A three-dimensional numerical model of laser-arc hybrid plasma for aluminum alloy fillet joints is developed in this study.This mod-el accounts for the geometric complexity of fillet joints,the physical properties of ...A three-dimensional numerical model of laser-arc hybrid plasma for aluminum alloy fillet joints is developed in this study.This mod-el accounts for the geometric complexity of fillet joints,the physical properties of shielding gases with varying He-Ar ratios,and the coupling between arc plasma and laser-induced metal plume.The accuracy of the model is validated using a high-speed camera.The effects of varying He contents in the shielding gas on both the temperature and flow velocity of hybrid plasma,as well as the distribu-tion of laser-induced metal vapor mass,were investigated separately.The maximum temperature and size of arc plasma decrease as the He volume ratio increases,the arc distribution becomes more concentrated,and its flow velocity initially decreases and then sharply increases.At high helium content,both the flow velocity of hybrid plasma and metal vapor are high,the metal vapor is con-centrated on the right side of keyhole,and its flow appears chaotic.The flow state of arc plasma is most stable when the shielding gas consists of 50%He+50%Ar.展开更多
Polymer flooding is an important means of improving oil recovery and is widely used in Daqing,Xinjiang,and Shengli oilfields,China.Different from conventional injection media such as water and gas,viscoelastic polymer...Polymer flooding is an important means of improving oil recovery and is widely used in Daqing,Xinjiang,and Shengli oilfields,China.Different from conventional injection media such as water and gas,viscoelastic polymer solutions exhibit non-Newtonian and nonlinear flow behavior including shear thinning and shear thickening,polymer convection,diffusion,adsorption,retention,inaccessible pore volume,and reduced effective permeability.However,available well test model of polymer flooding wells generally simplifies these characteristics on pressure transient response,which may lead to inaccurate results.This work proposes a novel two-phase numerical well test model to better describe the polymer viscoelasticity and nonlinear flow behavior.Different influence factors that related to near-well blockage during polymer flooding process,including the degree of blockage(inner zone permeability),the extent of blockage(composite radius),and polymer flooding front radius are explored to investigate these impacts on bottom hole pressure responses.Results show that polymer viscoelasticity has a significant impact on the transitional flow segment of type curves,and the effects of near-well formation blockage and polymer concentration distribution on well test curves are very similar.Thus,to accurately interpret the degree of near-well blockage in injection wells,it is essential to first eliminate the influence of polymer viscoelasticity.Finally,a field case is comprehensively analyzed and discussed to illustrate the applicability of the proposed model.展开更多
Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthqu...Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthquakes.However,no previous studies have assessed the mechanisms underlying seismic failure in rock slopes.In this study,large-scale shaking table tests and numerical simulations were conducted to delineate the seismic failure mechanism in terms of acceleration,displacement,and earth pressure responses combined with shattering failure phenomena.The results reveal that acceleration response mutations usually occur within weak interlayers owing to their inferior performance,and these mutations may transform into potential sliding surfaces,thereby intensifying the nonlinear seismic response characteristics.Cumulative permanent displacements at the internal corners of the berms can induce quasi-rigid displacements at the external corners,leading to greater permanent displacements at the internal corners.Therefore,the internal corners are identified as the most susceptible parts of the slope.In addition,the concept of baseline offset was utilized to explain the mechanism of earth pressure responses,and the result indicates that residual earth pressures at the internal corners play a dominant role in causing deformation or shattering damage.Four evolutionary deformation phases characterize the processes of seismic responses and shattering failure of the bedding parallel stepped rock slope,i.e.the formation of tensile cracks at the internal corners of the berm,expansion of tensile cracks and bedding surface dislocation,development of vertical tensile cracks at the rear edge,and rock mass slipping leading to slope instability.Overall,this study provides a scientific basis for the seismic design of engineering slopes and offers valuable insights for further studies on preventing seismic disasters in bedding parallel stepped rock slopes.展开更多
Rock is geometrically and mechanically multiscale in nature,and the traditional phenomenological laws at the macroscale cannot render a quantitative relationship between microscopic damage of rocks and overall rock st...Rock is geometrically and mechanically multiscale in nature,and the traditional phenomenological laws at the macroscale cannot render a quantitative relationship between microscopic damage of rocks and overall rock structural degradation.This may lead to problems in the evaluation of rock structure stability and safe life.Multiscale numerical modeling is regarded as an effective way to gain insight into factors affecting rock properties from a cross-scale view.This study compiles the history of theoretical developments and numerical techniques related to rock multiscale issues according to different modeling architectures,that is,the homogenization theory,the hierarchical approach,and the concurrent approach.For these approaches,their benefits,drawbacks,and application scope are underlined.Despite the considerable attempts that have been made,some key issues still result in multiple challenges.Therefore,this study points out the perspectives of rock multiscale issues so as to provide a research direction for the future.The review results show that,in addition to numerical techniques,for example,high-performance computing,more attention should be paid to the development of an advanced constitutive model with consideration of fine geometrical descriptions of rock to facilitate solutions to multiscale problems in rock mechanics and rock engineering.展开更多
Software systems are vulnerable to security breaches as they expand in complexity and functionality.The confidentiality,integrity,and availability of data are gravely threatened by flaws in a system’s design,implemen...Software systems are vulnerable to security breaches as they expand in complexity and functionality.The confidentiality,integrity,and availability of data are gravely threatened by flaws in a system’s design,implementation,or configuration.To guarantee the durability&robustness of the software,vulnerability identification and fixation have become crucial areas of focus for developers,cybersecurity experts and industries.This paper presents a thorough multi-phase mathematical model for efficient patch management and vulnerability detection.To uniquely model these processes,the model incorporated the notion of the learning phenomenon in describing vulnerability fixation using a logistic learning function.Furthermore,the authors have used numerical methods to approximate the solution of the proposed framework where an analytical solution is difficult to attain.The suggested systematic architecture has been demonstrated through statistical analysis using patch datasets,which offers a solid basis for the research conclusions.According to computational research,learning dynamics improves security response and results in more effective vulnerability management.The suggested model offers a systematic approach to proactive vulnerability mitigation and has important uses in risk assessment,software maintenance,and cybersecurity.This study helps create more robust software systems by increasing patch management effectiveness,which benefits developers,cybersecurity experts,and sectors looking to reduce security threats in a growing digital world.展开更多
