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An extended micromechanical-based plastic damage model for understanding water effects on quasi-brittle rocks

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International Journal of Mining Science and Technology 2024年第3期34卷 289-304页

作者： Qiaojuan Yu Shigui Du Qizhi Zhu Zhanyou Luo Sili Liu Lunyang Zhao Institute of Rock Mechanics Ningbo UniversityNingbo 315211China Ningbo Key Laboratory of Energy Geostructure Ningbo UniversityNingbo 315211China college of civil and Transportation Engineering Hohai UniversityNanjing 210098China college of civil Engineering Jiangsu Open UniversityNanjing 210036China South China Institution of Geotechnical Engineering School of Civil Engineering and TransportationSouth China University of TechnologyGuangzhou 510641China

Water effects on the mechanical properties of rocks have been extensively investigated through experiments and numerical ***,few studies have established a comprehensive link between the microscopic mechanisms of water-related micro-crack and the constitutive behaviors of *** this work,we shall propose an extended micromechanical-based plastic damage model for understanding weakening effect induced by the presence of water between micro-crack’s surfaces on quasi-brittle rocks,based on the Mori-Tanaka homogenization and irreversible thermodynamics *** the physical mechanism,water strengthens micro-crack propagation,which induces damage evolution during the pre-and post-stage,and weakens the elastic effective properties of rock *** proposing a special calibration procedure for the determination of model parameters based on the laboratory compression tests,the proposed micromechanical-based model is verified by comparing the model predictions to the experimental *** model effectively captures the mechanical behaviors of quasibrittle rocks subjected to the weakening effects of water.

关键词： Water Micro-crack Damage Micro-mechanics Constitutive model Cohesive force

Macro-micro behaviors and failure mechanism of frozen weakly cemented mudstone

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1337-1347页

作者： Xianzhou Lyu Jijie Du Hao Fu Dawei Lyu Weiming Wang college of Earth Science and Engineering Shandong University of Science and TechnologyQingdao266590China college of civil Engineering and Architecture Shandong University of Science and TechnologyQingdao266590China

Understanding the mechanical properties and multiscale failure mechanism of frozen soft rock is an important prerequisite for the construction safety of tunnels,artificially frozen ground and other infrastructure in cold *** this study,the triaxial compression test are performed on mudstone in the weakly cemented soft rock strata in the mining area of western China,and the mechanical characteristics and failure mechanism of weakly cemented mudstone are systematically investigated under the combined action of freezing and ***,the quantitative relationship between the microstructural parameters and the macroscopic strength and deformation parameters is established based on fractal ***,the failure mechanism of frozen weakly cemented mudstone is revealed on both micro- and *** results show that temperature and confining pressure significantly affects the elastic modulus and peak strength of weakly cemented *** decreasing temperature,the compressive strength increases,while the corresponding peak strain decreases *** the deformation curve,the plastic deformation stage is shortened,and the brittle fracture feature at the post-peak stage is more prominent,and the elastic modulus correspondingly increases with decreasing *** low-temperature conditions,most of the weakly cemented mudstone undergoes microscopic shear failure along the main fracture *** micro-fracture morphology characteristics of weakly cemented mudstone under different temperatures are quantified via the fractal dimension,and an approximately exponential relationship can be obtained among the fractal dimension and the temperature,compressive strength and elastic modulus.

关键词： Weakly cemented mudstone Artificial freezing Mechanical properties Linkage destruction mechanism Fractal dimension

Factors affecting college students’attitudes towards carpooling

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Transportation Safety and Environment 2024年第2期6卷 55-62页

作者： Linchao Li Huali Zhang Zuoxian Gan college of civil and Transportation Engineering Shenzhen UniversityShenzhen 518060China college of Transportation Engineering Dalian Maritime UniversityDalian 116026LiaoningChina

As a sustainable mode of travel,carpooling is an effective solution to environmental and energy problems,but it has not been fully *** research on carpooling attitudes,especially for college students,still needs to be *** response to this problem,this paper aims to investigate the effect of personal attributes,travel attributes,attitude attributes and other attributes of students on carpooling attitudes in *** collect the data,an online questionnaire survey was implemented at Shenzhen University,and 514 students *** on the samples,the multinomial logit model is used to explore the contribution of all *** model results showed that personal attributes such as sex and age had no significant effect on the attitude of college students towards *** safety of carpooling and its high cost make college students have a neutral attitude towards *** most concerning factor for college students in carpooling is *** findings can provide valuable suggestions for measures to be taken in response to different attributes affecting students’attitudes and are particularly important for the university and government to make optimal decisions to motivate students to select carpooling.

