Volume 44, Issue 6 (2024)
Subgrade Engineering
Comparison Analysis of Different Settlement Prediction Models under Small Post‑ Constructio n Load on Soft Foundation
HAN S hanpeng, FU Wei, ZHANG Junhui, and LIN Chen
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.001
Settlement deformatio n is a key conc ern in soft foundation construction.Since there is still a small load applied after the filling of soft foundation in the actual project,based on the settlement monitoring data of the high-fill section of Zhaoyang West Ring Expressway in Zhaotong City,Yunnan Province,three settlement prediction methods,namely the hyperbolic method,the three-point method,and the Hoshino method,were used to predict,compare,and analyze the settlement of the fill foundation,and the fitting characteristics of each model were summarized.By comparing the fitting curves and the actual settlement curves,it was found that the loading on the roadbed will cause large errors in the prediction of settlement for the three methods;when the three prediction methods use the data of n − 1 level post-fill interval and n level post-fill interval for fitting,the effect is not as good as using the data of constant load period;for the hyperbolic method and the three-point method,longer time interval of the data points chosen for the fit indicates better prediction effect;for the Hoshino method,a better fit is achieved by using data from the constant load period.
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.002
With the intensifying development density of urban underground space in China，the impact of ultra-large foundation pit construction on the normal operation of adjacent structures cannot be ignored.Relying on the Huangmugang Comprehensive Transportation Hub Project in Shenzhen，this paper studied the deformation of the envelope structure and soil caused by the excavation of the ultra-large special-shaped foundation pit，as well as the structural response of the deformation of the adjacent existing station and the temporary steel bridge.The paper optimized the construction scheme of the special-shaped foundation pit excavation.The results show that the deformation trend of the envelope structure on the north and south sides of the foundation pit is the same as a whole，but the deformation at the external corner on the north side is large.The envelope structure of the existing station as a whole is displaced into the pit，with a maximum horizontal displacement of 9.4 mm，and the horizontal displacement of the steel box girder bridge pile after excavation of the foundation pit is large，with the maximum value reaching 10.5 mm.The overall construction safety is ensured by adding temporary concrete supports on the lower ground and adding steel sleeves on the piers of the temporary steel bridge in the pit.
Experimental Study on Deformation Characteristics of High Liquid Limit Soil Considering the Effect of Temperature
LI Bangwu, SHEN Xuning, ZHANG Rui, and CHEN Yanrong
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.003
In order to study the influence of temperature on the absorbed bound water and deformation characteristics of high liquid limit soil，the high liquid limit soil in Hunan and Hainan provinces were selected for test.The influence of temperature on the content of bound water was measured by a temperature-controlled water bath volumetric flask test.The consolidation test was carried out on the samples with a one-dimensional temperature-controlled consolidometer，and the variation law of high liquid limit soil deformation affected by temperature was analyzed under the modified pore ratio considering the bound water content.The results show that the absorbed bound water in the high liquid limit soil decreases with the increase in temperature.Under the same load gradient and different constant temperatures，higher temperature causes greater deformation of the samples.At 15 ℃ and 45 ℃，the difference in the pore ratio of the samples is 0.1 at most.The same sample with stable deformation under the same initial load and temperature is found to deform again after heating up for three gradients with an interval of 10 ℃，and the deformation is up to 0.6 mm.The results can provide some reference for the compaction and deformation control of high liquid limit soil embankments.
Pavement Structure and Materials
Research Progress of Rubber‑Modified Asphalt by Wet Process
GE Dongdong, JIANG Xiangyang, LYU Songtao, ZHANG Honggang, and SONG Xiaojin
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.004
The application of waste tires in asphalt pavements can not only effectively reduce resource consumption but also significantly reduce environmental pollution.Crumb rubber could be obtained by processing waste tires and used as a modifier by mixing with asphalt through the wet process to improve the performance of asphalt.This paper reviewed the research progress of rubber-modified asphalt by wet process and discussed its preparation process，influencing factors of performance，and modification mechanism.By reviewing the relevant studies，the critical conditions in the preparation process and their effects on storage stability were summarized.Furthermore，the effects of rubber dosage，particle size，matrix asphalt type，and preparation parameters on the physical and rheological properties of asphalt were analyzed.The interaction mechanism between rubber and asphalt was revealed by spectroscopic analysis and microscopic morphology analysis.In addition，the synergistic enhancement effect of rubber compounded with other modifiers on asphalt properties was explored，which provided a useful reference for the further optimization and application of rubber-modified asphalt by wet process.Finally，the paper proposed future development trends and key research directions of rubber-modified asphalt by wet process in terms of preparation process，performance evaluation，and modification mechanism.
