Volume 43, Issue 2 (2023)
Articles
Interlayer bonding performance of WTR/APAO composite modified asphalt
JI Hongyan, YAN Kezhen, YUAN Jian, and ZHANG Xuanyu
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.031
To investigate the bonding performance of waste tire rubber (WTR)/ amorphous α-olefin copolymer (APAO) composite modified asphalt as a waterproof bonding layer in asphalt pavements on cement concrete bridges, shear and pull-off tests were conducted. The shear strength and pull-off strength of SBS-modified asphalt, WTR-modified asphalt, and WTR/APAO composite modified asphalt were compared under different application rates and temperatures. The results show that WTR/APAO composite modified asphalt exhibits the best bonding performance, followed by WTR-modified asphalt, with SBS-modified asphalt performing the worst. Based on the shear and pull-off strengths at different temperatures, the optimal application rates were determined as 1.7 kg/m² for SBS-modified asphalt and 1.2 kg/m² for both WTR-modified asphalt and WTR/APAO composite modified asphalt. As the temperature increases, the shear and pull-off strengths of all three asphalts decrease significantly, indicating the strong influence of temperature on bonding performance. Among the three, WTR/APAO composite modified asphalt demonstrates superior shear and pull-off strength at elevated temperatures, highlighting its better bonding performance under high-temperature conditions.
Study on modification of phosphate pretreated aggregate vegetation porous concrete
LI Zhengxing and HOU Zebiao
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.032
To enhance the interfacial structure between aggregates and cementitious materials in vegetation porous concrete and improve its compressive strength, this paper investigates the effects of phosphate pretreatment on aggregate properties and the corresponding compressive strength of vegetation porous concrete. The performance of untreated aggregates, water-washed aggregates, and acid-treated aggregates was evaluated, and the modification mechanism was explored from the perspective of the interfacial transition zone (ITZ) using scanning electron microscopy (SEM). The results show that phosphate effectively removes impurities from the aggregate surface and increases surface roughness, thus improving the compactness and stability of the ITZ. After soaking the aggregates in phosphate for approximately 50 minutes, the 28-day compressive strength of the porous concrete prepared with acid-treated aggregates reached 16.47 MPa, which represents an 83% improvement compared to porous concrete made with untreated aggregates. Observations of the ITZ revealed that, unlike the loose and porous ITZ of untreated aggregate concrete, the ITZ of the acid-treated aggregate concrete exhibited jagged surface textures and greater compactness.
Optimization study on indoor vibratory compaction curves of cement stabilized macadam
QIU Youqiang and ZHANG Liujun
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.033
To obtain well-defined secondary convex vibratory compaction curves and reduce the need for supplemental compaction point tests, this paper uses vibratory compaction tests for cement stabilized macadam in laboratory settings. Tests were conducted for two pavement sections along National Highway 110 (Hohhot to Bikeqi), exploring the influence of predefined moisture content intervals on vibratory compaction curves under varying cement dosages. The vibratory compaction curves were also compared with heavy compaction curves for analysis. The results show that the vibratory compaction curve is significantly influenced by the predefined moisture content intervals and cement dosage. For a moisture content interval of 1%, high cement dosages (>5%) resulted in clustering of test points as moisture content increased, whereas low cement dosages (≤5%) produced well-defined vibratory compaction curves. Conversely, with smaller moisture content intervals (0.5%), the curves consistently exhibited better secondary convex characteristics under reasonable cement dosages, allowing the maximum dry density and optimum moisture content of cement stabilized macadam to be quickly and accurately determined. Comparison with heavy compaction tests confirmed that the dry density of cement stabilized macadam under vibratory compaction is more sensitive to moisture content. An optimized method for drawing vibratory compaction curves for cement stabilized macadam in the laboratory is proposed. This research not only provides accurate control parameters for mix design under vibratory compaction but also fills a gap in the experience and methodology for drawing indoor vibratory compaction curves.
Selection of phase change materials for asphalt pavement based on molecular dynamics simulation
LIU Fujun, TIAN Xin, LIANG Meichen, and GUO Meng
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.034
Phase change materials (PCMs) have significant application potential in temperature regulation for asphalt pavements. To select suitable PCMs for road applications, this paper utilizes molecular dynamics simulation to analyze the molecular behaviors of lauric acid and polyethylene glycol (PEG). Experimental studies were conducted to validate the simulation results. The results show that molecular dynamics simulation provides an efficient and convenient method for comparing the performance of PCMs. PEG outperforms lauric acid in terms of molecular density, cohesive energy density, solubility parameters, and thermal conductivity, making it more suitable as a phase change material for asphalt pavements.
Experimental study on water stability of sand compound modified mud road
CHAI Ruixiang, WU Kai, YE Wei, CUI Jinmei, WANG Jicheng, and LI Zhantao
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.035
Sand compound modified mud, as a coupled medium of sand and soil, differs from traditional modified mud. To further investigate its water stability indicators, orthogonal design was employed to conduct indoor water stability simulation tests (surface infiltration test, underground capillary water test, and dry-wet cycle test) on sand compound modified mud. The water stability of the modified mud was characterized using the change rate of unconfined compressive strength (UCS). The results show that the unconfined compressive strength and water stability of the modified mud were significantly improved. Under different water disturbance conditions, the order of influence of factors such as sea sand content, compaction degree, and curing age on water stability varied. Analysis graphs indicate that all three factors exhibit a positive correlation with water stability. In practical engineering, a combination of sea sand content, compaction degree, and curing age can be comprehensively considered to meet the water stability requirements for modified mud in road applications in the Ningbo region.
