The uplift resistance of the soil overlying shield tunnels significantly impacts their anti-floating stability.However,research on uplift resistance concerning special-shaped shield tunnels is limited.This study combi...The uplift resistance of the soil overlying shield tunnels significantly impacts their anti-floating stability.However,research on uplift resistance concerning special-shaped shield tunnels is limited.This study combines numerical simulation with machine learning techniques to explore this issue.It presents a summary of special-shaped tunnel geometries and introduces a shape coefficient.Through the finite element software,Plaxis3D,the study simulates six key parameters—shape coefficient,burial depth ratio,tunnel’s longest horizontal length,internal friction angle,cohesion,and soil submerged bulk density—that impact uplift resistance across different conditions.Employing XGBoost and ANN methods,the feature importance of each parameter was analyzed based on the numerical simulation results.The findings demonstrate that a tunnel shape more closely resembling a circle leads to reduced uplift resistance in the overlying soil,whereas other parameters exhibit the contrary effects.Furthermore,the study reveals a diminishing trend in the feature importance of buried depth ratio,internal friction angle,tunnel longest horizontal length,cohesion,soil submerged bulk density,and shape coefficient in influencing uplift resistance.展开更多
Dear Editor,This letter addresses the formation control problem for unmanned surface vehicles(USVs)under GPS-denied environments.A novel visual servo formation control scheme,utilizing a monocular camera on the follow...Dear Editor,This letter addresses the formation control problem for unmanned surface vehicles(USVs)under GPS-denied environments.A novel visual servo formation control scheme,utilizing a monocular camera on the follower to obtain the leader’s global position,is developed,which is also capable of guaranteeing collision avoidance and visibility maintenance(CA&VM)raised by the requirement of actual formation navigation.展开更多
The rapid increase in traffic loads and frequencies has rendered conventional asphalt pavement inadequate to maintain its durability under tropical climates.This challenge has necessitated the exploration of new sourc...The rapid increase in traffic loads and frequencies has rendered conventional asphalt pavement inadequate to maintain its durability under tropical climates.This challenge has necessitated the exploration of new sources of modified asphalt with enhanced stiffness and superior performance at high temperatures.Natural rubber(NR)is a renewable biopolymer that has received growing interest as a modifier for asphalt binders.Cup lump rubber(CLR),a type of NR,is used to enhance asphalt properties and improve the performance of road pavements.This study evaluates the influence of wax-based surfactants(WS)on CLR-modified asphalt binder(CMB).The assessment focuses on changes in chemical characteristics,rheological behaviour,activation energy,and morphology.Four concentrations of WS(0.1%,0.15%,0.2%,and 0.25%)were incorporated into CMB.Analysis of CMB chemical changes showed that viscosity increased due to higher sulfoxide,carbonyl,and aromatic bond indices.These chemical modifications contributed to improved resistance of the binder to heat-induced deterioration.In both unaged and aged CMB samples,the incorporation of WS reduced the sulfoxide index of the binder.Rheological analysis indicated that CMB improved rutting resistance and anti-ageing performance,while WS further enhanced fatigue resistance.Activation energy analysis suggested that the combination of CMB with 0.15%WS produced the most favourable enhancement.Micrograph results showed that WS improved binder homogeneity and interconnectivity.In conclusion,the findings indicated that incorporating 0.15%WS into CMB enhanced the performance and durability of the asphalt pavement.展开更多
With the large-scale integration of new energy sources,various resources such as energy storage,electric vehicles(EVs),and photovoltaics(PV) have participated in the scheduling of active distribution networks(ADNs),po...With the large-scale integration of new energy sources,various resources such as energy storage,electric vehicles(EVs),and photovoltaics(PV) have participated in the scheduling of active distribution networks(ADNs),posing new challenges to the operation and scheduling of distribution networks.Aiming at the uncertainty of PV and EV,an optimal scheduling model for ADNs based on multi-scenario fuzzy set based charging station resource forecasting is constructed.To address the scheduling uncertainties caused by PV and load forecasting errors,a day-ahead optimal scheduling model based on conditional value at risk(CVaR) for cost assessment is established,with the optimization objectives of minimizing the operation cost of distribution networks and the risk cost caused by forecasting errors.An improved subtractive optimizer algorithm is proposed to solve the model and formulate day-ahead optimization schemes.Secondly,a forecasting model for dispatchable resources in charging stations is constructed based on event-based fuzzy set theory.On this basis,an intraday scheduling model is built to comprehensively utilize the dispatchable resources of charging stations to coordinate with the output of distributed power sources,achieving optimal scheduling with the goal of minimizing operation costs.Finally,an experimental scenario based on the IEEE-33 node system is designed for simulation verification.The comparison of optimal scheduling results shows that the proposed method can fully exploit the potential scheduling resources of charging stations,improving the operation stability of ADNs and the accommodution capacity of new energy.展开更多
Based on the surrounding rock arching and hingeless arch structure theories,a theoretical formula for the minimum overburden thickness was derived.By substituting different mechanical parameters of multiple tunnels at...Based on the surrounding rock arching and hingeless arch structure theories,a theoretical formula for the minimum overburden thickness was derived.By substituting different mechanical parameters of multiple tunnels at home and abroad into this formula,minimum self-supporting arch formulas under different surrounding rock classes were obtained.Based on the actual engineering case of a dual-mode shield tunnel,a numerical model for the tunnel boring machine excavation mode was established to verify the theoretical formulas.Next,three surrounding rock classes,four soil layer thickness gradients,and twelve overburden thickness gradients were designed,resulting in 144 models formed by the combination of the three factors.Uniform tests were conducted,and the pressure arch heights under different surrounding rock classes were obtained.The results show that in the theoretical formulas,the tunnel radius has a linear positive correlation with the pressure arch height,while the tunnel depth has a linear positive correlation with the square of the pressure arch height.According to numerical simulation results,the pressure arch height increases with the increase of the overburden thickness and then tends toward a critical value of twice the tunnel diameter.Finally,the results of the numerical model are in good agreement with those calculated using the theoretical formulas,verifying the rationality of the established theoretical formulas.展开更多