Friction‑ 1D Transformer ： A 1D Vision Transformer Hybrid Model for Skid Resistance Prediction on Asphalt Pavements
PEI Feifei, NIE Zilong, XU G uomin, ZHAN You, GONG Xianqi, AI Changfa, DENG Yuan, JI Zhengyun, and WANG Shifa
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.005
The friction performance of road surfaces is an important indicator of highway safety，which is closely related to road texture.In this paper，a set of three-dimensional denoising methods for road texture data with different noise levels was proposed，which could effectively remove noise while preserving local texture features.In addition，a skid resistance prediction model named Friction- 1D Transformer was developed based on the design concept of Vision Transformer （VIT） for skid resistance evaluation of asphalt pavements.Unlike traditional convolutional neural networks，the Friction- 1D Transformer utilized positional encoding structures and multi-head attention mechanisms to extract global features from one-dimensional （1D） texture signals along the direction of vehicle movement，thus accurately predicting the friction performance of road surfaces.Comparative analysis with four other models，namely random forest （RF），k-nearest neighbor （k-NN），residual neural network （Resnet），and VIT，shows that Friction- 1D Transformer has higher accuracy and faster training speed，with only 3 915 914 parameters.This research validates the feasibility of using raw texture data for training and skid resistance prediction，and the proposed model structure may facilitate the development of the testing technology for skid resistance of road surfaces.
Skid Resistance Detection Technology of Highway Pavement Based on Tie‑Pavement Coupling Noise
YE Wei, CHEN Fei, HU Xiaoyang, XU Zhengwei, and LI Liguo
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.006
In order to improve the skid resistance detection technology of highway pavement，this paper summarized the advantages and disadvantages of the traditional pavement noise measurement methods，adopted the vehicle-following method to collect the tie-pavement coupling noise，and optimized the specific positional parameters of the microphone.The speed correction of the equivalent continuous A-weighted sound level was realized through the fitting of driving speed and equivalent continuous A-weighted sound level.The characteristic signal of the tie-pavement coupling noise was extracted by the principal component analysis method，and it can effectively suppress interference signals such as traffic noise，wind noise，and engine noise.The envelope noise energy （ENE） was obtained by integrating the extracted first principal component （F1） in the frequency band of 100‒1 000 Hz，so as to characterize the energy of tie-pavement coupling noise generated under the excitation of road surface texture construction.Data fitting of ENE and sideway force coefficient （SFC） in road sections with different degrees of wear was carried out by using SPSS mathematical statistics software.The results indicate that the goodness of fit of ENE and SFC is the highest in the power function model，and R2 is as high as 0.978.
Mechanical Properties of Alkali‑Activated Slag‑Fly Ash Geopolymers
LIU Yang, WANG Jizhao, LU Naiwei, and WANG Bowen
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.007
In order to respond to the national strategy of energy saving and emission reduction and improve the comprehensive utilization rate of industrial waste，the influence of slag content，alkali equivalent，sodium silicate modulus，and water-cement ratio on the compressive strength of slag-fly ash geopolymers was investigated by single variable and orthogonal experiment method.The compressive strength of geopolymers was analyzed by combining XRD，SEM，and porosity.The results show that the gel formation is promoted with the increase in slag content，and the structure of geopolymers is more compact，which is conducive to the development of strength.After 28 days of standard curing，the influence of various factors on the compressive strength of geopolymers in descending order is as follows：slag content，alkali equivalent，water-cement ratio，and sodium silicate modulus.When the slag content，alkali equivalent，water-cement ratio，and sodium silicate modulus are 0.5，0.07，0.36，and 1.6，the compressive strength of geopolymers is the highest，reaching 78.84 MPa.
Mechanical Properties of Geopolymer‑Stabilized Recycled Aggregates from Construction Solid Wastes
YUAN Kaixin, HE Yongjian, ZHANG Laijun, LI Hai, and XU Gewei
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.008
In order to solve the problem of a sharp increase in construction solid wastes and insufficient utilization rate，this paper took slag-fly ash-based geopolymer as an inorganic binder，replaced natural gravels with recycled aggregates from construction solid wastes，and set urban road base layer as the target scene to study the mechanical properties of geopolymer-stabilized recycled aggregates at different contents.The results show that with the increase in geopolymer content，the maximum dry density of the mixture increases.The optimum moisture content increases.The unconfined compressive strength of the mixture increases with the increase in geopolymer content and curing age and decreases with the increase in recycled aggregate content.The variation law of splitting strength and compressive rebound modulus of the mixture is similar to that of unconfined compressive strength.It increases with the increase in precursor slag content，geopolymer content，and curing age and decreases with the increase in recycled aggregate content.
