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Theoretical and experimental study on multiscale coupled Mohr-Coulomb shear strength criterion of fibre-reinforced sand

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Underground Space 2024年第1期14卷 53-69页

作者： Deluan Feng Yuxin Wang Shihua Liang School of civil and transportation engineering Guangdong University of TechnologyGuangzhou 510006China

Fibre-reinforced sand(FRS)is a multiphase and multiscale geo-material,which is widely used in geotechnical engineering as supporting structure of excavation of underground space and reinforcement of foundation of underground structures,and its strength is determined by the properties of the heterogeneous substances of the FRS and their coupling mechanical *** order to investigate the influence of fibre characteristics and mechanical properties on the shear strength of the FRS,according to the microscopic interface slip effect generated by the interaction between sand particles and the interaction between these particles and fibre,the material phase of the FRS is divided to conceptualize a micro cell element of the FRS that is capable of reflecting the internal material characteristic information of the ***,based on the coordinated deformation condition between fibres and sand particles at the microscale and the couple stress theory that is capable of effectively describing the discontinuous mechanical responses at the sand-fibre interface,a mesomechanism-based multiscale Mohr–Coulomb shear strength criterion of the FRS is derived,and the yield locus of the FRS is also drawn on the p ***,a series of FRS samples with different fibre content and fibre length were prepared by adopting the freezing method,and consolidated and drained triaxial compression tests were conducted on these samples to validate the proposed multiscale coupled Mohr–Coulomb shear strength *** show that the multiscale coupled Mohr–Coulomb shear strength criterion is capable of effectively reproducing and predicting the yield strength of the *** yield locus of the FRS extends outwards as fibre content and fibre length *** yield stress of the FRS predicted by the proposed multiscale coupled Mohr–Coulomb shear strength criterion is in good agreement with that of the test result.

关键词： Multiscale coupling Fibre-reinforced sand(FRS) Interface slip effect Physical mechanism Shear strength criterion

Experimental Study on the Axial Compression Performance of Bamboo Scrimber Columns Embedded with Steel Reinforcing Bars

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Structural Durability & Health Monitoring 2024年第6期18卷 805-833页

作者： Xueyan Lin Mingtao Wu Guodong Li Nan Guo Lidan Mei College of civil engineering and transportation Northeast Forestry UniversityHarbin150000China department of Building engineering College of Civil EngineeringTongji UniversityShanghai200092China College of transportation and civil engineering Fujian Agriculture and Forestry UniversityFuzhou350002China

In this paper,a new type of bamboo scrimber column embedded with steel bars(rebars)was proposed,and the compression performance was improved by pre-embedding rebars during the preparation of the *** effects of the slenderness ratio and the reinforcement ratio on the axial compression performance of reinforced bamboo scrimber columns were studied by axial compression tests on 28 *** results showed that the increase in the slenderness ratio had a significant negative effect on the axial compression performance of the *** the slenderness ratio increased from 19.63 to 51.96,the failure mode changed from strength failure to buckling failure,and the maximum bearing capacity decreased by 43.03%.The axial compression performance of the reinforced bamboo scrimber columns did not significantly improve at a slenderness ratio of 19.63,but the opposite was true at slenderness ratios of 36.95 and *** the reinforcement ratio increased from 0%to 4.52%,the bearing capacity of those with a slenderness ratio of 51.96 increased by up to 16.99%,and the stiffness and ductility were also ***,based on existing specifications,two modification parameters,the overall elastic modulus Ec and the combined strength fcc,were introduced to establish a calculation method for the bearing capacity of the reinforced bamboo scrimber *** calculation results were compared with the test results,and the results showed that the proposed calculation models can more accurately predict the bearing capacity.

关键词： Bamboo scrimber column steel bar axial compression performance theoretical model

In-depth understanding of transport behavior of sulfided nano zerovalent iron/reduced graphene oxide@guar gum slurry: Stability and mobility

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Journal of Environmental Sciences 2024年第10期144卷 1-14页

作者： Yuheng Ma Wenhui You Zijiang Yang Zhongyu Ren Qi Jing Faculty of Architecture Civil and Transportation EngineeringBeijing University of TechnologyBeijing 100124China