Shield tunneling in saturated ground poses challenges due to the potential risk of ground collapse resulting from seepage force and inadequate support pressure.This study employed a laboratory model test and a theoret...Shield tunneling in saturated ground poses challenges due to the potential risk of ground collapse resulting from seepage force and inadequate support pressure.This study employed a laboratory model test and a theoretical validation to elucidate the mechanisms of face failure and subsequent ground collapse in saturated ground during slurry pressure-balanced shield(SPBS)tunneling operations.A slurry circulation system was developed to ensure steady shield tunneling and to replicate the phenomena of ground collapse.Investigations into shield tunneling parameters and ground responses,including soil pressure,pore water pressure,and surface subsidence,were conducted to understand the mechanisms of face failure and subsequent ground collapse.The theoretical solution for the critical collapse pressure of the tunnel face,based on the rotational failure mechanism,was validated through the comparison with the experimentally determined critical collapse pressure.The results indicate that:(1)appropriate adjustments of tunneling parameters are crucial for promoting filtercake formation,maintaining chamber pressure,and minimizing ground subsidence;(2)chamber pressure,soil pressure,pore water pressure,and ground subsidence are closely correlated with shield tunneling parameters and the formation of filter cake;(3)ground collapse follows a continuous failure mode due to the destruction of filtercake and the decrease in chamber pressure;(4)the soil pressure at the cutterhead is more sensitive to disturbances from shield tunneling than chamber pressure;and(5)experimentally determined critical collapse pressures is consistent with the theoretical solution of limit analysis.展开更多
Underground engineering projects such as deep tunnel excavation often encounter rockburst disasters accompanied by numerous microseismic events.Rapid interpretation of microseismic signals is crucial for the timely id...Underground engineering projects such as deep tunnel excavation often encounter rockburst disasters accompanied by numerous microseismic events.Rapid interpretation of microseismic signals is crucial for the timely identification of rockbursts.However,conventional processing encompasses multi-step workflows,including classification,denoising,picking,locating,and computational analysis,coupled with manual intervention,which collectively compromise the reliability of early warnings.To address these challenges,this study innovatively proposes the“microseismic stethoscope"-a multi-task machine learning and deep learning model designed for the automated processing of massive microseismic signals.This model efficiently extracts three key parameters that are necessary for recognizing rockburst disasters:rupture location,microseismic energy,and moment magnitude.Specifically,the model extracts raw waveform features from three dedicated sub-networks:a classifier for source zone classification,and two regressors for microseismic energy and moment magnitude estimation.This model demonstrates superior efficiency compared to traditional processing and semi-automated processing,reducing per-event processing time from 0.71 s to 0.49 s to merely 0.036 s.It concurrently achieves 98%accuracy in source zone classification,with microseismic energy and moment magnitude estimation errors of 0.13 and 0.05,respectively.This model has been well applied and validated in the Daxiagu Tunnel case in Sichuan,China.The application results indicate that the model is as accurate as traditional methods in determining source parameters,and thus can be used to identify potential geomechanical processes of rockburst disasters.By enhancing the signal processing reliability of microseismic events,the proposed model in this study presents a significant advancement in the identification of rockburst disasters.展开更多
Long-span suspension bridges are inherently vulnerable to earthquakes due to their low stiffness and damping.A novel design,the main-cable-looped(MCL)suspension bridge,features a looped main cable that alters the stru...Long-span suspension bridges are inherently vulnerable to earthquakes due to their low stiffness and damping.A novel design,the main-cable-looped(MCL)suspension bridge,features a looped main cable that alters the structure’s load transfer mechanism.The seismic response of this novel bridge type is not well understood,creating an urgent need for investigation to ensure its safety and performance.The global finite element model of this bridge was established by considering the interdependent behavior of the structure and the underlying soil.Based on the design seismic response spectrum,ground motion accelerations were selected,and the peak ground acceleration(PGA)was adjusted.The nonlinear time-history analysis method was adopted to calculate seismic responses of the novel MCL suspension bridge.A parametric study was conducted to investigate the effects of the PGA of seismic ground motion and the longitudinal position of ground-anchored rods on seismic responses of the novel suspension bridge.The research results show that under different seismic excitations with a design PGA of 0.1 g,the maximum longitudinal displacement at the tower top is 0.097 m,the maximum bending moment at the tower base reaches 2.20×10^(5)kN m,the maximum longitudinal displacement at the girder free end is 0.022 m,and the maximum vertical displacement at the girder mid-span is 0.647 m.The seismic performance of the novel MCL suspension bridge meets the specified design requirements,as it remains in the elastic working stage without material yielding or stiffness degradation.The PGA of seismic ground motion has a profound influence,with the structural response of the bridge tower and girder increasing linearly as PGA increases.An increase in PGA from 0.1 g to 0.35 g results in a 5.6%increase in the maximum longitudinal displacement at the tower top,a 21.8%increase in the maximum bending moment at the tower base,a 68.7%increase in the maximum longitudinal displacement at the girder free end,and a 0.6%increase in the maximum vertical displacement at the girder mid-span.Furthermore,the longitudinal position of ground-anchored rods was also found to be critical,with the structural responses of the bridge tower and girder exhibiting a nonlinear relationship with the longitudinal distance between the ground-anchored rods and the rotating saddle.The optimal longitudinal position of the ground-anchored rods is found to be as close as possible to the rotating saddle.These findings elucidate the seismic behavior mechanisms and provide critical quantitative guidance for the seismic design of MCL suspension bridges.展开更多
With the development of autonomous driving technologies,modern vehicles are confronted with two major challenges.On one hand,the rapid growth in electronic control units and data-intensive applications has led to a sh...With the development of autonomous driving technologies,modern vehicles are confronted with two major challenges.On one hand,the rapid growth in electronic control units and data-intensive applications has led to a sharp increase in invehicle data traffic,thereby demanding much higher communication bandwidth,lower latency,and enhanced security.On the other hand,ensuring driving safety calls for more advanced thermal management systems,as traditional point-type sensors face deployment challenges due to their limited monitoring range.展开更多
Dear Editor,This letter studies the motion planning issue for an autonomous underwater vehicle(AUV)in obstacle environment.We propose a novel integrated detection-communication waveform that enables simultaneous obsta...Dear Editor,This letter studies the motion planning issue for an autonomous underwater vehicle(AUV)in obstacle environment.We propose a novel integrated detection-communication waveform that enables simultaneous obstacle detection and self-localization.展开更多
