作者：
Tao Li*;Yongfei Lin;Ling Zeng;Xiaowei Tang;Gang Yang;...
期刊：
Soil Dynamics and Earthquake Engineering,2026年200:109721 ISSN：0267-7261
通讯作者：
Tao Li
作者机构：
Key Laboratory of Safety Control of Bridge Engineering, Ministry of Education, Changsha University of Science & Technology, Changsha, China;[Ling Zeng] School of Civil and Environmental Engineering, Changsha University of Science & Technology, Changsha, China;[Xiaowei Tang; Gang Yang] State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian, China;[Shun Liu] China Institute of Water Resources and Hydropower Research, Beijing, China;[Tao Li; Yongfei Lin] Key Laboratory of Safety Control of Bridge Engineering, Ministry of Education, Changsha University of Science & Technology, Changsha, China<&wdkj&>School of Civil and Environmental Engineering, Changsha University of Science & Technology, Changsha, China
通讯机构：
[Tao Li] K;Key Laboratory of Safety Control of Bridge Engineering, Ministry of Education, Changsha University of Science & Technology, Changsha, China<&wdkj&>School of Civil and Environmental Engineering, Changsha University of Science & Technology, Changsha, China
摘要：
Static liquefaction will occur in saturated sand-clay mixtures under static loading. Understanding the mechanical behavior of sand-clay mixtures is crucial for evaluating its safety and stability. Through a series of isotropically consolidated undrained triaxial compression tests (CU), the effect of clay content (CC) on static shear strength of sand-clay mixtures were studied under constant sand skeleton void ratio (e s ). Test results demonstrate that static liquefaction happened for specimens with CC = 0 % (pure sand), 3 %, 5 %, 7 %, and 10 % under different confining pressures. By contrast, no static liquefaction occurred for specimens with CC = 12 % and 15 %. When CC = 0 %∼15 %, the peak deviator stress (q peak ) and mean effective stress at the steady state (p ss ') of corresponding specimens raise 305.6 %, 94.4 % and 97.6 % as well as 114.1 %, 987.9 % and 266.2 % under three different confining pressures, respectively. In addition, the microscopic characteristics of sand-clay mixtures with various clay contents were observed. It can be found that when CC ≤ 10 %, the clay particles primarily filled in the inter-sand voids, distributed on the surfaces of sand particles and located at the sand-sand contact points. And these clay particles can lubricate and bond sand particles, which can promote the liquefaction of mixed soil. The bonding effect of clay on sand is further enhanced when CC = 12 % and 15 %, and clay play an inhibitory role in the liquefaction of sand. Finally, a calculation equation of clay participation coefficient was proposed in current study, which can consider the effect of content, particle size and plasticity index of clay on the mechanical properties of sand-clay mixtures. The equation demonstrates excellent fitting results for both steady state data and cyclic stress ratio data in the present study and relevant literature.
Static liquefaction will occur in saturated sand-clay mixtures under static loading. Understanding the mechanical behavior of sand-clay mixtures is crucial for evaluating its safety and stability. Through a series of isotropically consolidated undrained triaxial compression tests (CU), the effect of clay content (CC) on static shear strength of sand-clay mixtures were studied under constant sand skeleton void ratio (e s ). Test results demonstrate that static liquefaction happened for specimens with CC = 0 % (pure sand), 3 %, 5 %, 7 %, and 10 % under different confining pressures. By contrast, no static liquefaction occurred for specimens with CC = 12 % and 15 %. When CC = 0 %∼15 %, the peak deviator stress (q peak ) and mean effective stress at the steady state (p ss ') of corresponding specimens raise 305.6 %, 94.4 % and 97.6 % as well as 114.1 %, 987.9 % and 266.2 % under three different confining pressures, respectively. In addition, the microscopic characteristics of sand-clay mixtures with various clay contents were observed. It can be found that when CC ≤ 10 %, the clay particles primarily filled in the inter-sand voids, distributed on the surfaces of sand particles and located at the sand-sand contact points. And these clay particles can lubricate and bond sand particles, which can promote the liquefaction of mixed soil. The bonding effect of clay on sand is further enhanced when CC = 12 % and 15 %, and clay play an inhibitory role in the liquefaction of sand. Finally, a calculation equation of clay participation coefficient was proposed in current study, which can consider the effect of content, particle size and plasticity index of clay on the mechanical properties of sand-clay mixtures. The equation demonstrates excellent fitting results for both steady state data and cyclic stress ratio data in the present study and relevant literature.
