Abstract:In order to control differential settlement caused by new and old subgrade connections after expressway reconstruction and expansion，this paper proposed a layered treatment structure for the loose steps of the old road with high water content.A layer of construction and demolition waste was laid on the step surface of the old road to wrap the geogrid.The treatment effect was compared with that of sand wrapping and lime mixing，and the digital speckle correlation （DIC） was used to observe the reinforced influence zone，so as to determine the thickness of different layers of the subgrade wrapped by construction and demolition wastes.The particle rotation and displacement were further analyzed，and the reliability and accuracy of the reinforced influence zone determined by DIC observation were verified.The test results show that：① Among the measures to improve the interface strength of reinforced soil in the old road steps，the effect from good to bad is construction and demolition wastes C （particle size of 10?20 mm） > construction and demolition wastes B （particle size of 5?10 mm） > sand > construction and demolition wastes A （particle size of 1?5 mm） > mixed ash of 6% > mixed ash of 4%，and the reinforcement effect increases with the increase in the particle size of the construction and demolition wastes；② The DIC test results show that the area of the reinforced influence zone decreases with the increase in normal stress，and its thickness above the geogrid is greater than t hat below the geogrid.The particles that rotate are mainly concentrated within 3 cm below the geogrid and 5 cm above the geogrid；③ The recommended thickness of the layer wrapped by construction and demolition wastes is determined based on the thickness of the reinforced influence zone：about 20 cm in the middle of the subgrade，about 15 cm in the bottom of the subgrade，and not less than 25 cm in the upper part of the subgrade.

Abstract:In order to study the effect of temperature change on the bound water content adsorbed by high liquid limit clay and the deformation law of high liquid limit clay embankment，the high liquid limit clay in Hainan Province was selected as the primary research object and compared with the low liquid limit sand in Hunan Province.The effect of temperature on the bound water content adsorbed by high liquid limit clay was explored through a nuclear magnetic resonance test.In addition，the effect of temperature on the deformation of high liquid limit clay embankments was analyzed through the consolidation test with a temperature-controlled consolidometer.The molecular dynamics simulation software was used to reveal the mechanism of temperature affecting water adsorption by kaolinite from the microscopic level.The results show that when the temperature rises from 5 ℃ to 45 ℃，the bound water adsorbed by high liquid limit clay decreases by 4.3 percentage points，much greater than that adsorbed by low liquid limit sand （a decrease by 1.4 percentage points）.Under constant temperature and the same load path，the pore ratio of high liquid limit clay changes significantly with the temperature increase.In contrast，low liquid limit sand is almost unaffected，indicating that high liquid limit clay is more temperature-sensitive.The rise in temperature under constant pressure can weaken water adsorption by kaolinite.Under the same heating path，higher pressure indicates more water adsorbed by kaolinite.

Abstract:Jinqi Bridge on the Wudang-Changshun Expressway in Guizhou Province crosses the Maotiao River，and the poor geological conditions such as dangerous rock mass and collapse accumulation body on the bank slope of the river are relatively developed，which seriously affects the site selection and safety of the bridge.In order to study the stability of the high and steep bank slope of the bridge，the paper explored the main poor geological conditions in the bridge site through a comprehensive air-ground investigation.By means of numerical analysis，InSAR，and other technologies，the movement range of dangerous rock mass on the bank slope was quantitatively evaluated.The stability and deformation mode of the accumulation body on the bank slope under the action of internal and external dynamics were elucidated.The results show that：① The poor geological conditions in the bridge site are mainly cliff unloading zone，dangerous rock mass，and collapse accumulation body，and the failure mode of dangerous rock mass is pulling-toppling；② The movement distance of W 1，W2，and W 3 dangerous rock mass after failure is about 65 m，57 m，and 320 m，respectively，which affects the Wudangan abutment and Changshun pier；③ The accumulation body on the Wudang bank slope is very stable under normal，rainfall，and rainfall + earthquake conditions.The accumulation body on the Changshun bank slope is stable under normal and rainfall conditions.Under the rainfall + earthquake conditions，the shear plastic zone at the contact surface between the upper accumulation body and the bedrock is completely connected，and the accumulation body is in an unstable state.The failure mode is creep-pulling.The research results can provide a reference for comprehensive investigation and stability analysis of high and steep bank slopes of bridges in deep canyons and steep cliffs in Guizhou Province.

