Evolution of Ballastless Track Concrete Exposed to Flexural Fatigue Loads:The Application of Ultrasonic Pulse Velocity,Impact-echo and Surface Electrical Resistance Method

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Journal of Wuhan University of Technology(Materials Science) 2024年第2期39卷 353-363页

作者：杨志强李化建 WEN Jiaxing DONG Haoliang HUANG Fali WANG Zhen YI Zhonglai railway engineering research institute China Academy of Railway Science Corporation LimitedBeijing 100081China State Key Laboratory for Track System of High-Speed railway Beijing 100081China School of Civil engineering Beijing Jiaotong UniversityBeijing 100044China

In order to clarify the fatigue damage evolution of concrete exposed to flexural fatigue loads,ultrasonic pulse velocity(UPV),impact-echo technology and surface electrical resistance(SR) method were *** variable based on the change of velocity of ultrasonic pulse(Du) and impact elastic wave(Di)were defined according to the classical damage *** influences of stress level,loading frequency and concrete strength on damage variable were *** experimental results show that Du and Di both present a three-stages trend for concrete exposed to fatigue *** impact elastic wave is more sensitive to the microstructure damage in stage Ⅲ,the critical damage variable,i e,the damage variable before the final fracture of concrete of Di is slightly higher than that of ***,the evolution of SR of concrete exposed to fatigue loads were analyzed and the relationship between SR and Du,SR and Di of concrete exposed to fatigue loads were *** is found that the SR of concrete was decreased with the increasing fatigue cycles,indicating that surface electrical resistance method can also be applied to describe the damage of ballastless track concrete exposed to fatigue loads.

关键词： ballastless track fatigue damage ultrasonic pulse velocity impact-echo surface electrical resistance

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The effect of friction block hole configurations on the brake tribological performance of high-speed trains

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Friction 2024年第10期12卷 2241-2258页

作者： Yuanke WU Wei CHEN Youguang ZHU Zaiyu XIANG Honghua QIAN Jiliang MO Zhongrong ZHOU Tribology research institute School of Mechanical EngineeringSouthwest Jiaotong UniversityChengdu 610031China China railway engineering Equipment Group Co. Ltd.Zhengzhou 450016China

Three triangular friction block configurations are commonly employed in high-speed train brake systems,namely,unperforated,perforated configuration with one circular hole,and perforated with three circular *** this study,we adopted these friction block types to investigate the effect of perforated friction block configurations on the brake performance of high-speed trains based on a self-developed brake test *** results indicate the significant impact of the number of the holes on the wear behavior,temperature distribution,and vibration characteristics of the brake *** friction surface of the unperforated block is covered by wear debris,while the perforated blocks produce less wear ***,the one-hole block exhibits a more uniform temperature distribution and better vibration behavior than that with three *** friction brake is a dynamic process,during which separation and attachment between the pad and disc alternatively occur,and the perforated structure on the friction block can both trap and expel the wear debris.

关键词： high-speed train block brake performance wear debris flow

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Computer vision-aided DEM study on the compaction characteristics of graded subgrade filler considering realistic coarse particle shapes

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railway engineering Science 2024年第2期32卷 194-210页

作者： Taifeng Li Kang Xie Xiaobin Chen Zhixing Deng Qian Su railway engineering research institute China Academy of Railway Sciences Corporation LimitedBeijing 100081China Department of Civil engineering Central South UniversityChangsha 410075China School of Civil engineering Southwest Jiaotong UniversityChengdu 610031China

The compaction quality of subgrade filler strongly affects subgrade *** main objective of this research is to analyze the macro-and micro-mechanical compaction characteristics of subgrade filler based on the real shape of coarse ***,an improved Viola-Jones algorithm is employed to establish a digitalized 2D particle database for coarse particle shape evaluation and discrete modeling purposes of subgrade *** indexes of 2D subgrade filler are then computed and statistically ***,numerical simulations are performed to quantitatively investigate the effects of the aspect ratio(AR)and interparticle friction coefficient(μ)on the macro-and micro-mechanical compaction characteristics of subgrade filler based on the discrete element method(DEM).The results show that with the increasing AR,the coarse particles are narrower,leading to the increasing movement of fine particles during compaction,which indicates that it is difficult for slender coarse particles to inhibit the migration of fine ***,the average displacement of particles is strongly influenced by the AR,indicating that their occlusion under power relies on particle *** dis-placement and velocity of fine particles are much greater than those of the coarse particles,which shows that compaction is primarily a migration of fine *** the cyclic load,the interparticle friction coefficientμhas little effect on the internal structure of the sample;under the quasi-static loads,however,the increase inμwill lead to a significant increase in the porosity of the *** study could not only provide a novel approach to investigate the compaction mechanism but also establish a new theoretical basis for the evaluation of intelligent subgrade compaction.

