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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
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    <item>
      <title>Direct shear behavior of tire cells reinforced gravel: A coupled DEM-FDM investigation</title>
      <link>https://trid.trb.org/View/2690084</link>
      <description><![CDATA[Waste tires can be used as three-dimensional reinforcement materials to provide circumferential constraints to reinforce soil, demonstrating significant potential in transportation geotechnical applications. This paper conducts a direct shear test model integrating DEM and FDM to investigate the shear behavior and micro-reinforcement mechanisms of tire-reinforced gravel samples. Numerical results reveal that circumferential constraints imposed by tire cells enhance the peak shear strength but slightly increase dilatancy only at low normal stress, with both effects attenuating under higher normal stress. The obtained strength envelope indicates that the circumferential constraints significantly increase the apparent cohesion while having a negligible impacton the internal friction angle. These constraints also reduce the spatial directional concentration and anisotropy of force chains, suppressing their directional convergence. The sample reinforced by smaller-diameter tire cells exhibits a lower peak shear stress, a greater final volumetric strain, a weaker reduction in the extent of strong force chain concentration zones, and a more pronounced effect on lifting shear zone upward compared to the sample with larger-diameter tire cells. While peak shear stress typically decreases with decreasing tire elastic modulus, this trend may reverse at specific modulus values where the shear surface achieves an improved particle packing. The findings of this study provide a meso‑mechanical foundation for the engineered application of tire cells in transportation geotechnics.]]></description>
      <pubDate>Wed, 15 Jul 2026 09:23:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/2690084</guid>
    </item>
    <item>
      <title>Face instability mechanisms of shield tunnel undercrossing an existing tunnel: Insights from centrifuge model tests and FDM-DEM simulations</title>
      <link>https://trid.trb.org/View/2686707</link>
      <description><![CDATA[Urban underground tunnels are increasingly constructed to support the development of transportation network, necessitating shield tunnelling adjacent to existing tunnel(s). In such scenarios, the tunnel face stability, as one of the important factors affecting construction safety, has not been fully experimentally investigated. In addition, most existing researches treat the existing tunnel as a homogeneous rigid object, which does not accurately reflect actual conditions. Therefore, this study conducted centrifuge model tests to investigate the instability mechanisms of tunnel face undercrossing a segmental existing tunnel. The results demonstrated that the failure pattern showed a chimney-shaped area that bend near the segmental existing tunnel, and the failure-induced surface settlement trough was narrower than that under single tunnelling condition. The shield tunnel face instability triggered abrupt bending moment reductions along the transverse section of the segmental existing tunnel, while the bending moment increased at 1D from the central section along the longitudinal section. The earth pressure dropped rapidly and then partially recovered due to stress redistribution during the instability process. A coupled FDM-DEM numerical model was subsequently established to further study the evolution mechanism of tunnel face instability under different working conditions. Based on centrifuge and numerical results, the influence of existing tunnel on the face instability mechanism of the new tunnel has been fully discussed, and quantitative representations of the face failure modes and the limit support pressures have been provided. These findings could advance the understanding of instability mechanisms of shield tunnel face adjacent to existing tunnel and provide practical guidelines for optimizing tunnel face support pressure in high-density underground space.]]></description>
      <pubDate>Thu, 09 Jul 2026 13:29:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/2686707</guid>
    </item>
    <item>
      <title>Effect of preloaded gas foil conical bearing on the rotor dynamic performance of fuel cell air compressor</title>
      <link>https://trid.trb.org/View/2680767</link>
      <description><![CDATA[To investigate the effect of mechanical preload on the performance of gas foil conical bearing (GFCB), the Reynolds equation and elastic foil deformation were solved by the finite difference method (FDM). Three dimensional energy equation of the gas film is also derived and solved by FDM, and the influence of temperature rise on the static bearing performance is investigated. Moreover, the static and dynamic characteristics of GFCB were calculated and analyzed under different preload conditions. Based on the finite element method (FEM), a 5-DOF equation model considering radial and axial displacement was adopted for stability analysis of cone rotor system. In addition, the running test of an air compressor for Fuel cell vehicle supported by two shimmed GFCBs has been conducted to verify the actual effect of preload. The results show that the static load capacities, friction torque, and dynamic direct stiffness of GFCB are enhanced largely by the preload, especially under larger thickness. The consideration of gas film temperature can increase the bearing load capacities and friction torque, and will decrease the attitude angle. Both theory and experiment analysis show that the mechanical preload can improve the stability of high-speed cone rotor-bearing system, including the reduced axis trajectory and delayed occurrence of low-frequency vibration.]]></description>