Experimental Investigation on Shrinkage Effect of Ultra‑High Performance Concrete under Steam Curing
LI Bing, YANG Tengyu, FANG Changle, LUO Zirun, LI Chuanxi, and TAN Ke
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.009
Determining the free shrinkage of U HPC is an important basis for analyzing the shrinkage effect of steel UHPC composite bridge deck.Therefore，based on the UHPC materials to be used in a project，three batches of UHPC free shrinkage specimens were made，and three specimens were made in each batch.By testing the strain and temperature of specimens during curing，the free shrinkage strain-age curve and temperature-age curve of UHPC were obtained.The development and variation law of UHPC shrinkage strain are discussed.Based on the experimental results，the equivalent time is introduced on the basis of Arrhenius empirical formula，and a modified model of free shrinkage is proposed.Finally，based on the regression analysis of the test results，the coefficients of the modified model are obtained.According to this discussion，the corresponding theoretical UHPC shrinkage stress calculate formula is obtained.The results show that the shrinkage from time zero to the point that temperature rise to 90 ℃ accounts about 42% of the total shrinkage during steam curing，and then the free shrinkage developed to more than 95% of the total shrinkage during steam curing within 48 hours after steam curing with 90 ℃.and the shrinkage strain curve will gradually stabilize during this period.And under the equivalent sealing curing condition of 20 ℃，the free shrinkage of UHPC will be basically completed about 40 days after time zero.
Comparative Experimental Study on Deformation Characteristics of High Liquid Limit Soil under Different Dry and Wet States
QIN Lingwei, ZHANG Rui, LI Lu, and XIAO Yupeng
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.010
In order to further reveal the internal mechanism of the influence of solid-like bound water on the deformation characteristics of high liquid limit soil，the difference in the influence of different bound water contents on the deformation of soil samples was analyzed through the comparison of dry and wet sides.Four types of high liquid limit soil with different water contents at the same dry density were used，and a low liquid limit soil was used as a comparison sample to carry out a deformation test.The volumetric flask method was used to test the content of adsorbed bound water in each test soil sample.SEM and XRD tests were carried out from the micro level of the soil sample，and compaction tests were conducted on each soil sample.The points with the same compaction degree and different water contents were selected on the compaction curve as the initial control targets for compression tests，so as to compare the deformation characteristics of the dry and wet sides of the compaction curve of high liquid limit soil.
Influence of Loading Methods on Compression Modulus of Red Sandstone Soil Solidified with Biological Enzyme and Cement
HE Liang, ZHANG Haixiang, GUAN H ongxin, LI Huili, YANG Hairong, and LIU Hongfu
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.011
There are various methods to test the modulus of cement-stabilized mixtures.The stiffness performance of cement-stabilized materials will be affected after adding biological enzymes.In order to systematically analyze the influence of loading conditions on the compression modulus of the red sandstone soil solidified with biological enzyme and cement，compressive modulus tests were conducted on the red sandstone soil solidified with biological enzyme and cement by using three static modulus test methods including monotonic loading method of middle section，stepwise loading and unloading method of top surface，and stepwise loading and unloading method of middle section，as well as dynamic modulus method of top surface and dynamic modulus method of middle section.The experimental results show that the load rate of dynamic modulus tests is much higher than that of static modulus tests due to the difference in loading frequency，which affects the comparability between dynamic modulus and static modulus.When the load level and load rate are equivalent，the resilience modulus of the stepwise loading and unloading method of middle section is relatively close to the elastic modulus of the monotonic loading method of middle section.Moreover，the monotonic loading method of middle section makes it easier to obtain representative moduli.
Mechanical and Vegetative Performance of Bamboo Fiber‑Reinforced Eco‑Concrete with Recycled Aggregate
LI Tao, DENG Bofan, HE Maolin, LIU Ting, and CHEN Houde
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.012
In response to the current common urban construction waste disposal issue，this study utilized processed recycled construction waste aggregate and bamboo waste materials to produce bamboo fiber-reinforced eco-concrete with recycled aggregate.By adjusting the dosage of bamboo fiber，the effects of the dosage of bamboo fiber on the mechanical and vegetative performance of the concrete were systematically analyzed by means of orthogonal tests and verification methods.The test results indicate that bamboo fiber enhances the toughness of eco-concrete significantly.Particularly，when the dosage of bamboo fiber exceeds 3.0 kg/m3，there is a significant enhancement in the tensile performance of the eco-concrete with recycled aggregate.Due to the spatial network structure formed by bamboo fiber within the concrete，the highest tensile strength of the concrete reaches 4.71 MPa in the experiment.Furthermore，the vegetative performance test of concrete is carried out with an optimized mix ratio，and the test results show that bamboo fiber-reinforced eco-concrete with recycled aggregate exhibits excellent vegetative performance.The study provides reliable experimental and theoretical evidence for the application of bamboo fiber-reinforced eco-concrete with recycled aggregate in engineering.It also offers a viable solution to the urban construction waste disposal issue and promotes the sustainable utilization and recycling of construction materials.