During the use of robotics in applications such as antiterrorism or combat,a motion-constrained pursuer vehicle,such as a Dubins unmanned surface vehicle(USV),must get close enough(within a prescribed zero or positive...During the use of robotics in applications such as antiterrorism or combat,a motion-constrained pursuer vehicle,such as a Dubins unmanned surface vehicle(USV),must get close enough(within a prescribed zero or positive distance)to a moving target as quickly as possible,resulting in the extended minimum-time intercept problem(EMTIP).Existing research has primarily focused on the zero-distance intercept problem,MTIP,establishing the necessary or sufficient conditions for MTIP optimality,and utilizing analytic algorithms,such as root-finding algorithms,to calculate the optimal solutions.However,these approaches depend heavily on the properties of the analytic algorithm,making them inapplicable when problem settings change,such as in the case of a positive effective range or complicated target motions outside uniform rectilinear motion.In this study,an approach employing a high-accuracy and quality-guaranteed mixed-integer piecewise-linear program(QG-PWL)is proposed for the EMTIP.This program can accommodate different effective interception ranges and complicated target motions(variable velocity or complicated trajectories).The high accuracy and quality guarantees of QG-PWL originate from elegant strategies such as piecewise linearization and other developed operation strategies.The approximate error in the intercept path length is proved to be bounded to h^(2)/(4√2),where h is the piecewise length.展开更多
Investigating the wind-sand flow response regularity in the longitudinal slope sections of desert highways provides a scientific basis for selecting the slope of desert roads.This study uses the Tengger Desert section...Investigating the wind-sand flow response regularity in the longitudinal slope sections of desert highways provides a scientific basis for selecting the slope of desert roads.This study uses the Tengger Desert section of the Wuhai-Maqin Expressway as a case study,employing CFD numerical simulation methods to calculate and analyze the wind-sand flow field distribution characteristics in different longitudinal slope sections.The results show that:(1)Along with the direction of the incoming flow,the windward and leeward slope toes of the embankment are low-wind-speed zones,with the wind speed at the leeward slope toe being even lower.The higher the embankment,the larger the low-wind-speed zone at the windward and leeward slope toes.As the longitudinal slope increases,the extent of the lowwind-speed zone at the same location along the route also increases.(2)Along the route direction,the wind speed at the windward and leeward slope toes decreases as embankment height increases.At the embankment toe,sand particles are transported from the top to the bottom of the longitudinal slope,and the greater the longitudinal slope,the stronger the transport effect.(3)Along the route direction,the sand accumulation around the embankment gradually gathers toward the bottom of the longitudinal slope as the slope increases.When the longitudinal slope is 3%and 4%,the trend of sand accumulation moving from the windward side at the end of the route to the leeward side at the start of the route is more significant.When the longitudinal slope is less than or equal to 3%,severe sand accumulation within the embankment range is reduced by 86.4%or more compared to when the slope is 4%.(4)Under the same longitudinal slope,the higher the embankment height,the smaller its transport rate.When the embankment height is the same,the greater the longitudinal slope,the greater the embankment transport rate.展开更多
In real-world autonomous driving tests,unexpected events such as pedestrians or wild animals suddenly entering the driving path can occur.Conducting actual test drives under various weather conditions may also lead to...In real-world autonomous driving tests,unexpected events such as pedestrians or wild animals suddenly entering the driving path can occur.Conducting actual test drives under various weather conditions may also lead to dangerous situations.Furthermore,autonomous vehicles may operate abnormally in bad weather due to limitations of their sensors and GPS.Driving simulators,which replicate driving conditions nearly identical to those in the real world,can drastically reduce the time and cost required for market entry validation;consequently,they have become widely used.In this paper,we design a virtual driving test environment capable of collecting and verifying SiLS data under adverse weather conditions using multi-source images.The proposed method generates a virtual testing environment that incorporates various events,including weather,time of day,and moving objects,that cannot be easily verified in real-world autonomous driving tests.By setting up scenario-based virtual environment events,multi-source image analysis and verification using real-world DCUs(Data Concentrator Units)with V2X-Car edge cloud can effectively address risk factors that may arise in real-world situations.We tested and validated the proposed method with scenarios employing V2X communication and multi-source image analysis.展开更多
Traffic at urban intersections frequently encounters unexpected obstructions,resulting in congestion due to uncooperative and priority-based driving behavior.This paper presents an optimal right-turn coordination syst...Traffic at urban intersections frequently encounters unexpected obstructions,resulting in congestion due to uncooperative and priority-based driving behavior.This paper presents an optimal right-turn coordination system for Connected and Automated Vehicles(CAVs)at single-lane intersections,particularly in the context of left-hand side driving on roads.The goal is to facilitate smooth right turns for certain vehicles without creating bottlenecks.We consider that all approaching vehicles share relevant information through vehicular communications.The Intersection Coordination Unit(ICU)processes this information and communicates the optimal crossing or turning times to the vehicles.The primary objective of this coordination is to minimize overall traffic delays,which also helps improve the fuel consumption of vehicles.By considering information from upcoming vehicles at the intersection,the coordination system solves an optimization problem to determine the best timing for executing right turns,ultimately minimizing the total delay for all vehicles.The proposed coordination system is evaluated at a typical urban intersection,and its performance is compared to traditional traffic systems.Numerical simulation results indicate that the proposed coordination system significantly enhances the average traffic speed and fuel consumption compared to the traditional traffic system in various scenarios.展开更多
As a cornerstone for applications such as autonomous driving,3D urban perception is a burgeoning field of study.Enhancing the performance and robustness of these perception systems is crucial for ensuring the safety o...As a cornerstone for applications such as autonomous driving,3D urban perception is a burgeoning field of study.Enhancing the performance and robustness of these perception systems is crucial for ensuring the safety of next-generation autonomous vehicles.In this work,we introduce a novel neural scene representation called Street Detection Gaussians(SDGs),which redefines urban 3D perception through an integrated architecture unifying reconstruction and detection.At its core lies the dynamic Gaussian representation,where time-conditioned parameterization enables simultaneous modeling of static environments and dynamic objects through physically constrained Gaussian evolution.The framework’s radar-enhanced perception module learns cross-modal correlations between sparse radardata anddense visual features,resulting ina22%reduction inocclusionerrors compared tovisiononly systems.A breakthrough differentiable rendering pipeline back-propagates semantic detection losses throughout the entire 3D reconstruction process,enabling the optimization of both geometric and semantic fidelity.Evaluated on the Waymo Open Dataset and the KITTI Dataset,the system achieves real-time performance(135 Frames Per Second(FPS)),photorealistic quality(Peak Signal-to-Noise Ratio(PSNR)34.9 dB),and state-of-the-art detection accuracy(78.1%Mean Average Precision(mAP)),demonstrating a 3.8×end-to-end improvement over existing hybrid approaches while enabling seamless integration with autonomous driving stacks.展开更多
