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Accumulative deformation in railway track induced by high-speed traffic loading of the trains

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Earthquake Engineering and Engineering Vibration 2010年第3期9卷 319-326页

作者： bian xuecheng Jiang Hongguang Chen Yunmin Department of Civil Engineering MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Zhejiang University Hangzhou 310058 China

Prediction and control of the permanent settlement of a track caused by traffic loading from trains is crucial to high-speed railway design and maintenance. In this study, a unified prediction model of accumulative deformation of geomaterials used in railway construction subjected to cyclic loadings is introduced and calibrated using physical model testing. Based on this versatile model, a calculation approach to determine the track structure settlement under repeated loadings caused by the movement of the wheel axle of the train is proposed. Regression analysis on the physical model testing is adopted to determine the parameters involved in the computational approach. Comparison of model test data and computed results shows that the parameters obtained from the back-analysis are consistent throughout the various testing conditions, and the proposed calculation approach is capable of satisfactorily predicting the accumulative settlement of the railway roadbed and subgrade soil for various axle loads and loading cycles. A case study of a high-speed railway is performed to demonstrate the feasibility of the proposed approach in realistic engineering applications. The computation results from the settlement development of a roadbed and subgrade soil are presented and discussed.

关键词： cyclic loading aggregate clay accumulative settlement high-speed railway

Numerical simulation of high-speed train induced ground vibrations using 2.5D finite element approach

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Science China(Physics,Mechanics & Astronomy) 2008年第6期51卷 632-650页

作者： bian xuecheng CHEN YunMin HU Ting Department of Civil Engineering Zhejiang UniversityHangzhou 310027China

An efficient 2.5D finite element numerical modeling approach was developed to simulate wave motions generated in ground by high-speed train passages. Fourier transform with respect to the coordinate in the track direction was applied to re-ducing the three-dimensional dynamic problem to a plane strain problem which has been solved in a section perpendicular to the track direction. In this study, the track structure and supporting ballast layer were simplified as a composite Euler beam resting on the ground surface, while the ground with complicated geometry and physical properties was modeled by 2.5D quadrilateral elements. Wave dissipation into the far field was dealt with the transmitting boundary constructed with fre-quency-dependent dashpots. Three-dimensional responses of track structure and ground were obtained from the wavenumber expansion in the track direction. The simulated wave motions in ground were interpreted for train moving loads traveling at speeds below or above the critical velocity of a specific track-ground system. It is found that, in the soft ground area, the high-speed train operations can enter the transonic range, which can lead to resonances of the track structure and the sup-porting ground. The strong vibration will endanger the safe operations of high-speed train and accelerate the deterioration of railway structure.

关键词： high-speed train moving load ground vibration 2.5D finite element absorbing boundary

Mud pumping in high‑speed railway:in‑situ soil core test and full‑scale model testing

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Railway Engineering Science 2022年第3期30卷 289-303页

作者： Zhangbo Wan xuecheng bian Yunmin Chen Key Laboratory of Soft Soils and Geoenvironmental Engineering MOEDepartment of Civil EngineeringZhejiang UniversityHangzhou 310058People’s Republic of China Center for Hypergravity Experimental and Interdisciplinary Research Zhejiang UniversityHangzhou 310058People’s Republic of China