Effect of Corn Stover Oil on Rheological Properties of Aged Asphalt and Its Regeneration Effect
CHENG Peifeng, BAI Yue, LI Yiming, and ZHANG Zhanming
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.013
Corn stover oil，as a kind of bio-oil，is low-carbon and renewable.At the same time，it may restore the performance of aged asphalt.In order to further promote the application of corn stover oil in road engineering，this study explored the effect of corn stover oil as a kind of regeneration agent on the rheological properties of aged asphalt through laboratory experiments and analyzed the regeneration effect.On this basis，the regeneration mechanism of corn stover oil regeneration agent was revealed by using an infrared spectroscopy test and gel permeation chromatography test.The results show that the addition of corn stover oil changes the proportion of aged asphalt components and restores the stability of the asphalt ’s colloidal structure to a certain extent，and it can dilute and blend aged asphalt to restore the physical and rheological properties of aged asphalt.However，the regeneration effect is affected by the addition amount of corn stover oil.When the addition amount of corn stover oil is 20%，it has the most significant effect in restoring aged asphalt performance.
Optimization of Mix Proportion for New Jersey Precast Concrete Safety Barriers and Performance Tests under Integral Concrete Vibrating
CHEN Lin, LI Beian, LI Yuanrui, and ZHAO Zixiang
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.014
New Jersey safety barriers are the most commonly used form of guardrails in highway median separators due to their excellent safety protection.In response to the cost reduction and quality improvement，efficient and rapid preparation process，and quality issues of New Jersey precast concrete safety barriers，this article adopted the automation production process of New Jersey precast safety barriers，optimized concrete mix proportion for precast safety barriers，and studied their performance.The experimental results show that in the designed C 30 concrete，the compressive strength of the concrete mixed with 15% fly ash reaches 39.2 MPa，and th e slump reaches 185 mm.The concrete performance meets the requirements of the fabric.Compared with the compressive strength of concrete formed by traditional vibrating rods and integral vibrating tables，the compressive strength of concrete formed by integral vibrating tables at all ages is higher than that formed by vibrating rods，and the coefficient of variation is smaller.The concrete formed by the integral vibrating table has a smaller electrical flux at each age and better resistance to chloride ion penetration.Adjusting fly ash dosage to optimize the concrete mix proportion and applying integral vibrating compaction technology reduce concrete porosity and pore size，improve the compressive strength and durability of concrete，and efficiently and economically obtain concrete that meets the high-performance requirements of guardrails.
Curing Law and Road Performance of Polyurethane Mixture
SUN Shengkai, ZHENG Mao, TANG Xiong, LIU Li, ZHONG Shengran, and SI Te
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.015
Polyurethane mixture is composed of polyurethane binder，rubber particles，and stones.Compared with ordinary asphalt mixture，it has the characteristics of a higher content of rubber particles and large void ratios.This article first tested the viscosity-time curve and viscosity-temperature curve of one-component polyurethane and determined the compaction temperature of the polyurethane mixture.Based on the rutting test，three-point bending test，water immersion Marshall test，freeze-thaw splitting test，and pendulum friction test，the road performance of the polyurethane mixture under different replacement amounts of rubber particles was tested.The research results show that the mixing temperature of PU- 1 polyurethane mixture can be basically controlled between 73 ℃ and 81 ℃，and it can be spread and rolled at room temperature （25 ℃）；the polyurethane mixture is cured after four days at room temperature.To accelerate the curing，the water spraying method can be used；under the condition of ensuring high temperature performance，when the replacement amount of rubber particles continues to increase，the maximum flexural strain，RMSR value，RTSR value，and BBPN value of the polyurethane mixture increase linearly.It shows that the rubber particles can promote low temperature performance，water stability，and slip resistance of the polyurethane mixture.
Bridge Engineering & Tunnel Engineering
Elimination Method of Temperature Lag Effect in Deformation Monitoring Data of Cable‑Stayed Bridge Structures
LIU Hongshuang, ZHAI Wenqiang, and ZENG Guoliang
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.016
There is a temperature lag effect in the deformation monitoring data of the bridge structure.Eliminating the temperature lag effect is of great significance in the health monitoring of the bridge structure.Based on the linear correlation between the deformation of the bridge structure and the temperature，this paper applied the goodness of fit test and proposed a time-domain translation elimination method.On this basis，by taking the long-term synchronous monitoring of the tower inclination，beam end displacement，main girder deflection，and temperature data of a cable-stayed bridge as an example，this method was used to eliminate the temperature lag effect in the deformation monitoring data and compared with the existing Fourier series method.The research results show that there are obvious hysteresis phenomena among the tower inclination，beam end displacement，main beam deflection，and the temperature of the bridge structure，and there is a relatively obvious hysteresis loop in the scatter plot of structural deformation and temperature correlation.After using this method to eliminate the temperature lag effect，the goodness of fit between the structural deformation monitoring data and the temperature data can reach 0.99.Compared with the Fourier series method，this method has a better effect in eliminating the temperature lag effect in the structural deformation monitoring data.