Experimental study on influence of phosphorus slag powder on pervious concrete
LOU Jianxin, YANG Jianyong, ZHANG Yuxian, LI Jun, WANG Jie, and LIU Jian
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.036
This paper investigates the effects of replacing cement with phosphorus slag powder on the mechanical properties, permeability, and pavement performance of pervious concrete. The results show that incorporating a certain amount of phosphorus slag powder as a partial replacement for cement in pervious concrete is feasible. When the replacement ratio of phosphorus slag powder is within 10%, it enhances the strength of pervious concrete. The optimal replacement ratio of phosphorus slag powder is 8%, achieving a compressive strength of 24.18 MPa, a void ratio of 15.37%, and a permeability coefficient of 2.45 mm/s, which meet the requirements for fully permeable pavement applications. However, the effective replacement rate of phosphorus slag powder is limited to below 10% when used as a cement substitute.
Study on alkali excitation mechanism of large dosage slag fine powder
MEI Yang
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.037
To reveal the alkali excitation mechanism of high-dosage slag, this paper combines a three-factor, three-level orthogonal design with macro- and micro-performance tests and microstructure analysis. The effects of different activators, including Ca(OH)2, Na2SiO3, Na2SO4, and CaSO4, in single and dual combinations on the initial and final setting times, pore solution pH, and strength of concrete were explored. The results show that the impact on the strength of hardened paste of composite cementitious materials is ranked as: activator type > dosage > dual-mix ratio. The optimal dual-mix dosage is 4%, with the best combination being Ca(OH)2 and Na2SiO3 at a ratio of 5:1. Under the action of activators, the initial and final setting times of composite cementitious materials are reduced, and the pore solution pH values are higher than those of the control group. Macro- and micro-level results indicate that at 28 days of curing, the hardened paste achieves the highest hydration crystal phase compactness when the activator type is Ca(OH)2 and Na2SiO3, the dosage is 4%, and the dual-mix ratio is 5:1.
Specially Invited Article
Application research and prospect of passive battered pile
ZHOU Dequan, WANG Chuangye, ZHOU Yi, and ZHAO Yadang
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.001
Battered piles oriented in specific directions demonstrate superior horizontal load-bearing capacity compared to vertical piles. However, the working mechanism of battered piles remains inadequately understood, and corresponding design standards are yet to be established. These limitations hinder the effective utilization and application of the horizontal load-bearing and stability potential of battered piles. This paper comprehensively analyzes the soil-pile interaction mechanisms, horizontal displacement, and load-bearing behavior of passive battered piles and their composite systems under lateral unloading and lateral loading conditions, using model tests, numerical simulations, and theoretical analysis. In addition, it proposes future research directions aimed at advancing the study and engineering application of passive battered piles and their composite systems, with the ultimate goal of addressing soil sliding issues effectively.
Subgrade Engineering
Study on applicability of flexible gabion revetment in soft soil subgrade in lake district
SU Weiwei, LEI Mingxuan, LIU Guotian, ZHANG Liujun, and LIU Junyong
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.002
Based on FLAC3D finite difference software, this paper conducts numerical simulations of both flexible gabion revetment structures and rigid revetment structures to compare their deformation and stress characteristics. The results indicate that the flexible gabion revetment structure demonstrates excellent applicability for soft soil subgrades in lake districts. Compared with rigid revetment structures, the gabion revetment structure improves overturning stability through coordinated deformation within the foundation. It significantly reduces the basal stress, thus lowering the bearing capacity requirements for the foundation, and ensures a more uniform stress distribution at the base, minimizing differential settlement and enhancing foundation stability. Moreover, the gabion revetment structure achieves a more even distribution of earth pressure, avoiding stress concentration and effectively enhancing the durability of the structure.
Research and application of dynamic compaction treatment method for highway subgrade in karst development area
LIU Xiaoming, WANG Yigang, and ZHAO Minghua
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.003
This paper utilizes discrete-continuum coupled numerical simulation to investigate the failure modes of karst cave roofs with varying spans under specific compaction energy levels. The relationship between the span of the cave roof and the compaction energy required to cause roof collapse is established, providing an estimation method for the maximum unsupported span of cave roofs within the subgrade area. Based on this, the stability of karst cave foundations under the influence of subgrade loads can be evaluated. Depending on the results, a double-layer reinforced continuous concrete slab can be installed in the pavement base to enhance stability and mitigate the risk of collapse from undisturbed karst caves. Finally, a dynamic compaction treatment method for highway subgrades in karst areas is summarized. Based on preliminary survey data, dynamic compaction is applied to large areas of the karst zone using specific compaction energy. During the process, collapsed karst caves are filled, while the stability of undisturbed karst caves is assessed. If stability checks fail, reinforcement measures are implemented in the pavement base layer. This method eliminates the need to identify all karst cave locations and their geometric characteristics, making it a cost-effective and efficient approach to mitigating collapse risks in karst area subgrades. The proposed method has significant potential for widespread application.
Deformation monitoring of highway subgrade in alpine area based on spaceborne InSAR
LUO Boren, YU Fei, and YU Shaohuai
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.004
The harsh geological and climatic conditions in the high-altitude alpine regions of Northwest China, including the widespread distribution of seasonal permafrost and other unfavorable geological bodies, significantly affect the service life of highways and threaten driving safety. Traditional highway deformation monitoring methods are inefficient, limited in coverage, and provide incomplete deformation information. This study employs spaceborne InSAR technology for highway deformation monitoring, enabling large-scale extraction of deformation information along highway corridors. The findings reveal the deformation patterns of highway subgrades in permafrost regions, offering fundamental data for targeted remediation of hazardous highway sections. This approach ensures the scientific construction and safe operation of highways.