With the increasing development of deepburied engineering projects,rockburst disasters have become a frequent concern.Studies have indicated that tunnel diameter is a critical factor influencing the occurrence of rock...With the increasing development of deepburied engineering projects,rockburst disasters have become a frequent concern.Studies have indicated that tunnel diameter is a critical factor influencing the occurrence of rockbursts.To investigate the influence of tunnel diameter on the deformation and failure characteristics of surrounding rock,large-sized rocklike gypsum specimens were tested using a selfdeveloped true triaxial rockburst loading system containing circular tunnels with three different diameters(D=0.07 m,0.11 m,and 0.15 m).Acoustic emission monitoring,together with a miniature intelligent camera,was employed to analyze the entire process,focusing on macroscopic failure patterns,fragment characteristics,and underlying failure mechanisms.In addition,theoretical analyses were carried out and combined with numerical simulations to investigate the differences in energy evolution associated with rockburst physical models.The results indicate that:(1)The rockburst process with different tunnel diameters consistently evolved through three distinct stages—initial particle ejection,crack propagation accompanied by flake spalling,and,finally,fragment ejection leading to the formation of a‘V'-shaped notch.(2)Increasing tunnel diameter reduces rockburst failure load while increasing surrounding rock damage extent,total mass and average size of ejected fragments.Additionally,shear failure proportion decreases with tensile failure becoming increasingly dominant.(3)Larger tunnel diameters reduce the attenuation rate of elastic strain energy,thereby expanding the zone of elastic strain energy accumulation and disturbance and creating conditions for larger volume rockburst.(4)Larger tunnel diameters result in a smaller principal stress ratio at equivalent distances in the surrounding rock,indicating a higher likelihood of tensile failure.(5)Numerical analyses further reveal that larger tunnel diameters reduce the maximum elastic strain energy density around the tunnel,lowering the energy released per unit volume of rockburst fragments and their ejection velocities.However,both the total failure volume and overall energy release from rockburst increase.Model experiments with different tunnel diameters are of great significance for optimizing engineering design and parameter selection,as well as guiding tunnel construction under complex geological conditions.展开更多
The nozzle is a critical component responsible for generating most of the net thrust in a scramjet engine.The quality of its design directly affects the performance of the entire propulsion system.However,most turbule...The nozzle is a critical component responsible for generating most of the net thrust in a scramjet engine.The quality of its design directly affects the performance of the entire propulsion system.However,most turbulence models struggle to make accurate predictions for subsonic and supersonic flows in nozzles.In this study,we explored a novel model,the algebraic stress model k-kL-ARSM+J,to enhance the accuracy of turbulence numerical simulations.This new model was used to conduct numerical simulations of the design and off-design performance of a 3D supersonic asymmetric truncated nozzle designed in our laboratory,with the aim of providing a realistic pattern of changes.The research indicates that,compared to linear eddy viscosity turbulence models such as k-kL and shear stress transport(SST),the k-kL-ARSM+J algebraic stress model shows better accuracy in predicting the performance of supersonic nozzles.Its predictions were identical to the experimental values,enabling precise calculations of the nozzle.The performance trends of the nozzle are as follows:as the inlet Mach number increases,both thrust and pitching moment increase,but the rate of increase slows down.Lift peaks near the design Mach number and then rapidly decreases.With increasing inlet pressure,the nozzle thrust,lift,and pitching moment all show linear growth.As the flight altitude rises,the internal flow field within the nozzle remains relatively consistent due to the same supersonic nozzle inlet flow conditions.However,external to the nozzle,the change in external flow pressure results in the nozzle exit transitioning from over-expanded to under-expanded,leading to a shear layer behind the nozzle that initially converges towards the nozzle center and then diverges.展开更多
Systematic bias is a type of model error that can affect the accuracy of data assimilation and forecasting that must be addressed.An online bias correction scheme called the sequential bias correction scheme(SBCS),was...Systematic bias is a type of model error that can affect the accuracy of data assimilation and forecasting that must be addressed.An online bias correction scheme called the sequential bias correction scheme(SBCS),was developed using the6 h average bias to correct the systematic bias during model integration.The primary purpose of this study is to investigate the impact of the SBCS in the high-resolution China Meteorological Administration Meso-scale(CMA-MESO)numerical weather prediction(NWP)model to reduce the systematic bias and to improve the data assimilation and forecast results through this method.The SBCS is improved upon and applied to the CMA-MESO 3-km model in this study.Four-week sequential data assimilation and forecast experiments,driven by rapid update and cycling(RUC),were conducted for the period from 2–29 May 2022.In terms of the characteristics of systematic bias,both the background and analysis show diurnal bias,and these large biases are affected by complex underlying surfaces(e.g.,oceans,coasts,and mountains).After the application of the SBCS,the results of the data assimilation show that the SBCS can reduce the systematic bias of the background and yield a neutral to slightly positive result for the analysis fields.In addition,the SBCS can reduce forecast errors and improve forecast results,especially for surface variables.The above results indicate that this scheme has good prospects for high-resolution regional NWP models.展开更多
Oilfields worldwide are increasingly grappling with challenges such as early water breakthrough and high water production,yet direct,targeted solutions remain elusive.In recent years,chemical flooding techniques desig...Oilfields worldwide are increasingly grappling with challenges such as early water breakthrough and high water production,yet direct,targeted solutions remain elusive.In recent years,chemical flooding techniques designed for tertiary oil recovery have garnered significant attention,with microgel flooding emerging as a particularly prominent area of research.Despite its promise,the complex mechanisms underlying microgel flooding have been rarely investigated numerically.This study aims to address these gaps by characterizing the distribution of microgel concentration and viscosity within different pore structures.To enhance the accuracy of these characterizations,the viscosity of microgels is adjusted to account for the shear effects induced by flow rate and the swelling effects driven by salinity variations.The absolute permeability of the rock and the relative permeability of both oil and microgel are also analyzed to elucidate the mechanisms of microgel flooding.Additionally,a connectivity model is employed to achieve a quantitative representation of fluid flow capacity.The proposed model is validated through conceptual examples and applied to real oilfield blocks,demonstrating its accuracy and practical applicability.展开更多
The multi-scale modeling combined with the cohesive zone model(CZM)and the molecular dynamics(MD)method were preformed to simulate the crack propagation in NiTi shape memory alloys(SMAs).The metallographic microscope ...The multi-scale modeling combined with the cohesive zone model(CZM)and the molecular dynamics(MD)method were preformed to simulate the crack propagation in NiTi shape memory alloys(SMAs).The metallographic microscope and image processing technology were employed to achieve a quantitative grain size distribution of NiTi alloys so as to provide experimental data for molecular dynamics modeling at the atomic scale.Considering the size effect of molecular dynamics model on material properties,a reasonable modeling size was provided by taking into account three characteristic dimensions from the perspective of macro,meso,and micro scales according to the Buckinghamπtheorem.Then,the corresponding MD simulation on deformation and fracture behavior was investigated to derive a parameterized traction-separation(T-S)law,and then it was embedded into cohesive elements of finite element software.Thus,the crack propagation behavior in NiTi alloys was reproduced by the finite element method(FEM).The experimental results show that the predicted initiation fracture toughness is in good agreement with experimental data.In addition,it is found that the dynamics initiation fracture toughness increases with decreasing grain size and increasing loading velocity.展开更多