Dynamic Response Analysis of Bridge under Combined Action of Random Traffic Flow and Wind Based on SIMPACK Platform
XIONG Tao, HAN Yan, MA Xingchuan, LI Qianming, YAN Naijie, ZHANG Fei, and HU Peng
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.017
To deal with the time-consuming problem of calculating the dynamic responses of the bridge under the combined action of random traffic flow and wind，a steel box continuous girder bridge was taken as the engineering background，and the finite element model of the bridge and the vehicle model were established in the commercial software Ansys and SIMPACK，respectively.Then，the dynamic responses of the bridge subjected to the single vehicle load，wind loads，and multiple vehicle loads were calculated to verify the superposability of the dynamic responses of the bridge.On this basis，the Monte Carlo method was used to generate the random traffic flow samples.By using the verified superposability of the dynamic responses of the bridge，the dynamic responses of the bridge under the combined action of random traffic flow and wind were calculated under different random traffic flow conditions，different vehicle speeds，and different wind speeds.The research results show that the superposition method of the dynamic responses of the bridge proposed in this paper can effectively improve the calculation efficiency.The wind load mainly affects the lateral response of the bridge，while the vehicle load mainly affects the vertical response of the bridge.As the traffic flow changes from sparse to dense，the standard deviation values of the vertical displacement and vertical velocity of the main span of the bridge and their increases are larger than those of the side span，while the standard deviation values of the vertical acceleration of the side span and their increases are larger than those of the main span.As the vehicle speed increases，the standard deviation values of the vertical displacement and the vertical velocity of the bridge gradually increase，while those of the vertical acceleration of the side span first increase and then decrease.As the wind speed increases，the standard deviation values of the lateral response of the bridge gradually increase，and the increase of the main span is greater than that of the side span.
Sensitivity Analysis of Parameters of Cable‑Stayed Bridges with Full Floating Spatial Frame
LIU Anqing, YAN Tengfei, ZHENG Pengju, GU Yanlin, LI Jie, and WANG Qiang
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.018
In order to clarify the influence of design parameters on the mechanical behavior of a cable-stayed bridge of a floating system，a finite element model of the bridge was established by using the finite element analysis software MIDAS/Civil based on a single-tower double-cable plane steel-concrete composite beam cable-stayed bridge with full floating spatial frame.The sensitivity of parameters such as temperature effect，secondary dead load，and support system in the completed bridge state was analyzed and compared with the semi-floating system of the bridge.The results show that temperature and secondary dead load have a significant impact on the deflection and stress of the main beam.Overall，the sensitivity of the deformation and stress of the main beam of the full floating system to various parameters is lower than that of the semi-floating system.After the structural system is converted from full floating to semi-floating，the first-order natural frequency increases from 0.38 Hz to 1.09 Hz，and the overall stiffness of the structure is significantly improved.Under seismic excitation，the overall displacement of the full floating system is greater than that of the semi-floating system，but the bending moment of the tower root structure decreases.
Experimental Study on Shear Behavior between NRC‑UHPC Interface
CHEN Zhenkan, LI Junsheng, SHI Quan, FANG Haozhen, MO Fan, and JIANG Haibo
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.019
In order to investigate the effect of the screw diameter of planted bars and ultra-high performance concrete （UHPC） pouring method on the shear behavior of normal reinforced concrete （NRC） and UHPC， two groups of six push-out specimens were designed for shear behavior tests.The results show that after the failure of the concrete bonding force in the NRC-UHPC interface，the screw can maintain shear behavior so that the failure process of the specimen after the load reaches the peak shows ductile characteristics.For specimens with screw diameters of 12 mm and 16 mm，greater screw diameter indicates higher shear capacity of the specimens and ductility after interface failure.When the screw diameter is 16 mm，the specimens in Group ZJ using the post-pouring UHPC layer fail in a mode of partial shearing off and partial pulling out.The ductility at the interface of the specimens in Group GJ using high-strength mortar as filling material is lower than that of the specimens in Group ZJ using the post-pouring UHPC layer in terms of the load-slip curve.Based on the experimental results，the shear behavior formulas of ACI，AASHTO，and FIB specifications are compared.The FIB formula，which considers both the shear friction and the bolt pin effect，can accurately describe the interfacial shear capacity of the specimens.Therefore，it is recommended to use the FBI specification to calculate the shear capacity of NRC structures reinforced with UHPC.