摘要：
Internal damage imaging in concrete structures has consistently presented significant challenges as a complex multi-component material. To enhance the accuracy and efficiency of internal damage identification in concrete structures, an improved plane wave imaging technique based on the wavenumber algorithm is proposed in the paper. The introduction of the wavenumber algorithm provides a mathematical solution to the inverse problem for the assumed forward wave propagation model, which is more rigorous than the ray-based theory in mathematics. By comparing with the total focusing method and the conventional plane wave imaging technique, the proposed imaging technique exhibits significant advantages in imaging different types of damage in concrete structures. Subsequently, the 3D damage state of the simulated reinforcement steel debonding in concrete structures was reconstructed employing the proposed imaging technique. The enhanced imaging efficiency and optimized imaging quality settled the proposed imaging technique a promising candidate for future internal damage identification of concrete structures.
Internal damage imaging in concrete structures has consistently presented significant challenges as a complex multi-component material. To enhance the accuracy and efficiency of internal damage identification in concrete structures, an improved plane wave imaging technique based on the wavenumber algorithm is proposed in the paper. The introduction of the wavenumber algorithm provides a mathematical solution to the inverse problem for the assumed forward wave propagation model, which is more rigorous than the ray-based theory in mathematics. By comparing with the total focusing method and the conventional plane wave imaging technique, the proposed imaging technique exhibits significant advantages in imaging different types of damage in concrete structures. Subsequently, the 3D damage state of the simulated reinforcement steel debonding in concrete structures was reconstructed employing the proposed imaging technique. The enhanced imaging efficiency and optimized imaging quality settled the proposed imaging technique a promising candidate for future internal damage identification of concrete structures.
摘要：
The quantitative evaluation of bolt pre-load is crucial for the maintenance and prevention of accidents in bolt-connected structures. This study introduces the coda wave interferometry (CWI) method and the nonlinear coda wave interferometry (NCWI) method for quantitative evaluation of bolt pre-load. Experimental tests across three different scales of bolt pre-load changes were conducted on a bolt to compare the performances of CWI and NCWI in the quantitative evaluation of bolt pre-load. The results demonstrate that both CWI and NCWI can effectively characterize changes in bolt pre-load. For CWI, the relative velocity change (triangle v/v) exhibits a linear relationship with the bolt pre-load. Meanwhile, for NCWI, the effective nonlinear level, denoted as alpha Delta v / v \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\alpha }_{\Delta v/v}$$\end{document} , demonstrates a quadratic dependence on the bolt pre-load. In CWI, the calculation of triangle v/v is dependent on the correlation coefficient between the coda waves of signals before and after bolt pre-load changes. It is prone to failure when there are significant changes in bolt pre-load. Conversely, NCWI demonstrates enhanced robustness in evaluating bolt pre-load changes across a range of magnitudes.
摘要：
Bridge steel, frequently employed in cross-sea bridge construction, exhibits excellent weldability, superior strength, and toughness. The service life and stability of steel structures are influenced by the presence of corrosive ions within marine environments, necessitating an in-depth examination of the corrosion mechanisms affecting bridge steel. In this study, Q370qD bridge steel was subjected to heat treatment to evaluate the influence of microstructural variations on its corrosion behavior. The microstructure of untreated steel (alloy F) predominantly consists of granular ferrite. Subsequent high-temperature heat treatment induces a partial transformation in the steel microstructure (alloy A), yielding lath carbide-free bainite. Post-immersion tests show both alloy surfaces densely covered with γ - FeOOH , α - FeOOH , and a mixture of Fe 3 O 4 and Fe 2 O 3 . Over time, γ - FeOOH undergoes partial conversion into the more stable α - FeOOH form, enhancing the protective barrier against the matrix for both alloys. Alloy F exhibits a significant reduction in corrosion rate compared to alloy A. The proportion of α - FeOOH in alloy A initially decreases then increases with prolonged exposure, while in alloy F, it consistently rises. The corrosion resistance of alloy A surpasses that of alloy F, which is attributed to the lath-shaped carbide-free bainite’s effectiveness in obstructing Cl − penetration and thereby improving corrosion resistance.
作者机构：
[Long, Chengyun; Long, CY] South China Univ Technol, Shien Ming Wu Sch Intelligent Engn, Guangzhou 511442, Peoples R China.;[Cai, Zizheng; Zhao, Bing; Zhou, Weichao; He, Daji] Changsha Univ Sci & Technol, Sch Civil Engn, Dept Mech, Changsha 410114, Peoples R China.