Shotcrete is one of the common solutions for shallow sliding.It works by forming a protective layer with high strength and cementing the loose soil particles on the slope surface to prevent shallow sliding.However,the...Shotcrete is one of the common solutions for shallow sliding.It works by forming a protective layer with high strength and cementing the loose soil particles on the slope surface to prevent shallow sliding.However,the solidification time of conventional cement paste is long when shotcrete is used to treat cohesionless soil landslide.The idea of reinforcing slope with polyurethane solidified soil(i.e.,mixture of polyurethane and sand)was proposed.Model tests and finite element analysis were carried out to study the effectiveness of the proposed new method on the emergency treatment of cohesionless soil landslide.Surcharge loading on the crest of the slope was applied step by step until landslide was triggered so as to test and compare the stability and bearing capacity of slope models with different conditions.The simulated slope displacements were relatively close to the measured results,and the simulated slope deformation characteristics were in good agreement with the observed phenomena,which verifies the accuracy of the numerical method.Under the condition of surcharge loading on the crest of the slope,the unreinforced slope slid when the surcharge loading exceeded 30 k Pa,which presented a failure mode of local instability and collapse at the shallow layer of slope top.The reinforced slope remained stable even when the surcharge loading reached 48 k Pa.The displacement of the reinforced slope was reduced by more than 95%.Overall,this study verifies the effectiveness of polyurethane in the emergency treatment of cohesionless soil landslide and should have broad application prospects in the field of geological disasters concerning the safety of people's live.展开更多
In the past few decades,the navigation performance of ships and structures in ice-covered waters has not been fully studied,especially the influence of ice mechanical properties on icebreaking ability.Ice bending stre...In the past few decades,the navigation performance of ships and structures in ice-covered waters has not been fully studied,especially the influence of ice mechanical properties on icebreaking ability.Ice bending strength is a key ice parameter for predicting ship ice loads,and accurate ice bending strength is also the key to scaling model tests results to real ship.However,numerical simulation studies on model ice bending strength of ice tanks are often neglected.In this paper,an explicit finite element method model is used to simulate the ice cantilever beam test,and the failure load and bending strength of the ice are obtained.In this model,the Tsai-Wu failure criterion is used as the material constitutive model,and the required simulation parameters are obtained from the model ice test in ice tank.Parameter sensitivity analysis shows that the cantilever beam size of the model ice has a significant effect on the flexural strength.The results show that proper rounding at the root of the cantilever beam is beneficial to reduce stress concentration and obtain more accurate bending strength;the thickness,width and length of the cantilever beam should conform to a certain ratio,and consistent with the ITTC recommended reference.Therefore,the results of this study can promote model ice experiments and numerical studies and provide ice strength data support for ship design and polar ship maneuvering.展开更多
To ensure the operational safety of railways in the landslide-prone areas of mountainous regions,a large-scale model test and numerical simulation were conducted to study the bending moment distribution,internal force...To ensure the operational safety of railways in the landslide-prone areas of mountainous regions,a large-scale model test and numerical simulation were conducted to study the bending moment distribution,internal force distribution,deformation development,and crack propagation characteristics of a framed anti-sliding structure(FAS)under landslide thrust up to the point of failure.Results show that the maximum bending moment and its increase rate in the fore pile are greater than those in the rear pile,with the maximum bending moment of the fore pile approximately 1.1 times that of the rear pile.When the FAS fails,the displacement at the top of the fore pile is significantly greater,about 1.27 times that of the rear pile in the experiment.Major cracks develop at locations corresponding to the peak bending moments.Small transverse cracks initially appear on the upper surface at the intersection between the primary beam and rear pile and then spread to the side of the structure.At the failure stage,major cracks are observed at the pil-beam intersections and near the anchor points.Strengthening flexural stiffness at intersections where major cracks occur can improve the overall thrust-deformation coordination of the FAS,thereby maximizing its performance.展开更多
The seepage of groundwater and the strain-softening of rock mass in a submarine tunnel expand the plastic region of rock,thereby affecting its overall stability.It is therefore essential to study the stress and strain...The seepage of groundwater and the strain-softening of rock mass in a submarine tunnel expand the plastic region of rock,thereby affecting its overall stability.It is therefore essential to study the stress and strain fields in the rocks surrounding the submarine tunnel by considering the coupled effect of strainsoftening and seepage.However,the evolution equation for the hydro-mechanical parameters in the existing fully coupled solution is a uniform equation that is unable to reproduce the characteristics of rock mass in practice.In this study,an updated numerical procedure for the submarine tunnel is derived by coupling strain-softening and seepage effect based on the experimental results.According to the hydro-mechanical coupling theory,the hydro-mechanical parameters such as elastic modulus,Poisson's ratio,Biot's coefficient and permeability coefficient of rocks are characterized by the fitting equations derived from the experimental data.Then,the updated numerical procedure is deduced with the governing equations,boundary conditions,seepage equations and fitting equations.The updated numerical procedure is verified accurately compared with the previous analytical solution.By utilizing the updated numerical procedure,the characteristics of stress field and the influences of initial pore water pressure,Biot's coefficient,and permeability coefficient on the stress,displacement and water-inflow of the surrounding rocks are discussed.Regardless of the variations in hydro-mechanical parameters,the stress distribution has a similar trend.The initial permeability coefficient exerts the most significant influence on the stress field.With the increases in initial pore water pressure and Biot's coefficient,the plastic region expands,and the water-inflow and displacement increase accordingly.Given the fact that the stability of the tunnel is more sensitive to the seepage force controlled by the hydraulic parameters,it is suggested to dewater the ground above the submarine tunnel to control the initial pore water pressure.展开更多
A three-dimensional coupled sea ice-ice shelf-ocean numerical model is developed for the Prydz Bay,Antarctica,using the Regional Ocean Modeling System with a grid resolution of approximately 2 km.The influence of the ...A three-dimensional coupled sea ice-ice shelf-ocean numerical model is developed for the Prydz Bay,Antarctica,using the Regional Ocean Modeling System with a grid resolution of approximately 2 km.The influence of the grounding giant iceberg D15 on the distribution of sea ice and polynyas in the Prydz Bay is analyzed through two numerical experiments.Iceberg D15,grounded off the western edge of the West Ice Shelf(WIS),obstructs the southwestward transport of sea ice along the east coast of Prydz Bay,causing sea ice to accumulate to the east of the iceberg and form multi-year fast ice.Grounding of Iceberg D15 also decreases sea ice coverage off its south edge and creates ice-free openings in spring near Davis Station and Zhongshan Station,facilitating the accessibility of vessels to the research stations.These simulated sea ice patterns closely match current satellite observations.When Iceberg D15 is removed,the previously blocked sea ice north of the iceberg,which moved westward,shifts southwesterly along the coastline,leading to a reduction in sea ice thickness during winter and spring,as well as lower sea ice concentrations in spring across large areas north and west of the iceberg.In contrast,the sea ice thickness increases considerably southwest of the WIS,extending to the front of the Amery Ice Shelf during seasons covered by sea ice.The increase in sea ice concentration can also extend to as far as 75°E in spring.Without Iceberg D15,which previously contributed to the ice barrier of Barrier Polynya(BP),the shape of BP changes,the area of BP and Davis Polynya(DP)decreases,and the polynya off the northwest edge of the WIS near 83°E expands.These polynya patterns are much similar to the satellite remote sensing observations before Iceberg D15 was grounded.From April to October,the total area of BP and DP decreases by 2.83×10^(4)km^(2)(60%)and 2.20×10^(3)km^(2)(20%),respectively,while the total sea ice production decreases by 4.11×10^(10)m^(3)(66%)and 1.52×10^(10)m^(3)(52%)compared to the experiment with iceberg.These results indicate the substantial effects of grounding giant icebergs on the spatio-temporal distribution of sea ice,the area of polynyas,and sea ice production.High-resolution Antarctic coastal numerical models,typically with grid scales of kilometers,are sufficient to represent large icebergs,and adding the grounding giant icebergs is crucial for producing realistic simulations of sea ice and polynyas.展开更多