关键词： carpooling attitudes college students multinomial logit traffic environment

A theory for three-dimensional response of micropolar plates

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Applied Mathematics and Mechanics(English Edition) 2024年第8期45卷 1403-1414页

作者： Dianwu HUANG Linghui HE college of civil Engineering and Architectural Jiaxing University Department of Modern Mechanics and State Key Laboratory of Fire Science University of Science and Technology of China

Through combined applications of the transfer-matrix method and asymptotic expansion technique, we formulate a theory to predict the three-dimensional response of micropolar plates. No ad hoc assumptions regarding through-thickness assumptions of the field variables are made, and the governing equations are two-dimensional, with the displacements and microrotations of the mid-plane as the unknowns. Once the deformation of the mid-plane is solved, a three-dimensional micropolar elastic field within the plate is generated, which is exact up to the second order except in the boundary region close to the plate edge. As an illustrative example, the bending of a clamped infinitely long plate caused by a uniformly distributed transverse force is analyzed and discussed in detail.

关键词： 74H45 asymptotic expansion micropolar plate O341 three-dimensional response transfer-matrix

Hollow cathode effect in radio frequency hollow electrode discharge in argon

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Chinese Physics B 2024年第3期33卷 496-502页

作者：贺柳良何锋欧阳吉庭 college of Science Beijing University of Civil Engineering and ArchitectureBeijing 102616China School of Physics Beijing Institute of TechnologyBeijing 100081China

Radio frequency capacitively coupled plasma source(RF-CCP)with a hollow electrode can increase the electron density through the hollow cathode effect(HCE),which offers a method to modify the spatial profiles of the plasma *** this work,the variations of the HCE in one RF period are investigated by using a two-dimensional particle-in-cell/Monte-Carlo collision(PIC/MCC)*** results show that the sheath electric field,the sheath potential drop,the sheath thickness,the radial plasma bulk width,the electron energy distribution function(EEDF),and the average electron energy in the cavity vary in one RF *** the hollow electrode sheath's expansion phase,the secondary electron heating and sheath oscillation heating in the cavity are gradually enhanced,and the frequency of the electron pendular motion in the cavity gradually increases,hence the HCE is gradually ***,during the hollow electrode sheath's collapse phase,the secondary electron heating is gradually *** addition,when interacting with the gradually collapsed hollow electrode sheaths,high-energy plasma bulk electrons in the cavity will lose some ***,the frequency of the electron pendular motion in the cavity gradually ***,during the hollow electrode sheath's collapse phase,the HCE is gradually attenuated.

关键词： hollow cathode effect radio frequency hollow electrode particle-in-cell/Monte-Carlo collision(PIC/MCC)model

Infiltration,runoff,and slope stability behaviors of infinite slope with macropores based on an improved Green–Ampt model

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Journal of Mountain Science 2024年第7期21卷 2220-2235页

作者： LI Shanghui WU Guoxiong QUE Yun JIANG Zhenliang CHENG Gaoyun college of Intelligent Construction Fuzhou University of International Studies and TradeFuzhou 350202China college of civil Engineering Chongqing Jiao Tong UniversityChongqing 400074China Chongqing Vocational college of Architectural Engineering Chongqing 400072China college of civil Engineering Fuzhou UniversityFuzhou 350000China Department of civil and Environmental Engineering Hong Kong University of Science and TechnologyHong Kong 999077China T.Y.Lin International Engineering Consulting(China)Co.Ltd Chongqing 401120China

Infiltration–runoff–slope instability mechanism of macropore slope under heavy rainfall is *** paper studied its instability mechanism with an improved Green–Ampt(GA)model considering the dual-porosity(i.e.,matrix and macropore)and ponding condition,and proposed the infiltration equations,infiltration–runoff coupled model,and safety factor calculation *** show that the infiltration processes of macropore slope can be divided into three stages,and the proposed model is rational by a comparative *** wetting front depth of the traditional unsaturated slope is 17.2%larger than that of the macropore slope in the early rainfall stage and 27%smaller than that of the macropore slope in the late rainfall ***,macropores benefit the slope stability in the early rainfall but not in the *** flow does not occur initially but becomes pronounced with increasing rainfall *** equal depth of the wetting front in the two domains is regarded as the onset criteria of macropore *** analysis shows that macropore flow is delayed by increasing proportion of macropore domain(ω_(f)),whereas promoted by increasing ratio of saturated permeability coefficients between the two domains(μ).The increasing trend of ponding depth is sharp at first and then grows ***,when rainfall duration is less than 3 h,ωf andμhave no significant effect on the safety factor,whereas it decreases with increasingωf and increases with increasingμunder longer duration(≥3 h).With the increase ofω_(f),the slope maximum instability time advances by 10.5 h,and with the increase ofμ,the slope maximum instability time delays by 3.1 h.

