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Effect of Wave Nonlinearity on the Instantaneous Seabed Liquefaction

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China Ocean engineering 2024年第1期38卷 93-103页

作者： WANG Zhao-jun SUI Ti-ti ZHANG Chi PAN Jun-ning key laboratory of Port Waterway and Sedimentation Engineering of the Ministry of TransportNanjing Hydraulic Research InstituteNanjing 210024China key laboratory of Coastal disaster and Protection(Hohai University) Ministry of EducationNanjing 210098China The National key laboratory of Water disaster prevention Nanjing 210098China

The nonlinear variation of wave is commonly seen in nearshore area,and the resulting seabed response and liquefaction are of high concern to coastal *** this study,an analytical formula considering the nonlinear wave skewness and asymmetry is adopted to provide wave pressure on the seabed *** liquefaction depth attenuation coefficient and width growth coefficient are defined to quantitatively characterize the nonlinear effect of wave on seabed *** on the 2D full dynamic model of wave-induced seabed response,a detailed parametric study is carried out in order to evaluate the influence of the nonlinear variation of wave loadings on seabed ***,new empirical prediction formulas are proposed to fast predict the maximum liquefaction under nonlinear *** indicate that(1)Due to the influence of wave nonlinearity,the vertical transmission of negative pore water pressure in the seabed is hindered,and therefore,the amplitude decreases significantly.(2)In general,with the increase of wave nonlinearity,the liquefaction depth of seabed decreases *** under asymmetric and skewed wave loading,the attenuation of maximum seabed liquefaction depth is the most significant among all the nonlinear wave ***,highly skewed wave can cause the liquefaction depth of seabed greater than that under linear wave.(3)The asymmetry of wave pressure leads to the increase of liquefaction width,whereas the influence of skewedness is not significant.(4)Compared with the nonlinear waveform,seabed liquefaction is more sensitive to the variation of nonlinear degree of wave loading.

关键词： nonlinear wave seabed response seabed liquefaction numerical simulation liquefaction prediction

Numerical Study on the Aerodynamic and Fluid−Structure Interaction of An NREL-5MW Wind Turbine

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China Ocean engineering 2024年第3期38卷 363-378页

作者： ZHAO Mi YU Wan-li WANG Pi-guang QU Yang DU Xiu-li key laboratory of Urban Security and disaster engineering of ministry of education Beijing University of TechnologyBeijing 100124China State key laboratory of Bridge engineering safety and Resilience Beijing University of TechnologyBeijing 100124China

A 5-MW wind turbine has been modeled and analyzed for fluid-structure interaction and aerodynamic *** this study, a full-scale model of a 5-MW wind turbine is first developed based on a computational fluid dynamics(CFD) approach, in which the unsteady, noncompressible Reynolds Averaged Navier-Stokes(RANS) method is used. The main focus of the study is to analyze the tower shadow effect on the aerodynamic performance of the wind turbine under different inlet flow conditions. Subsequently, the finite element model is established by considering fluid/structure interactions to study the structural stress, displacement, strain distributions and flow field information of the structure under the uniform wind speed. Finally, the fluid-structure interaction model is established by considering turbulent wind and the tower shadow effect. The variation rules of the dynamic response of the one-way and two-way fluid-structure interaction(FSI) models under different wind speeds are analyzed, and the numerical calculation results are compared with those of the centralized mass model. The results show that the tower shadow effect and structural deformation are the main factors affecting the aerodynamic load fluctuation of the wind turbine, which in turn affects the aerodynamic performance and structural stability of the blades. The structural dynamic response of the coupled model shows significant similarity, while the structural displacement response of the former exhibits less fluctuation compared with the conventional centralized mass model. The one-way fluid-structure interaction(FSI)model shows a higher frequency of stress-strain and displacement oscillations on the blade compared with the two-way FSI model.

关键词： computational fluid dynamics methods(CFD) tower shadow effect aerodynamic performance fluidstructure interaction space flow field

Analytical Solution and Simplified Formula for Added Mass of Horizontal and Vertical Motions of Truncated Cylinders Under Earthquake Action

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China Ocean engineering 2024年第1期38卷 54-67页

作者： WANG Pi-guang LYU Si-yu QU Yang ZHAO Mi DU Xiu-li State key laboratory of Bridge engineering safety and Resilience Beijing University of TechnologyBeijing 100124China key laboratory of Urban Security and disaster engineering of ministry of education Beijing University of Tech-nologyBeijing 100124China

This paper investigates the hydrodynamic characteristics of floating truncated cylinders undergoing horizontal and vertical motions due to earthquake excitations in the finite water *** governing equation of the hydrodynamic pressure acting on the cylinder is derived based on the radiation theory with the inviscid and incompressible *** governing equation is solved by using the method of separating variables and analytical solutions are obtained by assigning reasonable boundary *** analytical result is validated by a numerical model using the exact artificial boundary simulation of the infinite *** main variation and distribution characteristics of the hydrodynamic pressure acting on the side and bottom of the cylinder are analyzed for different combinations of wide-height and immersion *** added mass coefficient of the cylinder is calculated by integrating the hydrodynamic pressure and simplified formulas are proposed for engineering *** calculation results show that the simplified formulas are in good agreement with the analytical solutions.