Both the complex geometrical morphology of rough-walled rock fractures and the nonlinearity of fluid flow contribute to resistance in fluid flow through rock fractures.The interactions of the shear-flow process furthe...Both the complex geometrical morphology of rough-walled rock fractures and the nonlinearity of fluid flow contribute to resistance in fluid flow through rock fractures.The interactions of the shear-flow process further complicate the characterisation of flow behaviours in rock fractures.In this study,an improved friction factor model involving both the effects of viscous and inertial forces is presented based on the Forchheimer equation.The model incorporates two key variables,i.e.Reynolds number and relative roughness,which reflect the effects of flow regimes and fracture roughness,respectively.The changes in geometrical parameters induced by shearing are considered,with the peak asperity height predicted through a correlation with post-peak roughness degradation.The hydraulic aperture during shearing is estimated using a suggested equation that accounts for the mobilised contact area ratio and variable aperture distribution.The parametric sensitivity analysis reveals that shear-induced changes in fracture geometry enhance the flow nonlinearity in rock fractures.The model performs well in predicting the friction factor based on two validation criteria.Then,the proposed friction factor model is incorporated into the three-dimensional distinct element code(3DEC)in the form of the Darcy-Weisbach equation.Coupled with the numerically implemented mechanical model and hydraulic aperture prediction model,numerical simulations of coupled shear-flow processes in single rock fractures are conducted.The simulation outcomes are validated through comparison with the experimental results,showing acceptable agreement and demonstrating that the numerical model is capable of accurately evaluating the hydro-mechanical coupling behaviour during the shearing of rock fractures.展开更多
A self-centering bridge bent equipped with energy-dissipation(ED)beams is proposed.Quasi-static tests are conducted on self-centering bridge bents,both with and without ED beams,to validate the accuracy of the corresp...A self-centering bridge bent equipped with energy-dissipation(ED)beams is proposed.Quasi-static tests are conducted on self-centering bridge bents,both with and without ED beams,to validate the accuracy of the corresponding numerical models.The effects of various param-eters,such as the web area of ED beams,prestressing force of tendons,tendon arrangements,and number of column segments,on the seismic performance of self-centering bridge bents with ED beams are evaluated using the validated numerical model.The results demonstrate that the nu-merical models accurately replicate the quasi-static test results,with average errors in the lateral force remaining below 9.6%.The web area of ED beams significantly affects the strength,cumulative energy dissipation,and relative self-centering index(RSI)of the self-centering bridge bents.Increasing the prestressing force enhances the lateral force and self-centering capability of the bridge bents but has minimal effect on their ED capacity.Reducing the num-ber of segments in each column enhances the lateral force and cumulative hysteretic energy dissipation of the self-centering bridge bents while exerting an insignificant effect on the RSI.Thus,the proposed novel system is highly suitable for doubleor multicolumn piers supporting bridges in regions prone to strong earthquakes.展开更多
The paper considers a catastrophic event-the eruption of Hunga Tonga-Hunga Ha’apai volcano on January 15,2022.The process of preparation and eruption of Hunga Tonga volcano generated tsunami waves that were observed ...The paper considers a catastrophic event-the eruption of Hunga Tonga-Hunga Ha’apai volcano on January 15,2022.The process of preparation and eruption of Hunga Tonga volcano generated tsunami waves that were observed throughout the World Ocean.This event was notable for its unprecedented global impact and the early appearance of tsunami waves at distant coastal stations.So,the first waves at tide gauge stations in Chile and Peru were recorded 4 hours earlier than the arrival time of tsunami waves to the tide gauge after the eruption of Tonga volcano.Two mechanisms are possible for the generation of early tsunami waves:acoustic Lamb waves generated by a volcanic explosion and submarine landslides that occurred on the slopes of the volcano during the preparatory phase of the eruption.In this study,numerical simulation of various pre-eruption landslide scenarios on the slope of Hunga Tonga volcano is carried out in an attempt to explain these early tsunami waves.Under computation the elastoplastic model of landslide was taken into account.Wave characteristics of a tsunami on the coast of Chile and Peru generated by a landslide process on a volcanic slope are obtained.A detailed comparison of virtual tide gauge data with observational ones is used to validate this model.The results obtained can be used to improve early warning systems.展开更多
Ensuring the stability of the surrounding rock mass is of great importance during the construction of a large underground powerhouse.The presence of unfavorable structural planes within the rock mass,such as faults,ca...Ensuring the stability of the surrounding rock mass is of great importance during the construction of a large underground powerhouse.The presence of unfavorable structural planes within the rock mass,such as faults,can lead to substantial deformation and subsequent collapse.A series of in situ experiments and discrete element numerical simulations have been conducted to gain insight into the progressive failure behavior and deformation response of rocks in relation to controlled collapse scenarios involving gently inclined faults.First,the unloading damage evolution process of the surrounding rock mass is characterized by microscopic analysis using microseismic(MS)data.Second,the moment tensor inversion method is used to elucidate the temporal distribution of MS event fracture types in the surrounding rock mass.During the development stage of the collapse,numerous tensile fracture events occur,while a few shear fractures corresponding to structural plane dislocation precede their occurrence.The use of the digital panoramic borehole camera,acoustic wave test,and numerical simulation revealed that gently inclined faults and deep cracks at a certain depth from the cavern periphery are the primary factors contributing to rock collapse.These results provide a valuable case study that can help anticipate and mitigate fault-slip collapse incidents while providing practical insights for underground cave excavation.展开更多
This paper focuses on the numerical solution of a tumor growth model under a data-driven approach.Based on the inherent laws of the data and reasonable assumptions,an ordinary differential equation model for tumor gro...This paper focuses on the numerical solution of a tumor growth model under a data-driven approach.Based on the inherent laws of the data and reasonable assumptions,an ordinary differential equation model for tumor growth is established.Nonlinear fitting is employed to obtain the optimal parameter estimation of the mathematical model,and the numerical solution is carried out using the Matlab software.By comparing the clinical data with the simulation results,a good agreement is achieved,which verifies the rationality and feasibility of the model.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52375340,51975263,52405366).