Study on treatment of karst foundation by dynamic compaction
LYU Jiang, ZHAO Hui, and YANG Biao
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.005
Dynamic compaction is a commonly used method for treating karst foundations with cavities; however, the design parameters of dynamic compaction under different working conditions lack clear standards. This paper employs the finite element software Abaqus to simulate the effects of surrounding rock quality and karst roof thickness on the stability of karst cave roofs during dynamic compaction treatment. The results indicate that the vertical displacement and maximum tensile stress of karst cave roofs are negatively correlated with roof thickness. For Grade II and III surrounding rocks with better properties, no cave collapse occurred after dynamic compaction treatment. In contrast, for Grade V surrounding rocks with poorer properties, no collapse occurs when the cave roof thickness exceeds 3 m, while treatment requires 2,000 kN·m of compaction energy for roof thicknesses below 2 m, 4,000 kN·m for thicknesses between 2 and 3 m, and 6,000 kN·m to break through and backfill the cave when the thickness is approximately 3 m.
Research on compaction control method of high water content and high liquid limit clay in Guizhou Province
XU Shuliang
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.006
To study and verify the compaction control method for high liquid limit clay subgrade in the humid and rainy regions of Guizhou Province, a series of experiments were conducted on high water content and high liquid limit clay from the Kaiyang Expressway (Kaili to Yangjia) in Guizhou. The experiments included wet heavy compaction tests, CBR strength tests, basic physical property tests, consolidation tests, thermogravimetric analysis, and trial road tests to analyze the performance of high liquid limit clay in road applications. The results show that for high liquid limit clay, increasing compaction energy does not always improve performance, as excessive energy reduces CBR strength. The compression coefficient of the soil increases with water content but remains within standard limits even at high water content. During compaction, the dry density reaches a peak value beyond which further rolling reduces efficiency. By considering adsorbed water as part of the solid phase, a compaction control standard for the high liquid limit clay of the Kaiyang Expressway was calculated, which aligns with the actual standard used in construction, validating its practicality and rationality.
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.007
This paper investigates representative fine-grained subgrade soils from a highway project. Samples with varying water content and compaction degrees were prepared, and the effects of water content, compaction degree, plasticity index, dynamic deviator stress, and confining pressure on the dynamic resilience modulus (Mr) were analyzed using dynamic triaxial tests. Matlab’s global optimization toolbox was employed to identify the relationships between model parameters ki and physical property indices, thus constructing a prediction model for the dynamic resilience modulus based on physical properties. The predictive performance of this model was compared with conventional models outlined in existing standards. The results show that Mr decreases nonlinearly with increasing dynamic deviator stress and water content, while it increases with rising confining pressure and compaction degree. Mr is inversely proportional to the plasticity index (Ip). Using Matlab’s built-in artificial neural network (ANN) and genetic algorithm (GA) toolkits, a relationship was established between ki and water content (w), compaction degree (K), plasticity index (Ip), and fine particle content (P0.075). This relationship was used to construct a predictive model for the dynamic resilience modulus. Compared to conventional models in standards, the proposed model achieves an average prediction error of 5.03% and a maximum prediction error of less than 15%, demonstrating improved predictive accuracy. Therefore, conducting targeted dynamic resilience modulus tests to develop prediction models based on physical properties holds practical value for specific highway subgrade construction projects.
Study on failure mechanism of rainfall slope based on full‐scale slope model experiment
ZHANG Yongchuang
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.008
Field investigations in debris flow source areas reveal that granite is exposed on slope surfaces, while a thin layer of sandy, weathered residual soil is distributed at the slope tops. This paper focuses on the significant permeability differences between the slope base and the upper weathered soil layer. A full-scale slope model experiment was conducted to replicate these characteristics, including rainfall infiltration simulations under both exposed surface conditions and conditions with non-woven fabric filter mats applied. The aim was to investigate the failure mechanism of rainfall-induced debris flows. The results show that the primary trigger for debris flows is the presence of a highly permeable coarse-grained layer between the sandy soil layer and the impermeable soil layer. This coarse-grained layer facilitates groundwater infiltration and interlayer flow, causing a rapid increase in pore water pressure and leading to soil liquefaction phenomena. The paper confirms the effectiveness of non-woven fabric filter mats in inhibiting infiltration during rainfall events.
Pavement Engineering
Detection method of rural road pavement damage based on smart phone
ZHANG Yang, HE Li, TANG Qingzhou, and ZHANG Dejin
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.009
Automatic detection of rural road pavement damage is a critical prerequisite for scientific maintenance. To address issues such as high false detection rates, missed detection, and the inability to quantify damage when using smartphones for pavement damage detection, this paper proposes a novel detection method. The proposed method involves using a smartphone to capture pavement images. A region of interest is first selected in the image, followed by weighted least-squares filtering, Canny edge detection, and Hough transform line detection to identify the pavement, minimizing environmental interference and reducing false detection rates. Perspective transformation is then applied to the pavement region to generate orthophotos, decreasing missed detection rates. Finally, the Mask-RCNN model is utilized to identify damage. Experimental results show that compared to the SSD detection model, the proposed method reduces the average false detection and missed detection rates for cracks, potholes, and repairs by 15.4% and 19.6%, respectively. In addition, the method can measure the length and width of cracks and the area of potholes and repairs, effectively meeting the practical requirements for rural road pavement damage detection.
