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A comprehensive comparison of different regression techniques and nature-inspired optimization algorithms to predict carbonation depth of recycled aggregate concrete

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Frontiers of Structural and civil engineering 2024年第1期18卷 30-50页

作者： Bin XI Ning ZHANG Enming LI Jiabin LI Jian ZHOU Pablo SEGARRA Department of civil and Environmental engineering Politecnico Di MilanoMilano 20133Italy Leibniz Institute of Ecological Urban and Regional Development(IOER) Dresden 01217Germany Universidad Politécnica de Madrid-ETSI Minas y Energía Madrid 28003Spain Department of civil engineering KU Leuven CampusBrugge 8200Belgium school of resources and Safety engineering Central South UniversityChangsha 410083China

The utilization of recycled aggregates(RA)for concrete production has the potential to offer substantial environmental and economic ***,RA concrete is plagued with considerable durability concerns,particularly *** advance the application of RA concrete,the establishment of a reliable model for predicting the carbonation is *** the one hand,concrete carbonation is a long and slow process and thus consumes a lot of time and energy to *** the other hand,carbonation is influenced by many factors and is hard to *** this,this paper proposes the use of machine learning techniques to establish accurate prediction models for the carbonation depth(CD)of RA *** types of regression techniques and meta-heuristic algorithms were employed to provide more alternative predictive *** was found that the best prediction performance was obtained from extreme gradient boosting-multi-universe optimizer(XGB-MVO)with R^(2) value of 0.9949 and 0.9398 for training and testing sets,***-MVO was used for evaluating physical laws of carbonation and it was found that the developed XGB-MVO model could provide reasonable predictions when new data were *** also showed better generalization capabilities when compared with different models in the ***,this paper emphasizes the need for sustainable solutions in the construction industry to reduce its environmental impact and contribute to sustainable and low-carbon economies.

关键词： recycled aggregate concrete carbonation depth nature-inspired optimization algorithms extreme gradient boosting technique parametric analysis

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Wetting front migration model of ion-adsorption rare earth during the multi-hole unsaturated liquid injection

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Journal of Rock Mechanics and Geotechnical engineering 2024年第2期16卷 483-496页

作者： Yu Wang Xiaojun Wang Yuchen Qiu Hao Wang Gang Li Kaijian Hu Wen Zhong Zhongqun Guo Bing Li Chunlei Zhang Guangxiang Ye Jiangxi Key Laboratory of Mining engineering Jiangxi University of Science and TechnologyGanzhou341000China school of resources and Environment engineering Jiangxi University of Science and TechnologyGanzhou341000China school of civil engineering and Surveying&Mapping engineering Jiangxi University of Science and TechnologyGanzhou341000China Ganzhou Nonferrous Metallurgy Research Institute Ganzhou341000China

In the process of ion-adsorption rare earth ore leaching,the migration characteristics of the wetting front in multi-hole injection holes and the influence of wetting front intersection effect on the migration distance of wetting fronts are still ***,wetting front migration distance and leaching time are usually required to optimize the leaching *** this study,wetting front migration tests of ionadsorption rare earth ores during the multi-hole fluid injection(the spacing between injection holes was 10 cm,12 cm and 14 cm)and single-hole fluid injection were completed under the constant water head *** the pre-intersection stage,the wetting front migration laws of ion-adsorption rare earth ores during the multi-hole fluid injection and single-hole fluid injection were *** the postintersection stage,the intersection accelerated the wetting front *** using the Darcy’s law,the intersection effect of wetting fronts during the multi-hole liquid injection was transformed into the water head height directly above the ***,based on the Green-Ampt model,a wetting front migration model of ion-adsorption rare earth ores during the multi-hole unsaturated liquid injection was *** analysis results showed that the proposed model can accurately simulate the infiltration process under experimental *** research results enrich the infiltration law and theory of ion-adsorption rare earth ores during the multi-hole liquid injection,and this study provides a scientific basis for optimizing the liquid injection well pattern parameters of ion-adsorption rare earth in situ leaching in the future.