关键词： Subgrade filler particles Deep learning particle Shape analysis Particle library Compaction characteristics Discrete element method(DEM)

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Dynamic response and failure process of horizontal-layered fractured structure rock slope under strong earthquake

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Journal of Mountain Science 2024年第3期21卷 882-900页

作者： WANG Tong LIU Xianfeng HOU Zhaoxu XU Jiahang ZHANG Jun YUAN Shengyang JIANG Guanlu HU Jinshan School of Civil engineering Southwest Jiaotong UniversityChengdu 610031China Key Laboratory of High-Speed railway engineering of Ministry of Education Southwest Jiaotong UniversityChengdu 610031China School of Civil engineering Xinjiang Institute of EngineeringUrumqi 830023China China railway First Survey and Design institute Group Co.LTD Xi'an 710043China

Rock slope with horizontal-layered fractured structure(HLFS)has high stability in its natural ***,a strong earthquake can induce rock fissure expansion,ultimately leading to slope *** this study,the dynamic response,failure mode,and spectral characteristics of rock slope with HLFS under strong earthquake conditions were investigated based on the large-scale shaking table model *** this basis,multiple sets of numerical calculation models were further established by UDEC discrete element *** influencing factors were considered in the parametric study of numerical simulations,including slope height,slope angle,bedding-plane spacing and secondary joint spacing as well as bedrock dip *** results showed that the failure process of rock slope with HLFS under earthquake action is mainly divided into four phases,i.e.,the tensile crack of the slope shoulder joints and shear dislocation at the top bedding plane,the extension of vertical joint cracks and increase of shear displacement,the formation of step-through sliding surfaces and the instability,and finally collapse of fractured rock *** acceleration response of slopes exhibits elevation amplification effect and surface *** simulations indicate that the seismic stability of slopes with HLFS exhibits a negative correlation with slope height and angle,but a positive correlation with bedding-plane spacing,joint spacing,and bedrock dip *** results of this study can provide a reference for seismic stability evaluation of weathered rock slopes.

关键词： Seismic behavior Horizontal layered Weathered rock slope Shaking table test Failure mode

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Experimental and Numerical Investigation on the Aerodynamic Characteristics of High-Speed Pantographs with Supporting Beam Wind Deflectors

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Fluid Dynamics & Materials Processing 2024年第1期20卷 127-145页

作者： Shiyang Song Tongxin Han Postgraduate Department China Academy of Railway SciencesBeijing100081China Locomotive&Car research institute China Academy of Railway Sciences Corporation LimitedBeijing100081China

Aiming to mitigate the aerodynamic lift force imbalance between pantograph strips,which exacerbates wear and affects the current collection performance of the pantograph-catenary system,a study has been conducted to support the beam deflector optimization using a combination of experimental measurements and computational fluid dynamics(CFD)*** results demonstrate that the size,position,and installation orientation of the wind deflectors significantly influence the amount of force *** also indicate that the front strip deflectors should be installed downwards and the rear strip deflectors upwards,thereby forming a“π”***,the lift force compensation provided by the wind deflectors increases with the size of the *** wind compensation strategies,such as control circuits,are also discussed,putting emphasis on the pros and cons of various pantograph types and wind compensation approaches.

关键词： High-speed pantograph aerodynamic lift force supporting beam wind deflectors computational fluid dynamics(CFD)

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Effect of Lightweight Aggregates Incorporation on the Mechanical Properties and Shrinkage Compensation of a Cement-Ground Granulated Blast Furnace Slag-Phosphogypsum Ternary System

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Fluid Dynamics & Materials Processing 2024年第8期20卷 1773-1784页

作者： Yu Wang Mengyang Ma Yong Long Qingxiang Zhao Zhifei Cheng State Key Laboratory of Bridge Intelligent and Green Construction China Railway Major Bridge Engineering Group Co.Ltd.Wuhan430034China China railway Bridge Science research institute. Ltd.Wuhan430034China

Shrinkage-induced cracking is a common issue in concrete structures,where the formation of cracks not only affects the aesthetic appearance of concrete but also potentially reduces its durability and *** this study,the effect of ceramsite sand addition on the properties of a ternary system of cement-ground granulated blast furnace slag(GGBFS)-phosphogypsum(PG)is *** particular,the fluidity,rheology,hydration heat,compressive strength,autogenous shrinkage,and drying shrinkage of the considered mortar specimens are *** results indicate that an increase in PG content leads to a decrease in fluidity,higher viscosity,lower exothermic peak,and lower compressive ***,the shrinkage of the mortar specimens is effectively *** incorporation of internal curing water from ceramsite sand improves fluidity,decreases both yield stress and viscosity,enhances the degree of hydration,and induces mortar ***,the inferior mechanical properties of the ceramsite sand generally produce a decrease in the compressive strength.

