This study proposes a new post-tensioned precast bridge column(PT-PBC)with a socket connection.Compared to conventional PBCs connected by PT tendons,the combination of the PT tendons with the socket connection can avo...This study proposes a new post-tensioned precast bridge column(PT-PBC)with a socket connection.Compared to conventional PBCs connected by PT tendons,the combination of the PT tendons with the socket connection can avoid tensioning the PT tendons on site,which further accelerates construction speed while improving construction quality and safety.In addition,compared to conventional PBCs with a socket connection,a rocking interface can avoid the formation of a plastic hinge in a column,which greatly alleviates seismic damage to that area.One specimen for quasi-static testing is used to validate the feasibility of this connection type.Subsequently,finite element models(FEM)are established to systematically predict the responses of the proposed columns under lateral cyclic loading.The accuracy of the FEM is verified through quasistatic testing.Next,the influences of the key design parameters of the PT-PBC,including the area ratio and prestress level of the PT tendons,the area ratio of energy dissipation(ED)steel rebars,and the total axial compression ratio on the seismic performances of PT-PBC are systematically investigated.The use of shape memory alloy(SMA)rods as energy dissipation devices and their performances also are investigated.The results show that increasing the area ratio and prestress level of PT tendons has an overall positive impact on the self-centering capacity of the column.The prestress level of PT tendons should be kept between 35%and 55%,depending on different conditions.The total compression axial ratio of the columns should be maintained between 0.3 and 0.4.Both ED steel rebars and SMA rods can boost the column’s energy dissipation capacity,while SMA rods can reduce residual deformation due to their inherent mechanical properties.展开更多
Scientific development is an invaluable asset to a country.Policies and development modes should be carried out based on scientific findings not only in industry,but also in transportation infrastructure construction....Scientific development is an invaluable asset to a country.Policies and development modes should be carried out based on scientific findings not only in industry,but also in transportation infrastructure construction.Building an integrated transportation system,which is in line with the national requirements of China and supports sustainable socio-economic development,is a key strategic issue related to building a moderately prosperous society and achieving realistic goals of a medium-level developed country.Based on a systematic review of the advances in China's transportation infrastructure over the last 60 years,this paper explores the main drivers of transportation development,including national policy,transportation structure,investment efficiency,and technological innovation.Analysis shows that China's comprehensive transportation infrastructure construction since 1949 can be divided into five stages initiated by these drivers,which correspond to four transition modes:policy transition,structural transition,efficiency transition,and technology transition.The transition path of China's transportation development shows that the dominant factors have changed,and the interval for each transition has shortened.With the implementation of the '12th Five-Year Plan',China's transportation infrastructure construction is showing some new characteristics and facing a new development transition.Finally,this paper analyzes the trends in transportation development in China and concludes that technological innovation will be the main driving force to increase the transportation supply and service area in the future.展开更多
Transportation planning is a critical component for creating an orderly,intensive,and sustainable pattern of land development.By comprehensively considering the potential and suitability of transport construction,a co...Transportation planning is a critical component for creating an orderly,intensive,and sustainable pattern of land development.By comprehensively considering the potential and suitability of transport construction,a comprehensive method combining resources and environmental carrying capacity(RECC)and land development suitability(LDS)was developed by using techniques of GIS,analytic hierarchy process(AHP)and threedimensional magic cube.Taking Aba prefecture in Sichuan Province of Southwest China as a case study,LDS for transportation was analyzed from three aspects,including overall planning layout,different transport modes,and transportation projects.The results showed that the transport planning scales of most counties in Aba were suitable,and the order of LDS of different transport modes was railway>highway=superhighway>tourism track,which already included 42 new transportation projects.We found that two counties(Maoxian County and Jiuzhaigou County)should improve the ecological protection level of transportation,in which the railway network construction should be encouraged,and some transportation projects with low LDS should be postponed or constructed harmlessly.We suggest the combination of RECC and LDS for transportation could enhance the territorial space optimization and sustainable transport construction.展开更多
[Objective]The channel straightening project of the Pinglu Canal has fragmented the river course,compromising the integrity of original river course and causing ecosystem patchiness.Understanding the current status of...[Objective]The channel straightening project of the Pinglu Canal has fragmented the river course,compromising the integrity of original river course and causing ecosystem patchiness.Understanding the current status of fish resources and the characteristics of their diversity is crucial for the ecological management of the Pinglu Canal.[Methods]During the spring and autumn in 2021 and 2022,a survey of fish resources and species diversity in the Pinglu Canal was conducted using multi-mesh gill nets.A total of 125 fish species were collected,belonging to 10 orders,34 families,and 89 genera.[Results]The result showed that the Pinglu Canal contained three nationally protected Class II species,two endemic species of the Qinjiang River,three anadromous/migratory species,and eight invasive species,accounting for 2.4%,1.6%,2.4%,and 6.4%of the total species,respectively.The fish community primarily consisted of mid-and bottom-dwelling,adhesive-egg-laying,and omnivorous species.The Shannon-Wiener,Simpson,Margalef,and Pielou indices of the fish community in the Pinglu Canal ranged from 2.347 to 2.757,0.081 to 0.151,3.493 to 4.382,and 0.812 to 0.892,respectively.These indices showed relatively uniform distribution across different river reaches.[Conclusion]The result indicate that the fish community structure in the Pinglu Canal is relatively uniform.The reach from the Yujiang River to the Shaping River shows higher stability,while other river reaches experience moderate or severe disturbances.This study provides supplementary baseline data on the fish community structure in the Pinglu Canal and explores the potential impact of inter-basin connectivity on fish resources,aiming to provide a scientific basis for habitat restoration assessments after the channel straightening project.展开更多
Although air pollutant emissions have sharply reduced in recent years,the occurrence of PM_(2.5) pollution events remains an intractable environmental problem in Beijing,and regional transport is the key influence fac...Although air pollutant emissions have sharply reduced in recent years,the occurrence of PM_(2.5) pollution events remains an intractable environmental problem in Beijing,and regional transport is the key influence factor.However,it has been difficult to identify regional transport characteristics and the main contributors to pollution events in recent years.In this study,the relative contribution of regional transport was quantified(61.3%)in PM_(2.5) pollution events during 2018-2021 by the Community Multiscale Air Quality model embedded with the Integrated Source Apportionment Model(CMAQ-ISAM).The four regions with the largest fractional contributions to Beijing for all events were Shandong(7.7%),South Hebei(7.3%),Baoding(6.2%),and Langfang(5.8%).Pollution events were classified into the following types based on regional transport directions:local,southwest(SW),southeast(SE),south-mixed(SM),and others.Based on the transport distance,the SW,SE,and SM types can be subdivided into SW-short,SW-long,SE-short,SE-long,SM-short,SM-long distance from southwest,SM-long distance from southeast,and SM-long distance from southwest and southeast.SE-long was regarded as the most important type,with the highest relative frequency(20%).The transport directions were related to the southwest wind at 925 hPa and southeast wind at 1000 hPa in the south of the Beijing–Tianjin–Hebei(BTH)region,and the distance was mainly controlled by wind strength.The wind-field difference can be attributed to the low-pressure and high-pressure systems that control the BTH region.The results suggest that regional joint pollution control should be optimized based on the transport type.展开更多