Pile group-supported bridges in liquefied sloping ground with crust are prone to severe damage.However,there remains a limited comprehension of the intricate interactions among pile group,soil,and superstructures,as w...Pile group-supported bridges in liquefied sloping ground with crust are prone to severe damage.However,there remains a limited comprehension of the intricate interactions among pile group,soil,and superstructures,as well as the associated failure mechanisms.To address this issue,this paper presents large-scale shaking table tests conducted on pile group-supported bridges in sloping liquefiable ground with crust to uncover the intricate interaction mechanisms.Firstly,the dynamic characteristics and interaction of the pile-soil-superstructure system were explored.Then,the lateral displacement and acceleration of the superstructure and pile were presented.Next,the curvature and damage characteristics of the pile group-supported bridge were discussed.Finally,through cross-correlation analysis,the study revealed the inertia and kinematic effects,focusing on how the effects influenced the seismic demands.Results indicate that significant differences are observed in pile-soil interactions during strong seismic events depending on the depth and liquefaction stage.As earthquake intensity increases,peak displacement in the superstructure rises linearly while residual displacement grows exponentially.Moreover,the pile group effect becomes more pronounced,especially at the pile head,with the trailing piles showing greater curvature than the leading ones.Due to significant soil lateral spreading and the shadowing effect within the pile group,the leading piles experience prominent kinematic effects from the surface down to the intermediate layer of saturated sand compared to the trailing piles.These findings contribute valuable insights for improving the seismic design approach for bridges with pile groups in sloping liquefied soils.展开更多
Head-up displays(HUDs)are emerging as key components of intelligent vehicles,requiring wide-depth,large-area,and high-efficiency dynamic imaging,which remains difficult to realize with traditional refractive optics.Co...Head-up displays(HUDs)are emerging as key components of intelligent vehicles,requiring wide-depth,large-area,and high-efficiency dynamic imaging,which remains difficult to realize with traditional refractive optics.Computer-generated holography(CGH)with diffraction optics offers a promising solution to these technical demands.However,CGH optimization based on the fast Fourier transform(FFT)faces limitations such as zero-padding redundancy,coupled sampling intervals,and incompatible near-and farfield propagation models.Here,we report a holography-based multiplane HUD using a matrix multiplication(MM)-assisted diffraction algorithm that restructures the Fresnel integral into two sequential matrix operations,thus eliminating zero-padding and enabling fully decoupled sampling between object and image planes.Compared with FFT-based angular spectrum methods,the MM approach significantly improves computational speed and memory efficiency for hologram design,which is validated by demonstrating dual-plane holography with a size ratio exceeding 100:1 and unified reconstruction across Fresnel and Fraunhofer regimes within a single computation.A prototype HUD system is demonstrated successfully to exhibit multiple-plane holographic virtual images that can be mixed with real-world objects at three independent planes.The technique might be one of the potential candidates for next-generation intelligent vehicle displays.展开更多
This study investigates the influence of loading frequency on the fatigue behavior of ballastless track concrete for high-speed railways,aiming to support the development of concrete capable of withstanding higher ope...This study investigates the influence of loading frequency on the fatigue behavior of ballastless track concrete for high-speed railways,aiming to support the development of concrete capable of withstanding higher operational speeds.Fatigue tests were conducted at loading frequencies ranging from 5 to 40 Hz,with a focus on fatigue life,damage evolution,energy dissipation,and residual fatigue strain in the concrete.The results indicate that between 5 and 15 Hz,the fatigue life and energy dissipation remain relatively stable,with minimal damage evolution and small residual strains.As the frequency increases to 15-20 Hz,the fatigue life and energy dissipation gradually decrease,while damage accumulation and residual strain increase.Beyond 20 Hz,both fatigue life and energy dissipation decrease rapidly,damage accumulation becomes more pronounced,and residual strain continues to rise.These phenomena are primarily attributed to the increased strain rate and load change rate at higher frequencies,which affect the microstructure evolution and lead to reduced fatigue performance.展开更多
Grouting is an essential technique for reinforcing tunnel rock masses following deformation and failure.However,the mechanisms and effectiveness evaluation of grouting in fractured rock masses that have experienced su...Grouting is an essential technique for reinforcing tunnel rock masses following deformation and failure.However,the mechanisms and effectiveness evaluation of grouting in fractured rock masses that have experienced substantial deformation and transition into the residual stage remain insufficiently understood.To elucidate the relationship between grouting effectiveness and pre-cracking strain,grouting and subsequent re-fracturing tests were conducted on sandy mudstone specimens with varying levels of pre-cracking strain.Additionally,a model was developed to determine the optimal grouting timing during the residual stage.The results indicate that the failure mode of specimens in the residual stage exhibits banded and localized distribution patterns.As pre-cracking strain increases,both the maximum fracture aperture and the relative grout injection ratio increase,with the increases becoming more pronounced at higher strain levels.After grouting,the consolidation coefficient and strength enhancement coefficient exhibit a positive correlation with pre-cracking strain,although the rate of increase gradually decreases.Grouting does not alter the initial failure mode of residual-stage fractured specimens but effectively suppresses secondary crack propagation in regions distant from primary fractures.At the microscale,grout bonds within the rock matrix form cavity structures that delay tensile failure and generate an interconnected network,thereby enhancing crack resistance.Based on the evolution of rock damage and the efficiency of grouting materials utilization,a method is proposed to determine the optimal grouting timing for fractured specimens in the residual stage.At the optimal timing,specimens exhibit moderate damage while maintaining high reinforcement efficiency per unit mass of grout.展开更多
基金Guangzhou Metro Scientific Research Project(No.JT204-100111-23001)Chongqing Municipal Special Project for Technological Innovation and Application Development(No.CSTB2022TIAD-KPX0101)Science and Technology Research and Development Program of China State Railway Group Co.,Ltd.(No.N2023G045)。
文摘The uplift resistance of the soil overlying shield tunnels significantly impacts their anti-floating stability.However,research on uplift resistance concerning special-shaped shield tunnels is limited.This study combines numerical simulation with machine learning techniques to explore this issue.It presents a summary of special-shaped tunnel geometries and introduces a shape coefficient.Through the finite element software,Plaxis3D,the study simulates six key parameters—shape coefficient,burial depth ratio,tunnel’s longest horizontal length,internal friction angle,cohesion,and soil submerged bulk density—that impact uplift resistance across different conditions.Employing XGBoost and ANN methods,the feature importance of each parameter was analyzed based on the numerical simulation results.The findings demonstrate that a tunnel shape more closely resembling a circle leads to reduced uplift resistance in the overlying soil,whereas other parameters exhibit the contrary effects.Furthermore,the study reveals a diminishing trend in the feature importance of buried depth ratio,internal friction angle,tunnel longest horizontal length,cohesion,soil submerged bulk density,and shape coefficient in influencing uplift resistance.