Mud pumping induced by moving train loads on rainwater-intruded roadbed causes intensive track vibrations and threatens safety of high-speed *** this paper,a vehicle–track–subgrade finite element model was established to analyze the dynamic responses of a ballastless track,and results showed that the concrete base and roadbed were detached because of the whipping effect arising from the rainwater intrusion *** in-situ soil core test showed that the intruded rainwater accumulated in roadbed to form standing water and saturated the *** flapping action of the concrete base caused by the whipping effect led to mud formation mixed with fine particles and rainwater,which migrated upward under the pore-water pressure(PWP)*** pumping resulted from continuous particle migration in the saturated roadbed under moving train loads:under normal roadbed condition,coarse and fine particles were uniformly distributed in the roadbed;in early period of mud pumping,fine particles migrated downward to bottom of the roadbed because of the rainwater infiltration flow;in middle stage of mud pumping,fine particles migrated upward and gathered at the roadbed surface under PWP gradient;in later period of mud pumping,fine particles were entrained and removed with the dissipation of excess ***,a full-scale physical model was established to reproduce mud pumping,and polyurethane injection remediation against mud pumping was validated on this physical *** remediation method was applied to an in-situ mud *** deviation of the vertical track profile reduced remarkably and remained at a low level within half a year,showing a good long-term service performance of the polyurethane remediated roadbed.

关键词： Ballastless track Mud pumping Rainwater intrusion Particle migration Polyurethane injection

Image-Aided Analysis of Ballast Particle Movement Along a High-Speed Railway

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Engineering 2023年第8期27卷 161-177页

作者： xuecheng bian Wenqing Cai Zheng Luo Chuang Zhao Yunmin Chen Key Laboratory of Soft Soils and Geoenvironmental Engineering Ministry of EducationDepartment of Civil EngineeringZhejiang UniversityHangzhou 310058China Center for Hypergravity Experimental and Interdisciplinary Research Zhejiang UniversityHangzhou 310058China

As a core infrastructure of high-speed railways,ballast layers constituted by graded crushed stones feature noteworthy particle movement compared with normal railways,which may cause excessive settlement and have detrimental effects on train ***,the movement behavior remains ambiguous due to a lack of effective measurement approaches and analytical *** this study,an image-aided technique was developed in a full-scale model test using digital cameras and a colorbased identification approach.A total of 1274 surface ballast particles were manually dyed by discernible colors to serve as tracers in the *** movements of the surface ballast particles were tracked using the varied pixels displaying tracers in the photos that were intermittently taken during the test in the perpendicular *** movement behavior of ballast particles under different combinations of train speeds and axle loads was quantitatively *** obtained results indicated that the surface ballast particle movements were slight,mainly concentrated near sleepers under low-speed train loads and greatly amplified and extended to the whole surface when the train speed reached 360 ***,the development of ballast particle displacement statistically resembled its *** vibration contributed to the movements of ballast particles,which specifically were driven by vertical acceleration near the track center and horizontal acceleration at the track ***,the development trends of ballast particle movements and track settlement under long-term train loading were similar,and both stabilized at nearly the same *** track performance,including the vibration characteristics,accumulated settlement,and sleeper support stiffness,was determined to be closely related to the direction and distribution of ballast particle flow,which partly deteriorated under high-speed train loads.

关键词： High-speed railway Full-scale model test Image-aided technique Ballast particle movement Track vibration Accumulated settlement

A substructure approach for analyzing pile foundation and soil vibrations due to train running over viaduct and its validation

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Railway Engineering Science 2022年第4期30卷 468-481页

作者： Ying Wu xuecheng bian Chong Cheng Jianqun Jiang Department of Civil Engineering MOE Key Laboratory of Soft Soils and Geoenvironmental EngineeringZhejiang UniversityAnzhong Building of Civil Engineering B406Zijingang CampusHangzhou 310058China

An efficient computational approach based on substructure methodology is proposed to analyze the viaduct-pile foundation-soil dynamic interaction under train ***-viaductsubsystemissolvedusingthe dynamic stiffness integration method,and its accuracy is verified by the existing analytical solution for a moving vehicle on a simply supported *** the pile foundation-soil subsystem,the geometric and material properties of piles and soils are assumed to be invariable along the azimuth *** introducing the equivalent stiffness of grouped piles,the governing equations of pile foundation-soil interaction are simplified based on Fourier decomposition method,so the three-dimensional problem is decomposedintoseveraltwo-dimensionalaxisymmetricfinite element *** pile foundation-soil interaction model is verified by field measurements due to shaker loading at pile foundation *** addition,these two substructures are coupled with the displacement compatibility condition at interface of pier bottom and pile foundation ***,the proposed train-viaduct-pile foundation-soil interaction model was validated by field *** results show that the proposed model can predict vibrations of pile foundation and soil accurately,thereby providing a basis for the prediction of pile-soil foundation *** frequency spectra of the vibration in Beijing-Tianjin high-speed railway demonstrated that the main frequencies of the pier top and ground surface are below 100 and 30 Hz,respectively.