关键词： Ion-adsorption rare earth ore Multi-hole unsaturated liquid injection In situ leaching Intersection effect Calculation model

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On hypersurfaces of H2×H2

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Science China Mathematics 2024年第2期67卷 339-366页

作者： Dong Gao Hui Ma Zeke Yao school of Science Beijing University of Civil Engineering and Architecture Department of Mathematical Sciences Tsinghua University

In this paper, we study hypersurfaces of H2× H2. We first classify the hypersurfaces with constant principal curvatures and constant product angle functions. Then we classify homogeneous hypersurfaces and isoparametric hypersurfaces, respectively. Finally, we classify the hypersurfaces with at most two distinct constant principal curvatures, as well as those with three distinct constant principal curvatures under some additional conditions.

关键词： constant principal curvature homogeneous hypersurface isoparametric hypersurface 53C42 53B25 53C40

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Transfer relation between subgrade frost heave and slab track deformation and vehicle dynamic response in seasonally frozen ground

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Journal of Zhejiang University-Science A(Applied Physics & engineering) 2024年第2期25卷 130-146页

作者： Juanjuan REN Junhong DU Kaiyao ZHANG Bin YAN Jincheng TIAN MOE Key Laboratory of High-speed Railway engineering Southwest Jiaotong UniversityChengdu610031China school of civil engineering Southwest Jiaotong UniversityChengdu610031China school of civil engineering Central South UniversityChangsha410075China Airport Planning and Design Institute POWERCHINA Kunming Engineering Corporation LimitedKunming650051China

Subgrade frost heave in seasonally frozen ground can greatly influence the safety and smooth running of high-speed trains and the service performance of track *** this study,we used a static model to:(1)investigate track-subgrade frost heave and develop a dynamic model of vehicle-track-subgrade frost heave;(2)explore the transfer relation between subgrade frost heave and track structure deformation;(3)examine the characteristics of interlayer debonding;(4)study the influence of subgrade frost heave on the dynamic response of vehicles in high-speed railways in seasonally frozen regions.A Fourier series was used to fit the frost heave waveform and simulate the behavior of subgrade uneven frost heave using data collected *** results show:(i)The position of frost heave significantly affects the transfer of deformation to a slab *** largest deformation of the track slab,with the amplitude transfer ratio reaching 20%,was recorded when the frost heave occurred near the joint of the base plate.(ii)At the same frost heave amplitude,long-wave frost heave causes smaller deformation and debonding of the track structure than short-wave frost *** the wavelength range of 10-30 m,the main frequency of the acceleration spectral density was concentrated between 3.5 and 3.7 Hz,with larger frost heave wavelengths producing smaller superposition on the vertical acceleration of the vehicle.(ii)The maximum wheel-rail force occurs when the front bogie passes the frost heave peak,with greater frost heave amplitudes producing greater wheel-rail *** these results,we conclude there is a clear need to control the frost heave deformation of the track to reduce the dynamic response of the vehicle and in turn improve train operatSubgrade frost heave in seasonally frozen ground can greatly influence the safety and smooth running of high-speed trains and the service performance of track *** this study,we used a static model to:(1)investigate track`-subgr

关键词： Slab track Subgrade frost heave Transfer relation Vehicle-track-subgrade coupling Dynamic response

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Influence of Recycled Concrete Fine Powder on Durability of Cement Mortar

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Fluid Dynamics & Materials Processing 2024年第1期20卷 45-58页

作者： Yadong Bian Xuan Qiu Jihui Zhao Zhong Li Jiana Ouyang school of Architectural and civil engineering Zhongyuan University of TechnologyZhengzhou450007China school of civil engineering Sun Yat-Sen University&Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai519082China

In this paper,the durability of cement mortar prepared with a recycled-concrete fine powder(RFP)was examined;including the analysis of a variety of aspects,such as the carbonization,sulfate attack and chloride ion erosion *** results indicate that the influence of RFP on these three aspects is *** carbonization depth after 30 days and the chloride diffusion coefficient of mortar containing 10%RFP decreased by 13.3%and 28.19%.With a further increase in the RFP content,interconnected pores formed between the RFP particles,leading to an acceleration of the penetration rate of CO_(2)and Cl^(−).When the RFP content was less than 50%,the corrosion resistance coefficient of the compressive strength of the mortar was 0.84-1.05 after 90 days of sulfate *** the expansion and cracking of the mortar was effectively alleviated due to decrease of the gypsum *** electron microscope(SEM)analysis has confirmed that 10%RFP contributes to the formation of a dense microstructure in the cement mortar.