通讯机构：
[Long, CY ] S;[Zhao, B ] C;South China Univ Technol, Shien Ming Wu Sch Intelligent Engn, Guangzhou 511442, Peoples R China.;Changsha Univ Sci & Technol, Sch Civil Engn, Dept Mech, Changsha 410114, Peoples R China.
摘要：
Accurate assessment of the thermal buckling behavior of microdevices is critical for the safe and secure operation of MEMS. However, the coupling of shearing and size effects on the thermal buckling of microbeams remains elusive and needs to be clarified. Here, we propose a theoretical model for the thermal buckling of microbeams that considers both the shearing and size effects, based on the modified gradient elasticity theory combined with the Timoshenko beam model. The explicit analytical forms of the deflection, the bending angle, the shearing angle and the critical buckling temperature rise are presented. The results show that the bending angle increases with the length/thickness ratio while the shearing angle decreases. It is confirmed that the shearing effect cannot be ignored in the thermal buckling of the doubly clamped microbeams with low aspect ratio. The size effect is captured in the thermal buckling of microbeams, which shows an increase in thermoelastic strength with the size reduction. The coupling effect on thermal buckling shows a weakening of the shearing effect by the size effect as the microbeam size decreases. This work could provide a theoretical reference for the design and monitoring of microdevices operating in high temperature environments.
摘要：
Critical shear stress and erosion rate are two key factors for the prediction of the incipient motion of sediment and the transport of sediment. Seabed seepage can significantly alter the pore pressure gradient within the soil and the hydrodynamics around the surface of the seabed, further affecting erosion processes. Previous studies attempted to theoretically clarify the effect of the seepage force on sediment incipient motion. In this study, a newly designed erosion–seepage system (ESS) that considers the effect of seepage under steady or oscillatory flow is used to simulate the erosion process. Through the designed ESS, the erosion height per unit time was measured directly on the Yellow River sand, and the upward seepage force was applied at the bottom of the soil sample in the process. Then, the relationship between the erosion rate and seepage was established.The experimental results show that upward seepage reduces the critical shear stress of the sand bed and increases the erosion rate of the soils under both steady flow and oscillatory flow conditions. The erosion coefficients in the erosion models decrease with increasing seepage gradient. The effect of seepage on erosion is more obvious when the flow velocity of the steady stream is large, while the effect of seepage on erosion is relatively small under the oscillatory state with a shorter period. However, when violent erosion of soil samples occurs, seepage under both flow conditions greatly increases the erosion rate.
摘要：
This study investigates the strength, deformation, and failure characteristics of sandstone specimens under different loading paths and examines the impact of various loading histories on the mechanical behavior of sandstone after failure. The findings indicated that the loading path and history influence the strength and deformation behaviors in sandstone. The irreversible strain, elastic modulus, and Poisson's ratio of sandstone specimens vary significantly across different loading paths. The loading history exerts a greater impact on the irreversible volumetric strain of the sandstone specimens than on the irreversible axial and lateral strains, elastic modulus, and Poisson's ratio as the number of cycles increases. Typically, shear failure occurs in sandstone specimens under various loading paths, with each failed specimen exhibiting a diagonal crack. The experimental results provide important technical reference for geotechnical engineering involving sandstone in complex loading paths.
This study investigates the strength, deformation, and failure characteristics of sandstone specimens under different loading paths and examines the impact of various loading histories on the mechanical behavior of sandstone after failure. The findings indicated that the loading path and history influence the strength and deformation behaviors in sandstone. The irreversible strain, elastic modulus, and Poisson's ratio of sandstone specimens vary significantly across different loading paths. The loading history exerts a greater impact on the irreversible volumetric strain of the sandstone specimens than on the irreversible axial and lateral strains, elastic modulus, and Poisson's ratio as the number of cycles increases. Typically, shear failure occurs in sandstone specimens under various loading paths, with each failed specimen exhibiting a diagonal crack. The experimental results provide important technical reference for geotechnical engineering involving sandstone in complex loading paths.