Design and Construction Process of Cross‑Beam Supports for Main Tower of Changtai Changjiang River Bridge
ZENG Jian, HU Pei, and WANG Chao
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.020
The construction of the lower cross-beam structure of the main tower of Changtai Changjiang River Bridge has the characteristics of high construction height，large amount of concrete earth volume，and difficult control of down-warping deformation.In order to implement the pouring of the lower cross-beam of the main tower，floor-type steel pipe supports were set at the lower cross-beam，which were used to support the lower cross-beam formwork and bear the load during the concrete pouring.Through the finite element software analysis and calculation，it was found that the asymmetric deformation of the main structure of the lower cross-beam could be effectively controlled，and the overall force of the supports could be optimized by setting the splayed steel pipe supports in the midspan of the longitudinal beam of the lower cross-beam and making broken joints in the midspan and side span of the longitudinal beam.The supports were assembled，welded，and accepted on the ground.Then they were lifted and fixed to the installation level after completion.The combination of theoretical calculation and construction process reduces the high-altitude operation，effectively guarantees the construction quality and efficiency of the supports，improves the pouring quality of the lower cross-beam of the main tower，and achieves remarkable economic benefits.
Segment Connection Mod e for Stiffening Girder Hoisting Construction of Long‑Span Steel Truss Girder Suspension Bridge
SHAO Guangmiao, PAN Q uan, YAN Donghuang, and XU Hongsheng
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.021
In the process of stiffening girder construct ion of a long-span steel truss girder suspension bridge，different connection modes of stiffening girder segments will directly affect the internal force，alignment，and bridge state of the structure during construction.By taking the construction of the stiffening girder of a bridge as the research background，the finite element model of the whole process of the bridge was established.The advantages and disadvantages of the segmented hinge method and the segmented rigid connection method were compared，and the two-two segmented rigid connection scheme was proposed.On this basis，according to the changing law of steel truss section alignment and lower chord opening in the process of stiffening girder hoisting，the idea of synchronous operation of “rigid connection for small segments + rigid connection for large segments ” was put forward.In addition，the system conversion process scheme between stiffening girders was developed and implemented.The test results of the real bridge verified the correctness and feasibility of the analysis method in this paper.On the premise of ensuring the safety of the structure and the reasonable state of the bridge，it could save the construction period and reduce the construction cost.
Research on T‑Beam System with Diaphragm Based on Intelligent Construction
LIU LANG, TAO Qiyu, and XU Qigang
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.022
The traditional precast T-beam faces issues such as excessive diaphragms，difficult formwork installation and removal，and low levels of intelligence in intelligent bridge construction.To address these issues，this paper focused on the optimization of the number of diaphragms and the application of prefabricated diaphragms.By analyzing different diaphragm configuration schemes and comparing the contributions of prefabricated diaphragms and precast diaphragms to the lateral stiffness of the bridge，this paper deeply explored the impact of diaphragms on bridge performance.The research results indicate that the T-beam system with fewer diaphragms is feasible in intelligent construction，but the system without diaphragms places higher demands on the performance of bridge decks.Additionally，compared to precast diaphragms，prefabricated diaphragms contribute less to the lateral stiffness of the bridge，and their use increases the stress on bridge decks.Furthermore，the installation position of diaphragms has a significant impact on the lateral stiffness of the bridge.
Key Technology for Incremental Launching Construction of Double Guide Beam of Steel Box Girder
SUN Xiaoqiang and YUE Xinxing
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.023
By taking the incremental launching construction of the steel box girder at the 6th hole of the approach bridge of Baoji Taigu Bridge as the engineering background，the original plan adopted single-guide beam multi-point walking incremental launching technology for assembly and incremental launching on the prestressed reinforced concrete beam of the adjacent hole.Since the middle span of the concrete beam cannot withstand the concentrated force at the incremental launching points，the multi-guide beam multi-point walking incremental launching technology was finally used to arrange the incremental launching points at the transverse diaphragm plate of the end of the concrete beam.By increasing the incremental launching equipment number in each group and the spacing between two groups of incremental launching points，the above problems were solved，and incremental launching construction was successfully completed.
Determination of Manufacturing Parameters of Large Section of Continuous Steel Box Beam with Variable Section in Shenzhen‑Zhongshan Passage
DONG Chuangwen, CHEN Long, and LI Chuanxi
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.024
Accurate calculation of manufacturing parameters is the key to the efficient，high-precision，and rapid installation of large sections of continuous steel box beam bridges.Taking the steel box beam with the variable section in Shenzhen-Zhongshan Passage as the background，this paper first established a finite element model of the beam element in the whole construction process to obtain the pre-camper.Secondly，the average neutral axis position was calculated based on the height of the neutral axis of each beam section.Then，according to the deformation characteristic that the beam length remained unchanged at the mean neutral axis，the pre-camber was superimposed at the mean neutral axis to get the manufacturing line shape.Finally，according to the mechanical characteristics，the dip angle of the large section end face was given to obtain the complete manufacturing parameters of the steel box beam.The implementation results before the loading of the second-phase dead load show that the line shape of the top surface of the steel box beam is generally smooth，and the measured line shape is in good agreement with the predicted line shape，which verifies the correctness of the proposed method.