关键词： Macropore slope Green–Ampt infiltration model Equivalent wetting front Ponding response time Slope stability

The Analysis of the Correlation between SPT and CPT Based on CNN-GA and Liquefaction Discrimination Research

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Computer Modeling in Engineering & Sciences 2024年第2期138卷 1159-1182页

作者： Ruihan Bai Feng Shen Zihao Zhao Zhiping Zhang Qisi Yu Key Laboratory of the Ministry of Education for Geomechanics and Embankment Engineering College of Civil and Transportation EngineeringHohai UniversityNanjing210098China School of civil Engineering Suzhou University of Science and TechnologySuzhou215011China School of civil Engineering Shenyang Jianzhu UniversityShenyang110168China college of civil Engineering Tongji UniversityShanghai200092China

The objective of this study is to investigate themethods for soil liquefaction discrimination. Typically, predicting soilliquefaction potential involves conducting the standard penetration test (SPT), which requires field testing and canbe time-consuming and labor-intensive. In contrast, the cone penetration test (CPT) provides a more convenientmethod and offers detailed and continuous information about soil layers. In this study, the feature matrix based onCPT data is proposed to predict the standard penetration test blow count N. The featurematrix comprises the CPTcharacteristic parameters at specific depths, such as tip resistance qc, sleeve resistance f s, and depth H. To fuse thefeatures on the matrix, the convolutional neural network (CNN) is employed for feature extraction. Additionally,Genetic Algorithm (GA) is utilized to obtain the best combination of convolutional kernels and the number ofneurons. The study evaluated the robustness of the proposed model using multiple engineering field data *** demonstrated that the proposed model outperformed conventional methods in predicting N values forvarious soil categories, including sandy silt, silty sand, and clayey silt. Finally, the proposed model was employedfor liquefaction discrimination. The liquefaction discrimination based on the predicted N values was comparedwith the measured N values, and the results showed that the discrimination results were in 75% agreement. Thestudy has important practical application value for foundation liquefaction engineering. Also, the novel methodadopted in this research provides new ideas and methods for research in related fields, which is of great academicsignificance.

关键词： CNN liquefaction discrimination SPT CPT

Sensitivity Analysis of Electromagnetic Scattering from Dielectric Targets with Polynomial Chaos Expansion and Method of Moments

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 2079-2102页

作者： Yujing Ma Zhongwang Wang Jieyuan Zhang Ruijin Huo Xiaohui Yuan college of Architecture and civil Engineering Xinyang Normal UniversityXinyang464000China Henan International Joint Laboratory of Structural Mechanics and Computational Simulation College of Architecture and Civil EngineeringHuanghuai UniversityZhumadian463000China Academy of Military Sciences Beijing100091China Henan New Environmentally-Friendly civil Engineering Materials Engineering Research Center Xinyang Normal UniversityXinyang464000China

In this paper,an adaptive polynomial chaos expansion method(PCE)based on the method of moments(MoM)is proposed to construct surrogate models for electromagnetic scattering and further sensitivity *** MoM is applied to accurately solve the electric field integral equation(EFIE)of electromagnetic scattering from homogeneous dielectric *** the bistatic radar cross section(RCS)as the research object,the adaptive PCE algorithm is devoted to selecting the appropriate order to construct the multivariate surrogate *** corresponding sensitivity results are given by the further derivative operation,which is compared with those of the finite difference method(FDM).Several examples are provided to demonstrate the effectiveness of the proposed algorithm for sensitivity analysis of electromagnetic scattering from homogeneous dielectric targets.

关键词： Adaptive polynomial chaos expansion method method of moments radar cross section electromagnetic scattering

Quantitative characterization of fusion state of virgin and aged asphalt using nano-ferrous ferric oxide tracer

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第3期11卷 467-480页

作者： Qiang Li Song Liu Huameng Wen Zhou Zhou college of civil Engineering Nanjing Forestry UniversityNanjing 210037China School of Transportation Southeast UniversityNanjing 211189China

The exact evaluation of the fusion rate of virgin and aged asphalt is essential to optimize the performance of the recycled asphalt *** fusion rate index was developed by tracing the distribution of tracer asphalt,which contains nano-ferrous ferric oxide(nano-Fe_(3)O_(4))*** fusion simulation tests were performed on three types of asphalt to obtain different fusion states,and fatigue tests were performed to evaluate the influence of the fusion rate on the fatigue life of the recycled *** was found that the tracer asphalt containing 4%nano-Fe_(3)O_(4)shows the optimal trace effect,and the developed fusion rate index can quantitatively characterize the influence of different factors on the fusion state of the recycled *** fusion state is closely related to the fatigue performance of recycled asphalt,and the fusion rate index can fairly evaluate its fatigue *** relationship between the fusion rate and the fatigue life of recycled asphalt depends on the factors that cause the fusion rate *** the influence of the amount of rejuvenator,the fatigue life of recycled asphalt grows exponentially with increasing fusion rate due to enhancement of molecular motion as well as a supplement of lightweight *** the influence of heat preservation treatment,fatigue life increases linearly with increasing fusion *** proposed fusion rate index can be utilized to quantitatively characterize the fusion state of virgin and aged asphalt,thus providing a simple way to guide the practical application of recycled asphalt.

关键词： Recycled asphalt Rejuvenator Tracing technique Fusion rate Fatigue