Research on road crack recognition model based on YOLO v3 deep learning algorithm
SU Weiguo and WANG Jingxiao
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.010
To address the challenges of manual intervention in road crack detection and the inaccuracy of traditional recognition algorithms, this paper proposes a road crack recognition method based on the YOLO v3 deep learning algorithm. The dataset images were first resized to 416×416 pixels. Labelme was then used to annotate cracks in the images and convert the boundary box location information. Finally, the YOLO v3 algorithm framework was employed for model training. The results show that the YOLO v3 algorithm achieves precision, recall, and F1 scores above 95%, with an image detection speed of 0.123 seconds per image. The YOLO v3 deep learning algorithm meets the requirements for real-time road crack detection in terms of both accuracy and speed.
Comparative analysis of asphalt pavement performance prediction models based on Gamma and Markov processes
MA Shibin and CHEN Yonghao
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.011
Pavement performance prediction is a critical component of pavement management systems, serving as an essential basis and prerequisite for decision-making in asphalt pavement maintenance. This paper introduces the relevant theories of Gamma and Markov stochastic processes to construct asphalt pavement performance prediction models and address uncertainties related to pavement degradation. The results show that stochastic process models are effective in predicting pavement performance degradation and service life. Matlab programming was used to predict asphalt pavement performance and lifespan, yielding pavement degradation curves that significantly improve prediction accuracy and reliability. Finally, taking a test road section in Hebei Province as an example, a comparative analysis of the Gamma and Markov process prediction models was conducted. The analysis demonstrated the practicality and superiority of the Gamma process-based asphalt pavement performance prediction model, offering new insights for future predictions of asphalt pavement performance.
Study on interlayer bonding properties and influence factors of cape seal
LI Yan, ZHANG Chengxue, QIU Yeji, and ZHANG Haijun
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.012
To address pavement issues such as shoving and rutting caused by insufficient bonding strength in cape seal layers, this paper investigates the interlayer bonding properties and influencing factors of cape seal. Mechanical tests were conducted using a pavement interlayer shear-pull testing device. Through interlayer pull-off, direct shear, and torsional shear tests, the maximum tensile force, shear force, and torque at failure were obtained. The interlayer bonding performance of cape seal was analyzed in terms of gravel coverage rates, as well as upper and lower layer combinations. The results show that when the gravel coverage rate is 80%-90%, and the cape seal consists of an MS-III micro-surfacing layer combined with a 4.75-9.5 mm single-sized gravel seal, the bonding performance between the cape seal and the underlying layer is optimal.
Bridge Engineering & Tunnel Engineering
Analysis of socket depth between bridge pier and cap with improved socket connection
GE Jiping, LAI Luqi, and WANG Zhigang
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.013
Traditional prefabricated socket-type bridge piers are limited in engineering applications due to the requirement for deep socket connections. This paper proposes an improved socket connection design incorporating measures such as side shear keys, U-shaped anti-punching reinforcement at the pier base, high-strength non-shrink grouting materials, and large-diameter corrugated metal pipe constraints. The current formulas for calculating socket depth in socket-type connections are reviewed, and a modified calculation formula for improved socket-type piers is presented. The influence of factors such as axial compression ratio and concrete strength on socket depth is discussed. The analysis shows that the improved socket connection reduces socket depth, decreases cap thickness, and broadens the application range. In non-seismic regions with moderate load levels, the socket depth can be as low as 0.7 times the pier diameter. The shear key design contributes 20% to the bending resistance of the socket connection. When the axial force eccentricity is less than 0.5 times the pier diameter, axial force positively contributes to the bending resistance. However, when the eccentricity exceeds 0.5 times the pier diameter, the embedding depth needs to be increased appropriately. Enhancing concrete strength further reduces the required socket depth.
Finite element model updating of long span suspension bridge based on optimized radial basis function neural network
YANG Wenfu and CHEN Xin
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.014
To achieve accurate prediction and analysis of the structural behavior of long-span suspension bridges, a finite element model updating method is proposed. An optimized radial basis function neural network (RBFNN) is constructed using a genetic algorithm to map the relationship between structural responses and parameters. Using structural dynamic responses as inputs, the model updating was performed on a long-span suspension bridge using both numerical simulation data and actual data from a health monitoring system. The results show that the optimized RBFNN effectively represents the functional relationship between structural responses and parameters to be updated. Model updating via the optimized RBFNN significantly enhances the accuracy of finite element model calculations. After updating based on numerical simulation data, the calculation error was reduced to within 1.5%. When dynamic characteristics from the health monitoring system were used as feature data, the optimized RBFNN effectively updated the suspension bridge model. The maximum calculation error was reduced from 20.37% before updating to within 7%, achieving a maximum error reduction of 77.91%.
Study on relationship of solar radiation temperature and pier‐top displacement of ultra‐high thin‐walled hollow pier
LIU Zhishen, ZHANG Yifei, SONG Fei, SU Jufeng, and REN Xiang
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.015
Thin-walled hollow piers are widely used in high-pier and long-span continuous rigid-frame bridges. Solar radiation-induced displacements at the tops of ultra-high thin-walled hollow piers can negatively affect the structural alignment and stress during construction and post-construction phases. Based on a 180 m high thin-walled hollow pier of a large bridge in Shaanxi Province, this paper analyzes the temperature field and pier-top displacement using data collected during two 24-hour periods: August 28-29 and October 11-12. The temperature field and pier-top displacement patterns over time were studied using finite element analysis. The results show that the temperature difference between the north and south pier walls is significantly influenced by ambient temperature and diurnal temperature variations. In August, with high ambient temperatures and small diurnal variations, the wall temperature difference is smaller, resulting in smaller pier-top displacements. In October, with lower ambient temperatures and larger diurnal variations, the wall temperature difference is greater, leading to larger pier-top displacements. Pier-top displacement follows a pattern consistent with the temperature difference between the sunlit and shaded pier walls. At a height of 180 m, a temperature difference of 8 °C between the walls causes a maximum pier-top displacement of 52.6 mm. Displacements calculated using the finite element method and code-based methods align well with measured values, demonstrating high accuracy.