摘要：
In order to investigate the influence of the coexistence of clay and silt on the compression characteristics of sand, one-dimensional compression consolidation tests were carried out on reconstituted saturated sand-silt-clay mixtures with a constant initial void ratio, and the effects of fines content (FC) and clay-silt ratio (CS) on the compression characteristics of mixed soils were studied. The mechanism of the experimental results was additionally explained from a microscopic perspective. The test results show that: the compressibility of mixed soil increased with the increase in FC; the compressibility change rule of mixed soils with different CS is consistent under the same FC; the influence of CS on the e-lgp (the void ratio (e) versus logarithm of the pressure (p)) curve of mixed soil is inconsistent when FC is different: when FC = 3%, the compressibility of mixed soil decreased with the increase in CS; when FC = 7% and 10%, the compressibility of mixed soil gradually increased with the increase in CS; when FC = 5%, the compressibility of mixed soil did not show an obvious changing law with the increase in CS, and the compressibility of the specimen with FC = 5%-CS = 1 (FC = 5%, CS = 1) was the largest; when CS was same, the difference between e-lgp curves of mixed soil with different FC increased with the increase in CS. The compression model of sand-silt-clay mixtures was established, which can consider the effects of FC and CS. The reliability and applicability of the proposed model were verified by combining the experimental results of this paper and the test data of sand-clay mixture and sand-silt mixture in other literature.
摘要：
The solid propellant is a particle-reinforced material with significant tension-compression asymmetry. Based on the constant-speed tensile test, constant-speed compression test, and cross-sectional SEM scanning test, this study investigated the differences in the mechanical properties of the HTPB propellant under tensile and compressive loading and the underlying mechanisms. The results show that the tensile strength of HTPB propellant is much smaller than compressive strength. According to the SEM test results of the failure surface, the tensile mechanical properties of the propellant are mainly affected by matrix, and the influence of particles on the mechanical properties is more obvious during the compression process. According to test data, a tension-compression integrated nonlinear constitutive model was constructed, and its application in simulation calculation was realized. The results show that the theoretical, simulation calculation and test results are in good agreement. At 15% strain, the maximum error between the theoretical results and the experimental curve is 9.1% and 4.8% respectively in the process of tension and compression. Therefore, the model can accurately describe the stress-strain relationship of HTPB propellant under different strain rates of tensile and compression. This model can provide theoretical support for accurately evaluating the structural integrity of SRMs.
摘要：
Our study employs panel data from 272 Chinese prefecture-level cities (2003-2020), leveraging the "Civilized City" selection campaign as a quasi-natural experiment. Using a Spatial Durbin Difference-in-Differences model, we systematically analyze the policy's impact on local environmental governance performance and its spatial spillover effects, with rigorous robustness checks. Results reveal a significant positive spatial correlation in China's environmental governance performance, indicating interdependence among cities rather than isolated decision-making. The "Civilized City" initiative not only improves local environmental governance but also generates spillover benefits for neighboring regions, thereby enhancing coordinated regional sustainability. Finally, we propose policy recommendations grounded in empirical findings and China's governance context.
摘要：
Nonlinear flutter has attracted wide attention due to the bottleneck caused by linear flutter theory on flutter-resistant design of super-long-span bridges. The longer the span, the more closely spaced the natural modes, which may cause competition among flutter-modes in a nonlinear flutter, but it is rarely reported so far. To this end, this study experimentally investigates the 3D nonlinear flutter characteristics of a long-span suspension bridge with closely spaced natural modes based on full-bridge aeroelastic model wind tunnel tests. Since there are two unstable flutter-modes within the interested post-critical regime and thus various complex but interesting flutter-modes competition processes were observed, such as continuous modes competition where the vibration amplitude evolution exhibits various different types of “sawtooth” shapes during stable vibration stages. Meanwhile, the complex nonlinear bifurcation behaviors caused by modes competition were also observed. The evolutionary characteristics of flutter-modes competition are analyzed in detail and relevant mechanisms are discussed. As the wind speed increases, the flutter of the studied bridge mainly undergoes a transition from being dominated by the symmetric mode to being dominated by the antisymmetric mode, accompanied by a continuous modes competition zone in between as a transitional zone. The results show that the continuous modes competition will result in a decrease in the maximum amplitude RMS of the full-span, which is beneficial for the structure. But it may also lead to a transient increase in the maximum amplitude of the full-span due to the coupling vibration shape formed by the two significant flutter-modes, which may be bad for the structure.
Nonlinear flutter has attracted wide attention due to the bottleneck caused by linear flutter theory on flutter-resistant design of super-long-span bridges. The longer the span, the more closely spaced the natural modes, which may cause competition among flutter-modes in a nonlinear flutter, but it is rarely reported so far. To this end, this study experimentally investigates the 3D nonlinear flutter characteristics of a long-span suspension bridge with closely spaced natural modes based on full-bridge aeroelastic model wind tunnel tests. Since there are two unstable flutter-modes within the interested post-critical regime and thus various complex but interesting flutter-modes competition processes were observed, such as continuous modes competition where the vibration amplitude evolution exhibits various different types of “sawtooth” shapes during stable vibration stages. Meanwhile, the complex nonlinear bifurcation behaviors caused by modes competition were also observed. The evolutionary characteristics of flutter-modes competition are analyzed in detail and relevant mechanisms are discussed. As the wind speed increases, the flutter of the studied bridge mainly undergoes a transition from being dominated by the symmetric mode to being dominated by the antisymmetric mode, accompanied by a continuous modes competition zone in between as a transitional zone. The results show that the continuous modes competition will result in a decrease in the maximum amplitude RMS of the full-span, which is beneficial for the structure. But it may also lead to a transient increase in the maximum amplitude of the full-span due to the coupling vibration shape formed by the two significant flutter-modes, which may be bad for the structure.