关键词： earthquake hydrodynamic pressure truncated cylinder added mass simplified formula

Integrated multi-scale approach combining global homogenization and local refinement for multi-field analysis of high-temperature superconducting composite magnets

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 747-762页

作者： Hanxiao GUO Peifeng GAO Xingzhe WANG key laboratory of Mechanics on Western disaster and Environment of ministry of education Key Laboratory of Special Function Materials and Structure Design of Ministry of EducationCollege of Civil Engineering and MechanicsLanzhou UniversityLanzhou 730000China

Second-generation high-temperature superconducting(HTS)conductors,specifically rare earth-barium-copper-oxide(REBCO)coated conductor(CC)tapes,are promising candidates for high-energy and high-field superconducting *** respect to epoxy-impregnated REBCO composite magnets that comprise multilayer components,the thermomechanical characteristics of each component differ considerably under extremely low temperatures and strong electromagnetic *** numerical models include homogenized orthotropic models,which simplify overall field calculation but miss detailed multi-physics aspects,and full refinement(FR)ones that are thorough but computationally ***,we propose an extended multi-scale approach for analyzing the multi-field characteristics of an epoxy-impregnated composite magnet assembled by HTS pancake *** approach combines a global homogenization(GH)scheme based on the homogenized electromagnetic T-A model,a method for solving Maxwell's equations for superconducting materials based on the current vector potential T and the magnetic field vector potential A,and a homogenized orthotropic thermoelastic model to assess the electromagnetic and thermoelastic properties at the macroscopic *** then identify“dangerous regions”at the macroscopic scale and obtain finer details using a local refinement(LR)scheme to capture the responses of each component material in the HTS composite tapes at the mesoscopic *** results of the present GH-LR multi-scale approach agree well with those of the FR scheme and the experimental data in the literature,indicating that the present approach is accurate and *** proposed GH-LR multi-scale approach can serve as a valuable tool for evaluating the risk of failure in large-scale HTS composite magnets.

关键词： epoxy-impregnated high-temperature superconducting(HTS)magnet multi-scale method global homogenization(GH) local refinement(LR) multi-field analysis

Spalling characteristics of high-temperature treated granitic rock at different strain rates

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Journal of Rock Mechanics and Geotechnical engineering 2024年第4期16卷 1280-1288页

作者： L.F.Fan Q.H.Yang X.L.Du The key laboratory of Urban Security and disaster engineering of ministry of education Beijing University of TechnologyBeijing100124China

The dynamic spalling characteristics of rock are important for stability analysis in rock *** paper presented an experimental investigation on the dynamic spalling characteristics of granite with different temperatures and strain rates.A series of dynamic spalling tests with different impact velocities were conducted on thermally treated granite at different *** dynamic spalling strengths of granite with different temperatures and strain rates were determined.A model was proposed to correlate the dynamic spalling strength of granite,high temperature and strain *** results show that the spalling strength of granite decreases with increasing ***,the spalling strength of granite with a higher strain rate is larger than that with a lower strain *** proposed model can describe the relationship among dynamic spalling strength of granite,high temperature and strain rate.

关键词： Dynamic spalling characteristics High temperature Strain rate Dynamic loading Granite

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

Numerical investigation of hydro-morphodynamic characteristics of a cascading failure of landslide dams

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Journal of Mountain Science 2024年第6期21卷 1868-1885页

作者： ZHONG Qiming CHEN Lingchun MEI Shengyao SHAN Yibo WU Hao ZHAO Kunpeng Department of Geotechnical engineering Nanjing Hydraulic Research InstituteNanjing 210024China National key laboratory of Water disaster prevention Nanjing 210098China key laboratory of Reservoir and Dam safety of the ministry of Water Resources Nanjing 210029China

A cascading failure of landslide dams caused by strong earthquakes or torrential rains in mountainous river valleys can pose great threats to people’s lives,properties,and *** this study,based on the three-dimensional Reynoldsaveraged Navier-Stokes equations(RANS),the renormalization group(RNG)k-εturbulence model,suspended and bed load transport equations,and the instability discriminant formula of dam breach side slope,and the explicit finite volume method(FVM),a detailed numerical simulation model for calculating the hydro-morphodynamic characteristics of cascading dam breach process has been *** developed numerical model can simulate the breach hydrograph and the dam breach morphology evolution during the cascading failure process of landslide dams.A model test of the breaches of two cascading landslide dams has been used as the validation *** comparison of the calculated and measured results indicates that the breach hydrograph and the breach morphology evolution process of the upstream and downstream dams are generally consistent with each other,and the relative errors of the key breaching parameters,i.e.,the peak breach flow and the time to peak of each dam,are less than±5%.Further,the comparison of the breach hydrographs of the upstream and downstream dams shows that there is an amplification effect of the breach flood on the cascading landslide dam *** key parameters,i.e.,the distance between the upstream and the downstream dams,the river channel slope,and the downstream dam height,have been used to study the flood amplification *** parameter sensitivity analyses show that the peak breach flow at the downstream dam decreases with increasing distance between the upstream and the downstream dams,and the downstream dam ***,the peak breach flow at the downstream dam first increases and then decreases with steepening of the river channel *** the flood caused by the upstream dam failure flows to the