      <pubDate>Thu, 25 Jun 2026 09:10:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/2680767</guid>
    </item>
    <item>
      <title>Hybrid DEM-FDM modeling of heavy-haul railway transition zone slope effects on ballast particle movement and dynamic track responses</title>
      <link>https://trid.trb.org/View/2673337</link>
      <description><![CDATA[Ballasted track often suffers from weaker stability in bridge transition zones due to abrupt changes in track stiffness, leading to intensified structural damage, accelerated cumulative settlement, and thus increasing maintenance necessities. To scientifically assess the in-service performance of ballasted track in such bridge transition zones and recommend maintenance strategies, it becomes indispensable to investigate the underlying macro- and micro-mechanical mechanisms, including the evolution of ballast particle movement, interparticle contact force chains, and substructure foundation settlement. This study employed the hybrid computational framework integrating discrete element method (DEM) with finite difference method (FDM) to establish a discrete-continuum coupled model for the ballasted track system. The ballast bed in the bridge transition zone was modeled using DEM, whereas track superstructures and foundation were modeled using FDM. The validity of the fully coupled DEM-FDM model was confirmed from the comparisons against field-measured dynamic response data from the Daqin heavy-haul railway corridor. The effects of different slope patterns in the bridge transition zone were studied. The analysis results show that the dynamic responses of the transition section become smoother as the slope of the transition zone decreases. The displacement responses of the sleepers and ballast particles increase gradually with transition length, and reducing the slope can decrease such displacement amplitudes. However, changing the slope does not significantly affect the acceleration responses of the sleepers and ballast particles. The research findings could provide theoretical guidance for performance monitoring and dynamic response evaluation of ballasted heavy-haul railway tracks in bridge transition zones.]]></description>
      <pubDate>Fri, 15 May 2026 09:18:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/2673337</guid>
    </item>
    <item>
      <title>Numerical Analysis of the Potential for Joint Separation in Round Concrete Culverts</title>
      <link>https://trid.trb.org/View/2701137</link>
      <description><![CDATA[A common form of damage experienced by culverts is joint separation between culvert segments. Joint performance issues may allow water and soil to seep through the pipe leading to loss of soil support, which may ultimately result in roadway settlement or failure of the pipe. The factors that contribute to joint separation are unclear, and although past studies have investigated flexural demands across joints, no current studies are examining the axial tension demands that may develop across culvert joints. To this end, finite difference and finite element models of round concrete culverts were developed to examine the potential for separation from axial demands on culvert segments. The models investigated traffic loading, rise of the phreatic surface, freezing of the embankment, and dead load demands under the self-weight of the embankment. All of the above mechanisms led to axial tension along the length of the pipe. Of these, traffic loading caused the lowest separation forces, roughly 10% to 20% of the applied vertical load occurring under the roadway. Embankment self-weight caused built-in tensile demands under the driving surface. The rise of the phreatic surface and freezing of the embankment also caused significant separation forces, but near the embankment face. For untied pipe segments, increased depth to the culvert centerline and reduced embankment stiffness were the most critical parameters that increased the potential for joint separation. Further research focusing on detailed field observations to confirm the most likely locations of and conditions that lead to joint separation in culverts is recommended.]]></description>
      <pubDate>Tue, 12 May 2026 16:57:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/2701137</guid>
    </item>
    <item>
      <title>Mechanism and deformation characteristics of stress isolation method in controlling differential settlement of the subgrade widening over soft soil foundation</title>
      <link>https://trid.trb.org/View/2636299</link>
      <description><![CDATA[This paper proposes the Stress Isolation Method for subgrade widening projects on soft soil foundations, which use steel sheet piles as the isolation elements to control differential settlement during the widening process. First, a numerical model was built to verify the computational accuracy and applicability of the Finite Difference Method (FDM) in this study. On this basis, with the conventional treatment method using only prefabricated vertical drains (PVD) as a control group, a series of numerical simulations were conducted to systematically compare and analyze the distribution patterns of additional stresses and deformation characteristics during both the construction and post-construction phases. The influence of varying pile penetration depths and installation positions on the distribution of additional stresses and the variation of vertical and horizontal