To adapt to the unique demand-supply features of accessory parking lots at passenger transport hubs,a mixed parking demand assignment method based on regression modeling is proposed.First,an optimal model aiming to mi...To adapt to the unique demand-supply features of accessory parking lots at passenger transport hubs,a mixed parking demand assignment method based on regression modeling is proposed.First,an optimal model aiming to minimize total time expenditure is constructed.It incorporates parking search time,walking time,and departure time,focusing on short-term parking features.Then,the information dimensions that the parking lot can obtain are evaluated,and three assignment strategies based on three types of regression models-linear regression(LR),extreme gradient boosting(XGBoost),and multilayer perceptron(MLP)-are proposed.A parking process simulation model is built using the traffic simulation package SUMO to facilitate data collection,model training,and case studies.Finally,the performance of the three strategies is com-pared,revealing that the XGBoost-based strategy performs the best in case parking lots,which reduces time expendi-ture by 29.3%and 37.2%,respectively,compared with the MLP-based strategy and LR-based strategy.This method offers diverse options for practical parking manage-ment.展开更多
Structural damage detection is hard to conduct in large-scale civil structures due to enormous structural data and insufficient damage features.To improve this situation,a damage detection method based on model reduct...Structural damage detection is hard to conduct in large-scale civil structures due to enormous structural data and insufficient damage features.To improve this situation,a damage detection method based on model reduction and response reconstruction is presented.Based on the framework of two-step model updating including substructure-level localization and element-level detection,the response reconstruction strategy with an improved sensitivity algorithm is presented to conveniently complement modal information and promote the reliability of model updating.In the iteration process,the reconstructed response is involved in the sensitivity algorithm as a reconstruction-related item.Besides,model reduction is applied to reduce computational degrees of freedom(DOFs)in each detection step.A numerical truss bridge is modelled to vindicate the effectiveness and efficiency of the method.The results showed that the presented method reduces the requirement for installed sensors while improving efficiency and ensuring accuracy of damage detection compared to traditional methods.展开更多
To investigate the influence of the shear lag effect on the bending shear stress of single-box multicell box gird-ers(MCBG),the shear lag warping additional deflection is selected as the generalized displacement.The g...To investigate the influence of the shear lag effect on the bending shear stress of single-box multicell box gird-ers(MCBG),the shear lag warping additional deflection is selected as the generalized displacement.The governing dif-ferential equations and boundary conditions for the shear lag of the MCBG are derived using the energy variational method.Based on the shear lag warping deformation state of the MCBG and by employing the microelement equilib-rium differential equation and the coordination conditions for shear lag warping deformation,the calculation method for the bending-warping shear stress of the MCBG is de-rived,and the influence of the width-to-span and height-to span ratios on bending-warping shear stress is analyzed.Ex-ample analysis shows that the bending-warping shear stress of the MCBG calculated by the proposed calculation method coincides with the finite element solution,and the warping shear stress satisfies the self-balancing condition of shear warping,thus verifying the accuracy of the proposed method.The warping shear stress exhibits an antisymmetric distribution about the vertical axis of symmetry and has a weakening effect on the shear stress of the elementary beam(EB).The larger the width-to-span ratio is,the larger the proportion of the warping shear stress of the EB.The larger the height-to-span ratio is,the smaller the proportion of the warping shear stress and the more significant the influence of the width-to-span ratio.The more the number of cells is,the smaller the influence of the warping shear stress on the total bending shear stress.The influence of the shear lag ef-fect can be ignored in the calculation of the bending shear stress of three or more cells in the MCBG.展开更多
Urban traffic congestion is a significant challenge that contributes to high-density environments in urban areas,adversely impacting the living conditions of urban residents.The concept of urban renewal introduces new...Urban traffic congestion is a significant challenge that contributes to high-density environments in urban areas,adversely impacting the living conditions of urban residents.The concept of urban renewal introduces new requirements and challenges pertaining to urban transportation issues.To mitigate urban traffic congestion,enhance the greening rate of the city,and improve the urban environment,the concept of developing urban aerial ecological corridors is proposed.An analysis of the current state of various urban aerial corridors in different cities indicates that aerial ecological corridors effectively enhance connectivity and accessibility between different spaces,representing a significant strategy for addressing the issue of urban traffic congestion.Aerial ecological corridors have the potential to enhance the vertical space within urban environments,increase the greening rate of cities,and promote the physical and mental health of urban residents.Additionally,these corridors can improve the connectivity of habitat patches and address the developmental needs of biodiversity.Consequently,they serve as a crucial foundation for guiding the future transformation of urban development towards a healthier and greener direction.展开更多
To study the dynamic response rules of pile foundations of mega-bridges over faults in strong seismic areas,a finite element model of the pile foundation-soil-fault interaction of the Haiwen Bridge is established.The ...To study the dynamic response rules of pile foundations of mega-bridges over faults in strong seismic areas,a finite element model of the pile foundation-soil-fault interaction of the Haiwen Bridge is established.The 0.2-0.6 g peak acceleration of the 5010 seismic waves is input to study the effect of the seismic wave of different intensities and the distance changes between the fault and the pile foundation on the dynamic response of the pile body.The results show that the soil layer covering the bedrock amplifies the peak pile acceleration,and the amplifying effect decreases with increasing seismic wave intensity.However,bedrock has less of an effect on peak acceleration.The relative pile displacement shows the mechanical properties of elastic long piles.The pile foundation generates a large bending moment at the bedrock face and the upper soil layer interface,and a large shear force at the pile top and the soft-hard soil body interface.The relative displacement,bending,and shear bearing characteristics of the pile foundations on the upper and lower plates of the fault are significantly different.The deformation characteristics are affected by faults in a region ten times the pile diameter.Analysis of the dynamic p-y curves shows that the soil resistance on the pile side of the lower plate at the same depth is greater than that of the upper plate.Sensitivity of the dynamic response of pile foundations on either side of the fault to the effects of seismic intensity and distance between the pile foundation and the fault:distance l seismic intensity q.展开更多