关键词： Phosphogypsum ceramsite sand internal curing mechanical property shrinkage

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The Investigation of Data Voting Algorithm for Train Air-Braking System Based on Multi-Classification SVM and ANFIS

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Chinese Journal of Electronics 2024年第1期33卷 274-281页

作者： Juhan WANG Ying GAO Yuan CAO Tao TANG School of Electronics and Information engineering Beijing Jiaotong University Graduate Department China Academy of Railway Science National engineering research Center of Rail Transportation Operation and Control System Beijing Jiaotong University

The pressure data of the train air braking system is of great significance to accurately evaluate its operation state. In order to overcome the influence of sensor fault on the pressure data of train air braking system, it is necessary to design a set of sensor fault-tolerant voting mechanism to ensure that in the case of a pressure sensor fault, the system can accurately identify and locate the position of the faulty sensor, and estimate the fault data according to other normal data. A fault-tolerant mechanism based on multi-classification support vector machine(SVM) and adaptive network-based fuzzy inference system(ANFIS) is introduced. Multi-classification SVM is used to identify and locate the system fault state, and ANFIS is used to estimate the real data of the fault sensor. After estimation, the system will compare the real data of the fault sensor with the ANFIS estimated data. If it is similar,the system will recognize that there is a false alarm and record it. Then the paper tests the whole mechanism based on the real data. The test shows that the system can identify the fault samples and reduce the occurrence of false alarms.

关键词： Support vector machines Fault diagnosis Pressure sensors Fuzzy logic Fault tolerance Adaptive systems Fault tolerant systems

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Artificial-intelligent-powered safety and efficiency improvement for controlling and scheduling in integrated railway systems

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High-Speed railway 2024年第3期2卷 172-179页

作者： Jun Liu Gehui Liu Yu Wang Wanqiu Zhang Beijing National railway research&Design institute of Signal&Communication Group Co.Ltd. Beijing 100070China engineering research Center of railway Industry of Intelligent and Autonomous Train Control Beijing 100070China

The multi-mode integrated railway system,anchored by the high-speed railway,caters to the diverse travel requirements both within and between cities,offering safe,comfortable,punctual,and eco-friendly transportation *** the expansion of the railway networks,enhancing the efficiency and safety of the comprehensive system has become a crucial issue in the advanced development of railway *** light of the prevailing application of artificial intelligence technologies within railway systems,this study leverages large model technology characterized by robust learning capabilities,efficient associative abilities,and linkage analysis to propose an Artificial-intelligent(AI)-powered railway control and dispatching *** system is elaborately designed with four core functions,including global optimum unattended dispatching,synergetic transportation in multiple modes,high-speed automatic control,and precise maintenance decision and *** deployment pathway and essential tasks of the system are further delineated,alongside the challenges and obstacles *** AI-powered system promises a significant enhancement in the operational efficiency and safety of the composite railway system,ensuring a more effective alignment between transportation services and passenger demands.

关键词： High-speed railway Multi-mode railway system Artificial intelligence Large-scale mode,system framework Safety and efficiency improvement

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An alternative approach to improve the compatibility of PCE in cement paste blend with coal gangue powder

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Waste Disposal and Sustainable Energy 2024年第1期6卷 139-150页

作者： Zonglin Xie Yuxuan Li Dahui Sun Yi Tian Jinyuan Hu Qiang Yuan Zheng Chen School of Civil engineering Central South UniversityChangshaChina China railway NO.9 Group CO. LTDShenyangChina National engineering research Center for High-Speed railway Construction Technology ChangshaChina Guangxi Key Laboratory of Disaster Prevention and engineering Safety Guangxi UniversityNanningChina

Coal gangue(CG)is an environmental waste that faces an urgent demand for disposal in *** utilization of CG in construction materials has broad application prospects and gained increasing ***,the poor compatibility of polycarboxylate superplasticizer(PCE)with CG powder hinders its efficiency in a wide range of ***,this paper attempts to improve the compatibility of PCE with CG powder in cement paste based on the regulation of aggregation and the adsorption behavior of *** light scattering(DLS)and fluorescence spectroscopy tests were carried out to understand the improved *** results indicated that the addition of CG powder increases the ionic strengths of the cement liquid phase,which makes PCE tend to aggregate at a lower concentration compared with no CG powder ***(CH_(3)COO)_(2)Cu is beneficial for enhancing the workability of cement paste by reducing PCE aggregation while maintaining the compressive strength of cement ***,(CH_(3)COO)_(2)Cu extra addition can be regarded as an effective and sustainable way to improve the workability of cement paste with CG powder.

关键词： Coal gangue powder Polycarboxylate superplasticizer Compatibility Aggregation

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