摘要：
In order to enhance the efficiency of stochastic vibration analysis for train–bridge coupling systems, this paper proposes a novel approach based on the parallel adaptive enhanced (PAE)-surrogate model. First, an initial surrogate model is established to predict the extreme values of dynamic responses in the train–bridge coupling system using a small number of training samples. Second, a multipoint adaptive sampling method is employed to determine a set of new samples that provide more information. The theoretical extreme values of the dynamic responses corresponding to the new samples are calculated using parallel computing technology. Third, the surrogate model is optimized by incorporating the set of new samples and their corresponding theoretical extreme values. Finally, new samples are continuously added, and the surrogate model is enhanced until the number of training samples reaches the preset requirement. To validate the effectiveness of the proposed method, two examples are examined, encompassing analytical functions and the analysis of the wheel load reduction rate (WLRR) for trains on the bridge. The results show that the proposed PAE-surrogate model can select samples containing valuable information, significantly improving the prediction accuracy of the surrogate model without increasing the number of training samples. Additionally, the proposed method can fully exploit computational resources, thereby decreasing the number of iterations needed and increasing training efficiency. By considering a four-car CHR2 train passing through a three-span simply supported girder bridge as an example, the proposed method achieves 2.62[Formula: see text]times higher training efficiency compared to the nonparallel method.
关键词：
Pile foundation;Karst cave;Active and passive loading;Model experiment;Numerical simulation
摘要：
This study, part of a preliminary safety evaluation for a real project, investigates the responses of karst-penetrating piles under active and passive loading, compared to non-cave cases. A series of reduced-scale model experiments and numerical simulations were conducted with a 1:35 similarity ratio, considering the effects of cave number and height on dimensionless pile responses. The results revealed that the decrease in axial force within and near the caves is due to the vertical resistance generated by the bulged pile segment, the pile-rock interface, and the cave bottom against the bulged pile segment. The deflection and bending moment profiles of karst-penetrating piles, which are significantly affected by pile head constraints, resemble those in non-cave cases, but with increased magnitudes as cave number and height rise. Additionally, reduced pile-rock contact shortens the effective pile length, preventing the shallow soil layer from providing sufficient lateral resistance. Consequently, deeper soil layers must mobilize their resistance to maintain lateral equilibrium. The effects of caves on pile responses depend on their position relative to the critical pile length of 4/ α . Finally, pile head settlement and deflection exhibit a nearly linear positive relationship with both cave number and height. To simplify future predictions, several fitting formulas are proposed to link pile responses with and without karst caves. These formulas enable convenient prediction of the responses of karst-penetrating piles by scaling non-cave responses, reducing the need for extensive testing across various undetected cave scenarios.
This study, part of a preliminary safety evaluation for a real project, investigates the responses of karst-penetrating piles under active and passive loading, compared to non-cave cases. A series of reduced-scale model experiments and numerical simulations were conducted with a 1:35 similarity ratio, considering the effects of cave number and height on dimensionless pile responses. The results revealed that the decrease in axial force within and near the caves is due to the vertical resistance generated by the bulged pile segment, the pile-rock interface, and the cave bottom against the bulged pile segment. The deflection and bending moment profiles of karst-penetrating piles, which are significantly affected by pile head constraints, resemble those in non-cave cases, but with increased magnitudes as cave number and height rise. Additionally, reduced pile-rock contact shortens the effective pile length, preventing the shallow soil layer from providing sufficient lateral resistance. Consequently, deeper soil layers must mobilize their resistance to maintain lateral equilibrium. The effects of caves on pile responses depend on their position relative to the critical pile length of 4/ α . Finally, pile head settlement and deflection exhibit a nearly linear positive relationship with both cave number and height. To simplify future predictions, several fitting formulas are proposed to link pile responses with and without karst caves. These formulas enable convenient prediction of the responses of karst-penetrating piles by scaling non-cave responses, reducing the need for extensive testing across various undetected cave scenarios.