Nanoscale zero-valent iron(NZVI),which has the advantages of small particle size,large specific surface area,and high reactivity,is often injected into contaminated aquifers in the form of ***,the prone to passivation and agglomeration as well as poor stability andmobility of NZVI limit the further application of this technology in ***,sulfided NZVI loaded on reduced graphene oxide(S-NZVI/rGO)and guar gum(GG)with shearthinning properties as stabilizers were used to synthesize S-NZVI/rGO@GG ***,TEM,and FT-IR confirmed that the dispersion and anti-passivation of NZVI were optimized in the coupled *** stability and mobility of the slurry were improved by increasing the GG concentration,enhancing the pH,and decreasing the ionic strength and the presence of Ca^(2+)ions,respectively.A modified advection-dispersion equation(ADE)was used to simulate the transport experiments considering the strain and physicochemical deposition/***,colloidal filtration theory(CFT)demonstrated that Brownian motion plays a dominant role in themigration of S-NZVI/rGO@GG slurry,and the maximummigration distance can be increased by appropriately increasing the injection ***-Derjaguin-Landau-Verwey-Overbeek(XDLVO)theory showed that the excellent stability and migration of S-NZVI/rGO@GG slurry mainly came from the GG spatial *** study has important implications for the field injection of S-NZVI/rGO@GG *** to the injection parameters,the injection range of S-NZVI/rGO@GG slurry is effectively controlled,which lays the foundation for the promotion of application in actual fields.

关键词： S-NZVI rGO Guar gum Transport Stability

A cumulative damage model for predicting and assessing raveling in asphalt pavement using an energy dissipation approach

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Frontiers of Structural and civil engineering 2024年第6期18卷 949-962页

作者： Kailing DENG Duanyi WANG Cheng TANG Jianwen SITU Luobin CHEN School of civil engineering and transportation South China University of TechnologyGuangzhou 510640China

Raveling is a common distress of asphalt pavements,defined as the removal of stones from the pavement *** predict and assess raveling quantitatively,a cumulative damage model based on an energy dissipation approach has been developed at the meso *** construct the model,a new test method,the pendulum impact test,was employed to determine the fracture energy of the stone-mastic-stone meso-unit,while digital image analysis and dynamic shear rheometer test were used to acquire the strain rate of specimens and the rheology property of mastic,*** of the model reveals that when the material properties remain constant,the cumulative damage is directly correlated with loading time,loading amplitude,and loading ***,damage increases with superimposed linear and cosine variations over time.A higher stress amplitude results in a more rapidly increasing rate of damage,while a lower load frequency leads to more severe damage within the same loading ***,an example of the application of the model has been presented,showing that the model can be utilized to estimate failure life due to *** model is able to offer a theoretical foundation for the design and maintenance of anti-raveling asphalt pavements.

关键词： asphalt pavement raveling cumulative damage dissipation energy theory

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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Analytical model for predicting time-dependent lateral deformation of geosynthetics-reinforced soil walls with modular block facing

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Journal of Rock Mechanics and Geotechnical engineering 2024年第2期16卷 711-725页

作者： Luqiang Ding Chengzhi Xiao Feilong Cui School of civil and transportation engineering Hebei University of TechnologyTianjin300401China

To date,few models are available in the literature to consider the creep behavior of geosynthetics when predicting the lateral deformation(d)of geosynthetics-reinforced soil(GRS)retaining *** this study,a general hyperbolic creep model was first introduced to describe the long-term deformation of geosynthetics,which is a function of elapsed time and two empirical parameters a and *** conventional creep tests with three different tensile loads(Pr)were conducted on two uniaxial geogrids to determine their creep behavior,as well as the a-Pr and b-Pr *** test results show that increasing Pr accelerates the development of creep deformation for both ***,a and b respectively show exponential and negatively linear relationships with Pr,which were confirmed by abundant experimental data available in other *** on the above creep model and relationships,an accurate and reliable analytical model was then proposed for predicting the time-dependent d of GRS walls with modular block facing,which was further validated using a relevant numerical investigation from the previous *** evaluation and comparison of the proposed model with six available prediction models were *** a parametric study was carried out to evaluate the effects of wall height,vertical spacing of geogrids,unit weight and internal friction angle of backfills,and factor of safety against pullout on d at the end of construction and 5 years *** findings show that the creep effect not only promotes d but also raises the elevation of the maximum d along the wall ***,the limitations and application prospects of the proposed model were discussed and analyzed.