Railway infrastructure is a crucial asset for the mobility of people and goods.The increased traffic frequency imposes higher loads and speeds,leading to accelerated infrastructure degradation.Asset managers require t...Railway infrastructure is a crucial asset for the mobility of people and goods.The increased traffic frequency imposes higher loads and speeds,leading to accelerated infrastructure degradation.Asset managers require timely information regarding the current(diagnosis)and future(prognosis)condition of their assets to make informed decisions on maintenance and renewal actions.In recent years,in-service vehicles equipped with on-board monitoring(OBM)measuring devices,such as accelerometers,have been introduced on railroad networks,traversing the network almost daily.This article explores the application of state-of-the-art OBM-based track quality indicators for railway infrastructure condition assessment and prediction,primarily under the prism of track geometry quality.The results highlight the similarities and advantages of applying track quality indicators generated from OBM measurements(high frequency and relatively lower accuracy data)compared to those generated from higher precision,yet temporally sparser,data collected by traditional track recording vehicles(TRVs)for infrastructure management purposes.The findings demonstrate the performance of the two approaches,further revealing the value of OBM information for monitoring the track status degradation process.This work makes a case for the advantageous use of OBM data for railway infrastructure management,and attempts to aid understanding in the application of OBM techniques for engineers and operators.展开更多
Intact rocks with layered microstructures,such as gneiss,exhibit strong anisotropy.Although anisotropy in the macroscopic strength of gneiss has been widely reported,the role of microstructures in tensile mechanics re...Intact rocks with layered microstructures,such as gneiss,exhibit strong anisotropy.Although anisotropy in the macroscopic strength of gneiss has been widely reported,the role of microstructures in tensile mechanics remains largely unclear.Utilizing a range of methodologies,it was determined that the tensile strength,deformation,and fracturing behavior of Himalayan gneiss are predominantly influenced by biotite.In contrast to the behavior of other transversely isotropic rocks,the apparent tensile strength of the gneiss first decreased and then increased with anisotropic angleβ,rather than the widely reported monotonic increase or single-shoulder response.The shear sliding of biotite along cleavage planes caused stress concentrations in the surrounding brittle minerals,inducing cracks and reducing the overall tensile strength of the gneiss.Micro-observations of the relationship between cracks and biotite orientation identified three types of biotite crystal fragmentation:tensile fragmentation along cleavage planes,shear fragmentation along cleavage planes,and tensile fragmentation perpendicular to cleavage planes.Tensile and shear fragmentation of biotite along cleavage planes negatively affected the gneiss'macroscopic tensile strength.Conversely,when the tensile stress was parallel to the biotite cleavage planes,tensile fragmentation perpendicular to the cleavage planes increased the macroscopic tensile strength of the gneiss due to plastic deformation and high surface energy.Quantitative analysis of shear stress along biotite cleavage planes revealed the mechanical mechanism behind the reduced tensile strength of the East Himalayan gneisses near an anisotropic angle of 30°.These results elucidated the influence of grain-level anisotropy on the macroscopic tensile mechanical properties of intact layered rocks.展开更多
In this study,avalanches in the Aerxiangou section of the Duku Expressway in the Tianshan Mountain area of Xinjiang were taken as the research object,and 92 avalanches were accurately identified through onsite researc...In this study,avalanches in the Aerxiangou section of the Duku Expressway in the Tianshan Mountain area of Xinjiang were taken as the research object,and 92 avalanches were accurately identified through onsite research.A high-resolution three-dimensional model was established by collecting images from unmanned aerial vehicles for an in-depth understanding of the avalanche danger of the region,according to the sample set selection of different uses of machine learning support vector machines to establish the S1-RBFKSVM,S1-PKSVM,S2-RBFKSVM,and S2-PKSVM avalanche susceptibility coupling models.On the basis of the avalanche point susceptibility,the impact velocity,impact force,avalanche volume,and throw distance constitute the hazard evaluation system.The study results revealed that slopes in the range of 26.6°–46.9°are more prone to avalanches,and sample set 2 improved the accuracy by approximately 30%compared with sample set 1 trained in the avalanche susceptibility model.Principal component analysis revealed a total of 16 high-risk avalanches,which were distributed mainly on the southern side of the route.This study provides data support for avalanche simulations as well as early warning and prevention and provides theoretical and methodological guidance for the construction and operation of the Duku Expressway.展开更多
During underground mining,accurate revelation on the deformation and failure mechanisms of a high-steep slope under multi-layer mining conditions facilitates the prevention and control of geological disasters in mines...During underground mining,accurate revelation on the deformation and failure mechanisms of a high-steep slope under multi-layer mining conditions facilitates the prevention and control of geological disasters in mines.Numerical simulation based on discrete element theory can be used to explore the characteristics and mechanism of action of deformation and failure of a slope under complex geological and multi-layer mining conditions.By utilising PFC2 D(particle flow code) software,the deformation and failure characteristics of a high-steep slope in Faer Coal Mine in Guizhou Province,China were investigated.Additionally,the mechanism of influence of different numbers of mining layers on the deformation and failure of the high and steep slope was elucidated.The result showed that after the goaf passed by the slope toe,multi-layer mining aggravated the subsidence and deformation of the slope toe:the slope toppled forward as it sank.The toppling of the slope changed the slope structures:the strata in the front of the slope were transformed from anti-dip to down-dip features.Extruded by collapsedtoppled rock mass,the slope toe and the rock mass located in the lower part of the slope toe generally exhibited a locking effect on the slope.Multi-layer mining degraded the overall stability of the slope,in that the total displacement of the slope was much greater than the total mining thickness of the coal seams.Based on the aforementioned research,ideas for preventing and controlling geological disasters during mining operations under a high-steep slope were proposed.展开更多
Based on the driver surveillance video data and controller area network(CAN)data,the methods of studying commercial vehicles’driving behavior is relatively advanced.However,these methods have difficulty in covering p...Based on the driver surveillance video data and controller area network(CAN)data,the methods of studying commercial vehicles’driving behavior is relatively advanced.However,these methods have difficulty in covering private vehicles.Naturalistic driving studies have disadvantages of small sample size and high cost,one new driving behavior evaluation method using massive vehicle trajectory data is put forward.An automatic encoding machine is used to reduce the noise of raw data,and then driving dynamics and self-organizing mapping(SOM)classification are used to give thresholds or the judgement method of overspeed,rapid speed change,rapid turning and rapid lane changing.The proportion of different driving behaviors and typical dangerous driving behaviors is calculated,then the temporal and spatial distribution of drivers’driving behavior and the driving behavior characteristics on typical roads are analyzed.Driving behaviors on accident-prone road sections and normal road sections are compared.Results show that in Shenzhen,frequent lane changing and overspeed are the most common unsafe driving behaviors;16.1%drivers have relatively aggressive driving behavior;the proportion of dangerous driving behavior is higher outside the original economic special zone;dangerous driving behavior is highly correlated with traffic accident frequency.展开更多
It is assumed that, during the design period, the waves acting on breakwaters are divided into three types： standing wave, broken wave and breaking wave,and the wave heights fit the Rayleigh distribution while the wa...It is assumed that, during the design period, the waves acting on breakwaters are divided into three types： standing wave, broken wave and breaking wave,and the wave heights fit the Rayleigh distribution while the water depths, wave periods and duration of breaking wave impact force fit normal distribution. Based on the random samples of water depths, wave heights, wave periods and duration of breaking wave impact force, the types of waves acting on breakwaters are distinguished and the time-history model of the wave force is determined. The motions of caisson breakwaters under the wave force are simulated by a dynamic numerical model and the statistic characteristics of the dynamic responses are analyzed with the Monte Carlo method. A probabilistic procedure to analyze the motion of the breakwater is developed therein. The procedure is illustrated by an example.展开更多