displacements of the subgrade was considered to determine optimal configurations.The results demonstrate that the continuous rigid vertical barrier effectively hinders the lateral transfer of additional stresses induced by the new subgrade load to the underlying soft soil foundation under the existing subgrade. This mechanism redirects the additional stresses downward along the pile surface, leading to stress concentration at the pile tip. The concentrated stress at the pile tip ultimately dissipates into the underlying soil layer. During the construction phase, this isolation system significantly reduces disturbance to the existing subgrade and effectively reduces both vertical settlement and horizontal displacement of the underlying soft soil layer. After 15 years of post-construction operation, the subgrade deformation has been effectively controlled. Increasing the pile penetration depth helps reduce the additional stresses in the soft soil under the existing subgrade and at the pile tip. The optimal pile penetration depth is determined to be 1 m below the bottom of the soft soil layer, which effectively reduces the additional stress at the pile tip by 25.0 % and minimizes both vertical settlement and horizontal displacement during the construction and post-construction phases. As the horizontal distance between the isolation piles and the centerline of the new subgrade increases, deformation at both the surface of foundation and the subgrade gradually decreases. Installing the isolation piles at the edge of the existing shoulder achieves the optimal isolation range, thereby minimizing disturbance to the existing subgrade and realizing the best isolation effectiveness with the smallest post-construction deformation.]]></description>
      <pubDate>Wed, 04 Feb 2026 16:28:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2636299</guid>
    </item>
    <item>
      <title>A Method for Measuring Instantaneous Structural Intensity in Flat Structures</title>
      <link>https://trid.trb.org/View/2606634</link>
      <description><![CDATA[We propose a method for measuring instantaneous structural intensity (SI) in flat structures using finite difference approximations. Based on flat plate theory, stress components associated with axial forces, bending moments, torsional moments, and shear forces are described in terms of vibration displacement. The derivation formulation is established by applying finite difference approximations to partial differential terms up to fourth order in both time and space. To achieve high temporal and spatial resolution, wave propagation after input is measured non-invasively using a Laser Doppler Vibrometer (LDV). This approach ensures precision and avoids contact-induced measurement errors. The proposed method demonstrated correlation with finite element method (FEM) simulations, confirming its validity and practicality for analyzing instantaneous SI.]]></description>
      <pubDate>Mon, 08 Dec 2025 11:43:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/2606634</guid>
    </item>
    <item>
      <title>Probabilistic seismic performance analysis of railway embankments on spatially variable loose deposit slopes</title>
      <link>https://trid.trb.org/View/2608735</link>
      <description><![CDATA[A systematic assessment of the influence of soil spatial variability parameters on railway embankment seismic performance under near-fault pulse-like ground motions is essential. This study employs a three-dimensional random finite difference method to investigate the effects of spatially variable loose deposits on seismic failure mechanisms and the probabilistic characteristics of peak permanent settlement (PPS) at railway embankment crests. The results demonstrate that loose deposit spatial variability directly governs potential slip surface evolution through strength heterogeneity, inducing two distinct seismic failure mechanisms: shallow and deep sliding along continuous weak zones. Probabilistic seismic analysis reveals that spatially variable loose deposits significantly increase both the geometric mean and standard deviation of PPS compared to deterministic results. Specifically, the probabilistic characteristics of PPS are more sensitive to the coefficient of variation than to the correlation distance, both of which are key parameters for random fields. Finally, this study develops the amplification factor method (AFM) and parameter reduction method (PRM), providing statistically based dynamic response amplification factors and internal friction angle reduction factors at the 95% confidence interval to simplify the incorporation of spatial variability effects. The findings advance reliable seismic design methodologies for railway embankments on spatially variable loose deposits by quantifying the impact of spatial uncertainty and providing practical simplification frameworks.]]></description>
      <pubDate>Tue, 02 Dec 2025 09:56:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/2608735</guid>
    </item>
    <item>
      <title>Theoretical and practical fusion investigation for the intelligent real-time control technology of pavement fracturing recycling</title>
      <link>https://trid.trb.org/View/2609039</link>