基金supported by the National Natural Science Foundation of China(62421004,U24A20279,62473243,62533004)。
文摘Dear Editor,This letter addresses the formation control problem for unmanned surface vehicles(USVs)under GPS-denied environments.A novel visual servo formation control scheme,utilizing a monocular camera on the follower to obtain the leader’s global position,is developed,which is also capable of guaranteeing collision avoidance and visibility maintenance(CA&VM)raised by the requirement of actual formation navigation.
基金the financial support provided under the Fundamental Research Grant Scheme(FRGS),Project Code:FRGS/1/2021/TK01/USM/02/1,which made this research possible,The kind assistance and collaboration of all material suppliers were also gratefully acknowledged.Additional appreciation is extended to the Public Works Department Malaysia for the scholarship provided through the Hadiah Latihan Persekutuan programme for professional and managerial officers pursuing doctoral studies(JPA-1-840622086040)The APC was funded by Prof.Hui Yao from Beijing University of Technology.
文摘The rapid increase in traffic loads and frequencies has rendered conventional asphalt pavement inadequate to maintain its durability under tropical climates.This challenge has necessitated the exploration of new sources of modified asphalt with enhanced stiffness and superior performance at high temperatures.Natural rubber(NR)is a renewable biopolymer that has received growing interest as a modifier for asphalt binders.Cup lump rubber(CLR),a type of NR,is used to enhance asphalt properties and improve the performance of road pavements.This study evaluates the influence of wax-based surfactants(WS)on CLR-modified asphalt binder(CMB).The assessment focuses on changes in chemical characteristics,rheological behaviour,activation energy,and morphology.Four concentrations of WS(0.1%,0.15%,0.2%,and 0.25%)were incorporated into CMB.Analysis of CMB chemical changes showed that viscosity increased due to higher sulfoxide,carbonyl,and aromatic bond indices.These chemical modifications contributed to improved resistance of the binder to heat-induced deterioration.In both unaged and aged CMB samples,the incorporation of WS reduced the sulfoxide index of the binder.Rheological analysis indicated that CMB improved rutting resistance and anti-ageing performance,while WS further enhanced fatigue resistance.Activation energy analysis suggested that the combination of CMB with 0.15%WS produced the most favourable enhancement.Micrograph results showed that WS improved binder homogeneity and interconnectivity.In conclusion,the findings indicated that incorporating 0.15%WS into CMB enhanced the performance and durability of the asphalt pavement.
基金Supported by the Technology Project of State Grid Corporation Headquarters(No.5100-202322029A-1-1-ZN)the 2024 Youth Science Foundation Project of China (No.62303006)。
文摘With the large-scale integration of new energy sources,various resources such as energy storage,electric vehicles(EVs),and photovoltaics(PV) have participated in the scheduling of active distribution networks(ADNs),posing new challenges to the operation and scheduling of distribution networks.Aiming at the uncertainty of PV and EV,an optimal scheduling model for ADNs based on multi-scenario fuzzy set based charging station resource forecasting is constructed.To address the scheduling uncertainties caused by PV and load forecasting errors,a day-ahead optimal scheduling model based on conditional value at risk(CVaR) for cost assessment is established,with the optimization objectives of minimizing the operation cost of distribution networks and the risk cost caused by forecasting errors.An improved subtractive optimizer algorithm is proposed to solve the model and formulate day-ahead optimization schemes.Secondly,a forecasting model for dispatchable resources in charging stations is constructed based on event-based fuzzy set theory.On this basis,an intraday scheduling model is built to comprehensively utilize the dispatchable resources of charging stations to coordinate with the output of distributed power sources,achieving optimal scheduling with the goal of minimizing operation costs.Finally,an experimental scenario based on the IEEE-33 node system is designed for simulation verification.The comparison of optimal scheduling results shows that the proposed method can fully exploit the potential scheduling resources of charging stations,improving the operation stability of ADNs and the accommodution capacity of new energy.
基金The National Natural Science Foundation of China(No.52478426)the Natural Science Foundation of Hunan Province(No.2024JJ5428).
文摘Based on the surrounding rock arching and hingeless arch structure theories,a theoretical formula for the minimum overburden thickness was derived.By substituting different mechanical parameters of multiple tunnels at home and abroad into this formula,minimum self-supporting arch formulas under different surrounding rock classes were obtained.Based on the actual engineering case of a dual-mode shield tunnel,a numerical model for the tunnel boring machine excavation mode was established to verify the theoretical formulas.Next,three surrounding rock classes,four soil layer thickness gradients,and twelve overburden thickness gradients were designed,resulting in 144 models formed by the combination of the three factors.Uniform tests were conducted,and the pressure arch heights under different surrounding rock classes were obtained.The results show that in the theoretical formulas,the tunnel radius has a linear positive correlation with the pressure arch height,while the tunnel depth has a linear positive correlation with the square of the pressure arch height.According to numerical simulation results,the pressure arch height increases with the increase of the overburden thickness and then tends toward a critical value of twice the tunnel diameter.Finally,the results of the numerical model are in good agreement with those calculated using the theoretical formulas,verifying the rationality of the established theoretical formulas.
基金support of the National Natural Science Foundation of China(Grant Nos.52179116 and 51991392)the support of Key Deployment Projects of Chinese Academy of Sciences(Grant No.ZDRW-ZS-2021-3).