关键词： Recycled concrete fine powder cement mortar carbonization sulfate chloride ion durability

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Automatic detection and assessment of crack development in ultra-high performance concrete in the spatial and Fourier domains

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Frontiers of Structural and civil engineering 2024年第3期18卷 350-364页

作者： Jixing CAO Yao ZHANG Haijie HE Weibing PENG Weigang ZHAO Zhiguo YAN Hehua ZHU school of Safety engineering and Emergency Management Shijiazhuang Tiedao UniversityShijiazhuang 050043China College of civil engineering and Architecture Zhejiang UniversityHangzhou 310058China College of civil and Architectural engineering Taizhou UniversityTaizhou 318000China College of civil engineering and Architecture Zhejiang University of TechnologyHangzhou 310014China Department of Geotechnical engineering Tongji UniversityShanghai 200092China

Automatic detection and assessment of surface cracks are beneficial for understanding the mechanical performance of ultra-high performance concrete(UHPC).This study detects crack evolution using a novel dynamic mode decomposition(DMD)*** this method,the sparse matrix‘determined’from images is used to reconstruct the foreground that contains cracks,and the global threshold method is adopted to extract the crack *** application of the DMD method to the three-point bending test demonstrates the efficiency in inspecting cracks with high ***,the geometric features,including the area and its projection in two major directions,are evaluated over *** relationship between the geometric properties of cracks and load-displacement curves of UHPC is *** to the irregular shape of cracks in the spatial domain,the cracks are then transformed into the Fourier domain to assess their *** indicate that crack patterns in the Fourier domain exhibit a distinct concentration around a central ***,the power spectral density of cracks exhibits an increasing trend over *** investigation into crack evolution in both the spatial and Fourier domains contributes significantly to elucidating the mechanical behavior of UHPC.

关键词： dynamic mode decomposition ultra-high performance concrete crack detection geometric features Fourier domain

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Resilience-incorporated seismic risk assessment of precast concrete frames with“dry”connections

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Earthquake engineering and engineering Vibration 2024年第2期23卷 403-425页

作者： Wu Chenhao Tang Yuchuan Cao Xuyang Wu Gang Key Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of Education Nanjing 211102China Department of civil and Environmental engineering University of CaliforniaLos AngelesCA 90095USA school of civil engineering Southeast UniversityNanjing 211102China College of civil and Transportation engineering Hohai UniversityNanjing 210024China

A resilience-incorporated risk assessment framework is proposed and demonstrated in this study to manifest the advantageous seismic resilience of precast concrete frame(PCF)structures with“dry”connections in terms of their low damage and rapid *** framework integrates various uncertainties in the seismic hazard,fragility,capacity,demand,loss functions,and post-earthquake *** this study,the PCF structures are distinguished from ordinary reinforced concrete frame(RCF)structures by characterizing multiple limit states for the PCF based on its unique damage ***,probabilistic story-wise pushover analyses are performed to yield story-wise capacities for the predefined limit *** the seismic resilience analysis,a step-wise recovery model is proposed to idealize the functionality recovery process,with separate considerations of the repair and non-repair *** recovery model leverages the economic loss and downtime to delineate the stochastic post-earthquake recovery curves for the resilience loss *** such,contingencies in the probabilistic post-earthquake repairs are incorporated and the empirical judgments on the recovery parameters are largely *** proposed framework is demonstrated through a comparative study between two“dry”connected PCFs and one RCF designed as alternative structural systems for a prototype *** results from the risk quantification indicate that the PCFs show reduced loss hazards and lower expected losses relative to the ***,the PCF equipped with energy dissipation devices at the“dry”connections largely reduces the expected economic loss,downtime,and resilience loss by 29%,56%,and 60%,respectively,compared to the RCF.