Key Technology for Construction of New Single‑Wall Steel Suspended Box Cofferdam with High Pile Tied Beams in Deep Water
YANG Jinlong, ZHAO Lin, and JIANG Qunlong
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.025
In order to ensure the safe，efficient，and economical completion of the construction of the high pile tied beam of Muping Xiangjiang River Bridge in deep water，a new type of single-wall steel suspended box cofferdam was designed to act as the water retaining and enclosure structure during high pile tied beam construction according to the characteristics of deep water level and shallow stratum cover layer at the high pile tied beam location.Through the innovative design of steel casing on the bottom of the steel suspended box cofferdam，the design height of the wall panel and the amount of steel input were reduced.On the basis of innovative design，the bottom sealing construction process was optimized.Different from the traditional full bottom sealing construction process of the steel suspended box，the new single-wall steel suspended box cofferdam only needed to pour the bottom sealing concrete in the steel casing，which greatly reduced the amount of bottom sealing concrete and saved the construction cost under the premise of satisfying the structural force and system stability.The stability of the whole structure system was enhanced by welding the stiffening plate on the surface of the bottom sealing concrete，and the safety of operation in water was further guaranteed.The construction effect of pile tied beams in water was good，which indicated that the new single-wall steel suspended box cofferdam was more suitable for the construction of high pile tied beams in deep water.
3D Reconstruction Method of Tunnel Surrounding Rock Fracture Based on VTK
LIU Houxiang and SU Heng
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.026
Fracture parameters are important reference factors for surrounding rock stability analysis.To realize the visualization analysis of surrounding rock fractures，this paper proposed a three-dimensional （3D） reconstruction method of surrounding rock fractures based on the visualization toolkit （VTK）.Firstly，the collected tunnel surrounding rock images were preprocessed by OpenCV for image grayscale and noise reduction.Secondly，the Otsu method and the open operation in morphology were used to segment the image，and the complete surrounding rock fracture map was obtained.Then，the median method was used to replace the linear interpolation method with the traditional Marching Cubes algorithm in VTK to calculate the equivalent point，and the improved Marching Cubes algorithm was used to carry out the 3D reconstruction of the processed fracture image.Finally，the 3D model reconstruction rates of the improved algorithm were compared with that of the original algorithm.The results show that ① by applying VTK to 3D reconstruction of tunnel surrounding rock fractures，a complete 3D model of fractures can be obtained to realize 3D reconstruction of local surrounding rock fractures；② there are no significant differences between the two algorithms in the 3D model of fractures，but the 3D model reconstruction rate of the improved algorithm is increased by 18%.
Surface Grouting Reinforcement Technology for Shallowly Buried Tunnel in Coastal Zone
XIANG Ze, DENG Shiping, SHENG Zhang, ZHOU Ye, WANG Wei, and PEI Yabing
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.027
The Ⅵ level surrounding rock section of a project water intake tunnel is located in the coastal zone，with thick overlying sand layers，broken surrounding rock，and other characteristics.To address these issues，laboratory tests were conducted to explore the effect of water glass volume dosing on the final setting time and strength of cement-sodium silicate （CS） liquid slurry，and field tests were carried out for a comprehensive analysis of grouting methods.The constraint-dispersion mode was finally determined to divide the grouting area into several small grouting units.Advance plastic pipe grouting reinforcement was performed according to the grouting sequence of the outermost circle hole interval first，followed by the inner hole interval.The effect of core sampling and concealed excavation shows that the rock fissures are effectively filled and reinforced by surface pre-grouting，which reduces the occurrence of water gushing and collapse during excavation，ensures normal tunnel excavation，and achieves good economic and social benefits.
Influence Factors of Carbonization of Tunnel Segment Structure and Life Prediction Analysis
LI Dongbiao, MIAO Miao, SHEN Caihua, and CHEN Wei
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.028
There are many factors that affect the carbonization life of concrete segments in underwater tunnels，and the prediction methods are not uniform.In this paper，combined with actual engineering，the influencing factors and laws of carbonization of concrete segments in underwater tunnels were analyzed，and three methods for predicting the life of concrete segments were established with the crack limit as the control target.The prediction results of the three methods were compared.The results show that the influence of the temperature and CO2 concentration in the tunnel predicted by the three methods on the life of the tunnel lining structure is basically consistent with the existing experimental rules.The temperature in the tunnel has the greatest influence on the life of the concrete lining，followed by that of CO2 concentration.The three methods obtain non-ideal results in predicting the influence of relative humidity on the life of tunnel lining structure and need to be further improved.The predicted annual average corrosion rate of steel bars after rust expansion of the protective layer is about three times that before rust expansion of the protective layer.Timely detection and repair of cracks can effectively prolong the life of tunnel lining.The prediction result based on XU Shanhua ’s method is the most conservative and slightly smaller than that of the standard method.The predicted value based on YANG Xiaoming ’s method is more than 25% larger than the standard method，and it is recommended based on the actual situation.