关键词： Geosynthetics Creep behavior Geosynthetics-reinforced soil(GRS)walls Lateral deformation Analytical model

Effects of grain's shape-and size-polydispersities,orientation,and area fraction on tortuosity and permeability of 2D granular media

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Particuology 2024年第7期90卷 535-557页

作者： Ke Cao Huisu Chen Mohammad Iqbal Khan Mingqi Li Lin Liu Jiangsu Key Laboratory of Construction Materials School of Materials Science and EngineeringSoutheast UniversityNanjing 211189China department of civil engineering College of EngineeringKing Saud UniversityP.O.Box 800Riyadh 11421Saudi Arabia School of civil and transportation engineering Hebei University of TechnologyTianjin 300401China College of civil and transportation engineering Hohai UniversityNanjing210098China

The microstructure of granular media, including grain's shape- and size-polydispersities, orientation, and area fraction can potentially affect its permeability. However, few studies consider the coupling effects of these features. This work employs geometrical probability and stereology to establish quantitative relationships between the above microstructural features and the geometric tortuosity of the two-dimensional granular media containing superellipse, superoval, and polygon grains. Then the lattice Boltzmann method (LBM) is used to determine the permeabilities of these granular media. By combining the tortuosity model and the LBM-derived permeabilities, modified K–C equations are formulated to predict the permeability and the shape factor, considering the grain's shape- and size-polydispersities, orientation, and area fraction. The reliability of these methods can be verified by comparing them with both our simulations and available experimental, theoretical, and numerical data reported in the literature. The findings implicate that the tortuosity and permeability of the granular media are strongly correlated with the grain's shape, orientation, and area fraction but unaffected by the size polydispersity and spatial arrangement of grains. Only circularity is not enough to derive a unified formula for considering the impact of grain shape on tortuosity and permeability, other shape parameters need to be explored in the future.

关键词： Geometric tortuosity Konzey-Carman equation Shape and size ploydispersities Grain orientation Lattice Boltzmann method Granular media

Dynamic Response of A Group of Cylindrical Storage Tanks with Baffles Considering the Effect of Soil Foundation

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China Ocean engineering 2024年第1期38卷 129-143页

作者： SUN Ying WANG Jia-dong HUO Rui-li ZHOU Ding GU Zhen-yuan QIAN Wang-ping School of transportation and civil engineering Nantong UniversityNantong 226019China Faculty of civil engineering and Mechanics Jiangsu UniversityZhenjiang 212013China College of civil engineering Nanjing Tech UniversityNanjing 211816China

The sloshing in a group of rigid cylindrical tanks with baffles and on soil foundation under horizontal excitation is studied *** solutions for the velocity potential are derived out by the liquid subdomain *** models with mass-spring oscillators are established to replace continuous *** with the least square technique,Chebyshev polynomials are employed to fit horizontal,rocking and horizontal-rocking coupling impedances of soil,respectively.A lumped parameter model for impedance is presented to describe the effects of soil on tank structures.A mechanical model for the soil-foundation-tank-liquid-baffle system with small amount of calculation and high accuracy is proposed using the substructure *** analytical solutions are in comparison with data from reported literature and numerical codes to validate the effectiveness and correctness of the *** dynamic properties and seismic responses of the soil-tank system are given for the baffle number,size and location as well as soil parameter.

关键词： cylindrical tanks multiple annular baffles equivalent analytical model soil−structure interaction subdomain method dynamic response

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Enhanced air-coupled impact echo technique by phase analysis of signals from multiple sensors

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Earthquake engineering and engineering Vibration 2024年第2期23卷 297-310页

作者： Najjiya Almallah Nenad Gucunski New Jersey department of transportation New Jersey 08625USA department of civil&Environmental engineering Rutgers University-New BrunswickNJ 08854USA

This paper presents an air-coupled impact echo(IE)technique that relies on the phase spectrum of the collected data to find the frequencies corresponding to the reflections from *** proposed technique takes advantage of the fact that the IE compression wave is not a propagating wave,but it is the 1st order symmetrical(S1)mode Lamb wave at zero group velocity(S1-ZGV).Therefore,it searches the phase spectra of the data collected by multiple sensors to locate the frequency corresponding to the lowest phase *** a result,the technique reduces the effect of propagating waves,including the direct acoustic wave and ambient *** is named the Constant Phase IE(CPIE).The performance of the CPIE is experimentally compared with the regular amplitude spectrum-based IE technique and two other multisensor IE *** CPIE shows a performance advantage,especially in a noisy environment.

关键词： nondestructive testing(NDT) nondestructive evaluation(NDE) bridge inspection bridge evaluation impact echo bridge delamination concrete bridge deck air-coupled sensing MEMS

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