关键词： precast concrete frame non-emulative precast system seismic resilience seismic risk functional recovery

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Effect of NaCl Concentration on the Cumulative Strain and Pore Distribution of Clay under Cyclic Loading

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Fluid Dynamics & Materials Processing 2024年第2期20卷 447-461页

作者： Xinshan Zhuang Shunlei Xia Ruijie Pan school of civil engineering and Architecture Hubei University of TechnologyWuhan430068China

Clay,as the most common soil used for foundationﬁll,is widely used in various infrastructure *** phy-sical and mechanical properties of clay are inﬂuenced by the pore solution *** study uses a GDS static/dynamic triaxial apparatus and nuclear magnetic resonance experiments to investigate the effects of cyclic loading on clay ***,the development of cumulative strain in clay is analyzed,and aﬁtting model for cumulative plastic strain is introduced by considering factors such as NaCl solution concentration,con-solidation stress ratio,and cycle *** particular,the effects of the NaCl solution concentration and con-solidation stress ratio on the pore distribution of the test samples before and after cyclic loading are examined,and the relationship between microscopic pore size and macroscopic cumulative strain is obtained *** results show that as the consolidation stress ratio grows,an increasing number of large pores in the soil samples are transformed into small *** the NaCl solution concentration becomes higher,the number of small pores gradually decreases,while the number of large pores remains *** loading causes the disappearance of the large pores in the samples,and the average pore size before cyclic loading is posi-tively correlated with the axial cumulative strain after cyclic *** cumulative strain produced by the soil under cyclic loading is inversely proportional to the NaCl solution concentration and consolidation stress ratio.

关键词： Geotechnical engineering clay cyclic loading nuclear magnetic resonance NaCl solution consolidation ratio accumulative strain

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Coupling Effect of Cryogenic Freeze-Thaw Cycles and Chloride Ion Erosion Effect in Pre-Cracked Reinforced Concrete

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Structural Durability & Health Monitoring 2024年第3期18卷 255-276页

作者： Yang Li Sibo Jiang Ruixin Lan school of civil engineering and Architecture Hubei University of TechnologyWuhan430068China

Chloride (Cl−) ion erosion effects can seriously impact the safety and service life of marine liquefied natural gas(LNG) storage tanks and other polar offshore structures. This study investigates the impact of different low-temperaturecycles (20°C, –80°C, and −160°C) and concrete specimen crack widths (0, 0.3, and 0.6 mm) on the Cl−ion diffusion performance through rapid erosion tests conducted on pre-cracked concrete. The results show thatthe minimum temperature and crack width of freeze-thaw cycles enhance the erosive effect of chloride ions. TheCl− ion concentration and growth rate increased with the increasing crack width. Based on the experimental modeland in accordance with Fick’s second law of diffusion, the Cl− ion diffusion equation was modified by introducingcorrection factors in consideration of the freeze-thaw temperature, crack width, and their coupling *** experimental and fitting results obtained from this model can provide excellent reference for practical engineeringapplications.

关键词： Chloride ions freeze-thaw cycles cracks

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Preparation and Analysis of Carbon Fiber-Silicon Carbide Thermally Conductive Asphalt Concrete

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Fluid Dynamics & Materials Processing 2024年第4期20卷 705-723页

作者： Zhiyong Yang Enjie Hu Lei Xi Zhi Chen Feng Xiong Chuanhai Zhan school of civil engineering and Environment Hubei University of TechnologyWuhan430068China

An experimental investigation into the thermal conductivity of CF-SiC two-phase composite asphalt concrete is *** main objective of this study was to verify the possibility of using SiC powder instead of mineral powder as the thermal conductive filler to prepare a new type of asphalt concrete and improve the efficiency of electrothermal snow and ice melting systems *** thermal conductivity of asphalt concrete prepared with different thermally conductive fillers was tested by a transient plane source method,and the related performances were *** the temperature rise rate and surface temperature were studied through field heating ***,the actual ice melting efficiency of the thermally conductive asphalt concrete was evaluated using an effective electrothermal *** shown by the experimental results,the composite made of SiC powder and carbon fiber has a high thermal *** SiC replaces mineral powder,the thermal conductivity of the asphalt mixture increases first and then decreases with the increase of carbon fiber *** the present study,in particular,the thermal conductivity attained a peak when the carbon fiber content was 0.2%of the aggregate mass.

关键词： Carbon fiber silicon carbide thermally conductive asphalt concrete road performance electrothermal snow melting

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