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Heterogeneities of grain boundary contact for simulation of laboratoryscale mechanical behavior of granitic rocks

Journal of Rock Mechanics and Geotechnical engineering 2024年第7期16卷 2629-2644页

作者： Xiongyu Hu Marte Gutierrez Zhiwei Yan key laboratory of transportation tunnel engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu610031China University transportation Center for underground transportation Infrastructure Colorado School of MinesGoldenUSA School of Civil engineering Southwest Jiaotong UniversityChengdu610031China

From a practical point of view,grain structure heterogeneities are key parameters that control the rock response and still remains a challenge to incorporate in a quantitative *** of the less discussed topics in the context of the grain-based model(GBM)in the particle flow code(PFC)is the contact heterogeneities and the appropriate contact model to mimic the grain boundary ***,the smooth joint(SJ)model and linear parallel bond(LPB)model are used to simulate the grain boundary ***,the literature does not document the suitability of different models for specific *** challenge in implementing GBM in PFC is that only a single bonding parameter is used at the grain *** aim of this study is to investigate the responses of a laboratory-scale specimen with SJ and LPB models,considering grain boundary heterogeneous and homogeneous contact *** and biaxial compression tests are performed to calibrate the response of Creighton *** stressestrain curves,volumetric dilation,inter-crack(crack in the grain boundary),and intra-crack(crack within the grain)development,and failure patterns associated with different contact models are *** was found that both the SJ and LPB models can reproduce the pre-peak behavior observed for a granitic rock ***,the LPB model is unable to reproduce the post-peak *** to the large interlocking effect originating from the balls in contact and the ball size in the LPB model,local dilation is induced at the grain *** overestimates the volumetric dilation and residual shear *** LPB model tends to result in discontinuous inter-cracks and stress localization in the rock specimen,resulting in fine fragments at the rock surface during failure.

关键词： Grain boundary contact Smooth joint(SJ)model Linear parallel bond(LPB)model Contact heterogeneities Particle flow code(PFC) Granitic rock

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Evidence-based practices in sustainable travel behavior intervention: A knowledge graph-based systematic review

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Journal of Traffic and transportation engineering(English Edition) 2024年第2期11卷 293-311页

作者： Jian Li Chenjie Xu key laboratory of Road and Traffic engineering of the ministry of education College of Transportation EngineeringTongji UniversityShanghai 201804China

Sustainable travel behavior intervention is an essential strategy to promote the development of urban *** interventions offer personalized strategies based on certain scenario and participants to promote its effectiveness over hard travel ***,personalized strategies may also bring about difficulties to identify the actual effect of the ***,based on current practice,to make full use of travel behavior interventions,it is necessary to construct a unified methodological evidencebased framework to assess the reliability and effectiveness of travel behavior intervention *** response to these issues,we applied evidence-based knowledge graph to the field of sustainable travel behavior interventions to help decision supporters design sustainable travel behavior interventions wisely and in turn avoid excessive use of hard travel *** introduced concept of evidence-based practice to conduct a systematic analysis concerning reliability and validity of current full volume empirical studies by dimensions of scenarios,types of interventions and *** addition,we took advantage of high extensivity and integrability of knowledge graph to organize evidence-based related *** of the systematic analysis shows that in terms of reliability of evidence,school intervention is the best scenario,knowledge incentive is the best intervention type and promoting public transit and walking proportion are the best ***,the reliability of interventions in workplace,belonging to reward and threat along with aiming at changing travel patterns generally and lowering travel carbon emission need to be *** the study,various research prospects are raised to promote evidence quality in the field of travel behavior intervention *** a pioneer study,our research contributes to the field of urban transportation in introducing concepts of evidence-based practice and enabling optimization and

关键词： Evidence-based decision-making Evidence assessment Knowledge graph Travel behavior intervention Sustainable travel

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Comparative analysis between single-train passing and double-train intersection in a tunnel

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Journal of Zhejiang University-Science A(Applied Physics & engineering) 2024年第5期25卷 429-442页

作者： Jianming DU Qian FANG Xuan ZHANG Hualao WANG Bridge and tunnel Research Center Research Institute of Highway Ministry of TransportBeijing 100088China tunnel and underground engineering Research Center of ministry of education Beijing Jiaotong UniversityBeijing 00044China