摘要：
Understanding the dynamic response and failure mechanisms of rock slopes during earthquakes is crucial in sustainable geohazard prevention and mitigation engineering. The initiation of landslides involves complex interactions between seismic wave propagation, dynamic rock mass behavior, and crack network evolution, and these interactions are heavily influenced by the slope geometry, lithology, and structural parameters of the slope. However, systematic studies remain limited due to experimental challenges and the inherent variability of landslide scenarios. This study employs Discrete Element Method (DEM) modeling to comprehensively investigate how geological structure parameters control the dynamic amplification and deformation characteristic of typical bedding/anti-dip layered slopes consist of parallel distributed rock masses and joint faces, with calibrated mechanical properties. A soft-bond model (SBM) is utilized to accurately simulate the quasi-brittle rock behavior. Numerical results reveal distinct dynamic responses between bedding and anti-dip slopes, where local amplification zones (LAZs) act as seismic energy concentrators, while potential sliding zones (PSZs) exhibit hindering effects. Parametric analyses of strata dip angles and thicknesses identify a critical dip range where slope stability drastically decreases, highlighting high-risk configurations for earthquake-induced landslides. By linking the slope failure mechanism to seismic risk reduction strategies, this work provides practical guidelines for sustainable slope design and landslide mitigation in tectonically active regions.
摘要：
Stress-constrained topology optimization under geometrical nonlinear conditions is still an open topic as it often encounter difficulties such as mesh distortion, inaccurate stress evaluation and low computational efficiency. For this purpose, this paper develops a novel parallel-computing based topology optimization methodology for geometrically nonlinear continuum structures with stress constraints. To alleviate the mesh distortions in the low-density regions, a smooth material interpolation scheme from with different penalization for the elastic and nonlinear stiffness is proposed. Moreover, a new hybrid stress finite element formulation is included into the geometrically nonlinear topology optimization to capture a more accurate stress distribution that is less sensitive to mesh distortions. Then, to improve the computational efficiency of geometrically nonlinear and sensitivity analysis, a parallel computing framework based on the assembly free iterative solution is established. Meanwhile, an efficient sparse matrix-vector multiplication strategy, which is applicable to solve the geometrically nonlinear problems, is proposed to exploit the computing power of GPU effectively. Finally, several numerical examples are given to illustrate the efficiency and feasibility of the proposed method.
Stress-constrained topology optimization under geometrical nonlinear conditions is still an open topic as it often encounter difficulties such as mesh distortion, inaccurate stress evaluation and low computational efficiency. For this purpose, this paper develops a novel parallel-computing based topology optimization methodology for geometrically nonlinear continuum structures with stress constraints. To alleviate the mesh distortions in the low-density regions, a smooth material interpolation scheme from with different penalization for the elastic and nonlinear stiffness is proposed. Moreover, a new hybrid stress finite element formulation is included into the geometrically nonlinear topology optimization to capture a more accurate stress distribution that is less sensitive to mesh distortions. Then, to improve the computational efficiency of geometrically nonlinear and sensitivity analysis, a parallel computing framework based on the assembly free iterative solution is established. Meanwhile, an efficient sparse matrix-vector multiplication strategy, which is applicable to solve the geometrically nonlinear problems, is proposed to exploit the computing power of GPU effectively. Finally, several numerical examples are given to illustrate the efficiency and feasibility of the proposed method.
摘要：
The existence of multiple cracks accelerates chloride ion penetration within damaged concrete, substantially shortening the lifespan of the structure. Therefore, this paper conducts an in-depth analysis of chloride migration mechanisms in cracked concrete subjected to multiple cracks under drying-wetting cycles. Firstly, a series of accelerated chloride diffusion experiments were conducted on prestressed concrete beams subjected to multiple cracks. The analysis examines how crack width, depth, and density affect chloride concentration distribution. Then, a chloride diffusion coefficient prediction model incorporating the effects of multiple cracks was established using the crack interaction function and verified through experimental data. Finally, this paper explored the distribution patterns of chloride concentration and convection zones in concrete subjected to multiple cracks under various environmental conditions. The experimental results showed that crack width exerts the strongest effect on chloride diffusion, followed by crack depth, while crack density has the smallest impact. At the same depth of diffusion, the chloride concentration in concrete specimens with crack width of 0.3 mm increased by 45 % and 25 % on average compared with those with crack width of 0.1 mm and 0.2 mm, respectively. The dry-wet time ratio and initial moisture saturation significantly affect chloride concentration distribution, with the depth of the convection zone showing a negative correlation with initial moisture saturation.