Abstract:To study the time-dependent creep effect of siliceous slate and the deformation and failure evolution law of high slope，in this paper，the shear creep test of indoor rock mass was carried out to plot the shear creep duration curves of siliceous slate under different normal stresses，the shear displacement-time curve，and the creep rate-time curve under different normal loads and shear loads.The average creep rate and shear load variation of siliceous slate were studied，and the long-term shear strength parameters of siliceous slate were determined by the steady-state creep rate method.The results show that in the creep test，the sensitivity of cohesion is significantly greater than that of internal friction angle.Finally，the high slope of ZK 33 + 450 siliceous slate on the Shiyan-Wuxi Expressway is used.Based on the Mohr-Coulomb model，the finite difference method was used to analyze the deformation and failure mechanism of the high slope of the typical siliceous slate under shear creep conditions.

Abstract:In order to analyze the influence of cavity depth on runway safety，a numerical simulation was carried out using the finite difference method.A total of 208 sets of different working conditions were designed by taking into account factors such as different aircraft types，runway dimensions，and cavity depth and area.Based on the runway life model considering the exponential decay of the structural condition，an analytical method was proposed to evaluate the impact of the cavity on the runway life.The results show that the bending and stress of the runway increase gradually with the increase in the cavity depth，but the growth rate is getting slower and slower.There is a coupling effect between the impact of cavity depth and cavity area，and the impact of cavity depth starts to appear when the cavity area is larger.In the cloud diagram of the influence of runway bending and stress，there is a non-sensitive area. The proposed runway bending rate development index and stress development index can be used to evaluate the influence of the trend of the cavity，and with the increase in the cavity area and depth，the above indexes have a peak area.According to different loads，runway structures，and take-off and landing times，the influence diagrams of cavity degree and remaining service life are drawn，which can quickly evaluate and analyze the influence of the cavity，thus guaranteeing the structural safety of the airfield runway.

Abstract:Intelligent compaction，as a new type of road construction quality monitoring and management technology，has been widely used in the compaction process of asphalt pavement.However，due to the lack of understanding of the compaction process and the interaction mechanism between asphalt mixture particles，the problems of over-compaction and non-uniformity of compaction often occur in the actual construction，which seriously affects the quality of road construction and service performance.In this study，through the combination of the engineering field and indoor tests，the variation characteristics of asphalt mixture compaction with the number of compaction were analyzed by using the semi-variance function of the geostatistical model，and the effect of temperature on the mixture compaction was discussed.Moreover，through the indoor gyratory compactor and SmartRock sensor，the force and rotational angle characteristics of mixture particles were revealed from the fine scale under different compaction temperatures.The results show that the size and uniformity of compaction are not always positively correlated with the number of compaction.Over-compaction may result in lower compaction and uniformity.Meanwhile，the variation of field compaction temperature has a significant effect on the compaction of mixtures.At higher temperatures，the compaction of the asphalt mixture increases faster，and the final compaction uniformity is higher.Through the quantitative study of the fine-scale response of the mixture by considering the force and rotational angle characteristics by SmartRock sensor，it is found that the dynamic response within the mixture can directly reflect the asphalt mixture compaction changes，and the temperature change and compaction effect do not always show a positive correlation.Only in the appropriate temperature range，the asphalt mixture can achieve the best compaction effect.

Abstract:At present，the common asphalt regenerant is used for treating the aged styrene-butadiene-styrene （SBS） modified asphalt in China，which fails to repair the SBS cross-networking structure，resulting in the poor regeneration effect of the aged SBS modified asphalt.In this study，a new reactive regenerator containing a structural repair agent，extractive oil，plasticizer，solubilizer，and a small amount of SBS was used to regenerate the aged SBS modified asphalt.The conventional properties and rheological properties of reclaimed SBS modified asphalt were studied by three index tests，Brookfield viscosity test，dynamic shear rheological test，and low temperature bending rheological test.Then，a fluorescence microscope and infrared spectrometer were used to study the regeneration mechanism of the reclaimed SBS modified asphalt.The results show that the conventional properties of the aged SBS modified asphalt can be restored after the addition of the reactive regenerant，and the regenerant content for achieving the optimal conventional properties of the reclaimed SBS modified asphalt is 10%.Under the optimal regenerant content，the conventional property indexes of the reclaimed SBS modified asphalt meet the technical requirements of Class I-D SBS modified asphalt in the Technical Specifications for Construction of Highway Asphalt Pavements （JTG F 40—2004）.After the aged SBS modified asphalt is regenerated，the SBS particles increase significantly and are distributed evenly，and the cross-networking structure is restored to a certain extent.The epoxy group in the regenerant polymerizes with the carboxyl group in the aged SBS modified asphalt to generate ester compounds and connect the b roken SBS molecular chains.