Fracture mechanics‐based fatigue study of corrugated steel webs
LI Haidi and YANG Lei
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.016
To develop fatigue analysis and evaluation methods for corrugated steel web structures, constant-amplitude fatigue load tests were conducted on experimental beam models, supplemented by fatigue test data from domestic and international studies. The finite element submodeling method was employed to obtain stress distribution functions at structural details, and the weight function method was used to derive the stress intensity factor at the crack tip. The Paris law in fracture mechanics was applied to derive the S-N curve for corrugated steel web structures. Comparative analysis with fatigue test results shows that when the initial crack depth is set as a0=t/20 (accounting for plate thickness effects), the calculated results align more closely with experimental data.
Discussion on formula of off‐load increase coefficient of single‐box multi‐cell wide girder
GAO Qingfei, WANG Renzhi, LI Jun, GUO Binqiang, and QIN Weijun
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.017
Single-box multi-cell wide girders are widely applied in highway and urban bridges due to their excellent integrity and large width, especially with increasing traffic volumes. However, existing methods for calculating the off-load increase coefficient of single-box multi-cell wide girders are either too complex or fail to meet engineering needs, limiting their applicability in preliminary design. This paper explores eight influencing factors of the off-load increase coefficient, calculates the coefficients using the transverse frame method, and proposes an empirical formula for the off-load increase coefficient. The proposed formula is validated using the Xiushui Street Wide Girder Bridge in Jilin City.
Research on multi‐source and heterogeneous data integration of large bridge health monitoring system
WANG Daijun, ZHOU Tiantu, FU Junmin, CHEN Xing, LU Shuai, and YU Zheng
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.018
Large bridge health monitoring systems are characterized by numerous sensors, diverse types, various communication methods, and flexible network configurations. The multi-source heterogeneous nature of the data poses significant challenges for data integration. To address the application requirements of bridge health monitoring, this paper designs a multi-source heterogeneous data integration scheme. The scheme achieves structured storage of multi-source heterogeneous data and introduces the concept of “structured communication.” This enables structured communication configuration, unified communication control, and flexible data processing, standardizing and simplifying communication configuration management in data acquisition systems. These improvements enhance code simplicity, maintainability, and the overall integration level of the software platform for large bridge health monitoring systems. The proposed scheme has been applied to the structural health monitoring system of the Jiujiang Yangtze River Highway Bridge. The results show that the system interface is user-friendly, and the system operates stably and reliably, demonstrating practical value.
Selection and design of anchorage for suspension bridge in downhill area under complex geological conditions
CHEN Yongliang, HE Shiyong, XIA Zhixian, and WU Wenxiang
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.019
Due to the complexities of design and construction, long-span single-tower suspension bridges are rarely applied in practice. The main bridge of the Jinsha River Bridge at Tiger Leaping Gorge adopts a 766 m single-span single-tower steel truss suspension bridge. On the Lijiang anchorage side, complex geological conditions posed significant challenges due to geological structures, while the reservoir level of the planned hydropower station created adverse hydrological conditions for waterproofing and durability of the anchorage system. The selection of an appropriate anchorage type was therefore particularly challenging. This paper first details the selection process for anchorage under complex geological conditions. It then introduces the structural design of the anchorage and the high-strength steel rod anchoring system. Finally, it outlines the main steps and key outcomes of anchorage calculations.
Study on countermeasures and genetic analysis of sloping bridge pile hole wall failure
YANG Hua and YIN Xiaotao
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.020
The stability of slopes and the safety of bridge piles are interdependent, and ensuring the safety of sloping terrain is crucial for the safe construction of bridge piles. Based on three collapsed pile sections of the Huadizhai No. 2 Bridge, this paper utilized geological surveys to design initial terrain and altered terrain slope stability calculation conditions, along with horizontal compensation force calculation conditions under a safety standard of 1.35. By integrating geological analysis, slope stability assessment, and compensation force evaluations, the causes of pile hole collapse and corresponding countermeasures were analyzed. The results show that under the initial terrain, the slopes of the three collapsed pile sections ranged from unstable to relatively stable. After altering the terrain with waste fill, the slopes became relatively stable, with required horizontal compensation forces under a safety factor of 1.35 as follows: K32+973 (4,667 kN/m) > K33+053 (1,478 kN/m) > K32+733 (815 kN/m). The primary cause of pile hole collapse was slope deformation induced by waste fill in gravel soil layers. Secondary factors included the poor bonding and low vertical stability of thick gravel soil layers. The severity of collapses was consistent with the compensation force ranking: K32+973 (severe) > K33+053 (moderate) > K32+733 (mild). The disturbed upper 20 m soil layer of the pile could not support loads effectively, requiring recalibration of effective pile length. Vertical load-bearing characteristics were altered, necessitating reinforcement using anti-slide piles before bridge pile construction. For the K32+973 section, one row of three anti-slide piles was placed on the inner and outer sides of the slope near the pier. For the K33+053 and K32+733 sections, only one row of three anti-slide piles on the slope’s inner side was needed. Deep slope displacement monitoring and structural internal force monitoring for the three problematic pile sections should be enhanced to assess slope reinforcement effectiveness and ensure bridge pile structural safety.