文摘Shield tunneling in saturated ground poses challenges due to the potential risk of ground collapse resulting from seepage force and inadequate support pressure.This study employed a laboratory model test and a theoretical validation to elucidate the mechanisms of face failure and subsequent ground collapse in saturated ground during slurry pressure-balanced shield(SPBS)tunneling operations.A slurry circulation system was developed to ensure steady shield tunneling and to replicate the phenomena of ground collapse.Investigations into shield tunneling parameters and ground responses,including soil pressure,pore water pressure,and surface subsidence,were conducted to understand the mechanisms of face failure and subsequent ground collapse.The theoretical solution for the critical collapse pressure of the tunnel face,based on the rotational failure mechanism,was validated through the comparison with the experimentally determined critical collapse pressure.The results indicate that:(1)appropriate adjustments of tunneling parameters are crucial for promoting filtercake formation,maintaining chamber pressure,and minimizing ground subsidence;(2)chamber pressure,soil pressure,pore water pressure,and ground subsidence are closely correlated with shield tunneling parameters and the formation of filter cake;(3)ground collapse follows a continuous failure mode due to the destruction of filtercake and the decrease in chamber pressure;(4)the soil pressure at the cutterhead is more sensitive to disturbances from shield tunneling than chamber pressure;and(5)experimentally determined critical collapse pressures is consistent with the theoretical solution of limit analysis.
基金supported by the National Natural Science Foundation of China(Grant Nos.42130719 and 42177173)the Doctoral Direct Train Project of Chongqing Natural Science Foundation(Grant No.CSTB2023NSCQ-BSX0029).
文摘Underground engineering projects such as deep tunnel excavation often encounter rockburst disasters accompanied by numerous microseismic events.Rapid interpretation of microseismic signals is crucial for the timely identification of rockbursts.However,conventional processing encompasses multi-step workflows,including classification,denoising,picking,locating,and computational analysis,coupled with manual intervention,which collectively compromise the reliability of early warnings.To address these challenges,this study innovatively proposes the“microseismic stethoscope"-a multi-task machine learning and deep learning model designed for the automated processing of massive microseismic signals.This model efficiently extracts three key parameters that are necessary for recognizing rockburst disasters:rupture location,microseismic energy,and moment magnitude.Specifically,the model extracts raw waveform features from three dedicated sub-networks:a classifier for source zone classification,and two regressors for microseismic energy and moment magnitude estimation.This model demonstrates superior efficiency compared to traditional processing and semi-automated processing,reducing per-event processing time from 0.71 s to 0.49 s to merely 0.036 s.It concurrently achieves 98%accuracy in source zone classification,with microseismic energy and moment magnitude estimation errors of 0.13 and 0.05,respectively.This model has been well applied and validated in the Daxiagu Tunnel case in Sichuan,China.The application results indicate that the model is as accurate as traditional methods in determining source parameters,and thus can be used to identify potential geomechanical processes of rockburst disasters.By enhancing the signal processing reliability of microseismic events,the proposed model in this study presents a significant advancement in the identification of rockburst disasters.
基金funded by the financial support from the National Natural Science Foundation of China(Grant No.52208214)Henan Transport Investment Group Co.,Ltd.(Grant No.HNJT-2025-2-45)Qing Lan project of Yangzhou University.
文摘Long-span suspension bridges are inherently vulnerable to earthquakes due to their low stiffness and damping.A novel design,the main-cable-looped(MCL)suspension bridge,features a looped main cable that alters the structure’s load transfer mechanism.The seismic response of this novel bridge type is not well understood,creating an urgent need for investigation to ensure its safety and performance.The global finite element model of this bridge was established by considering the interdependent behavior of the structure and the underlying soil.Based on the design seismic response spectrum,ground motion accelerations were selected,and the peak ground acceleration(PGA)was adjusted.The nonlinear time-history analysis method was adopted to calculate seismic responses of the novel MCL suspension bridge.A parametric study was conducted to investigate the effects of the PGA of seismic ground motion and the longitudinal position of ground-anchored rods on seismic responses of the novel suspension bridge.The research results show that under different seismic excitations with a design PGA of 0.1 g,the maximum longitudinal displacement at the tower top is 0.097 m,the maximum bending moment at the tower base reaches 2.20×10^(5)kN m,the maximum longitudinal displacement at the girder free end is 0.022 m,and the maximum vertical displacement at the girder mid-span is 0.647 m.The seismic performance of the novel MCL suspension bridge meets the specified design requirements,as it remains in the elastic working stage without material yielding or stiffness degradation.The PGA of seismic ground motion has a profound influence,with the structural response of the bridge tower and girder increasing linearly as PGA increases.An increase in PGA from 0.1 g to 0.35 g results in a 5.6%increase in the maximum longitudinal displacement at the tower top,a 21.8%increase in the maximum bending moment at the tower base,a 68.7%increase in the maximum longitudinal displacement at the girder free end,and a 0.6%increase in the maximum vertical displacement at the girder mid-span.Furthermore,the longitudinal position of ground-anchored rods was also found to be critical,with the structural responses of the bridge tower and girder exhibiting a nonlinear relationship with the longitudinal distance between the ground-anchored rods and the rotating saddle.The optimal longitudinal position of the ground-anchored rods is found to be as close as possible to the rotating saddle.These findings elucidate the seismic behavior mechanisms and provide critical quantitative guidance for the seismic design of MCL suspension bridges.
文摘With the development of autonomous driving technologies,modern vehicles are confronted with two major challenges.On one hand,the rapid growth in electronic control units and data-intensive applications has led to a sharp increase in invehicle data traffic,thereby demanding much higher communication bandwidth,lower latency,and enhanced security.On the other hand,ensuring driving safety calls for more advanced thermal management systems,as traditional point-type sensors face deployment challenges due to their limited monitoring range.
基金supported in part by the National Natural Science Foundation of China(U25A20473,62222314)the YanZhao Young Scientist Project of Hebei Province(F2024203047)+2 种基金the Natural Science Foundation of Hebei Province(F2022203001,F2024203072)the State Key Laboratory of Submarine Geoscience(sglkt2025-7)the Education Department Foundation of Hebei Province(JCZX2025027)。
文摘Dear Editor,This letter studies the motion planning issue for an autonomous underwater vehicle(AUV)in obstacle environment.We propose a novel integrated detection-communication waveform that enables simultaneous obstacle detection and self-localization.