The existence of multiple cracks accelerates chloride ion penetration within damaged concrete, substantially shortening the lifespan of the structure. Therefore, this paper conducts an in-depth analysis of chloride migration mechanisms in cracked concrete subjected to multiple cracks under drying-wetting cycles. Firstly, a series of accelerated chloride diffusion experiments were conducted on prestressed concrete beams subjected to multiple cracks. The analysis examines how crack width, depth, and density affect chloride concentration distribution. Then, a chloride diffusion coefficient prediction model incorporating the effects of multiple cracks was established using the crack interaction function and verified through experimental data. Finally, this paper explored the distribution patterns of chloride concentration and convection zones in concrete subjected to multiple cracks under various environmental conditions. The experimental results showed that crack width exerts the strongest effect on chloride diffusion, followed by crack depth, while crack density has the smallest impact. At the same depth of diffusion, the chloride concentration in concrete specimens with crack width of 0.3 mm increased by 45 % and 25 % on average compared with those with crack width of 0.1 mm and 0.2 mm, respectively. The dry-wet time ratio and initial moisture saturation significantly affect chloride concentration distribution, with the depth of the convection zone showing a negative correlation with initial moisture saturation.
作者机构：
[Huang, MaoTong; Nie, Rusong; Zhang, Jie; Tan, Yongchang] Cent South Univ, Sch Civil Engn, Changsha 410075, Peoples R China.;[Nie, Rusong] Cent South Univ, MOE Key Lab Engn Struct Heavy Haul Railway, Changsha 410075, Peoples R China.;[Li, Yafeng] Anhui Univ Sci & Technol, Sch Civil Engn & Architecture, Huainan 232000, Peoples R China.;[Guo, Yipeng] Changsha Univ Sci & Technol, Sch Civil Engn, Changsha 410114, Peoples R China.
通讯机构：
[Nie, RS ] C;Cent South Univ, Sch Civil Engn, Changsha 410075, Peoples R China.;Cent South Univ, MOE Key Lab Engn Struct Heavy Haul Railway, Changsha 410075, Peoples R China.
关键词：
Heavy haul railway;Ballasted track;Ballast penetration;Parallel gradation method;Discrete element method
摘要：
Treating ballast and subgrade soil as an integrated unit for sampling and loading has proven to be an effective method for investigating the interaction between ballast and subgrade soil. Given that direct testing of specimens containing large ballast is constrained by the capabilities of standard laboratory equipment, adopting a model material of smaller size is recommended. Parallel gradation method is widely used for this purpose. This study performed an evaluation of parallel gradation method based on the response of ballast penetration into subgrade soil. Discrete element models were developed to simulate the penetration of crushed ballast, featuring three different parallel gradations, into subgrade soil. On this basis, dynamic triaxial simulations were conducted on these models. By comparing the macroscopic and mesoscopic mechanical characteristics at different scaling ratio, the applicability of the parallel gradation method for assessing ballast penetration into subgrade soil was evaluated. At the macroscopic scale, the scaling ratio of crushed ballast significantly influences the axial, volumetric, and lateral deformations observed during penetration into subgrade soil. Specifically, a smaller average grain size of ballast correlates with reduced deformations in these specimens. The penetration of crushed ballast into subgrade soil significantly increases the porosity of subgrade soil, particularly at the interface between ballast and subgrade. This increase in porosity is more pronounced with larger average grain sizes of ballast. At the mesoscopic scale, larger average grain sizes of ballast lead to more localized high contact forces and more significant stress concentrations. The parallel gradation method substantially affects the mechanical properties of ballast penetration into subgrade soil, at both macroscopic and mesoscopic scales. Therefore, a cautious approach is necessary when relying on this method for precise assessments.