Key technology for design of composition section of hybrid girder cable‐stayed bridge
TIAN Bo and SONG Lubing
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.021
The main bridge of the Yibin Nanxi (Xianyuan) Yangtze River Bridge adopts an asymmetric hybrid girder cable-stayed design with a 572 m main span. The main span and the north-side span utilize hybrid girders, while the south-side span uses a concrete girder. A steel-concrete composite section is introduced between the south-side span and the main span. This paper explores multiple schemes for the location and key structural design of the steel-concrete composite section, prioritizing a full-section rib connection with a pressure-bearing shear transfer transition structure. The structural rationality and construction feasibility were verified through on-site static model tests, failure model tests, and casting tests for the steel-concrete composite section. Comparative studies between the on-site model tests and structural analysis show that the structural design of the steel-concrete transition section of the Yibin Nanxi (Xianyuan) Yangtze River Bridge is rational. The structure ensures smooth stiffness transitions, reliable safety under loads, and practical constructability, providing valuable reference and guidance for similar bridge projects.
Inspection and evaluation of load‐bearing capacity of hollow‐box arch bridge
SONG Zegang and YANG Min
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.022
The inspection and evaluation of the load-bearing capacity of in-service bridges are crucial for ensuring structural and operational safety. This paper investigates a 90 m span hollow-box arch bridge, assessing its damage condition, material properties, and state parameters to determine partial evaluation coefficients. The bridge’s ultimate limit state and serviceability limit state load-bearing capacities of the main arch ring were then evaluated using both the original design standards and the current code. The results show that, compared to the original design standards, the safety factor for the compressive load-bearing capacity of the main arch ring cross-section is significantly reduced when evaluated with the current code. In addition, deflection under vehicle load increases noticeably, indicating an insufficient safety reserve in the main arch ring’s load-bearing capacity. This finding warrants serious attention.
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.023
As a critical load-bearing component in bridge swivel systems, the mechanical behavior of spherical joints is essential for the safety of bridge swiveling operations. This study focuses on the spherical joints of a multi-point support swivel system for the bridge over the Xiangyang North Marshalling Yard. Model tests were conducted to analyze the effects of the number of supporting legs, swivel speed, track smoothness, and wind load on the stress of spherical joints. The stress variation patterns of spherical joints under different working conditions were investigated. The results show that increasing the number of supporting legs improves the uniformity of stress distribution in both upper and lower spherical joints. During the acceleration phase of swiveling, the spherical joints are significantly affected by acceleration effects. In the steady swiveling phase, the stress of the upper spherical joint increases with the swivel angle, while the lower spherical joint maintains relatively uniform stress. A recommended swivel speed of 0.02-0.04 rad/min is proposed. Track irregularities increase the stress variation in spherical joints. As the degree of irregularity increases, the stress variation also intensifies. Under wind loads, the lower spherical joint maintains uniform stress, but the stress in the upper spherical joint increases with the swivel angle. Swiveling operations under high wind speeds should be avoided.
Analysis on vehicle‐bridge interaction of high‐pier continuous rigid frame bridge
LIU Huaquan, YANG Dehai, CAI Chengqi, HUANG Zhenming, and CHEN Zhouqi
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.024
To study the dynamic response characteristics of the vehicle-bridge system under moving vehicle loads, a three-span high-pier continuous rigid frame bridge was selected as the research object. A 2-axle, 7-degree-of-freedom vehicle model was applied to explore the effects of vehicle speed, number of vehicles, and vehicle load on the dynamic response of the vehicle-bridge system. The results show that vehicle speed has minimal impact on the peak displacement response of the bridge. However, when vehicles travel at the same speed, the peak displacement response differs across bridge spans, with resonance occurring at a vehicle speed of 40 km/h. As the number of vehicles increases, the duration of significant displacement response at the mid-span of the bridge spans noticeably lengthens. The maximum displacement response at the mid-span of the main span occurs with two vehicles, while the peak vehicle acceleration and the weighted root mean square of acceleration are highest when six vehicles pass over the bridge. As vehicle loads increase, both the displacement and acceleration responses of the bridge show an overall upward trend, while the bridge’s impact factor and various dynamic indices of the vehicles exhibit a decreasing trend.
Analysis and reinforcement measures for unconventional cracks in gravity U‐type abutment
CHENG Kun, DU Yinguang, and LIU Zhang
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.025
Horizontal cracking at the foundation level is uncommon in gravity U-type abutments. This paper investigates the causes and reinforcement measures for unconventional horizontal cracks in the foundation and vertical cracks in the abutment wall of a gravity U-type abutment on a highway bridge. Survey and analysis results show that the vertical cracks in the abutment wall are structural cracks caused by excessive reaction forces from permanent loads combined with the impact loads from vehicles at expansion joints. The horizontal foundation cracks result from the presence of filler interlayers at the foundation, which softened over time due to water exposure, leading to foundation voiding or poor contact. The long-term impact of vehicle loads caused delamination failure. To address the causes of these cracks, reinforcement measures such as steel pipe grouting to fill voids and strengthen the foundation, concrete section enlargement to enhance structural capacity, and the addition of auxiliary supports to distribute loads and reduce stress concentrations are proposed.
Research on application of equivalent stiffened plate elements in local stability calculation of U‐shaped stiffened plates
CHEN Xiangjun
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.026
To address the issue of excessively large computational models in the numerical simulation of U-shaped stiffened plates in large-span flat steel box girder main girders, this paper proposes a finite element calculation theory using equivalent stiffened plate elements and a simplified method for U-shaped stiffened plates. By simplifying the U-shaped small box ribs in U-shaped stiffened plates into equivalent stiffening strips, the transverse stiffness of the cover plate is redistributed, and the effect of equivalent stiffeners on the stress of the plates is calculated. Stability analysis was conducted using Fortran language developed on the Ansys platform, and the results were compared with those from full shell finite element models. The results show that, compared to full shell finite element models, the proposed equivalent stiffened plate element model yields a relative error of only 5.9% in deflection calculations and approximately 2% in buckling factors for lower-order modes. In addition, the time required to calculate the first five modes using the equivalent stiffened plate element model is about one-third of that required for the full shell finite element model.