Abstract:In recent years，with the rapid development of road engineering construction，subgrade settlement caused by vertical compression of compacted loess has become increasingly serious.The previous research on the deformation of compacted loess mostly focuses on moisture content，porosity，saturation，and other aspects，ignoring the influence of lateral constraint conditions and different compaction on compacted loess.To address these issues，based on the reconstruction and expansion project of G 307 road in northern Shaanxi，this paper selected compacted soil samples of subgrade on site to carry out indoor compression tests.By applying different lateral constraint conditions，the stress-strain curves of compacted loess subjected to vertical multistage load under different compactness and confining pressures were analyzed.The results indicate that the vertical compression of soil samples is positively correlated with the applied vertical load and inversely correlated with compactness.Confining pressure and lateral constraint can reduce the vertical compression of soil samples.The results reflect the working state of the soil sample in the actual project，providing reference and guidance for the subgrade filling in the loess region.

Abstract:In order to study the influence of short-term aging temperature on the properties of sealant,a sealant was prepared,and field construction conditions were simulated.The properties of the sealant before and after short-term aging at 180?220 ℃ were tested.The viscoelastic properties,physicochemical properties,and microstructures of the sealant were studied,and the mechanism of property changes was discussed.The results show that the cone penetration and flow value of the aged sealant decrease,while the softening point and elastic recovery rate increase.Aging at high temperature (>180 ℃) for a short time and low temperature (160 ℃) for a long time will cause obvious property changes.The tensile properties under low temperatures do not decrease monotonically as the temperature increases.The results of the physicochemical property test and microstructure characterization show that the polar groups of the aged sealant at higher temperatures increase significantly,and the glass-transition temperature of the components increases.The storage modulus increases,while the sealant prepared at a higher temperature has a lower viscosity,which makes it much easier to penetrate into the pores at the bonding surface to form mechanical anchorage.Meanwhile,the increase in polarity due to aging generates a higher chemical interaction force with the bonding surface,thus improving the bonding performance.With ongoing aging,the viscosity of the sealant increases,and the bonding performance decreases.Therefore,the comprehensive properties of the sealant do not linearly decrease with the increase in short-term aging temperature but are affected by the viscoelasticity and bonding performance.

Abstract:The municipal ecological ditches have the basic functions of accumulating water for infiltration in the rainy season and conserving moisture in the dry season.However，the design of loess backfill in ecological ditches is based on no evidence，which often leads to landscape vegetation drowning in the rainy season or dying in the dry season.For this reason，a study was carried out by remoulding loess with a small-size capillary water rise height test，a large-size water-holding characteristic model test，and an unsaturated numerical analysis.The results show that the final capillary water rise height of the soil column can reach 100 cm when the dry density is 1.3 g/cm3 and 1.4 g/cm3，respectively，and the water content of the soil column is basically stable after the height of the soil column exceeds 20 cm，with the stable water content of 30.0% and 28.0%，respectively.In the process of capillary water rise of remoulded loess，a transient saturation zone exists，in which smaller dry density indicates larger pore ratio，increased large pores，and weakened capillary suction，resulting in a slower rate of water migration.At the same time，the number of large bubbles closed by the wet bridge is also larger，so the duration of the transient saturation zone is longer.For a soil column of 1.3 g/cm3，the simulated value of the wetting front time curve is basically consistent with the measured value.By considering the stable natural average dry density of loess stratum，the height of capillary water rise，and its water-holding characteristics，as well as the fact that the backfill in ecological ditches will undergo repeated infiltration，consolidation，and capillary action in the later stage，1.2 g/cm3 is adopted as the dry density for backfill control，so as to ensure that the planting soil in the municipal ecological ditches can still maintain the soil humidity necessary for the growth of the vegetation in the dry season.