Machine learning is currently one of the research hotspots in the field of landslide prediction.To clarify and evaluate the differences in characteristics and prediction effects of different machine learning models,Co...Machine learning is currently one of the research hotspots in the field of landslide prediction.To clarify and evaluate the differences in characteristics and prediction effects of different machine learning models,Conghua District,which is the most prone to landslide disasters in Guangzhou,was selected for landslide susceptibility evaluation.The evaluation factors were selected by using correlation analysis and variance expansion factor method.Applying four machine learning methods namely Logistic Regression(LR),Random Forest(RF),Support Vector Machines(SVM),and Extreme Gradient Boosting(XGB),landslide models were constructed.Comparative analysis and evaluation of the model were conducted through statistical indices and receiver operating characteristic(ROC)curves.The results showed that LR,RF,SVM,and XGB models have good predictive performance for landslide susceptibility,with the area under curve(AUC)values of 0.752,0.965,0.996,and 0.998,respectively.XGB model had the highest predictive ability,followed by RF model,SVM model,and LR model.The frequency ratio(FR)accuracy of LR,RF,SVM,and XGB models was 0.775,0.842,0.759,and 0.822,respectively.RF and XGB models were superior to LR and SVM models,indicating that the integrated algorithm has better predictive ability than a single classification algorithm in regional landslide classification problems.展开更多
Fault detection and isolation of high-speed train suspension systems is of critical importance to guarantee train running safety. Firstly, the existing methods concerning fault detection or isolation of train suspensi...Fault detection and isolation of high-speed train suspension systems is of critical importance to guarantee train running safety. Firstly, the existing methods concerning fault detection or isolation of train suspension systems are briefly reviewed and divided into two categories, i.e., model-based and data-driven approaches. The advantages and disadvantages of these two categories of approaches are briefly summarized. Secondly, a 1D convolution network-based fault diagnostic method for highspeed train suspension systems is designed. To improve the robustness of the method, a Gaussian white noise strategy(GWN-strategy) for immunity to track irregularities and an edge sample training strategy(EST-strategy) for immunity to wheel wear are proposed. The whole network is called GWN-EST-1 DCNN method. Thirdly, to show the performance of this method, a multibody dynamics simulation model of a high-speed train is built to generate the lateral acceleration of a bogie frame corresponding to different track irregularities, wheel profiles, and secondary suspension faults. The simulated signals are then inputted into the diagnostic network, and the results show the correctness and superiority of the GWN-EST-1DCNN method. Finally,the 1DCNN method is further validated using tracking data of a CRH3 train running on a high-speed railway line.展开更多
China has a large solid waste stockpile and a low resource utilisation rate,and the utilisation of solid waste resources is of great significance in promoting sustainable social development.In order to further promote...China has a large solid waste stockpile and a low resource utilisation rate,and the utilisation of solid waste resources is of great significance in promoting sustainable social development.In order to further promote the green and efficient development of China's road field,an overview of the current status of the application,research progress,hot frontiers,problems and their countermeasures based on the three aspects of industrial solid wastes,engineering solid wastes and municipal solid wastes in highway engineering was conducted,and the development prospect of the resourceful utilisation of solid waste in highway engineering was outlooked,with a view to promoting the development of China's green roads.Statistics on the stockpile,utilisation and comprehensive utilisation rate of industrial solid wastes in China are presented,and the optimal mixing amount,production process and application technology of industrial solid wastes for road base materials are systematically summarised.Based on the concept of high-value utilisation of solid waste,the mechanical properties,durability,construction technology and quality control standards of engineering solid waste applied in roadbed engineering are summarised,and the difficulties in the application of engineering solid waste in road engineering are summarised.Finally,the feasibility,mechanical properties and environmental characteristics of municipal solid waste domestic waste incinerator slag,waste tyres and plastics applied in road engineering are summarised.This review can provide references and lessons for the design and development of green roads,and promote the innovation and development of greening road engineering.展开更多
Comparative analyses were conducted to compare the effects of the behavioral characteristics of the drivers of taxis and private cars on the capacity and safety of signalized intersections. Data were collected at sixt...Comparative analyses were conducted to compare the effects of the behavioral characteristics of the drivers of taxis and private cars on the capacity and safety of signalized intersections. Data were collected at sixteen signalized intersections in the Nanjing area in China. The risk-taking behaviors of the drivers of taxis and private cars were compared. The results suggest that 19.9% of taxi drivers have committed at least one of the identified risky behaviors, which is 2.37 times as high as that of the drivers of private cars(8.4%). The traffic conflicts technique was used to estimate the safety effects of taxis and private cars. The overall conflict rate for taxis is 21.4% higher than that for private cars, implying that taxis are more likely to be involved in conflicts. Almost all of the identified traffic conflicts can be attributed to certain levels of risk-taking behaviors committed by either taxi drivers or the drivers of private cars, and taxi drivers are more likely to be at fault in a conflict. Failure to yield to right-of-way and improper lane change is the leading causes of the conflicts in which taxis are at-fault. The research team further studied the effects of taxis on the queue discharge characteristics at signalized intersections. The results show that the presence of taxis significantly reduces both start-up lost time and saturation headways. The effects of taxis on saturation flow rates are dependent on the proportion of taxis in the discharge flow, and the saturation flow rates increase with the increase in the proportion of taxis. The adjustment factors for various proportions of taxis for different turning movements are then calculated to quantitatively evaluate the effects of taxis on the capacity of signalized intersections.展开更多
基金Natural Science Foundation of China under Grant No.52178449,the Beijing Natural Science Foundation under Grant No.8234060the Innovation Center of Beijing Association for Science and Technology。
文摘This study proposes a new post-tensioned precast bridge column(PT-PBC)with a socket connection.Compared to conventional PBCs connected by PT tendons,the combination of the PT tendons with the socket connection can avoid tensioning the PT tendons on site,which further accelerates construction speed while improving construction quality and safety.In addition,compared to conventional PBCs with a socket connection,a rocking interface can avoid the formation of a plastic hinge in a column,which greatly alleviates seismic damage to that area.One specimen for quasi-static testing is used to validate the feasibility of this connection type.Subsequently,finite element models(FEM)are established to systematically predict the responses of the proposed columns under lateral cyclic loading.The accuracy of the FEM is verified through quasistatic testing.Next,the influences of the key design parameters of the PT-PBC,including the area ratio and prestress level of the PT tendons,the area ratio of energy dissipation(ED)steel rebars,and the total axial compression ratio on the seismic performances of PT-PBC are systematically investigated.The use of shape memory alloy(SMA)rods as energy dissipation devices and their performances also are investigated.The results show that increasing the area ratio and prestress level of PT tendons has an overall positive impact on the self-centering capacity of the column.The prestress level of PT tendons should be kept between 35%and 55%,depending on different conditions.The total compression axial ratio of the columns should be maintained between 0.3 and 0.4.Both ED steel rebars and SMA rods can boost the column’s energy dissipation capacity,while SMA rods can reduce residual deformation due to their inherent mechanical properties.