Study on supporting effect of pre‐stressed rock bolts on tunnel face
SHEN Xiangqian, CHEN Daoyun, and ZHENG Chao
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.027
Focusing on the stability issues of the tunnel face in the large deformation section of soft rock in the Muzhailing Tunnel on the Weiyuan-Wudu Expressway, this paper proposes a technical solution for temporary reinforcement of the tunnel face using pre-stressed rock bolts. Numerical simulations were conducted to evaluate the reinforcement effect and effective range of pre-stressed rock bolts on the tunnel face, and the influence of initial ground stress on the reinforcement effect was further analyzed. The results show that under the given engineering conditions, pre-stressed rock bolts demonstrate significantly better reinforcement effects on the tunnel face compared to fully bonded rock bolts. The reinforcement effect of pre-stressed rock bolts on the rock surrounding the tunnel face contour is limited, suggesting that simplification of reinforcement near the contour may be considered in practical applications. A critical embedding depth exists beyond which pre-stressed rock bolts lose their effectiveness in controlling the final deformation of the tunnel face when their support parameters are determined.
Optimization research of laying method and material type selection of thermal insulation layer for tunnels in cold region
WU Tao, LIU Zhichun, LIU Xuejiao, and ZHANG Hongfei
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.028
To address the issue of frost damage in tunnels in cold regions, research on thermal insulation and frost prevention is crucial. This paper utilizes an improved analytic hierarchy process combined with grey relational analysis to identify optimal insulation materials suitable for different laying methods that provide effective insulation. Numerical simulation methods were then used to calculate and analyze the tunnel temperature field under various combinations of insulation materials and laying methods. Based on the “composite temperature field” comparison results, the optimal insulation scheme was determined. The results show that the “off-wall laying + Furritek insulation board” combination is the optimal insulation scheme. Its advantage lies in the double-layer insulation formed by the air gap created by the off-wall laying method and the Furritek insulation board, which effectively blocks the transmission of negative temperatures, reducing the impact on the lining structure and surrounding rock. Furthermore, this method is easy to construct and has low maintenance costs. The research results can be applied in engineering practice to reduce the probability of frost damage and provide a reference for thermal insulation and frost prevention design in cold-region tunnels.
Research on gas migration and ventilation disaster prevention in highway tunnel
WANG Zhongqi, LIN Zhi, FENG Sen, YANG Hongyun, CHEN Xiang, and LIU Jiang
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.029
To understand the gas migration patterns and ventilation disaster prevention techniques during tunnel construction, this paper uses a real tunnel as the engineering context. A 3D transient ventilation physical model was established using Ansys Fluent, and the effects of ventilation on gas concentration were analyzed in combination with on-site monitoring data. The results show that the uneven diffusion of gas and airflow is prominent. Gas concentration and wind speed stabilize at a distance of 120 m from the tunnel face as ventilation time increases. During gas monitoring and prevention, special attention should be paid to the area between the tunnel face and the second lining formwork to ensure gas concentration does not exceed limits. After blasting, the gas concentration at the tunnel face continuously increases, peaking after approximately 15 minutes of ventilation. After 30 minutes of ventilation, the gas concentration stabilizes and falls within the allowable range for construction. Proper control of ventilation time and volume, along with enhanced ventilation in critical areas such as the tunnel arch foot and bottom plate, ensures the safety of tunnel construction.
Study on health state evaluation method of highway tunnel based on neutrosophic theory
DENG Fayou, XIA Caichu, and XU Chongbang
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.030
The structural complexity and inherent uncertainties of highway tunnels necessitate comprehensive consideration of various uncertain factors to reasonably evaluate their health state. By introducing neutrosophic theory, which accounts for structural uncertainties, this paper proposes a health state evaluation method for highway tunnels based on neutrosophic cosine and tangent similarity measures. The proposed method was applied to evaluate the health state of 10 samples. A comparison between the actual evaluation grades and the results obtained using the proposed method shows that the evaluation results are consistent with the actual grades. This indicates that the proposed method effectively addresses uncertainties in the structure and is simpler and more practical. In addition, it broadens the evaluation framework for highway tunnel health assessment.
Pavement Structure and Materials
Aging asphalt concrete cracking performance under different cyclic loading frequencies
YAN Jingchen, MA Yanpei, and YAN Junjie
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.038
Using digital speckle technology, this paper examines the crack propagation behavior of asphalt concrete under repeated loading, analyzing the crack propagation mechanism from macro- and micro-perspectives under different aging conditions and loading frequencies for four types of asphalt concrete. The results show that the basalt fiber-reinforced asphalt concrete beam specimens delay the onset of the unstable crack propagation phase, thus extending the service life of the asphalt concrete. Aging accelerates the progression of asphalt concrete to the unstable crack propagation point, advancing this stage by 4%-5%. Under repeated loading frequencies of 5 Hz, 10 Hz, and 15 Hz, the damage factors of the asphalt concrete beam specimens exhibit a nonlinear increasing trend. However, for the same number of loading cycles, the damage factor under 5 Hz cyclic loading is higher than those under 10 Hz and 15 Hz, indicating that 5 Hz repeated loading causes more significant damage to asphalt concrete.