Aerodynamic pressure significantly impacts the scientific evaluation of tunnel service *** aerodynamic pressure of two trains running in a double-track tunnel is considerably more complicated than that of a single *** used the numerical method to investigate the difference in aerodynamic pressure between a single train and two trains running in a double-track ***,the numerical method was verified by comparing the results of numerical simulation and on-site ***,the characteristics of aerodynamic pressure were ***,the influence of various train-tunnel factors on the characteristics of aerodynamic pressure was *** results show that the aerodynamic pressure variation can be divided into stage I:irregular pressure fluctuations before the train tail leaves the tunnel exit,and stage II:periodic pressure declines after the train tail leaves the tunnel *** addition,the aerodynamic pressure simultaneously jumps positively or drops negatively for a single train or two trains running in double-track tunnel *** pressure amplitude in the two-train case is higher than that for a single *** maximum positive peak pressure difference(P_(STP))and maximum negative peak pressure difference(P_(STN))increase as train speed rises to the power from 2.256 to 2.930 in stage *** P_(STP) and P_(STN) first increase and then decrease with the increase of tunnel length in stage *** P_(STP) and P_(STN) increase as the blockage ratio rises to the power from 2.032 to 2.798 in stages I and II.

关键词： Railway tunnel Aerodynamic effect Pressure characteristic Train speed tunnel length Blockage ratio

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走滑断层黏滑作用下隧道纵向及横断面分区破坏机理

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Journal of Central South University 2024年第1期31卷 250-271页

作者：杨恒洪王明年罗勋于丽张霄唐浪洲 School of Civil engineering Southwest Jiaotong UniversityChengdu 610036China key laboratory of transportation tunnel engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China

黏滑作用下走滑断层将出现永久性的错动位移,当隧道与此类断层相交时将发生严重破坏,并且具有明显的分区特征。为了揭示隧道纵向和横断面的分区破坏机理,为穿越活动断裂带隧道抗震设计提供支撑,本文首先通过震害实例调研总结得到隧道的... 详细信息

黏滑作用下走滑断层将出现永久性的错动位移,当隧道与此类断层相交时将发生严重破坏,并且具有明显的分区特征。为了揭示隧道纵向和横断面的分区破坏机理,为穿越活动断裂带隧道抗震设计提供支撑,本文首先通过震害实例调研总结得到隧道的三种破坏模式,即环向裂缝、斜向裂缝和纵向裂缝。给出并讨论了断层类型、交角、错动量和隧道刚度等关键影响因素。结果表明:1)断层类型是影响隧道力学响应和安全性的最显著因素,而倾角影响很小;2)受左旋走滑断层黏滑作用的隧道沿纵向可分为弯曲-压缩-剪切(L-BCS)区和弯曲-压缩(L-BC)区,而受右旋走滑断层黏滑作用的隧道可分为弯曲-拉伸-剪切(L-BTS)区和弯曲-拉伸(L-BT)区;3)L-BCS区和L-BTS区的范围为1.4D~1.7D(D为隧道直径),而L-BC区和L-BT区范围随关键影响因素变化而变化;4)隧道横断面可分为偏心受压(C-EC)区和偏心受拉(C-ET)区,分别发生偏心受压破坏或偏心受拉破坏。C-EC区和C-ET区的范围约为距断层面5D;5)穿越左旋走滑断层隧道的C-EC区包括上盘左拱腰、下盘右拱腰、拱顶和仰拱,C-ET区包括下盘左拱腰和上盘右拱腰。穿越右旋走滑断层隧道的横断面分区分布与左旋对称。

关键词：走滑断层黏滑隧道工程分区破坏机理力学响应

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Carbon emission quantification and reduction in pavement use phase:A review

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Journal of Traffic and transportation engineering(English Edition) 2024年第1期11卷 69-91页

作者： Linjie Zhu Jin Li Feipeng Xiao key laboratory of Road and Traffic engineering of ministry of education Tongji UniversityShanghai 201804China

The carbon emissions arising from road pavement infrastructures have emerged as critical issue in recent *** life cycle of a pavement can be divided into five phases,namely raw materials and production,construction,use,maintenance and end of *** the use phase generates the highest carbon emissions throughout the pavement's life cycle,it is usually neglected in most pavement life cycle assessment(LCA)studies due to its complexity and ***,this review selected 126 relevant references,focuses on quantification methods,influential factors and reduction technologies of carbon emissions in pavement use *** the carbon accounting approached,the LCA approach,remains the most widely used for evaluating the environmental impact of ***,the primary influential factors on the use phase'carbon emission include pavement-vehicle interaction primarily affected by pavement roughness,pavement albedo and climate *** influential factors above indirectly cause changes in carbon emissions by influencing the pavement performance and subsequent vehicle ***,the review surveys carbon emission reduction technologies during pavement use phase,focusing mainly on reducing pavement rolling resistance and constructing cool *** pavements and permeable pavements are the most widely used cool pavement ***,the aspects involved in this paper hold significant promise for quantifying and reducing carbon emissions in the pavement use phase.