基金supported by the National Natural Sci‐ence Foundation of China(Grant No.62306325)。
文摘During the use of robotics in applications such as antiterrorism or combat,a motion-constrained pursuer vehicle,such as a Dubins unmanned surface vehicle(USV),must get close enough(within a prescribed zero or positive distance)to a moving target as quickly as possible,resulting in the extended minimum-time intercept problem(EMTIP).Existing research has primarily focused on the zero-distance intercept problem,MTIP,establishing the necessary or sufficient conditions for MTIP optimality,and utilizing analytic algorithms,such as root-finding algorithms,to calculate the optimal solutions.However,these approaches depend heavily on the properties of the analytic algorithm,making them inapplicable when problem settings change,such as in the case of a positive effective range or complicated target motions outside uniform rectilinear motion.In this study,an approach employing a high-accuracy and quality-guaranteed mixed-integer piecewise-linear program(QG-PWL)is proposed for the EMTIP.This program can accommodate different effective interception ranges and complicated target motions(variable velocity or complicated trajectories).The high accuracy and quality guarantees of QG-PWL originate from elegant strategies such as piecewise linearization and other developed operation strategies.The approximate error in the intercept path length is proved to be bounded to h^(2)/(4√2),where h is the piecewise length.
基金financially supported by Youth Science“Research on Failure Mechanism and Evaluation Method of Sand Control Measures for Railway Machinery in Sandy Area”(12302511)Ningxia Transportation Department Science and Technology Project(20200173)The Central Guidance on Local Science and Technology Development Funds(22ZY1QA005)。
文摘Investigating the wind-sand flow response regularity in the longitudinal slope sections of desert highways provides a scientific basis for selecting the slope of desert roads.This study uses the Tengger Desert section of the Wuhai-Maqin Expressway as a case study,employing CFD numerical simulation methods to calculate and analyze the wind-sand flow field distribution characteristics in different longitudinal slope sections.The results show that:(1)Along with the direction of the incoming flow,the windward and leeward slope toes of the embankment are low-wind-speed zones,with the wind speed at the leeward slope toe being even lower.The higher the embankment,the larger the low-wind-speed zone at the windward and leeward slope toes.As the longitudinal slope increases,the extent of the lowwind-speed zone at the same location along the route also increases.(2)Along the route direction,the wind speed at the windward and leeward slope toes decreases as embankment height increases.At the embankment toe,sand particles are transported from the top to the bottom of the longitudinal slope,and the greater the longitudinal slope,the stronger the transport effect.(3)Along the route direction,the sand accumulation around the embankment gradually gathers toward the bottom of the longitudinal slope as the slope increases.When the longitudinal slope is 3%and 4%,the trend of sand accumulation moving from the windward side at the end of the route to the leeward side at the start of the route is more significant.When the longitudinal slope is less than or equal to 3%,severe sand accumulation within the embankment range is reduced by 86.4%or more compared to when the slope is 4%.(4)Under the same longitudinal slope,the higher the embankment height,the smaller its transport rate.When the embankment height is the same,the greater the longitudinal slope,the greater the embankment transport rate.
基金supported by Institute of Information and Communications Technology Planning and Evaluation(IITP)grant funded by the Korean government(MSIT)(No.2019-0-01842,Artificial Intelligence Graduate School Program(GIST))supported by Korea Planning&Evaluation Institute of Industrial Technology(KEIT)grant funded by the Ministry of Trade,Industry&Energy(MOTIE,Republic of Korea)(RS-2025-25448249+1 种基金Automotive Industry Technology Development(R&D)Program)supported by the Regional Innovation System&Education(RISE)programthrough the(Gwangju RISE Center),funded by the Ministry of Education(MOE)and the Gwangju Metropolitan City,Republic of Korea(2025-RISE-05-001).
文摘In real-world autonomous driving tests,unexpected events such as pedestrians or wild animals suddenly entering the driving path can occur.Conducting actual test drives under various weather conditions may also lead to dangerous situations.Furthermore,autonomous vehicles may operate abnormally in bad weather due to limitations of their sensors and GPS.Driving simulators,which replicate driving conditions nearly identical to those in the real world,can drastically reduce the time and cost required for market entry validation;consequently,they have become widely used.In this paper,we design a virtual driving test environment capable of collecting and verifying SiLS data under adverse weather conditions using multi-source images.The proposed method generates a virtual testing environment that incorporates various events,including weather,time of day,and moving objects,that cannot be easily verified in real-world autonomous driving tests.By setting up scenario-based virtual environment events,multi-source image analysis and verification using real-world DCUs(Data Concentrator Units)with V2X-Car edge cloud can effectively address risk factors that may arise in real-world situations.We tested and validated the proposed method with scenarios employing V2X communication and multi-source image analysis.
基金supported by the Japan Society for the Promotion of Science(JSPS)Grants-in-Aid for Scientific Research(C)23K03898.
文摘Traffic at urban intersections frequently encounters unexpected obstructions,resulting in congestion due to uncooperative and priority-based driving behavior.This paper presents an optimal right-turn coordination system for Connected and Automated Vehicles(CAVs)at single-lane intersections,particularly in the context of left-hand side driving on roads.The goal is to facilitate smooth right turns for certain vehicles without creating bottlenecks.We consider that all approaching vehicles share relevant information through vehicular communications.The Intersection Coordination Unit(ICU)processes this information and communicates the optimal crossing or turning times to the vehicles.The primary objective of this coordination is to minimize overall traffic delays,which also helps improve the fuel consumption of vehicles.By considering information from upcoming vehicles at the intersection,the coordination system solves an optimization problem to determine the best timing for executing right turns,ultimately minimizing the total delay for all vehicles.The proposed coordination system is evaluated at a typical urban intersection,and its performance is compared to traditional traffic systems.Numerical simulation results indicate that the proposed coordination system significantly enhances the average traffic speed and fuel consumption compared to the traditional traffic system in various scenarios.
文摘As a cornerstone for applications such as autonomous driving,3D urban perception is a burgeoning field of study.Enhancing the performance and robustness of these perception systems is crucial for ensuring the safety of next-generation autonomous vehicles.In this work,we introduce a novel neural scene representation called Street Detection Gaussians(SDGs),which redefines urban 3D perception through an integrated architecture unifying reconstruction and detection.At its core lies the dynamic Gaussian representation,where time-conditioned parameterization enables simultaneous modeling of static environments and dynamic objects through physically constrained Gaussian evolution.The framework’s radar-enhanced perception module learns cross-modal correlations between sparse radardata anddense visual features,resulting ina22%reduction inocclusionerrors compared tovisiononly systems.A breakthrough differentiable rendering pipeline back-propagates semantic detection losses throughout the entire 3D reconstruction process,enabling the optimization of both geometric and semantic fidelity.Evaluated on the Waymo Open Dataset and the KITTI Dataset,the system achieves real-time performance(135 Frames Per Second(FPS)),photorealistic quality(Peak Signal-to-Noise Ratio(PSNR)34.9 dB),and state-of-the-art detection accuracy(78.1%Mean Average Precision(mAP)),demonstrating a 3.8×end-to-end improvement over existing hybrid approaches while enabling seamless integration with autonomous driving stacks.