Dynamic load response analysis of rubber powder modified asphalt mixture
YANG Sanqiang, SUN Shuang, LI Qian, LIU Xinlei, and QIN Lusheng
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.039
To investigate the mechanical response of rubber powder modified asphalt pavement under dynamic loads, this paper, based on the “Full-Scale Accelerated Pavement Loading Testing” project, designed experimental schemes for asphalt mixtures with varying rubber powder contents. The paper employed accelerated loading test equipment to evaluate the stress and deformation of pavement structures, obtaining dynamic strain response data to analyze the strain response patterns of various structural layers. Combining finite element numerical simulations and a custom loading program, the paper examined the dynamic responses of rubber powder modified asphalt pavements under variable temperature conditions. The results show that through microscopic testing, Marshall tests, and SHRP tests, the optimal rubber powder content for 70# asphalt modification was determined. Performance technical parameters of rubber powder modified asphalt mixtures were obtained through experimental analysis. Using accelerated loading tests and finite element modeling, the paper compared the rutting deformation patterns of different pavement structures under varying axle load cycles.
Study on microstructure of asphalt modified by oil‐coal blend
GUO Pengfei and ZHOU Xinfeng
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.040
To investigate the microstructure and modification mechanism of asphalt modified with oil-coal blend, SK-90# asphalt was mixed with 5%, 10%, 15%, 20%, and 25% (external blending method) oil-coal blend to produce modified asphalt. The performance and microstructural changes of the modified asphalt were analyzed using contact angle testing, infrared spectroscopy, cross-sectional SEM, and X-ray photoelectron spectroscopy. The results show that the oil-coal blend exhibits good compatibility with asphalt. During the modification process, esterification reactions occurred, resulting in a decrease in hydroxyl-containing aromatic compounds and an increase in carbonyl-containing aromatic compounds. Macroscopically, the oil-coal blend-modified asphalt demonstrated excellent high-temperature performance.
Traffic Engineering and Management
Design and development of two and three dimensional integration system for highway based on WebGIS
CHE Defu and ZHOU Huajun
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.041
To address the inefficiencies, lengthy cycles, and high resource demands in the process of determining the annual project database for highway maintenance quotas in Liaoning Province, a 2D and 3D integration system for highways based on WebGIS was designed and developed. This system not only provides a macroscopic view of the geographic distribution and overall characteristics of highways but also offers a detailed and intuitive representation of the spatial relationships and conditions of roadbeds and pavement damage. The system meets the needs of modern highway management and can serve as a reference for other highway maintenance quota tasks.
Research on influence factors and efficiency analysis of expressway maintenance marketization
ZHONG Wen, HE Shoukui, and WANG Xiaodong
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.042
To promote market-oriented reform of highway maintenance, this paper investigates its influencing factors and outcomes and proposes an evaluation model for assessing its effects. A panoramic analysis method within a three-dimensional framework was employed to determine the evaluation content. Drawing on the balanced scorecard concept, the analysis incorporates four dimensions: business, user, internal management, and learning and growth, with the innovative addition of a social responsibility dimension to construct an evaluation indicator system. Subsequently, a cloud-based extension model was developed to evaluate the effectiveness of expressway maintenance marketization and calculate the evaluation grade. Empirical analysis was conducted using data from Guizhou Province for 2014 and 2019. The results show that most indicators improved in 2019 compared to 2014, demonstrating that the overall effect of marketization in the province was positive. However, challenges remain in further advancing marketization. Suggestions are provided regarding maintenance funding, new maintenance policies, equipment upgrades, and cost management.
Analysis of expressway routine maintenance performance management based on DEA
LI Yuhuan, SHI Xiaoli, and GAO Nan
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.043
To allocate maintenance resources efficiently and improve management levels, this paper examines the maintenance performance and improvement strategies of routine maintenance projects for 23 expressways in Shaanxi Province using 2018 operational maintenance data and data envelopment analysis. The results show that for some inefficient subsidiaries, traditional radial- and slack-based performance improvement methods are challenging and impractical in the short term. Therefore, a scenario-dependent model-based long-term incremental improvement strategy is proposed. By leveraging relative improvement values, this strategy enables phased improvements for inefficient subsidiaries. It provides a feasible approach for subsidiaries to set lower short-term performance improvement targets while achieving gradual long-term enhancements.
Study on the minimum radius of vertical curve of highway main line entrance section based on merging sight distance
LI Yang, ZHAO Yemei, and CHEN Tianxing
Date posted: 5-11-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.02.044
Given the limited research on the vertical curve radius of highway mainline entrance sections and the lack of differentiation between entrance and exit sections in existing studies, this paper identifies merging sight distance as the primary influencing factor for the vertical curve radius of entrance sections. Using merging sight distance as the control condition, the vertical curve radius of entrance sections was studied. A safety merging sight distance calculation model for highway mainline entrance sections was established by analyzing the traffic behavior characteristics of vehicles on the entrance mainline and considering drivers’ psychological and physiological characteristics. The sight distance model incorporates three key indicators: reaction distance, lane-changing distance, and deceleration distance. The smaller value between lane-changing and deceleration distances was used as the control basis to calculate the recommended merging sight distance. The paper considered both crest vertical curves and sag vertical curves. For crest curves, the analysis focused on the top of the grade change point, while for sag curves, it included the influence of headlight illumination distance at night and obstruction of the driver’s sightline by overhead structures. Vertical geometric relationships were used to establish calculation models for the crest and sag curve radii required to meet merging sight distance requirements. By substituting the recommended merging sight distance into the calculation models, the minimum recommended radii for crest and sag vertical curves at entrance sections were obtained. The results show that the requirements for entrance sections are lower than those for exit sections, and the recommended vertical curve radius values calculated using sight distance considerations are lower than those specified in current standards.