      <description><![CDATA[Conventional methods for evaluating pavement fracturing afford limited spatial coverage and provide little support for process control. This study develops a real-time, full-coverage assessment by extracting per-blow impact indices from falling-weight acceleration during free-fall impacts and embedding them in an integrated, closed-loop workflow. The methodology derives impact indices from the measured acceleration waveform, establishes their mechanics via a Hertz impact model, employs a DEM–FDM representation that accounts for layered pavement characteristics to simulate falling weight–pavement interaction, and uses an instrumented falling weight with wireless cloud telemetry for on-site threshold calibration, per-blow classification into under-fractured, acceptable, and over-fractured states, and immediate targeted secondary treatments. The results show that the Hertz formulation links impact acceleration to structural response and that the influence of Poisson’s ratio is negligible, yielding a single-valued mapping from impact acceleration to composite modulus. Simulations demonstrate the theoretical feasibility of using the impact indices to evaluate fracturing effectiveness, with R2 not less than 0.86 relative to mechanical response. In field application on a control section of China National Highway G329, identification accuracies reached 69.2 %-92.3 %; target-deflection compliance increased from 85 % after initial microcracking to 99 % after secondary remediation through supplemental impacts or grouting, and modulus uniformity improved by 14 % under closed-loop operation. In conclusion, real-time impact indices effectively evaluate fracturing quality. Furthermore, they lay the foundation for the automation and intelligent upgrading of fracturing equipment and on-site process control.]]></description>
      <pubDate>Mon, 24 Nov 2025 17:04:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/2609039</guid>
    </item>
    <item>
      <title>Mechanism of the inclined and advanced rockbolt support system and dynamic evaluation of its reinforcement range in mechanized tunneling for high-speed railways</title>
      <link>https://trid.trb.org/View/2605358</link>
      <description><![CDATA[To tackle the challenges of tunnel over-excavation, the Chongqing-Kunming High-speed Railway has optimized rockbolt arrangements by replacing traditional radial rockbolts near the tunnel face with pre-stressed inclined rockbolts that are positioned more forward and set at angles of 45° to 60°. This adjustment thereby aims to enhance the stability of the tunnel face, delay steel arch installation, and expand operational space for drilling equipment. Focusing on the case of the Jinyunshan Tunnel, this study employs finite difference modeling (FDM) to analyze the distribution of support stress fields under varying conditions, thereby enabling a quantitative assessment of the rockbolt-reinforced zones. This quantitative evaluation allows for an effective assessment of the feasibility and safety of implementing delayed support sections. Furthermore, triaxial compression simulations that incorporate prestressed rockbolts reveal the impact of confining pressures on the properties of anchored rock masses. Additionally, field and laboratory tests were conducted to further evaluate the effectiveness of tunnel deformation control, the enhancement of surrounding rock stress, and the practical support capabilities of inclined rockbolts. The research results indicate that: (1) The support system establishes an elevated minimum principal stress zone near the tunnel face, enhancing physico-mechanical parameters of the anchored rock as the minimum principal stress increases. (2) With diminishing tunnel face spatial effects, prestress diffusion extends from the vault to the surrounding rock. (3) In the early stages of excavation (0 ∼ 4 m from the tunnel face), inclined rockbolts outperform radial rockbolts by providing more timely support to improve the stress state of the delayed support zone. (4) Critical factors such as burial depth, lateral pressure coefficients, prestress, and rockbolt angle significantly influence the stress field. When the stress in the rockbolts does not exceed their yield strength, optimal support efficiency and cost-effectiveness can be achieved by using 5-meter-long rockbolts installed at a 60° angle.]]></description>
      <pubDate>Thu, 20 Nov 2025 09:10:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/2605358</guid>
    </item>
    <item>
      <title>Coupled DEM-FDM study on the dynamic performance of ballast-subgrade system under cyclic axle loading</title>
      <link>https://trid.trb.org/View/2605356</link>
      <description><![CDATA[The coupled Discrete Element Method − Finite Difference Method (DEM-FDM) offers a useful approach for comprehensively investigating the micro–macro behavior of ballast-subgrade systems. Previous research primarily focused on the mechanical characteristics of ballast particles, with subgrade response seldom reported simultaneously under cyclic axle loading. This study employs the coupled DEM-FDM method to investigate the dynamic response of the ballast-subgrade system under cyclic axle loading. The movement, contact force, and energy dissipation of the ballast, combined with the stress and settlement of the subgrade, were analyzed in detail to comprehensively understand the influence of axle load magnitude on system behavior.]]></description>
      <pubDate>Wed, 19 Nov 2025 09:27:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2605356</guid>
    </item>
    <item>
      <title>Evaluating soil compaction in the field using a solitary strain wave device with a modified contact interface</title>
      <link>https://trid.trb.org/View/2573569</link>