关键词： Train moving load Viaduct Pile foundation Soil Vibration Substructure method

Soil disturbance evaluation of soft clay based on stress-normalized smallstrain stiffness

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 990-999页

作者： Yanguo Zhou Yu Tian Junneng Ye xuecheng bian Yunmin Chen MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Institute of Geotechnical EngineeringCenter for Hypergravity Experiment and Interdisciplinary ResearchZhejiang UniversityHangzhou310058China Ningbo Rail Transit Group Co. Ltd.Ningbo315010China

Soil disturbance includes the change of stress state and the damage of soil *** field testing indices reflect the combined effect of both changes and it is difficult to identify the soil structure disturbance directly from these *** the present study,the small-strain shear modulus is used to characterize soil structure disturbance by normalizing the effective stress and void ratio based on Hardin *** procedure for evaluating soil sampling disturbance in the field and the further disturbance during the subsequent consolidation process in laboratory test is proposed,and then validated by a case study of soft clay *** seismic testing in the field,portable piezoelectric bender elements for the drilled sample and bender elements in triaxial apparatus for the consolidated sample were used to monitor the shear wave velocity of the soil from intact to disturbed and even remolded *** is found that soil sampling disturbance degree by conventional thin-wall sampler is about 30%according to the proposed procedure,which is slightly higher than that from the modified volume compression method proposed by Hong and Onitsuka(1998).And the additional soil disturbance induced by consolidation in laboratory could reach about 50%when the consolidation pressure is far beyond the structural yield stress,and it follows the plastic volumetric strain quite well.

关键词： Natural clay Soil sample disturbance Shear wave velocity Small-strain shear modulus Hardin equation

Adaptive mutation sparrow search algorithm-Elman-AdaBoost model for predicting the deformation of subway tunnels

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Underground Space 2024年第4期17卷 320-360页

作者： Xiangzhen Zhou Wei Hu Zhongyong Zhang Junneng Ye Chuang Zhao xuecheng bian MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering College of Civil Engineering and ArchitectureZhejiang UniversityHangzhou 310058China Hangzhou Canal Group Construction Management Co.LTD Hangzhou 310015China Ningbo Rail Transit Project Construction Headquarter Ningbo 315012China Center for Hypergravity Experimental and Interdisciplinary Research Zhejiang UniversityHangzhou 310058China

A novel coupled model integrating Elman-AdaBoost with adaptive mutation sparrow search algorithm(AM-SSA),called AMSSAElman-AdaBoost,is proposed for predicting the existing metro tunnel deformation induced by adjacent deep excavations in soft *** novelty is that the modified SSA proposes adaptive adjustment strategy to create a balance between the capacity of exploitation and *** AM-SSA,firstly,the population is initialized by cat mapping chaotic sequences to improve the ergodicity and randomness of the individual sparrow,enhancing the global search *** the individuals are adjusted by Tent chaotic disturbance and Cauchy mutation to avoid the population being too concentrated or scattered,expanding the local search ***,the adaptive producer-scrounger number adjustment formula is introduced to balance the ability to seek the global and local *** addition,it leads to the improved algorithm achieving a better accuracy level and convergence speed compared with the original *** demonstrate the effectiveness and reliability of AM-SSA,23 classical benchmark functions and 25 IEEE Congress on Evolutionary Computation benchmark test functions(CEC2005),are employed as the numerical examples and investigated in comparison with some wellknown optimization *** statistical results indicate the promising performance of AM-SSA in a variety of optimization with constrained and unknown search *** utilizing the AdaBoost algorithm,multiple sets of weak AMSSA-Elman predictor functions are restructured into one strong predictor by successive iterations for the tunnel deformation prediction ***,the on-site monitoring data acquired from a deep excavation project in Ningbo,China,were selected as the training and testing ***,the predictive outcomes are compared with those of other different optimization and machine learning *** the end,the obtained results in this real-world geotechnical eng