基金Under the auspices of National Natural Science Foundation of China(No.41171107,41001082)Programme of Bingwei Excellent Young Scientists of Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences
文摘Scientific development is an invaluable asset to a country.Policies and development modes should be carried out based on scientific findings not only in industry,but also in transportation infrastructure construction.Building an integrated transportation system,which is in line with the national requirements of China and supports sustainable socio-economic development,is a key strategic issue related to building a moderately prosperous society and achieving realistic goals of a medium-level developed country.Based on a systematic review of the advances in China's transportation infrastructure over the last 60 years,this paper explores the main drivers of transportation development,including national policy,transportation structure,investment efficiency,and technological innovation.Analysis shows that China's comprehensive transportation infrastructure construction since 1949 can be divided into five stages initiated by these drivers,which correspond to four transition modes:policy transition,structural transition,efficiency transition,and technology transition.The transition path of China's transportation development shows that the dominant factors have changed,and the interval for each transition has shortened.With the implementation of the '12th Five-Year Plan',China's transportation infrastructure construction is showing some new characteristics and facing a new development transition.Finally,this paper analyzes the trends in transportation development in China and concludes that technological innovation will be the main driving force to increase the transportation supply and service area in the future.
基金funded by Key Scientific Research Project of the Ministry of Transport(No.2020-MS4113)Scientific and Technological Development Project,Transport Planning and Research Institute of the Ministry of Transport(No.092117-434)Science and Technology Project of Henan Provincial Department of Transport(No.2020G-2-15)。
文摘Transportation planning is a critical component for creating an orderly,intensive,and sustainable pattern of land development.By comprehensively considering the potential and suitability of transport construction,a comprehensive method combining resources and environmental carrying capacity(RECC)and land development suitability(LDS)was developed by using techniques of GIS,analytic hierarchy process(AHP)and threedimensional magic cube.Taking Aba prefecture in Sichuan Province of Southwest China as a case study,LDS for transportation was analyzed from three aspects,including overall planning layout,different transport modes,and transportation projects.The results showed that the transport planning scales of most counties in Aba were suitable,and the order of LDS of different transport modes was railway>highway=superhighway>tourism track,which already included 42 new transportation projects.We found that two counties(Maoxian County and Jiuzhaigou County)should improve the ecological protection level of transportation,in which the railway network construction should be encouraged,and some transportation projects with low LDS should be postponed or constructed harmlessly.We suggest the combination of RECC and LDS for transportation could enhance the territorial space optimization and sustainable transport construction.
文摘[Objective]The channel straightening project of the Pinglu Canal has fragmented the river course,compromising the integrity of original river course and causing ecosystem patchiness.Understanding the current status of fish resources and the characteristics of their diversity is crucial for the ecological management of the Pinglu Canal.[Methods]During the spring and autumn in 2021 and 2022,a survey of fish resources and species diversity in the Pinglu Canal was conducted using multi-mesh gill nets.A total of 125 fish species were collected,belonging to 10 orders,34 families,and 89 genera.[Results]The result showed that the Pinglu Canal contained three nationally protected Class II species,two endemic species of the Qinjiang River,three anadromous/migratory species,and eight invasive species,accounting for 2.4%,1.6%,2.4%,and 6.4%of the total species,respectively.The fish community primarily consisted of mid-and bottom-dwelling,adhesive-egg-laying,and omnivorous species.The Shannon-Wiener,Simpson,Margalef,and Pielou indices of the fish community in the Pinglu Canal ranged from 2.347 to 2.757,0.081 to 0.151,3.493 to 4.382,and 0.812 to 0.892,respectively.These indices showed relatively uniform distribution across different river reaches.[Conclusion]The result indicate that the fish community structure in the Pinglu Canal is relatively uniform.The reach from the Yujiang River to the Shaping River shows higher stability,while other river reaches experience moderate or severe disturbances.This study provides supplementary baseline data on the fish community structure in the Pinglu Canal and explores the potential impact of inter-basin connectivity on fish resources,aiming to provide a scientific basis for habitat restoration assessments after the channel straightening project.
基金supported by the National Key R&D program of China(No.2022YFC3703404)the National Natural Science Foundation of China(No.22188102)the Samsung Advanced Institute of Technology.
文摘Although air pollutant emissions have sharply reduced in recent years,the occurrence of PM_(2.5) pollution events remains an intractable environmental problem in Beijing,and regional transport is the key influence factor.However,it has been difficult to identify regional transport characteristics and the main contributors to pollution events in recent years.In this study,the relative contribution of regional transport was quantified(61.3%)in PM_(2.5) pollution events during 2018-2021 by the Community Multiscale Air Quality model embedded with the Integrated Source Apportionment Model(CMAQ-ISAM).The four regions with the largest fractional contributions to Beijing for all events were Shandong(7.7%),South Hebei(7.3%),Baoding(6.2%),and Langfang(5.8%).Pollution events were classified into the following types based on regional transport directions:local,southwest(SW),southeast(SE),south-mixed(SM),and others.Based on the transport distance,the SW,SE,and SM types can be subdivided into SW-short,SW-long,SE-short,SE-long,SM-short,SM-long distance from southwest,SM-long distance from southeast,and SM-long distance from southwest and southeast.SE-long was regarded as the most important type,with the highest relative frequency(20%).The transport directions were related to the southwest wind at 925 hPa and southeast wind at 1000 hPa in the south of the Beijing–Tianjin–Hebei(BTH)region,and the distance was mainly controlled by wind strength.The wind-field difference can be attributed to the low-pressure and high-pressure systems that control the BTH region.The results suggest that regional joint pollution control should be optimized based on the transport type.