Abstract:Asphalt pavement is prone to pla stic deformation and aggregate raveling when it is in torsion.At present，there is no standard test method and equipment to evaluate the torsional resistance of asphalt mixtures.In order to study the effective evaluation method for the torsional shear resistance of asphalt mixtures，this paper introduced the structures and working principles of three kinds of equipment developed in Japan.The torsional resistance of five typical asphalt mixtures was evaluated by rotating wheel tracking tests，and factors affecting the torsional resistance of asphalt mixtures were analyzed.The results show that the types of structures and binders of asphalt mixtures have an obvious influence on the torsional resistance of asphalt mixtures.Though I-D modified asphalt SMA- 13 mixtures and high-viscosity modified asphalt OGFC- 13 mixtures have similar dynamic stability，the torsional resistance of void-skeleton asphalt mixtures is worse than that of dense-skeleton ones.The torsional resistance of asphalt mixtures with different types of binders in descending order is high-viscosity modified asphalt + high modulus additive，high-viscosity modified asphalt，and I-D modified asphalt.Although semi-flexible pavement has excellent torsional resistance，it cracks easily.

Abstract:In order to improve the comprehensive performance of permeable concrete，nano-silicon and polypropylene fiber were added to permeable concrete to study the performance of the composite modified permeable concrete.Firstly，the influence of single-doped nano-silicon on the performance of cement paste and permeable concrete was studied，and the content of nano-silicon and the optimal water-to-binder ratio were determined.On this basis，different proportions of polypropylene fiber were mixed，and the reasonable content of polypropylene fiber was determined.The results show that nano-silicon improves the porosity of permeable concrete and increases the optimal water-to-binder ratio.When the content of nano-silicon is 0.5%，and the water-to-binder ratio is 0.32，the compressive strength of permeable concrete is the highest.Based on this ratio，the maximum compressive strength can be obtained by adding 1.0 kg/m3 polypropylene fiber，and the compressive strength after 7 d and 28 d is increased by 29.9% and 42.2%，respectively.Adding 1.5 kg/m3 polypropylene fiber has the most significant effect in improving the frost resistance of permeable concrete.After 300 freeze-thaw cycles，the residual rate of compressive strength and flexural strength are 62% and 75%，respectively，which are far higher than 40% and 55% of single-doped nano-silicon.

Abstract:Coal gangue is an industrial solid waste produced in the process of raw coal mining.It has a large stock and a relatively low utilization rate.Using coal gangue as concrete aggregate can not only solve the environmental pollution caused by coal gangue storage but also make up for the shortage of natural sand and gravel resources，which opens up an effective way for the large-scale utilization of coal gangue.According to the application characteristics of coal gangue as concrete aggregate，the chemical component，mineral composition，and physical properties of coal gangue were systematically analyzed.The influence of coal gangue as aggregate on the working performance，mechanical properties，volume stability，and durability of concrete in China and abroad was summarized.The development trend of coal gangue used as concrete aggregate was prospected，so as to provide a reference for the large-scale popularization and utilization of coal gangue in concrete.

Abstract:Asphalt aging is one of the most important concerns during the use of asphalt pavement.However，asphalt usually exists in the form of a film in the mixture.Oxygen diffusion is an important factor affecting asphalt aging.To investigate the oxygen diffusion behavior in asphalt film under different working conditions，an oxygen-asphalt-aggregate （OAA） model was developed in this study to simulate the state of the asphalt film on the aggregate surface under real conditions.Oxygen diffusion and asphalt component migration in the OAA model were investigated under different conditions of time，temperature，oxygen concentration，and aggregate type.The influence of each factor on the molecular behavior of the model was compared by calculating the relative concentration of molecules，radial distribution function，mean square displacement，and diffusion coefficient，and the connection between the parameters was further analyzed.From the molecular simulation results，it is clear that the oxygen concentration increases with the increase in diffusion time，and the oxygen concentration at the interface between aggregate and asphalt increases significantly.Higher temperature promotes the diffusion of oxygen into the asphalt film，and oxygen concentration varies nearly linearly with temperature.Increasing the number of oxygen molecules can make the relative concentration of oxygen molecules wi thin the asphalt film increase overall，and the CaCO3 aggregate is more favorable for oxygen diffusion into the asphalt film.