Smart Road and Intelligent Transportation
Emergency Vehicle Dispatching Model Considering Demand Urgency and Delivery Fairness
LONG Kejun, LIU Jia, GAO Zhibo, CHEN Suqian, and ZHANG Zhonggen
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.029
In emergency vehicle dispatching after unexpected events，it is crucial to prioritize critical nodes with high demand urgency while minimizing excessive delivery delays at other nodes to prevent secondary impacts.On this basis，this study developed an emergency vehicle dispatching model that considered demand urgency and delivery delay fairness.Firstly，the entropy weight-TOPSIS method was used to calculate the demand urgency for each node，and a delivery delay balance index was introduced to minimize disparities in delivery delays between nodes.Secondly，a multi-objective optimization model was established with total delivery time，overall cost，and delivery delay balance as objectives，while considering constraints such as inventory levels at distribution centers and route continuity.Finally，the K-Means algorithm and the Clarke-Wright （CW） saving algorithm were employed to partition the sub-networks，and an improved ant colony algorithm incorporating a variable neighborhood local search was applied.The results indicate that compared with the basic model，the proposed model reduces the average and maximum delivery delays at nodes with high demand urgency by 25.26% and 22.98%，respectively，while increasing the delivery delay variance by 34.30%.Compared with a model considering only demand urgency，the proposed model decreases the average delivery delay，maximum delivery delay，and delivery delay variance at nodes with high demand urgency by 10.79%，20.26%，and 40.57%，respectively.These findings demonstrate that the proposed model effectively balances priority for critical nodes with fairness for standard nodes.
Research and Practice on Demolition of Lane Separator in Same Direction along Zhengzhou‒Luoyang Section of Lianyungang‒Khorgos Expressway
ZHANG Nan, JI Xiang, and MA Gang
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.030
In order to solve the problem arising after the demolition and closure of the lane separator in the same direction along the expressway，this paper systematically introduced the reconstruction method of the lane separator in the same direction by studying the overhaul project along Zhengzhou-Luoyang section of Lianyungang‒Khorgos Expressway.The paper explored the main diseases and potential safety hazards existing in the lane separator in the same direction by checking the compliance of specifications，analyzing the traffic operation status，exploring the characteristics of traffic accidents，and investigating the traffic safety facilities.On this basis，it demonstrated the feasibility of demolishing the lane separator in the same direction.According to the results of previous investigation，analysis，and demonstration，the corresponding disposal measures were put forward from the aspects of lane division，crown slope，path guidance system improvement，and road closure and bridge closure with lane separators，which solve a series of problems existing in the lane separator in the same direction along the expressway.
Linkage Control Method for Expressway Toll Stations and Plane Intersections
LEI Qing, WANG Zhaoyong, WU Yurong, JIANG Weiwei, and LUO Zhongbin
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.031
In order to solve the problem of vehicle queuing overflow caused by the mismatch between the expressway toll stations and the capacity of plane intersections，the formula for calculating the maximum queue length was given by analyzing the traffic operation characteristics between toll stations and plane intersections and considering vehicles ’ lane-changing behavior.Due to the strong coupling of the traffic operation between toll stations and plane intersections caused by a short distance between them，a unified linkage control optimization model was established.The research shows that if the queue length in the connecting direction of the plane intersections exceeds the allowable maximum queue length，some vehicles find it difficult to find a suitable lane-changing opportunity and thus will stop and wait，which affects the stable operation state of the toll stations and plane intersections.Compared with the conventional control，the linkage control reduces the average vehicle delay by 6.48%，13.43%，and 10.46% in three traffic schemes （schemes 2，4，and 6） respectively.
Foreign Highway
Working Properties of Steel Tube Batter Piles with Concrete Infill Based on ABAQUS
YANG Meiliang, LI Liemin, SUN Kunjiang, HAN Rui, and ZHONG Yang
Date posted: 12-17-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.06.032
In order to explore the respons e characteristics of steel tube batter piles with concrete infill under vertical load，the steel tube batter pile with concrete infill used in Saribas Bridge in Malaysia was taken as the research object.Based on the numerical simulation method，the frictional resistance of the inner and outer walls of the steel tube，the frictional resistance around the pile at the section，and the bending moment bearing ratio between the steel tube and the concrete core of this type of batter pile under vertical load were studied.The results show that the passive-side frictional resistance of the 0–15 m pile section is greater than the active-side frictional resistance on the outer wall of the steel tube，but the active-side frictional resistance of other pile sections is greater than the passive-side frictional resistance.The frictional resistance of the inner wall of the steel tube is complicated，and there is a pile section with zero frictional resistance.The frictional resistance of the inner and outer wall of the steel tube at different sections shows a non-uniform distribution around the pile；the steel tube at the top of the pile bears a larger bending moment，while at 37 m from the top of the pile and at the end of the concrete core，the concrete core bears a larger bending moment，and the bending moment bearing ratio of steel tube and concrete core in other pile sections is close to 50%.