基金supported by the National Natural Science Foundation of China(Grant No.52408513)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(Grant No.GZB20240153)the China Postdoctoral Science Foundation(Grant No.2024M760465).
文摘Pile group-supported bridges in liquefied sloping ground with crust are prone to severe damage.However,there remains a limited comprehension of the intricate interactions among pile group,soil,and superstructures,as well as the associated failure mechanisms.To address this issue,this paper presents large-scale shaking table tests conducted on pile group-supported bridges in sloping liquefiable ground with crust to uncover the intricate interaction mechanisms.Firstly,the dynamic characteristics and interaction of the pile-soil-superstructure system were explored.Then,the lateral displacement and acceleration of the superstructure and pile were presented.Next,the curvature and damage characteristics of the pile group-supported bridge were discussed.Finally,through cross-correlation analysis,the study revealed the inertia and kinematic effects,focusing on how the effects influenced the seismic demands.Results indicate that significant differences are observed in pile-soil interactions during strong seismic events depending on the depth and liquefaction stage.As earthquake intensity increases,peak displacement in the superstructure rises linearly while residual displacement grows exponentially.Moreover,the pile group effect becomes more pronounced,especially at the pile head,with the trailing piles showing greater curvature than the leading ones.Due to significant soil lateral spreading and the shadowing effect within the pile group,the leading piles experience prominent kinematic effects from the surface down to the intermediate layer of saturated sand compared to the trailing piles.These findings contribute valuable insights for improving the seismic design approach for bridges with pile groups in sloping liquefied soils.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFB3607300)the National Natural Science Foundation of China(Grant Nos.62322512,62225506,and 12134013)+7 种基金the Fundamental Research Funds for the Central Universities(Grant Nos.WK2030000108 and WK2030000090)the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-049)supported by the National Natural Science Foundation of China(Grant Nos.12174260 and 12574326)the Shanghai Rising-Star Program(Grant No.21QA1406400)the Shanghai Science and Technology Development Fund(Grant Nos.21ZR1443500 and 21ZR1443600)the support from the China Postdoctoral Science Foundation(Grant No.2023M743364)support from the Center for Micro and Nanoscale Research and Fabrication,University of Science and Technology of Chinasupported by the UPOLabs,which provided the experimental and technical support。
文摘Head-up displays(HUDs)are emerging as key components of intelligent vehicles,requiring wide-depth,large-area,and high-efficiency dynamic imaging,which remains difficult to realize with traditional refractive optics.Computer-generated holography(CGH)with diffraction optics offers a promising solution to these technical demands.However,CGH optimization based on the fast Fourier transform(FFT)faces limitations such as zero-padding redundancy,coupled sampling intervals,and incompatible near-and farfield propagation models.Here,we report a holography-based multiplane HUD using a matrix multiplication(MM)-assisted diffraction algorithm that restructures the Fresnel integral into two sequential matrix operations,thus eliminating zero-padding and enabling fully decoupled sampling between object and image planes.Compared with FFT-based angular spectrum methods,the MM approach significantly improves computational speed and memory efficiency for hologram design,which is validated by demonstrating dual-plane holography with a size ratio exceeding 100:1 and unified reconstruction across Fresnel and Fraunhofer regimes within a single computation.A prototype HUD system is demonstrated successfully to exhibit multiple-plane holographic virtual images that can be mixed with real-world objects at three independent planes.The technique might be one of the potential candidates for next-generation intelligent vehicle displays.
基金sponsored by the National Natural Science Foundation of China(Grant No.52438002)the New Cornerstone Science Foundation through the XPLORER PRIZE.
文摘This study investigates the influence of loading frequency on the fatigue behavior of ballastless track concrete for high-speed railways,aiming to support the development of concrete capable of withstanding higher operational speeds.Fatigue tests were conducted at loading frequencies ranging from 5 to 40 Hz,with a focus on fatigue life,damage evolution,energy dissipation,and residual fatigue strain in the concrete.The results indicate that between 5 and 15 Hz,the fatigue life and energy dissipation remain relatively stable,with minimal damage evolution and small residual strains.As the frequency increases to 15-20 Hz,the fatigue life and energy dissipation gradually decrease,while damage accumulation and residual strain increase.Beyond 20 Hz,both fatigue life and energy dissipation decrease rapidly,damage accumulation becomes more pronounced,and residual strain continues to rise.These phenomena are primarily attributed to the increased strain rate and load change rate at higher frequencies,which affect the microstructure evolution and lead to reduced fatigue performance.
基金supported by the National Natural Science Foundation of China(Grant Nos.52274091 and 51974193).
文摘Grouting is an essential technique for reinforcing tunnel rock masses following deformation and failure.However,the mechanisms and effectiveness evaluation of grouting in fractured rock masses that have experienced substantial deformation and transition into the residual stage remain insufficiently understood.To elucidate the relationship between grouting effectiveness and pre-cracking strain,grouting and subsequent re-fracturing tests were conducted on sandy mudstone specimens with varying levels of pre-cracking strain.Additionally,a model was developed to determine the optimal grouting timing during the residual stage.The results indicate that the failure mode of specimens in the residual stage exhibits banded and localized distribution patterns.As pre-cracking strain increases,both the maximum fracture aperture and the relative grout injection ratio increase,with the increases becoming more pronounced at higher strain levels.After grouting,the consolidation coefficient and strength enhancement coefficient exhibit a positive correlation with pre-cracking strain,although the rate of increase gradually decreases.Grouting does not alter the initial failure mode of residual-stage fractured specimens but effectively suppresses secondary crack propagation in regions distant from primary fractures.At the microscale,grout bonds within the rock matrix form cavity structures that delay tensile failure and generate an interconnected network,thereby enhancing crack resistance.Based on the evolution of rock damage and the efficiency of grouting materials utilization,a method is proposed to determine the optimal grouting timing for fractured specimens in the residual stage.At the optimal timing,specimens exhibit moderate damage while maintaining high reinforcement efficiency per unit mass of grout.