Abstract:In order to promote the reuse of waste tires and reduce environmental pollution，chips were replaced with the same volume of waste tire rubber particles to prepare a new rubber particle chip seal pavement.In order to ensure the bonding between asphalt and aggregate of the rubber particle chip seal，the surface of rubber particles was processed，and the texture characteristics of chip seal specimens with different aggregate particle sizes and rubber content were evaluated.The five indexes of rubber particle content，aggregate particle size ratio，shedding rate，structural depth，and pendulum friction coefficient were correlated and evaluated by SPSS，and the MMLS 3 test was conducted to simulate the driving load，so as to explore the influence of external water temperature on the bonding strength.The results show that the rubber particles pre-coated with 1.5% hot asphalt can effectively improve the aggregate shedding of the chip seal.The shedding rate and structural depth will increase with the increase in particle size in the range of 7.1?9.5 mm and rubber particle ratio.The pendulum friction coefficient shows the opposite trend with the increase in rubber particle content.The influence of low-temperature single factor on the aggregate shedding of the chip seal is greater than that of high temperature and water immersion，while water-temperature coupling will aggravate the looseness of aggregates.Overall，in order to ensure that the chip seal aggregate and asphalt have good bonding strength，the rubber particle content and the amount of hot asphalt for coating should not exceed 50.0% and 1.5%，respectively.

Abstract:Ultra-high performance concrete （UHPC） has great application prospects in engineering structure reinforcement.The reliability of the bonding properties at the interface between the new UHPC reinforcement layer and the old concrete structure is critical for ensuring the serviceability of the reinforced structures.To determine the influence of different interface treatments on the bonding properties at the interface between the UHPC and normal concrete （NC），six Z-shaped UHPC-NC bonding specimens were designed，and the bonding properties of the UHPC-NC with three different kinds of interface，namely smooth，chisel，chisel + reinforced，were investigated.In addition，nonlinear finite element models for the concrete interface were established to determine the distribution law of bonding stresses of different UHPC-NC interfaces under shear loads.The results show that the bonding properties of the UHPC-NC interface increase with the increase in the interface roughness，and interfacial shear reinforcements can postpone the debonding and cracking of the concrete interface.Compared to the smooth UHPC-NC interface，the shear strength，stiffness，and elastic stiffness of the concrete interface with an average chisel depth of 4 mm and four shear reinforcements with a diameter of 8 mm are improved by 156.1%，10.9%，and 101.0%，respectively.With the continuous development of interfacial cracks，the shear stress distribution of the UHPC-NC interface treated with chisel and reinforcement becomes more and more uniform，and the residual bonding effect of the interface is mainly provided by the interfacial shear reinforcement.

Abstract:When the construction of a cable-stayed bridge enters the completion stage，due to various factors，there is a certain error between the actual alignment and internal force of the structure and the theoretical completion state，and it is usually necessary to adjust the cable force.In order to calculate the cable force adjustment of a cable-stayed bridge in the adjustment stage，a method based on an influence matrix and sequential quadratic programming was proposed to solve the cable force adjustment.A large-span hybrid girder cable-stayed bridge was taken as the background，and the alignment and internal force response values of the structure with varying cable units were calculated to obtain the influence matrix of the cable force.Then，suitable objective functions and constraints were selected to construct the calculation model of the cable force adjustment.Finally，the sequential quadratic programming method was introduced to solve the cable force adjustment，and the internal force and alignment state of the structure after the cable force adjustment were obtained.The calculation results show that the method facilitates calculation，and the alignment and internal force of the structure after the cable force adjustment can meet the construction control requirements.

Abstract:As one of the main structures of highways，a culvert has the characteristics of large quantity and wide range.Affected by design and construction factors，engineering diseases of culverts have been prominent for a long time.With the extensive promotion of the green highway construction concept and the continuous updating of technical standards and design specifications，the original general drawing of culverts fails to meet the needs of the sustainable and healthy development of highway construction under the new situation.Hunan Provincial Communications Planning，Survey & Design Institute has conducted extensive and in-depth investigation and research on the key technologies of highway culvert design and prepared a new version of general drawings of culvert，which can meet the requirements of sustainable development of highway construction，and it serves as a powerful promotion and application of bridge and culvert construction standardization.