文摘A three-dimensional numerical model of laser-arc hybrid plasma for aluminum alloy fillet joints is developed in this study.This mod-el accounts for the geometric complexity of fillet joints,the physical properties of shielding gases with varying He-Ar ratios,and the coupling between arc plasma and laser-induced metal plume.The accuracy of the model is validated using a high-speed camera.The effects of varying He contents in the shielding gas on both the temperature and flow velocity of hybrid plasma,as well as the distribu-tion of laser-induced metal vapor mass,were investigated separately.The maximum temperature and size of arc plasma decrease as the He volume ratio increases,the arc distribution becomes more concentrated,and its flow velocity initially decreases and then sharply increases.At high helium content,both the flow velocity of hybrid plasma and metal vapor are high,the metal vapor is con-centrated on the right side of keyhole,and its flow appears chaotic.The flow state of arc plasma is most stable when the shielding gas consists of 50%He+50%Ar.
基金supported by the National Natural Science Foundation of China(52104049)the Young Elite Scientist Sponsorship Program by Beijing Association for Science and Technology(BYESS2023262)。
文摘Polymer flooding is an important means of improving oil recovery and is widely used in Daqing,Xinjiang,and Shengli oilfields,China.Different from conventional injection media such as water and gas,viscoelastic polymer solutions exhibit non-Newtonian and nonlinear flow behavior including shear thinning and shear thickening,polymer convection,diffusion,adsorption,retention,inaccessible pore volume,and reduced effective permeability.However,available well test model of polymer flooding wells generally simplifies these characteristics on pressure transient response,which may lead to inaccurate results.This work proposes a novel two-phase numerical well test model to better describe the polymer viscoelasticity and nonlinear flow behavior.Different influence factors that related to near-well blockage during polymer flooding process,including the degree of blockage(inner zone permeability),the extent of blockage(composite radius),and polymer flooding front radius are explored to investigate these impacts on bottom hole pressure responses.Results show that polymer viscoelasticity has a significant impact on the transitional flow segment of type curves,and the effects of near-well formation blockage and polymer concentration distribution on well test curves are very similar.Thus,to accurately interpret the degree of near-well blockage in injection wells,it is essential to first eliminate the influence of polymer viscoelasticity.Finally,a field case is comprehensively analyzed and discussed to illustrate the applicability of the proposed model.
基金supported by the National Natural Science Foundation of China (Grant No.52108361)the Sichuan Science and Technology Program of China (Grant No.2023YFS0436)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project (Grant No.SKLGP2022Z015).
文摘Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthquakes.However,no previous studies have assessed the mechanisms underlying seismic failure in rock slopes.In this study,large-scale shaking table tests and numerical simulations were conducted to delineate the seismic failure mechanism in terms of acceleration,displacement,and earth pressure responses combined with shattering failure phenomena.The results reveal that acceleration response mutations usually occur within weak interlayers owing to their inferior performance,and these mutations may transform into potential sliding surfaces,thereby intensifying the nonlinear seismic response characteristics.Cumulative permanent displacements at the internal corners of the berms can induce quasi-rigid displacements at the external corners,leading to greater permanent displacements at the internal corners.Therefore,the internal corners are identified as the most susceptible parts of the slope.In addition,the concept of baseline offset was utilized to explain the mechanism of earth pressure responses,and the result indicates that residual earth pressures at the internal corners play a dominant role in causing deformation or shattering damage.Four evolutionary deformation phases characterize the processes of seismic responses and shattering failure of the bedding parallel stepped rock slope,i.e.the formation of tensile cracks at the internal corners of the berm,expansion of tensile cracks and bedding surface dislocation,development of vertical tensile cracks at the rear edge,and rock mass slipping leading to slope instability.Overall,this study provides a scientific basis for the seismic design of engineering slopes and offers valuable insights for further studies on preventing seismic disasters in bedding parallel stepped rock slopes.
基金National Natural Science Foundation of China,Grant/Award Numbers:52192691,52192690。
文摘Rock is geometrically and mechanically multiscale in nature,and the traditional phenomenological laws at the macroscale cannot render a quantitative relationship between microscopic damage of rocks and overall rock structural degradation.This may lead to problems in the evaluation of rock structure stability and safe life.Multiscale numerical modeling is regarded as an effective way to gain insight into factors affecting rock properties from a cross-scale view.This study compiles the history of theoretical developments and numerical techniques related to rock multiscale issues according to different modeling architectures,that is,the homogenization theory,the hierarchical approach,and the concurrent approach.For these approaches,their benefits,drawbacks,and application scope are underlined.Despite the considerable attempts that have been made,some key issues still result in multiple challenges.Therefore,this study points out the perspectives of rock multiscale issues so as to provide a research direction for the future.The review results show that,in addition to numerical techniques,for example,high-performance computing,more attention should be paid to the development of an advanced constitutive model with consideration of fine geometrical descriptions of rock to facilitate solutions to multiscale problems in rock mechanics and rock engineering.
基金supported by grants received by the first author and third author from the Institute of Eminence,Delhi University,Delhi,India,as part of the Faculty Research Program via Ref.No./IoE/2024-25/12/FRP.
文摘Software systems are vulnerable to security breaches as they expand in complexity and functionality.The confidentiality,integrity,and availability of data are gravely threatened by flaws in a system’s design,implementation,or configuration.To guarantee the durability&robustness of the software,vulnerability identification and fixation have become crucial areas of focus for developers,cybersecurity experts and industries.This paper presents a thorough multi-phase mathematical model for efficient patch management and vulnerability detection.To uniquely model these processes,the model incorporated the notion of the learning phenomenon in describing vulnerability fixation using a logistic learning function.Furthermore,the authors have used numerical methods to approximate the solution of the proposed framework where an analytical solution is difficult to attain.The suggested systematic architecture has been demonstrated through statistical analysis using patch datasets,which offers a solid basis for the research conclusions.According to computational research,learning dynamics improves security response and results in more effective vulnerability management.The suggested model offers a systematic approach to proactive vulnerability mitigation and has important uses in risk assessment,software maintenance,and cybersecurity.This study helps create more robust software systems by increasing patch management effectiveness,which benefits developers,cybersecurity experts,and sectors looking to reduce security threats in a growing digital world.