      <description><![CDATA[Non-destructive tests are used to evaluate the mechanical properties of construction materials. Solitary strain wave (SSW) devices estimate Young’s modulus of a material by measuring the time of flight (TOF), defined as the time between the incident and reflected wave propagating through a chain of steel spheres. This study evaluates the incorporation of a PLA plate between the last element of the chain and the tested medium (soil). This plate aims to evenly distribute contact forces and reduce plastic deformations at the soil surface. This is addressed by modifying the Hertz contact equation using a finite element approach. Then, the dynamic equilibrium equations of the device were solved using a finite difference method to establish a relationship between TOF and the soil’s Young’s modulus. This relationship was validated by comparing the modulus of seven control polyurethane foams with measurements obtained from the SSW device. After validation, the device was tested on compacted soil samples using SSW and wave velocity methods. Finally, the device was employed for field compaction assessment. Results show that the modified setup improves the consistency of TOF measurements and opens new possibilities for using TOF as a parameter for compaction control.]]></description>
      <pubDate>Mon, 08 Sep 2025 14:54:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/2573569</guid>
    </item>
    <item>
      <title>Rapid Prediction of Magnetic and Temperature Field Based on Hybrid Subdomain Method and Finite-Difference Method for the Interior Permanent Magnet Synchronous Motor</title>
      <link>https://trid.trb.org/View/2511861</link>
      <description><![CDATA[The solution speed of the finite-element method (FEM) limits the design and analysis of the motors in various physical fields. This article presents a rapid prediction method for the magnetic and temperature field of the U-shaped interior permanent magnet synchronous motor (IPMSM). First, an analytical method combining the magnetomotive force (MMF)-permeance method and the subdomain method is performed to predict the magnetic field distribution. Considering the complex rotor structure, a novel subdivision equivalence method and boundary processing are employed to ensure the minimum loss of shape transformation. It dramatically expands the versatility of the analytical method and has unparalleled computational efficiency. Furthermore, this article introduces an original numerical computing technique to calculate the temperature distribution throughout the motor. The finite-difference method (FDM) is applied to the periodic model, specifically focusing on improving the calculation speed. By classifying the grid points, the temperature distribution can be obtained. The proposed method avoids the limitation of the analytical method in solving the temperature field and offers better computational efficiency than the FEM. Based on these models, the coupling between the two fields is discussed. Finally, a six-pole 36-slot prototype is manufactured. The presented approach is compared with FEM and experiment, demonstrating effectiveness.]]></description>
      <pubDate>Thu, 01 May 2025 09:36:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/2511861</guid>
    </item>
    <item>
      <title>Hydro-mechanical analysis of tunneling in saturated ground using an efficient sequential coupling technique (UTI-UTC 22)
</title>
      <link>https://trid.trb.org/View/2543417</link>
      <description><![CDATA[This project aims to enhance the understanding and simulation of the complex interactions between hydraulic and mechanical processes during tunnel excavation in saturated soils. The research focuses on developing an efficient sequential coupling technique to model pore water pressure dissipation and ground deformation, which are critical in ensuring tunnel stability and safety. By leveraging high-order finite difference methods and validated numerical simulations, the project enables detailed analysis of soil behavior under varying stress and seepage conditions. The methodology is designed to accurately capture the temporal and spatial evolution of ground responses during tunneling without incurring the computational cost of fully coupled models. Results from this study provide practical insights for the design and risk assessment of tunneling operations in soft, water-bearing ground conditions, contributing to safer and more efficient underground construction practices.
]]></description>
      <pubDate>Wed, 07 May 2025 18:01:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/2543417</guid>
    </item>
    <item>
      <title>Integration of brake block thermal equations within a railway vehicle multibody model: a multiphysics approach</title>
      <link>https://trid.trb.org/View/2494774</link>
      <description><![CDATA[The paper shows the development of a finite-difference (FD) railway brake block thermal model and its integration within the multibody (MB) formalism of the Simpack commercial code. The block nodal temperatures are included among the dynamic states computed by the MB solver, through the definition of a user-defined force element, which determines the braking torque based on the applied brake cylinder pressure. The proposed approach overcomes the main limitations of existing detailed railway vehicle models, which solve the thermal and vehicle dynamics equations in different computational environments. Furthermore, the new strategy can thrust the development of models able to account for the coupling between the wheel and block thermal behaviour and the whole vehicle dynamics. Preliminary simulations of drag and stop braking operations of a reference European freight wagon prove that the proposed model is able to effectively consider the main heat fluxes and nonlinearities involved in tread braking operations.]]></description>
      <pubDate>Fri, 28 Feb 2025 16:46:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2494774</guid>
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