基金The National Natural Science Foundation of China(No.52302388)the Natural Science Foundation of Jiangsu Province(No.BK20230853).
文摘To adapt to the unique demand-supply features of accessory parking lots at passenger transport hubs,a mixed parking demand assignment method based on regression modeling is proposed.First,an optimal model aiming to minimize total time expenditure is constructed.It incorporates parking search time,walking time,and departure time,focusing on short-term parking features.Then,the information dimensions that the parking lot can obtain are evaluated,and three assignment strategies based on three types of regression models-linear regression(LR),extreme gradient boosting(XGBoost),and multilayer perceptron(MLP)-are proposed.A parking process simulation model is built using the traffic simulation package SUMO to facilitate data collection,model training,and case studies.Finally,the performance of the three strategies is com-pared,revealing that the XGBoost-based strategy performs the best in case parking lots,which reduces time expendi-ture by 29.3%and 37.2%,respectively,compared with the MLP-based strategy and LR-based strategy.This method offers diverse options for practical parking manage-ment.
基金Projects(51925808,52078504)supported by the National Natural Science Foundation of ChinaProject(2022JJ10082)supported by the Natural Science Fund for Distinguished Young Scholar of Hunan Province,ChinaProject(2021RC3016)supported by the Science and Technology Innovation Program of Hunan Province,China。
文摘Structural damage detection is hard to conduct in large-scale civil structures due to enormous structural data and insufficient damage features.To improve this situation,a damage detection method based on model reduction and response reconstruction is presented.Based on the framework of two-step model updating including substructure-level localization and element-level detection,the response reconstruction strategy with an improved sensitivity algorithm is presented to conveniently complement modal information and promote the reliability of model updating.In the iteration process,the reconstructed response is involved in the sensitivity algorithm as a reconstruction-related item.Besides,model reduction is applied to reduce computational degrees of freedom(DOFs)in each detection step.A numerical truss bridge is modelled to vindicate the effectiveness and efficiency of the method.The results showed that the presented method reduces the requirement for installed sensors while improving efficiency and ensuring accuracy of damage detection compared to traditional methods.
基金The National Natural Science Foundation of China (No. 52368020)Gansu Provincial Universities Young Doctor Support Project (No. 2024QB-047)Gansu Province postdoctoral Fund (No. 386824)。
文摘To investigate the influence of the shear lag effect on the bending shear stress of single-box multicell box gird-ers(MCBG),the shear lag warping additional deflection is selected as the generalized displacement.The governing dif-ferential equations and boundary conditions for the shear lag of the MCBG are derived using the energy variational method.Based on the shear lag warping deformation state of the MCBG and by employing the microelement equilib-rium differential equation and the coordination conditions for shear lag warping deformation,the calculation method for the bending-warping shear stress of the MCBG is de-rived,and the influence of the width-to-span and height-to span ratios on bending-warping shear stress is analyzed.Ex-ample analysis shows that the bending-warping shear stress of the MCBG calculated by the proposed calculation method coincides with the finite element solution,and the warping shear stress satisfies the self-balancing condition of shear warping,thus verifying the accuracy of the proposed method.The warping shear stress exhibits an antisymmetric distribution about the vertical axis of symmetry and has a weakening effect on the shear stress of the elementary beam(EB).The larger the width-to-span ratio is,the larger the proportion of the warping shear stress of the EB.The larger the height-to-span ratio is,the smaller the proportion of the warping shear stress and the more significant the influence of the width-to-span ratio.The more the number of cells is,the smaller the influence of the warping shear stress on the total bending shear stress.The influence of the shear lag ef-fect can be ignored in the calculation of the bending shear stress of three or more cells in the MCBG.
基金Sponsored by Research Team Project of Anhui Xinhua University(kytd202202)Anhui Provincial Undergraduate Innovation Training Program(S202212216146,S202212216133,S202212216138,AH202112216114)Key Project of Anhui Provincial Higher Education Scientific Research Project(Natural Science)(2022AH051861,2024AH050601).
文摘Urban traffic congestion is a significant challenge that contributes to high-density environments in urban areas,adversely impacting the living conditions of urban residents.The concept of urban renewal introduces new requirements and challenges pertaining to urban transportation issues.To mitigate urban traffic congestion,enhance the greening rate of the city,and improve the urban environment,the concept of developing urban aerial ecological corridors is proposed.An analysis of the current state of various urban aerial corridors in different cities indicates that aerial ecological corridors effectively enhance connectivity and accessibility between different spaces,representing a significant strategy for addressing the issue of urban traffic congestion.Aerial ecological corridors have the potential to enhance the vertical space within urban environments,increase the greening rate of cities,and promote the physical and mental health of urban residents.Additionally,these corridors can improve the connectivity of habitat patches and address the developmental needs of biodiversity.Consequently,they serve as a crucial foundation for guiding the future transformation of urban development towards a healthier and greener direction.
基金funded by National Natural Science Foundation of China Projects(51708040)Hainan Provincial Transportation Science and Technology Project(HNZXY2015-045R)Changan University Central University Basic Research Business Fund Special Funds(No.300102218115).
文摘To study the dynamic response rules of pile foundations of mega-bridges over faults in strong seismic areas,a finite element model of the pile foundation-soil-fault interaction of the Haiwen Bridge is established.The 0.2-0.6 g peak acceleration of the 5010 seismic waves is input to study the effect of the seismic wave of different intensities and the distance changes between the fault and the pile foundation on the dynamic response of the pile body.The results show that the soil layer covering the bedrock amplifies the peak pile acceleration,and the amplifying effect decreases with increasing seismic wave intensity.However,bedrock has less of an effect on peak acceleration.The relative pile displacement shows the mechanical properties of elastic long piles.The pile foundation generates a large bending moment at the bedrock face and the upper soil layer interface,and a large shear force at the pile top and the soft-hard soil body interface.The relative displacement,bending,and shear bearing characteristics of the pile foundations on the upper and lower plates of the fault are significantly different.The deformation characteristics are affected by faults in a region ten times the pile diameter.Analysis of the dynamic p-y curves shows that the soil resistance on the pile side of the lower plate at the same depth is greater than that of the upper plate.Sensitivity of the dynamic response of pile foundations on either side of the fault to the effects of seismic intensity and distance between the pile foundation and the fault:distance l seismic intensity q.