基金funded by the National Natural Science Foundation of China(Nos.42077228,52174085)。
文摘With the increasing development of deepburied engineering projects,rockburst disasters have become a frequent concern.Studies have indicated that tunnel diameter is a critical factor influencing the occurrence of rockbursts.To investigate the influence of tunnel diameter on the deformation and failure characteristics of surrounding rock,large-sized rocklike gypsum specimens were tested using a selfdeveloped true triaxial rockburst loading system containing circular tunnels with three different diameters(D=0.07 m,0.11 m,and 0.15 m).Acoustic emission monitoring,together with a miniature intelligent camera,was employed to analyze the entire process,focusing on macroscopic failure patterns,fragment characteristics,and underlying failure mechanisms.In addition,theoretical analyses were carried out and combined with numerical simulations to investigate the differences in energy evolution associated with rockburst physical models.The results indicate that:(1)The rockburst process with different tunnel diameters consistently evolved through three distinct stages—initial particle ejection,crack propagation accompanied by flake spalling,and,finally,fragment ejection leading to the formation of a‘V'-shaped notch.(2)Increasing tunnel diameter reduces rockburst failure load while increasing surrounding rock damage extent,total mass and average size of ejected fragments.Additionally,shear failure proportion decreases with tensile failure becoming increasingly dominant.(3)Larger tunnel diameters reduce the attenuation rate of elastic strain energy,thereby expanding the zone of elastic strain energy accumulation and disturbance and creating conditions for larger volume rockburst.(4)Larger tunnel diameters result in a smaller principal stress ratio at equivalent distances in the surrounding rock,indicating a higher likelihood of tensile failure.(5)Numerical analyses further reveal that larger tunnel diameters reduce the maximum elastic strain energy density around the tunnel,lowering the energy released per unit volume of rockburst fragments and their ejection velocities.However,both the total failure volume and overall energy release from rockburst increase.Model experiments with different tunnel diameters are of great significance for optimizing engineering design and parameter selection,as well as guiding tunnel construction under complex geological conditions.
基金supported by the Zhejiang Provincial Key Research and Development Program of China(No.2020C01020).
文摘The nozzle is a critical component responsible for generating most of the net thrust in a scramjet engine.The quality of its design directly affects the performance of the entire propulsion system.However,most turbulence models struggle to make accurate predictions for subsonic and supersonic flows in nozzles.In this study,we explored a novel model,the algebraic stress model k-kL-ARSM+J,to enhance the accuracy of turbulence numerical simulations.This new model was used to conduct numerical simulations of the design and off-design performance of a 3D supersonic asymmetric truncated nozzle designed in our laboratory,with the aim of providing a realistic pattern of changes.The research indicates that,compared to linear eddy viscosity turbulence models such as k-kL and shear stress transport(SST),the k-kL-ARSM+J algebraic stress model shows better accuracy in predicting the performance of supersonic nozzles.Its predictions were identical to the experimental values,enabling precise calculations of the nozzle.The performance trends of the nozzle are as follows:as the inlet Mach number increases,both thrust and pitching moment increase,but the rate of increase slows down.Lift peaks near the design Mach number and then rapidly decreases.With increasing inlet pressure,the nozzle thrust,lift,and pitching moment all show linear growth.As the flight altitude rises,the internal flow field within the nozzle remains relatively consistent due to the same supersonic nozzle inlet flow conditions.However,external to the nozzle,the change in external flow pressure results in the nozzle exit transitioning from over-expanded to under-expanded,leading to a shear layer behind the nozzle that initially converges towards the nozzle center and then diverges.
基金supported by the National Natural Science Foundation of China(Grant Nos.U2242213,U2142213,42305167,42175105)。
文摘Systematic bias is a type of model error that can affect the accuracy of data assimilation and forecasting that must be addressed.An online bias correction scheme called the sequential bias correction scheme(SBCS),was developed using the6 h average bias to correct the systematic bias during model integration.The primary purpose of this study is to investigate the impact of the SBCS in the high-resolution China Meteorological Administration Meso-scale(CMA-MESO)numerical weather prediction(NWP)model to reduce the systematic bias and to improve the data assimilation and forecast results through this method.The SBCS is improved upon and applied to the CMA-MESO 3-km model in this study.Four-week sequential data assimilation and forecast experiments,driven by rapid update and cycling(RUC),were conducted for the period from 2–29 May 2022.In terms of the characteristics of systematic bias,both the background and analysis show diurnal bias,and these large biases are affected by complex underlying surfaces(e.g.,oceans,coasts,and mountains).After the application of the SBCS,the results of the data assimilation show that the SBCS can reduce the systematic bias of the background and yield a neutral to slightly positive result for the analysis fields.In addition,the SBCS can reduce forecast errors and improve forecast results,especially for surface variables.The above results indicate that this scheme has good prospects for high-resolution regional NWP models.
基金supported by the National Natural Science Foundation project“Micro-Scale Effect of Oil-Gas Flow and the Mechanism of Enhancing Shale Oil Recovery by Natural Gas Injection”(No.52074317)。
文摘Oilfields worldwide are increasingly grappling with challenges such as early water breakthrough and high water production,yet direct,targeted solutions remain elusive.In recent years,chemical flooding techniques designed for tertiary oil recovery have garnered significant attention,with microgel flooding emerging as a particularly prominent area of research.Despite its promise,the complex mechanisms underlying microgel flooding have been rarely investigated numerically.This study aims to address these gaps by characterizing the distribution of microgel concentration and viscosity within different pore structures.To enhance the accuracy of these characterizations,the viscosity of microgels is adjusted to account for the shear effects induced by flow rate and the swelling effects driven by salinity variations.The absolute permeability of the rock and the relative permeability of both oil and microgel are also analyzed to elucidate the mechanisms of microgel flooding.Additionally,a connectivity model is employed to achieve a quantitative representation of fluid flow capacity.The proposed model is validated through conceptual examples and applied to real oilfield blocks,demonstrating its accuracy and practical applicability.
基金Funded by the National Natural Science Foundation of China Academy of Engineering Physics and Jointly Setup"NSAF"Joint Fund(No.U1430119)。
文摘The multi-scale modeling combined with the cohesive zone model(CZM)and the molecular dynamics(MD)method were preformed to simulate the crack propagation in NiTi shape memory alloys(SMAs).The metallographic microscope and image processing technology were employed to achieve a quantitative grain size distribution of NiTi alloys so as to provide experimental data for molecular dynamics modeling at the atomic scale.Considering the size effect of molecular dynamics model on material properties,a reasonable modeling size was provided by taking into account three characteristic dimensions from the perspective of macro,meso,and micro scales according to the Buckinghamπtheorem.Then,the corresponding MD simulation on deformation and fracture behavior was investigated to derive a parameterized traction-separation(T-S)law,and then it was embedded into cohesive elements of finite element software.Thus,the crack propagation behavior in NiTi alloys was reproduced by the finite element method(FEM).The experimental results show that the predicted initiation fracture toughness is in good agreement with experimental data.In addition,it is found that the dynamics initiation fracture toughness increases with decreasing grain size and increasing loading velocity.