关键词： Cascading landslide dams Cascading dam failure process Detailed numerical simulation model Flood amplification effect Parameter sensitivity analyses

Intermittent disturbance mechanical behavior and fractional deterioration mechanical model of rock under complex true triaxial stress paths

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International Journal of Mining Science and Technology 2024年第1期34卷 117-136页

作者： Zhi Zheng Hongyu Xu Kai Zhang Guangliang Feng Qiang Zhang Yufei Zhao State key laboratory of Featured Metal Materials and Life-cycle safety for Composite Structures Key Laboratory of Disaster Prevention and Structural Safety of Ministry of EducationCollege of Civil Engineering and ArchitectureGuangxi UniversityNanning 530004China State key laboratory of Geomechanics and Geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China State key laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing 100080China State key laboratory for Geomechanics and Deep Underground engineering China University of Mining and TechnologyXuzhou 221116China

Mechanical excavation,blasting,adjacent rockburst and fracture slip that occur during mining excavation impose dynamic loads on the rock mass,leading to further fracture of damaged surrounding rock in three-dimensional high-stress and even causing ***,a novel complex true triaxial static-dynamic combined loading method reflecting underground excavation damage and then frequent intermittent disturbance failure is *** triaxial static compression and intermittent disturbance tests are carried out on *** effects of intermediate principal stress and amplitude on the strength characteristics,deformation characteristics,failure characteristics,and precursors of monzogabbro are analyzed,intermediate principal stress and amplitude increase monzogabbro strength and tensile fracture *** increases in microseismic parameters during rock loading can be precursors for intermittent rock *** on the experimental result,the new damage fractional elements and method with considering crack initiation stress and crack unstable stress as initiation and acceleration condition of intermittent disturbance irreversible deformation are proposed.A novel three-dimensional disturbance fractional deterioration model considering the intermediate principal stress effect and intermittent disturbance damage effect is established,and the model predicted results align well with the experimental *** sensitivity of stress states and model parameters is further explored,and the intermittent disturbance behaviors at different f are *** study provides valuable theoretical bases for the stability analysis of deep mining engineering under dynamic loads.

关键词： True triaxial static and disturbance test Mechanical properties Failure mechanism and precursor Intermittent disturbance effect Fractional mechanical model

Cross-linkedα-amylase aggregates on Fe3O4 magnetic nanoparticles modified with polydopamine/polyethyleneimine for efficient hydrolysis of starch

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Particuology 2024年第7期90卷 98-105页

作者： Jiandong Cui Xiuming Tang Qingqing Ma Yuyan Chang Qunli Zhang Shiru Jia State key laboratory of Food Nutrition and safety Laboratory of Industrial Fermentation MicrobiologyMinistry of EducationTianjin University of Science and TechnologyTianjin 300457China key laboratory of Biomass Chemical engineering of ministry of education Zhejiang UniversityHangzhou 310027China

In this workα-amylase was immobilized on magnetic Fe3O4 nanoparticles with polyethylenimine(PEI)/polydopamine(PDA)coating or 3-aminopropyl triethoxysilane(APTES)for the first time via adsorption–precipitation–*** with the freeα-amylase,the resultant magnetic cross-linkedα-amylase aggregates(PEI/PDA-M-CLEAs and N-M-CLEAs)exhibited excellent thermal and storage stability as well as pH *** storage at 25°C for 60 days,freeα-amylase only retained 60%of its initial activity,while PEI/PDA-M-CLEAs and N-M-CLEAs retained 80%and 78%of their initial activities,***,N-M-CLEAs and PEI/PDA-M-CLEAs showed good *** 6 repeated uses,PEI/PDA-M-CLEAs and N-M-CLEAs still maintained 65%and 62%of their initial activities,***,PEI/PDA-M-CLEAs and N-M-CLEAs exhibited higher starch hydrolysis efficiency than freeα-*** maximum dextrose equivalent(DE)values of starch hydrolysis by PEI/PDA-M-CLEAs and N-M-CLEAs reached 29.24%and 28.79%within 90 min,***,the maximum DE values of starch hydrolysis by the freeα-amylase was only 27.89%even in 150 *** magnetic cross-linkedα-amylase aggregates could be introduced as effective biocatalyst for industrial applications in production of maltose syrups.

关键词： α-amylase Magnetic nanoparticles Functional modification Magnetic cross-linked enzyme aggregates Hydrolysis of starch