关键词： Pavement Carbon emission Life cycle assessment Use phase Emission reduction

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Seismic-induced surficial failure of cohesive slopes using three-dimensional limit analysis:A case study of the Wangjiayan landslide in Beichuan, China

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Earthquake engineering and engineering Vibration 2024年第3期23卷 537-545页

作者： Gao Yufeng Liu Yang Geng Weijuan Zhang Fei key laboratory of the ministry of education for Geomechanics and Embankment engineering College of Civil and Transportation EngineeringHohai UniversityNanjing 210098China Department of Civil engineering Faculty of Civil Engineering and MechanicsJiangsu UniversityZhenjiang 212013China

A seismic-induced landslide is a common geological catastrophe that occurs in *** Wangjiayan landslide,which was triggered by the Wenchuan earthquake,is a typical case in *** Wanjiayan landslide caused many casualties and resulted in enormous property *** study constructs a simple surficial failure model based on the upper bound approach of three-dimensional(3D)limit analysis to evaluate the slope stability of the Wangjiayan case,while a traditional two-dimensional(2D)analysis is also conducted as a reference for comparison with the results of the 3D analysis.A quasi-static calculation is used to study the effect of the earthquake in terms of horizontal ground acceleration,while a parametric study is conducted to evaluate the critical cohesion of *** than employing a 3D analysis,using the 2D analysis yields an underestimation regarding the safety *** the Wangjiayan landslide,the difference in the factors of safety between the 3D and 2D analyses can reach 20%.The sliding surface morphology as determined by the 3D method is similar to actual morphology,and the parameters of both are also compared to analyze the reliability of the proposed 3D method.

关键词： landslide Wenchuan earthquake surficial failure limit analysis stability quasi-static

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Compatibility evaluation between waterborne epoxy resin and SBR latex modified asphalt emulsion

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Journal of Traffic and transportation engineering(English Edition) 2024年第1期11卷 160-171页

作者： Jianhua Yang Zhengqi Zhang Ying Fang key laboratory for Special Area Highway engineering of ministry of education Chang'an UniversityXi'an 710064China

Good compatibility between waterborne epoxy resin(WER)modifier and styrene-butadiene rubber(SBR)latex modified asphalt emulsion(SBRE)is an essential premise for good pavement performance of WER and SBR latex compositely modified asphalt emulsion(WSAE).This study aims to explore the compatibility between WER modifier and *** achieve the goal,several WER modifiers produced by two methods were first selected to modify SBRE,thus the WSAEs were ***,storage stability and workability of the WSAEs themselves,and high-temperature performance,rheological behavior and temperature sensitivity of their evaporated residues were compared and evaluated via performing a series of experiments,respectively,thus the WER modifier possessing an optimal modification effect was *** show that the storage stability of WSAEs is sensitive to the amount of *** incorporation of 1%WERs by the mass of SBRE improves the storage stability of SBRE,while WERs that exceed 1%weaken its storage *** the WERs reach 3%and 4%,the 5 d storage stability of prepared WSAEs will be beyond the limitation of *** WERs into SBRE negatively affects the workability of SBRE,and the workability of WSAEs is adversely influenced by the WERs content and the storage *** ensure the construction,the WSAEs with 3%and 4%WERs should not be stored for more than 36 h and 48 h,*** WERs effectively improve the high-temperature performance of SBRE residue,especially the 3%***,the WERs notably enhance the rheological property and thermal stability of SBRE *** contrast,the WER modifier produced by chemically modified method has a smaller adverse impact on the storage stability and workability of WSAE,and a larger enhancement on the high-temperature performance,rheological property and thermal stability of SBRE residue,which is thus recommended to modify SBRE.

关键词： Waterborne epoxy resin SBR modified asphalt emulsion Workability Rheological property Temperature sensitivity Compatibility evaluation

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Prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum

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Journal of Rock Mechanics and Geotechnical engineering 2024年第1期16卷 192-212页

作者： Fan Wang Xiuli Du Pengfei Li key laboratory of Urban Security and Disaster engineering Ministry of EducationBeijing University of TechnologyBeijing100124China

This study focuses on the analytical prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum considering the volumetric deformation modes of the soil above the tunnel crown.A series of numerical analyses is performed to examine the effects of cover depth ratio(C/D),tunnel volume loss rate(h t)and volumetric block proportion(VBP)on the characteristics of subsurface settle-ment trough and soil volume *** the ground loss variation with depth,three modes are deduced from the volumetric deformation responses of the soil above the tunnel ***,analytical solutions to predict subsurface settlement for each mode are presented using stochastic medium *** influences of C/D,h t and VBP on the key parameters(i.e.B and N)in the analytical expressions are discussed to determine the fitting formulae of B and ***,the proposed analytical solutions are validated by the comparisons with the results of model test and numerical *** show that the fitting formulae provide a convenient and reliable way to evaluate the key ***,the analytical solutions are reasonable and available in predicting the subsurface settlement induced by shield tunnelling in sandy cobble stratum.