基金the financial support from the Fujian Science Foundation for Outstanding Youth(2023J06039)the National Natural Science Foundation of China(Grant No.41977259,U2005205,41972268)the Independent Research Project of Technology Innovation Center for Monitoring and Restoration Engineering of Ecological Fragile Zone in Southeast China(KY-090000-04-2022-019)。
文摘Shotcrete is one of the common solutions for shallow sliding.It works by forming a protective layer with high strength and cementing the loose soil particles on the slope surface to prevent shallow sliding.However,the solidification time of conventional cement paste is long when shotcrete is used to treat cohesionless soil landslide.The idea of reinforcing slope with polyurethane solidified soil(i.e.,mixture of polyurethane and sand)was proposed.Model tests and finite element analysis were carried out to study the effectiveness of the proposed new method on the emergency treatment of cohesionless soil landslide.Surcharge loading on the crest of the slope was applied step by step until landslide was triggered so as to test and compare the stability and bearing capacity of slope models with different conditions.The simulated slope displacements were relatively close to the measured results,and the simulated slope deformation characteristics were in good agreement with the observed phenomena,which verifies the accuracy of the numerical method.Under the condition of surcharge loading on the crest of the slope,the unreinforced slope slid when the surcharge loading exceeded 30 k Pa,which presented a failure mode of local instability and collapse at the shallow layer of slope top.The reinforced slope remained stable even when the surcharge loading reached 48 k Pa.The displacement of the reinforced slope was reduced by more than 95%.Overall,this study verifies the effectiveness of polyurethane in the emergency treatment of cohesionless soil landslide and should have broad application prospects in the field of geological disasters concerning the safety of people's live.
文摘In the past few decades,the navigation performance of ships and structures in ice-covered waters has not been fully studied,especially the influence of ice mechanical properties on icebreaking ability.Ice bending strength is a key ice parameter for predicting ship ice loads,and accurate ice bending strength is also the key to scaling model tests results to real ship.However,numerical simulation studies on model ice bending strength of ice tanks are often neglected.In this paper,an explicit finite element method model is used to simulate the ice cantilever beam test,and the failure load and bending strength of the ice are obtained.In this model,the Tsai-Wu failure criterion is used as the material constitutive model,and the required simulation parameters are obtained from the model ice test in ice tank.Parameter sensitivity analysis shows that the cantilever beam size of the model ice has a significant effect on the flexural strength.The results show that proper rounding at the root of the cantilever beam is beneficial to reduce stress concentration and obtain more accurate bending strength;the thickness,width and length of the cantilever beam should conform to a certain ratio,and consistent with the ITTC recommended reference.Therefore,the results of this study can promote model ice experiments and numerical studies and provide ice strength data support for ship design and polar ship maneuvering.
基金The National Natural Science Foundation of China(No.52078427).
文摘To ensure the operational safety of railways in the landslide-prone areas of mountainous regions,a large-scale model test and numerical simulation were conducted to study the bending moment distribution,internal force distribution,deformation development,and crack propagation characteristics of a framed anti-sliding structure(FAS)under landslide thrust up to the point of failure.Results show that the maximum bending moment and its increase rate in the fore pile are greater than those in the rear pile,with the maximum bending moment of the fore pile approximately 1.1 times that of the rear pile.When the FAS fails,the displacement at the top of the fore pile is significantly greater,about 1.27 times that of the rear pile in the experiment.Major cracks develop at locations corresponding to the peak bending moments.Small transverse cracks initially appear on the upper surface at the intersection between the primary beam and rear pile and then spread to the side of the structure.At the failure stage,major cracks are observed at the pil-beam intersections and near the anchor points.Strengthening flexural stiffness at intersections where major cracks occur can improve the overall thrust-deformation coordination of the FAS,thereby maximizing its performance.
基金supported by the National Natural Science Foundation of China(Grant Nos.52279118 and U21A20159)Sub-project of National Key Research and Development(Grant No.2023YFC3007403).
文摘The seepage of groundwater and the strain-softening of rock mass in a submarine tunnel expand the plastic region of rock,thereby affecting its overall stability.It is therefore essential to study the stress and strain fields in the rocks surrounding the submarine tunnel by considering the coupled effect of strainsoftening and seepage.However,the evolution equation for the hydro-mechanical parameters in the existing fully coupled solution is a uniform equation that is unable to reproduce the characteristics of rock mass in practice.In this study,an updated numerical procedure for the submarine tunnel is derived by coupling strain-softening and seepage effect based on the experimental results.According to the hydro-mechanical coupling theory,the hydro-mechanical parameters such as elastic modulus,Poisson's ratio,Biot's coefficient and permeability coefficient of rocks are characterized by the fitting equations derived from the experimental data.Then,the updated numerical procedure is deduced with the governing equations,boundary conditions,seepage equations and fitting equations.The updated numerical procedure is verified accurately compared with the previous analytical solution.By utilizing the updated numerical procedure,the characteristics of stress field and the influences of initial pore water pressure,Biot's coefficient,and permeability coefficient on the stress,displacement and water-inflow of the surrounding rocks are discussed.Regardless of the variations in hydro-mechanical parameters,the stress distribution has a similar trend.The initial permeability coefficient exerts the most significant influence on the stress field.With the increases in initial pore water pressure and Biot's coefficient,the plastic region expands,and the water-inflow and displacement increase accordingly.Given the fact that the stability of the tunnel is more sensitive to the seepage force controlled by the hydraulic parameters,it is suggested to dewater the ground above the submarine tunnel to control the initial pore water pressure.
基金The National Natural Science Foundation of China under contract Nos 41976217 and 42306249the National Key Research and Development Program of China under contract No.2018YFA0605701.
文摘A three-dimensional coupled sea ice-ice shelf-ocean numerical model is developed for the Prydz Bay,Antarctica,using the Regional Ocean Modeling System with a grid resolution of approximately 2 km.The influence of the grounding giant iceberg D15 on the distribution of sea ice and polynyas in the Prydz Bay is analyzed through two numerical experiments.Iceberg D15,grounded off the western edge of the West Ice Shelf(WIS),obstructs the southwestward transport of sea ice along the east coast of Prydz Bay,causing sea ice to accumulate to the east of the iceberg and form multi-year fast ice.Grounding of Iceberg D15 also decreases sea ice coverage off its south edge and creates ice-free openings in spring near Davis Station and Zhongshan Station,facilitating the accessibility of vessels to the research stations.These simulated sea ice patterns closely match current satellite observations.When Iceberg D15 is removed,the previously blocked sea ice north of the iceberg,which moved westward,shifts southwesterly along the coastline,leading to a reduction in sea ice thickness during winter and spring,as well as lower sea ice concentrations in spring across large areas north and west of the iceberg.In contrast,the sea ice thickness increases considerably southwest of the WIS,extending to the front of the Amery Ice Shelf during seasons covered by sea ice.The increase in sea ice concentration can also extend to as far as 75°E in spring.Without Iceberg D15,which previously contributed to the ice barrier of Barrier Polynya(BP),the shape of BP changes,the area of BP and Davis Polynya(DP)decreases,and the polynya off the northwest edge of the WIS near 83°E expands.These polynya patterns are much similar to the satellite remote sensing observations before Iceberg D15 was grounded.From April to October,the total area of BP and DP decreases by 2.83×10^(4)km^(2)(60%)and 2.20×10^(3)km^(2)(20%),respectively,while the total sea ice production decreases by 4.11×10^(10)m^(3)(66%)and 1.52×10^(10)m^(3)(52%)compared to the experiment with iceberg.These results indicate the substantial effects of grounding giant icebergs on the spatio-temporal distribution of sea ice,the area of polynyas,and sea ice production.High-resolution Antarctic coastal numerical models,typically with grid scales of kilometers,are sufficient to represent large icebergs,and adding the grounding giant icebergs is crucial for producing realistic simulations of sea ice and polynyas.