Abstract:The collision accident types of middle piers of overpass bridges were summarized and analyzed，and it was proven that anti-collision and anti-scratching were two important requirements of pier protection.Then，the new concept of double protection and corresponding technical schemes were put forward.The first protection adopted the way of setting concrete barriers or ship-shaped elevating members on the periphery of the pier to prevent vehicles from impacting the pier，and the second protection used the self-wrapped steel plate or aluminum foam plate to prevent vehicles from scratching the pier.The safety of the pier protection structure schemes was verified by computer simulation and unit test，and their roles of anti-collision and anti-scratching were evaluated.The results show that the safety of people，vehicles，and bridges can be better protected，and accident severity and damage are reduced.Therefore，the schemes are beneficial for later maintenance and durability of bridge piers and have been applied and recognized in practical engineering.

Abstract:High-strength bolt loosening detection of bridges faces problems such as heavy workload，small targets，many anomalies，and difficult collection.Therefore，this paper proposed a semi-supervised deep learning model，which could obtain the bolt loosening detection model even with a small number of negative samples and solve the problem of unbalanced model training samples.The accuracy of the YOLOv 5-CT model for bolt target detection reached 98.33%.By preprocessing bolt data，the reconstruction ability of bolt images by the Ganomaly model was improved.When the hidden space vector value was 100，the model had the highest SAUC and the best discriminant performance.In the model test stage，the threshold of abnormal fraction was set to 0.295，and the accuracy of the calculation model for abnormal loosening detection of high-strength bolts could reach more than 85%.As a result，the automatic identification and detection of bolts were realized.

Abstract:Ganxi Super Bridge is an open web continuous rigid frame bridge with a main span of 300 m，and the upper chord box girder in the open web triangular area adopts the post support of a few telescopic columns with the hanging basket for suspension casting.The lower chord box girder adopts the full cable-stayed buckle method with a hanging basket for suspension casting.To analyze the force characteristics of the temporary structural system in the triangular area during the construction process using this method，the force variation law during the construction process of the temporary structural system in the triangular area was summarized to verify the effectiveness of the construction method，and the optimal time to remove temporary buckle cables and support columns was proposed.The finite element structural analysis software was used to simulate the entire bridge construction process.The results show that the force of the structure meets the specification requirements by using this construction method.During the construction of the triangular area，the upper and lower chord box girders constructed are mainly compressed，and there will be a temporary and slight tension state during this period affected by the concrete pouring of the next section，column roof support，buckle cable tensioning，and other processes.When the closure of the triangular area is completed，the section of the box girders is mainly compressed，and there is slight tension in some parts.After the closure of the whole bridge，the box girders in the triangular area are in the full compression state，and the compressive stress increases significantly compared with the closure state in the triangular area.After the removal of temporary cables and columns，the upper and lower chord box girders have obvious stress redistribution，but they are still in a full compression state.The peak value of temporary cable force appears before the closure of the triangular area.After the closure of the triangular area，it generally shows a downward trend and rises near the demolition.During the construction process，the support force of the rear temporary column generally shows a downward trend，and the front column shows an upward trend.The support force of the column near the demolition is greatly improved.After comparison，it is recommended to remove the column first and then the buckle cable after the closure of the whole bridge.

Abstract:The effective length coefficient of a pier is a controlling factor affecting the safety and economic index of bridge structures.The values of the effective length coefficient of compression members in Chinese and foreign codes are basically similar，and they are only applicable to ideal boundary conditions.In practical application，it is necessary to make appropriate adjustments according to the specific structural form.In order to get the value closer to the actual situation of the structure，this paper analyzed the overall stability of the structure and investigated the influence laws of different factors on the effective length coefficient of the continuous rigid frame bridge in the completion stage and the maximum double cantilever stage，mainly including different pier types，pier height，pile foundation flexibility，adjacent span boundary，single pier instability，or overall instability.The results show that the effective length coefficient of different pier types along and across the bridge is not a fixed value，and the variation of the effective length coefficient with the pier height is not a simple linear relationship.Due to the influence of pile foundation flexibility，the result will increase by about 20%，and the influence across the bridge direction is more significant than that along the bridge.After considering the influence of connecting piers，the value of the effective length coefficient is larger.It is necessary to consider the overall buckling response of each pier under axial load at the same time.The distribution range of the effective length coefficient along the bridge under the maximum double cantilever condition in the construction stage of a continuous rigid frame is 1.20?1.35.