关键词： Adjacent deep excavations Existing subway tunnels Adaptive mutation sparrow search algorithm Metaheuristic optimization Benchmark test functions Elman neural networks

Engineering properties for high kitchen waste content municipal solid waste

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Journal of Rock Mechanics and Geotechnical Engineering 2015年第6期7卷 646-658页

作者： Wu Gao Yunmin Chen Liangtong Zhan xuecheng bian MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Institute of Civil EngineeringZhejiang University

Engineering properties of municipal solid waste （MSW） depend largely on the waste＇s initial compositionand degree of degradation. MSWs in developing countries usually have a high kitchen waste content（called HKWC MSW）. After comparing and analyzing the laboratory and field test results of physicalcomposition, hydraulic properties, gas generation and gas permeability, and mechanical properties forHKWC MSW and low kitchen waste content MSW （called LKWC MSW）, the following findings wereobtained：（1） HKWC MSW has a higher initial water content （IWC） than LKWC MSW, but the field capacitiesof decomposed HKWC and LKWC MSWs are similar; （2） the hydraulic conductivity and gaspermeability for HKWC MSW are both an order of magnitude smaller than those for LKWC MSW; （3）compared with LKWC MSW, HKWC MSW has a higher landfill gas （LFG） generation rate but a shorterduration and a lower potential capacity; （4） the primary compression feature for decomposed HKWCMSW is similar to that of decomposed LKWC MSW, but the compression induced by degradation ofHKWC MSW is greater than that of LKWC MSW; and （5） the shear strength of HKWC MSW changessignificantly with time and strain. Based on the differences of engineering properties between these twokinds of MSWs, the geo-environmental issues in HKWC MSW landfills were analyzed, including highleachate production, high leachate mounds, low LFG collection efficiency, large settlement and slopestability problem, and corresponding advice for the management and design of HKWC MSW landfills wasrecommended.

关键词： High kitchen waste content (HKWC) Municipal solid waste (MSW) Landfill Engineering properties Leachate MSW management

Experimental study on dynamic load magnification factor for ballastless track-subgrade of high-speed railway

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Journal of Rock Mechanics and Geotechnical Engineering 2013年第4期5卷 306-311页

作者： Renpeng Chen Xing Zhao Zuozhou Wang Hongguang Jiang xuecheng bian Institute of Geotechnical Engineering Zhejiang University MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Zhejiang University Zhejiang Electric Power Design Institute

The magnitude of dynamic load produced by high-speed trains depends on many factors,of which train speed is the most critical ***,it is quite difficult to determine the effect of train speed on dynamic load using the theoretical methods due to the complexity of the interaction between vehicle and *** large-scale model test has gradually become an important approach for studying dynamic responses of ballastless track-subgrade of high-speed *** this study,a full-scale model of ballastless track-subgrade was constructed in accordance with the design and construction standards for Shanghai-Nanjing intercity high-speed railway line ***,the dynamic strain of slab and the dynamic earth pressure of subgrade were measured by conducting single wheel axle excitation *** addition,the relationship between the dynamic load magnification factor（DLF） and the train speed was ***,the DLF of track-subgrade under different train speeds was proposed,similar to that given by German Railway Standard.

关键词： High-speed railway Dynamic load magnification factor(DLF) Train speed Ballastless track-subgrade