基金supported by the China Scholarship Council(CSC)(Grant No.202006060033).
文摘Both the complex geometrical morphology of rough-walled rock fractures and the nonlinearity of fluid flow contribute to resistance in fluid flow through rock fractures.The interactions of the shear-flow process further complicate the characterisation of flow behaviours in rock fractures.In this study,an improved friction factor model involving both the effects of viscous and inertial forces is presented based on the Forchheimer equation.The model incorporates two key variables,i.e.Reynolds number and relative roughness,which reflect the effects of flow regimes and fracture roughness,respectively.The changes in geometrical parameters induced by shearing are considered,with the peak asperity height predicted through a correlation with post-peak roughness degradation.The hydraulic aperture during shearing is estimated using a suggested equation that accounts for the mobilised contact area ratio and variable aperture distribution.The parametric sensitivity analysis reveals that shear-induced changes in fracture geometry enhance the flow nonlinearity in rock fractures.The model performs well in predicting the friction factor based on two validation criteria.Then,the proposed friction factor model is incorporated into the three-dimensional distinct element code(3DEC)in the form of the Darcy-Weisbach equation.Coupled with the numerically implemented mechanical model and hydraulic aperture prediction model,numerical simulations of coupled shear-flow processes in single rock fractures are conducted.The simulation outcomes are validated through comparison with the experimental results,showing acceptable agreement and demonstrating that the numerical model is capable of accurately evaluating the hydro-mechanical coupling behaviour during the shearing of rock fractures.
基金The National Natural Science Foundation of China(No.52278189)Zhejiang Provincial Natural Science Foundation of China(No.LY24E080002).
文摘A self-centering bridge bent equipped with energy-dissipation(ED)beams is proposed.Quasi-static tests are conducted on self-centering bridge bents,both with and without ED beams,to validate the accuracy of the corresponding numerical models.The effects of various param-eters,such as the web area of ED beams,prestressing force of tendons,tendon arrangements,and number of column segments,on the seismic performance of self-centering bridge bents with ED beams are evaluated using the validated numerical model.The results demonstrate that the nu-merical models accurately replicate the quasi-static test results,with average errors in the lateral force remaining below 9.6%.The web area of ED beams significantly affects the strength,cumulative energy dissipation,and relative self-centering index(RSI)of the self-centering bridge bents.Increasing the prestressing force enhances the lateral force and self-centering capability of the bridge bents but has minimal effect on their ED capacity.Reducing the num-ber of segments in each column enhances the lateral force and cumulative hysteretic energy dissipation of the self-centering bridge bents while exerting an insignificant effect on the RSI.Thus,the proposed novel system is highly suitable for doubleor multicolumn piers supporting bridges in regions prone to strong earthquakes.
基金funded by the Ministry of Science and Higher Education of the Russian Federation(agreement No.075-15-2022-1127 dated July 1,2022).
文摘The paper considers a catastrophic event-the eruption of Hunga Tonga-Hunga Ha’apai volcano on January 15,2022.The process of preparation and eruption of Hunga Tonga volcano generated tsunami waves that were observed throughout the World Ocean.This event was notable for its unprecedented global impact and the early appearance of tsunami waves at distant coastal stations.So,the first waves at tide gauge stations in Chile and Peru were recorded 4 hours earlier than the arrival time of tsunami waves to the tide gauge after the eruption of Tonga volcano.Two mechanisms are possible for the generation of early tsunami waves:acoustic Lamb waves generated by a volcanic explosion and submarine landslides that occurred on the slopes of the volcano during the preparatory phase of the eruption.In this study,numerical simulation of various pre-eruption landslide scenarios on the slope of Hunga Tonga volcano is carried out in an attempt to explain these early tsunami waves.Under computation the elastoplastic model of landslide was taken into account.Wave characteristics of a tsunami on the coast of Chile and Peru generated by a landslide process on a volcanic slope are obtained.A detailed comparison of virtual tide gauge data with observational ones is used to validate this model.The results obtained can be used to improve early warning systems.
基金funding support from the National Natural Science Foundation of China(Grant Nos.U23A2060,42177143,and 42277461).
文摘Ensuring the stability of the surrounding rock mass is of great importance during the construction of a large underground powerhouse.The presence of unfavorable structural planes within the rock mass,such as faults,can lead to substantial deformation and subsequent collapse.A series of in situ experiments and discrete element numerical simulations have been conducted to gain insight into the progressive failure behavior and deformation response of rocks in relation to controlled collapse scenarios involving gently inclined faults.First,the unloading damage evolution process of the surrounding rock mass is characterized by microscopic analysis using microseismic(MS)data.Second,the moment tensor inversion method is used to elucidate the temporal distribution of MS event fracture types in the surrounding rock mass.During the development stage of the collapse,numerous tensile fracture events occur,while a few shear fractures corresponding to structural plane dislocation precede their occurrence.The use of the digital panoramic borehole camera,acoustic wave test,and numerical simulation revealed that gently inclined faults and deep cracks at a certain depth from the cavern periphery are the primary factors contributing to rock collapse.These results provide a valuable case study that can help anticipate and mitigate fault-slip collapse incidents while providing practical insights for underground cave excavation.
基金National Natural Science Foundation of China(Project No.:12371428)Projects of the Provincial College Students’Innovation and Training Program in 2024(Project No.:S202413023106,S202413023110)。
文摘This paper focuses on the numerical solution of a tumor growth model under a data-driven approach.Based on the inherent laws of the data and reasonable assumptions,an ordinary differential equation model for tumor growth is established.Nonlinear fitting is employed to obtain the optimal parameter estimation of the mathematical model,and the numerical solution is carried out using the Matlab software.By comparing the clinical data with the simulation results,a good agreement is achieved,which verifies the rationality and feasibility of the model.