作者机构：
[Hao Ge] School of Civil Engineering and Architecture, Guangxi University, Nanning 530004, China;[Miao Su] School of Civil Engineering, Changsha University of Science and Technology, Changsha 410114, China;[Yanqun Xu] School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue 639798, Singapore;[Gonglian Dai] Department of Civil Engineering, Central South University, Changsha 410083, China;[Guotang Zhao] China State Railway Group Co., Ltd, Beijing 100844, China
摘要：
To investigate the shear failure evolution at the weak interface between the prefabricated track slab and the mortar layer used in high-speed railway, push-shear tests were conducted on the 1:1 full-scale structural system. Based on the test results, a bond-slip constitutive model for the weak interface was developed. Additionally, the finite element model, validated by the experimental results, was employed to analyze the nonlinear dynamic evolution process of shear damage at the weak interface under cooling effects. Finally, based on the interface characteristics and mechanical theory, analytical formulas for the entire interface failure process were derived, establishing a quantitative relationship between the interface damage state and the equivalent temperature drop amplitude at different evolution stages. The main conclusions are as follows: In the elastic stage, the interface shear stress follows a hyperbolic sine distribution along the track slab length. When the cooling exceeds 7.28°C, the interface transitions from the elastic stage to the elastic-damage stage, where the shear stress obeys a cosine-like distribution. When the cooling exceeds 37.35°C, the interface further evolves into the elastic-damage-slip stage. Cooling-induced shear damage can be prevented if the interface shear strength exceeds 0.06 MPa. The theoretical analytical formula proposed in this study is also applicable to other types of track slabs with bonding interfaces. The research provides valuable insights for understanding the shear damage mechanism at the track slab interface, corresponding findings contribute significantly to the design optimization and scientific maintenance of track slab.
To investigate the shear failure evolution at the weak interface between the prefabricated track slab and the mortar layer used in high-speed railway, push-shear tests were conducted on the 1:1 full-scale structural system. Based on the test results, a bond-slip constitutive model for the weak interface was developed. Additionally, the finite element model, validated by the experimental results, was employed to analyze the nonlinear dynamic evolution process of shear damage at the weak interface under cooling effects. Finally, based on the interface characteristics and mechanical theory, analytical formulas for the entire interface failure process were derived, establishing a quantitative relationship between the interface damage state and the equivalent temperature drop amplitude at different evolution stages. The main conclusions are as follows: In the elastic stage, the interface shear stress follows a hyperbolic sine distribution along the track slab length. When the cooling exceeds 7.28°C, the interface transitions from the elastic stage to the elastic-damage stage, where the shear stress obeys a cosine-like distribution. When the cooling exceeds 37.35°C, the interface further evolves into the elastic-damage-slip stage. Cooling-induced shear damage can be prevented if the interface shear strength exceeds 0.06 MPa. The theoretical analytical formula proposed in this study is also applicable to other types of track slabs with bonding interfaces. The research provides valuable insights for understanding the shear damage mechanism at the track slab interface, corresponding findings contribute significantly to the design optimization and scientific maintenance of track slab.
摘要：
This study presents a novel method for calculating the stress and bending moment in reinforced concrete (RC) beams strengthened with prestressed near-surface-mounted (NSM) carbon fiber-reinforced polymer (CFRP), focusing specifically on separation failure at the end concrete cover. By characterizing the geometry of the failure body and integrating it with the concrete tooth model, a comprehensive theoretical framework has been developed. This framework utilizes sectional strain distribution characteristics to establish the bending moment–curvature relationship and the load–deflection curve during loading. Comparisons with experimental data confirm the accuracy and applicability of this analytical model. The results demonstrate that the model is capable of accurately predicting the load–deflection behavior of the strengthened beam. Additionally, this study underscores the substantial impact of the CFRP prestress level on the concrete cover separation failure, showing that optimizing prestress settings can effectively enhance the ductility and bearing capacity of the strengthened beam.
期刊：
IEEE Transactions on Geoscience and Remote Sensing,2025年:1-1 ISSN：0196-2892
作者机构：
[Yinshuo Li; Wenkai Lu; Cao Song] Department of Automation, Beijing National Research Center for Information Science and Technology (BNRist), Tsinghua University, P.R.China, Beijing, China;[Zhuo Jia] School of Civil Engineering, Changsha University of Science and Technology, Changsha, China
摘要：
Gravity inversion is the pioneer in exploring the structural characteristics of the Earth, the Moon, and other celestial bodies. Classical gravity inversion methods aim to estimate the 3D subsurface density distribution from the observed 2D surface gravity anomalies, which is an ill-posed problem. Constraints can provide vertical resolution and reduce uncertainty. However, these methods significantly increase the cost of data acquisition. This manuscript presents a novel joint inversion method to estimate subsurface density anomaly via a physics-inspired neural network. The observed signals in the proposed method are the gravity anomalies on multiple altitudes and their vertical gradients, which provide vertical resolution for gravity inversion. The proposed joint inversion method contains two stages. The proposed inversion model is initially pre-trained on the synthetic data. Self-supervised transform learning with a closed loop between inversion and forward models is applied to the target gravity anomalies and their gradients. The loss function is defined by mean absolute error, cross-gradient loss, and total variation. Experiments on independently and identically distributed synthetic data, as well as out-of-distribution field data, demonstrate the effectiveness of the proposed method.