Abstract:In view of the transverse deformation of super-wide steel box girders of cable-stayed bridges during the cantilever assembly，the construction characteristics of the two-way eight-lane super-wide steel box girder of Zhongshan Bridge over Shenzhen-Zhongshan Link were analyzed，and the main causes of the transverse deformation during the cantilever assembly of the super-wide steel box girder were investigated.According to the matching height difference adjustment technology in the cantilever assembly construction of the wide box girder in China and abroad，this paper innovatively proposed a matching process of straight beam locking + initial tension of hanging cables，which better solved the problem of poor transverse deformation during the cantilever assembly of the super-wide steel box girder of Zhongshan Bridge.

Abstract:Based on the construction data of continuous belt conveyors in shield construction，this paper evaluates two common calculation methods of slag weight （slag weight calculation based on loosening coefficient and slag weight calculation based on external additives ） to accurately manage slag in shield construction.According to the law of slag discharged from each ring in shield construction，an improved slag weight estimation method in shield construction was proposed.The results show that there is a big error in the slag weight calculation based on the loosening coefficient.When slag weight calculation based on external additives is used，the calculated value is always smaller than the actual slag weight，and the difference between them tends to be a definite value，which is also not strongly related to the two main formation conditions and the weighing mode of slag.The improved slag calculation method improves the accuracy of slag weight estimation，which is in good agreement with the actual slag weight in shield construction.

Abstract:In view of the random monitori ng of fum e emission in asphalt pavement construction sites，combined with the engineering application of fresh asphalt in the construction of hot-mixed and hot-spread asphalt pavement in large and long tunnels for fume emission reduction，the fume collection and evaluation method of asphalt pavement construction sites were studied，and the emission reduction effect of fresh asphalt was evaluated.The Summa tanks were used to collect the asphalt fume at different positions of the paver，and the asphalt fume was quantitatively analyzed by gas chromatograph-mass spectrometer （GC-MS）.The results show that compared with the non-fresh asphalt from the same source，the fresh asphalt reduces the total mass concentration of volatile organic compounds （VOCs） in the asphalt fume at the edge of the paver，the middle of the paver flank，and the upper position of the paver by 57.0%，22.6%，and 27.4% during pavement construction，respectively.The fresh asphalt mixture reduces the total mass concentration of class 1 and 2 carcinogens by 62.3% at the edge of the paver during construction，and the odor intensity is only about 1/3 of the non-fresh asphalt mixture.The study suggests that the total mass concentration of VOCs，the total mass concentration of carcinogens exceeding class 2，and the odor intensity at the edge of the paver should be used as the key environmental impact assessment indexes for fume emission monitoring in the asphalt pavement construction site.

Abstract:In order to better prevent tunnel concrete from cracking，the development law of concrete temperature and strain was studied.Based on the connection project of Sanjiang Middle Road in the Smart New City of Quzhou，a data acquisition system was established to monitor concrete temperature and strain on site.The defects of the traditional method that the temperature and strain monitoring are insensitive，and the monitoring data is discontinuous were overcome.In addition，the high-performance double grating temperature-strain sensor was used to simultaneously monitor the temperature and strain at the same position，and the temperature compensation method was used to overcome the influence of the ambient temperature on the monitoring results and improve the accuracy of the monitoring results.The monitoring results were analyzed to reveal the development law of temperature and strain during tunnel concrete construction.The analysis shows that the change of temperature with time can be divided into the initial stage，rapid heating stage，slow cooling stage，and stable stage.The variation trend of strain is similar to that of temperature，and the strain peak appears slightly later than the temperature.Due to the influence of various factors such as maintenance conditions，boundary conditions，and reinforcement arrangement，the strains of different measuring points are quite different in the horizontal direction.