基金supported financially by the project OMISM from the ETH Zurich Mobility Initiative。
文摘Railway infrastructure is a crucial asset for the mobility of people and goods.The increased traffic frequency imposes higher loads and speeds,leading to accelerated infrastructure degradation.Asset managers require timely information regarding the current(diagnosis)and future(prognosis)condition of their assets to make informed decisions on maintenance and renewal actions.In recent years,in-service vehicles equipped with on-board monitoring(OBM)measuring devices,such as accelerometers,have been introduced on railroad networks,traversing the network almost daily.This article explores the application of state-of-the-art OBM-based track quality indicators for railway infrastructure condition assessment and prediction,primarily under the prism of track geometry quality.The results highlight the similarities and advantages of applying track quality indicators generated from OBM measurements(high frequency and relatively lower accuracy data)compared to those generated from higher precision,yet temporally sparser,data collected by traditional track recording vehicles(TRVs)for infrastructure management purposes.The findings demonstrate the performance of the two approaches,further revealing the value of OBM information for monitoring the track status degradation process.This work makes a case for the advantageous use of OBM data for railway infrastructure management,and attempts to aid understanding in the application of OBM techniques for engineers and operators.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant No.2019QZKK0904)the National Natural Science Foundation of China(Grant No.42402277)the Fundamental Research Funds for the Central Universities(Grant No.300102264902).
文摘Intact rocks with layered microstructures,such as gneiss,exhibit strong anisotropy.Although anisotropy in the macroscopic strength of gneiss has been widely reported,the role of microstructures in tensile mechanics remains largely unclear.Utilizing a range of methodologies,it was determined that the tensile strength,deformation,and fracturing behavior of Himalayan gneiss are predominantly influenced by biotite.In contrast to the behavior of other transversely isotropic rocks,the apparent tensile strength of the gneiss first decreased and then increased with anisotropic angleβ,rather than the widely reported monotonic increase or single-shoulder response.The shear sliding of biotite along cleavage planes caused stress concentrations in the surrounding brittle minerals,inducing cracks and reducing the overall tensile strength of the gneiss.Micro-observations of the relationship between cracks and biotite orientation identified three types of biotite crystal fragmentation:tensile fragmentation along cleavage planes,shear fragmentation along cleavage planes,and tensile fragmentation perpendicular to cleavage planes.Tensile and shear fragmentation of biotite along cleavage planes negatively affected the gneiss'macroscopic tensile strength.Conversely,when the tensile stress was parallel to the biotite cleavage planes,tensile fragmentation perpendicular to the cleavage planes increased the macroscopic tensile strength of the gneiss due to plastic deformation and high surface energy.Quantitative analysis of shear stress along biotite cleavage planes revealed the mechanical mechanism behind the reduced tensile strength of the East Himalayan gneisses near an anisotropic angle of 30°.These results elucidated the influence of grain-level anisotropy on the macroscopic tensile mechanical properties of intact layered rocks.
基金funded by the Key Science and Technology Project of Transportation Industry(2022-ZD6-090)Xinjiang Transportation Science and Technology Project(2022-ZD-006)+1 种基金Xinjiang Transportation Investment 2021"Unveiling the List of Commander-in-Chief"Science and Technology Project(ZKXFWCG2022060004)the Science and Technology Research and Development Project(KY2022021501)of Xinjiang Transportation Design Institute。
文摘In this study,avalanches in the Aerxiangou section of the Duku Expressway in the Tianshan Mountain area of Xinjiang were taken as the research object,and 92 avalanches were accurately identified through onsite research.A high-resolution three-dimensional model was established by collecting images from unmanned aerial vehicles for an in-depth understanding of the avalanche danger of the region,according to the sample set selection of different uses of machine learning support vector machines to establish the S1-RBFKSVM,S1-PKSVM,S2-RBFKSVM,and S2-PKSVM avalanche susceptibility coupling models.On the basis of the avalanche point susceptibility,the impact velocity,impact force,avalanche volume,and throw distance constitute the hazard evaluation system.The study results revealed that slopes in the range of 26.6°–46.9°are more prone to avalanches,and sample set 2 improved the accuracy by approximately 30%compared with sample set 1 trained in the avalanche susceptibility model.Principal component analysis revealed a total of 16 high-risk avalanches,which were distributed mainly on the southern side of the route.This study provides data support for avalanche simulations as well as early warning and prevention and provides theoretical and methodological guidance for the construction and operation of the Duku Expressway.
基金funded by the National Natural Science Foundation of China (Grants No. 41877273)the Innovative Research Groups of the National Natural Science Foundation of China (Grants No. 41521002)+1 种基金the State Key Laboratory of Geohazard Disaster Prevention and Geoenvironment Protection (Chengdu University of Technology) (Grants No. SKLGP2017Z016)the Guizhou Provincial Geological Environment Monitoring Institute, and the Faer Coal Mine。
文摘During underground mining,accurate revelation on the deformation and failure mechanisms of a high-steep slope under multi-layer mining conditions facilitates the prevention and control of geological disasters in mines.Numerical simulation based on discrete element theory can be used to explore the characteristics and mechanism of action of deformation and failure of a slope under complex geological and multi-layer mining conditions.By utilising PFC2 D(particle flow code) software,the deformation and failure characteristics of a high-steep slope in Faer Coal Mine in Guizhou Province,China were investigated.Additionally,the mechanism of influence of different numbers of mining layers on the deformation and failure of the high and steep slope was elucidated.The result showed that after the goaf passed by the slope toe,multi-layer mining aggravated the subsidence and deformation of the slope toe:the slope toppled forward as it sank.The toppling of the slope changed the slope structures:the strata in the front of the slope were transformed from anti-dip to down-dip features.Extruded by collapsedtoppled rock mass,the slope toe and the rock mass located in the lower part of the slope toe generally exhibited a locking effect on the slope.Multi-layer mining degraded the overall stability of the slope,in that the total displacement of the slope was much greater than the total mining thickness of the coal seams.Based on the aforementioned research,ideas for preventing and controlling geological disasters during mining operations under a high-steep slope were proposed.
基金The National Natural Science Foundation of China(No.71641005)the National Key Research and Development Program of China(No.2018YFB1601105)
文摘Based on the driver surveillance video data and controller area network(CAN)data,the methods of studying commercial vehicles’driving behavior is relatively advanced.However,these methods have difficulty in covering private vehicles.Naturalistic driving studies have disadvantages of small sample size and high cost,one new driving behavior evaluation method using massive vehicle trajectory data is put forward.An automatic encoding machine is used to reduce the noise of raw data,and then driving dynamics and self-organizing mapping(SOM)classification are used to give thresholds or the judgement method of overspeed,rapid speed change,rapid turning and rapid lane changing.The proportion of different driving behaviors and typical dangerous driving behaviors is calculated,then the temporal and spatial distribution of drivers’driving behavior and the driving behavior characteristics on typical roads are analyzed.Driving behaviors on accident-prone road sections and normal road sections are compared.Results show that in Shenzhen,frequent lane changing and overspeed are the most common unsafe driving behaviors;16.1%drivers have relatively aggressive driving behavior;the proportion of dangerous driving behavior is higher outside the original economic special zone;dangerous driving behavior is highly correlated with traffic accident frequency.