关键词： Shield tunnelling Sandy cobble stratum Subsurface settlement Volumetric deformation mode Stochastic medium theory

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Multi-Objective Optimization of Aluminum Alloy Electric Bus Frame Connectors for Enhanced Durability

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Computer Modeling in engineering & Sciences 2024年第7期140卷 735-755页

作者： Wenjun Zhou Mingzhi Yang Qian Peng Yong Peng Kui Wang Qiang Xiao key laboratory of Traffic Safety on Track Ministry of EducationSchool of Traffic&Transportation EngineeringCentral South UniversityChangsha410018China School of Mechanical and Automotive engineering Xiamen University of TechnologyXiamen361024China

The widespread adoption of aluminumalloy electric buses,known for their energy efficiency and eco-friendliness,faces a challenge due to the aluminum frame’s susceptibility to deformation compared to *** issue is further exacerbated by the stringent requirements imposed by the flammability and explosiveness of batteries,necessitating robust frame *** study aims to optimize the connectors of aluminum alloy bus frames,emphasizing durability,energy efficiency,and *** research delves into Multi-Objective Coordinated Optimization(MCO)techniques for lightweight design in aluminum alloy bus body *** goal is to enhance lightweighting,reinforce energy absorption,and improve deformation resistance in connector *** typical aluminum alloy connectors were selected and a design optimization platform was built for their MCO using a variety of software and ***,through three-point bending experiments and finite element analysis on three types of connector components,we identified optimized design parameters based on deformation ***,employing Optimal Latin hypercube design(OLHD),parametric modeling,and neural network approximation,we developed high-precision approximate models for the design parameters of each connector component,targeting energy absorption,mass,and logarithmic ***,utilizing the Archive-based Micro Genetic Algorithm(AMGA),Multi-Objective Particle Swarm Optimization(MOPSO),and Non-dominated SortingGenetic Algorithm(NSGA2),we explored optimized design solutions for these joint ***,we simulated joint assembly buckling during bus rollover crash scenarios to verify and analyze the optimized solutions in three-point bending *** joint component showcased a remarkable 30%–40%mass reduction while boosting energy *** design optimization method exhibits high efficiency and *** contemporary automation technology,the design optimiza

关键词： Aluminum connectors three-point bending simulation parametric design model multi-objective collaborative optimization

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Bifunctional TiO_(2-x)nanofibers enhanced gel polymer electrolyte for high performance lithium metal batteries

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Journal of Energy Chemistry 2024年第2期89卷 437-448,I0011页

作者： Yixin Wu Zhen Chen Yang Wang Yu Li Chunxing Zhang Yihui Zhu Ziyu Yue Xin Liu Minghua Chen key laboratory of engineering Dielectric and Applications(ministry of education) School of Electrical and Electronic EngineeringHarbin University of Science and TechnologyHarbin 150080HeilongjiangChina

Exploration of advanced gel polymer electrolytes(GPEs)represents a viable strategy for mitigating dendritic lithium(Li)growth,which is crucial in ensuring the safe operation of high energy density Li metal batteries(LMBs).Despite this,the application of GPEs is still hindered by inadequate ionic conductivity,low Li^(+)transference number,and subpar physicochemical ***,Ti O_(2-x)nanofibers(NF)with oxygen vacancy defects were synthesized by a one-step process as inorganic fillers to enhance the thermal/mechanical/ionic-transportation performances of composite *** characterizations and theoretical calculations reveal that the oxygen vacancies on the surface of Ti O_(2-x)NF accelerate the dissociation of Li PF_6,promote the rapid transfer of free Li^(+),and influence the formation of Li F-enriched solid electrolyte ***,the composite GPEs demonstrate enhanced ionic conductivity(1.90m S cm^(-1)at room temperature),higher lithium-ion transference number(0.70),wider electrochemical stability window(5.50 V),superior mechanical strength,excellent thermal stability(210℃),and improved compatibility with lithium,resulting in superior cycling stability and rate performance in both Li||Li,Li||Li Fe PO_(4),and Li||Li Ni_(0.8)Co_(0.1)Mn_(0.1)O_(2)***,the synergistic influence of nanofiber morphology and enriched oxygen vacancy structure of fillers on electrochemical properties of composite GPEs is comprehensively investigated,thus,it is anticipated to shed new light on designing high-performance GPEs LMBs.

关键词： Nanofibers fillers Oxygen vacancies Gel polymer electrolytes Lithium metal batteries

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