基金This studyis supported bythe National Natural Science Foundation of China (Grant No.50579046) the ScienceFoundation of Tianjin Municipal Commission of Science and Technology (Grant No.043114711)
文摘It is assumed that, during the design period, the waves acting on breakwaters are divided into three types： standing wave, broken wave and breaking wave,and the wave heights fit the Rayleigh distribution while the water depths, wave periods and duration of breaking wave impact force fit normal distribution. Based on the random samples of water depths, wave heights, wave periods and duration of breaking wave impact force, the types of waves acting on breakwaters are distinguished and the time-history model of the wave force is determined. The motions of caisson breakwaters under the wave force are simulated by a dynamic numerical model and the statistic characteristics of the dynamic responses are analyzed with the Monte Carlo method. A probabilistic procedure to analyze the motion of the breakwater is developed therein. The procedure is illustrated by an example.
基金supported by the projects of the China Geological Survey(DD20221729,DD20190291)Zhuhai Urban Geological Survey(including informatization)(MZCD–2201–008).
文摘Machine learning is currently one of the research hotspots in the field of landslide prediction.To clarify and evaluate the differences in characteristics and prediction effects of different machine learning models,Conghua District,which is the most prone to landslide disasters in Guangzhou,was selected for landslide susceptibility evaluation.The evaluation factors were selected by using correlation analysis and variance expansion factor method.Applying four machine learning methods namely Logistic Regression(LR),Random Forest(RF),Support Vector Machines(SVM),and Extreme Gradient Boosting(XGB),landslide models were constructed.Comparative analysis and evaluation of the model were conducted through statistical indices and receiver operating characteristic(ROC)curves.The results showed that LR,RF,SVM,and XGB models have good predictive performance for landslide susceptibility,with the area under curve(AUC)values of 0.752,0.965,0.996,and 0.998,respectively.XGB model had the highest predictive ability,followed by RF model,SVM model,and LR model.The frequency ratio(FR)accuracy of LR,RF,SVM,and XGB models was 0.775,0.842,0.759,and 0.822,respectively.RF and XGB models were superior to LR and SVM models,indicating that the integrated algorithm has better predictive ability than a single classification algorithm in regional landslide classification problems.
基金supported by the National Nature Science Foundation of China(No.71871188)the Fundamental Research Funds for the Central Universities(No.2682021CX051)supported by China Scholarship Council(No.201707000113)。
文摘Fault detection and isolation of high-speed train suspension systems is of critical importance to guarantee train running safety. Firstly, the existing methods concerning fault detection or isolation of train suspension systems are briefly reviewed and divided into two categories, i.e., model-based and data-driven approaches. The advantages and disadvantages of these two categories of approaches are briefly summarized. Secondly, a 1D convolution network-based fault diagnostic method for highspeed train suspension systems is designed. To improve the robustness of the method, a Gaussian white noise strategy(GWN-strategy) for immunity to track irregularities and an edge sample training strategy(EST-strategy) for immunity to wheel wear are proposed. The whole network is called GWN-EST-1 DCNN method. Thirdly, to show the performance of this method, a multibody dynamics simulation model of a high-speed train is built to generate the lateral acceleration of a bogie frame corresponding to different track irregularities, wheel profiles, and secondary suspension faults. The simulated signals are then inputted into the diagnostic network, and the results show the correctness and superiority of the GWN-EST-1DCNN method. Finally,the 1DCNN method is further validated using tracking data of a CRH3 train running on a high-speed railway line.
文摘China has a large solid waste stockpile and a low resource utilisation rate,and the utilisation of solid waste resources is of great significance in promoting sustainable social development.In order to further promote the green and efficient development of China's road field,an overview of the current status of the application,research progress,hot frontiers,problems and their countermeasures based on the three aspects of industrial solid wastes,engineering solid wastes and municipal solid wastes in highway engineering was conducted,and the development prospect of the resourceful utilisation of solid waste in highway engineering was outlooked,with a view to promoting the development of China's green roads.Statistics on the stockpile,utilisation and comprehensive utilisation rate of industrial solid wastes in China are presented,and the optimal mixing amount,production process and application technology of industrial solid wastes for road base materials are systematically summarised.Based on the concept of high-value utilisation of solid waste,the mechanical properties,durability,construction technology and quality control standards of engineering solid waste applied in roadbed engineering are summarised,and the difficulties in the application of engineering solid waste in road engineering are summarised.Finally,the feasibility,mechanical properties and environmental characteristics of municipal solid waste domestic waste incinerator slag,waste tyres and plastics applied in road engineering are summarised.This review can provide references and lessons for the design and development of green roads,and promote the innovation and development of greening road engineering.
基金Projects(51322810,50908050)supported by the National Natural Science Foundation of China
文摘Comparative analyses were conducted to compare the effects of the behavioral characteristics of the drivers of taxis and private cars on the capacity and safety of signalized intersections. Data were collected at sixteen signalized intersections in the Nanjing area in China. The risk-taking behaviors of the drivers of taxis and private cars were compared. The results suggest that 19.9% of taxi drivers have committed at least one of the identified risky behaviors, which is 2.37 times as high as that of the drivers of private cars(8.4%). The traffic conflicts technique was used to estimate the safety effects of taxis and private cars. The overall conflict rate for taxis is 21.4% higher than that for private cars, implying that taxis are more likely to be involved in conflicts. Almost all of the identified traffic conflicts can be attributed to certain levels of risk-taking behaviors committed by either taxi drivers or the drivers of private cars, and taxi drivers are more likely to be at fault in a conflict. Failure to yield to right-of-way and improper lane change is the leading causes of the conflicts in which taxis are at-fault. The research team further studied the effects of taxis on the queue discharge characteristics at signalized intersections. The results show that the presence of taxis significantly reduces both start-up lost time and saturation headways. The effects of taxis on saturation flow rates are dependent on the proportion of taxis in the discharge flow, and the saturation flow rates increase with the increase in the proportion of taxis. The adjustment factors for various proportions of taxis for different turning movements are then calculated to quantitatively evaluate the effects of taxis on the capacity of signalized intersections.