Abstract:To improve the alignment in the old road reconstruction project，stress analysis was carried out，and the alignment and smoothness parameters were used as the major variables in the dynamic equation.A “human-vehicle-road ” dynamic analysis model was established，and alignment comparison groups were set，with only one group set with easing vertical curves.The Newmark- β method was used for programming and calculating the dynamic effects generated by the basic alignment with a radius of 7 000 m.The vibration indicators such as peak acceleration，root mean square of acceleration，vibration period，and frequency were used to analyze the dynamic effects of the basic alignment group.By analyzing the causes and decay rules of the vibration zone，the vibration zone and stable zone within the alignment were defined.The addition of easing vertical curves significantly changed the vibration mode of the vehicle，greatly reducing the peak acceleration and root mean square of acceleration to 5% within the conventional basic alignment and effectively eliminating the perception of vehicle vibration.The influence of vehicle type，vehicle weight，and suspension system parameters on the dynamic effects of the two alignment groups was analyzed.The addition of easing vertical curves greatly reduced the vibration，making the alignment more adaptable to various vehicles.The coupling effect between the alignment groups and different smoothness application states was analyzed.The coupling effect of the conventional basic alignment in the vibration zone was more significant，with the root mean square of acceleration being 95%?161% that of the straight slope shape.After adding easing vertical curves，the coupling coefficient approached 1，and the alignment was close to the ideal plane of the “human-vehicle-road ” system.Through the above research，it is found that adding easing vertical curves can effectively improve the vehicle running quality of the alignment and enhance its adaptability to vehicles and road conditions.

Abstract:With the continuous promotion of China ’s strategy of building the country with a strong transportation network，the proportion of high-grade highways in the road network continues to increase，and the number of traffic safety facilities is increasing.Xilingol League in the Inner Mongolia Autonomous Region has a long winter and strong wind，which is one of the typical areas in China deeply affected by snow drift disasters.Through field investigation，it is found that “road snow resistance ” “visual range obstacle ” and other snow drift disasters caused by traffic safety facilities are also increasingly prominent，which seriously restricts the effective play of road transportation functions and seriously affects the economic and social development of the region.Among them，the number and severity of road sections with snow drift disasters caused by anti-collision guardrails are far greater than those by other traffic safety facilities.Therefore，based on the field investigation and analysis of the snow drift disasters on the Xilingol League Highway，this paper mainly studied the impact and action law of the anti-collision guardrail，a highway traffic safety facility，on the wind speed and flow field of the integral highway subgrade section through computer simulation.It made up for the lag and deficiency in the research on the formation mechanism of snow drift disasters caused by anti-collision guardrails and provided a theoretical basis for the layout of highway anti-collision guardrails and snow disaster prevention in areas suffering from snow drift in China.

Abstract:In order to improve the green construction level of highways in dense urban areas，the project characteristics and engineering requirements of the Nansha-Zhongshan Expressway were analyzed，and the concept of green development was implemented in the whole life cycle of highway design，construction，operation，maintenance，and management.The research and development of ten innovative technologies in four categories were highlighted，including industrial intelligent construction of highway bridges，comprehensive utilization of highway resources，environmental protection of highways in coastal wet areas，and integrated design of transportation and tourism in the Guangdong-Hong Kong-Marco Greater Bay Area.Among them，the prefabricated beam annular production line and non-standard eight-lane were the unprecedented technologies first used in the project.In addition，the technical system of green highway bridges in typical urban agglomerations was initially constructed，and the key development directions in the future were prospected to enrich and improve the technical system for green highway construction in the Guangdong-Hong Kong-Marco Greater Bay Area.This provided a reference for the sustainable development of other highly urbanized regions.

Abstract:To construct a comprehensive carbon emission monitoring and management system for commercial vehicles，firstly，this article described the background and significance of carbon emission monitoring and management of commercial vehicles and summarized the research in relevant fields in China and abroad.Then，this article expounded on the carbon emission monitoring system for commercial vehicles，which covered three major levels：monitoring target layer，monitoring implementation layer，and monitoring summary layer，so as to achieve comprehensive and accurate carbon emission monitoring.Finally，combined with the carbon emission monitoring data of commercial vehicles，this article put forward a carbon emission management system for commercial vehicles based on data information，including carbon emission data sharing and opening，data management and analysis，management strategies and measures，as well as evaluation and optimization，so as to enhance the effective carbon emission management of commercial vehicles.

Abstract:The criteria for liquefaction judgment of fi ne-grained soil in current seismic design codes of China，the United States，and Bangladesh are quite different.In order to propose the judgment criteria for engineering application and Chinese code revision，this paper compared the judgment processes and criteria of the three countries.After analyzing the formation process，based on the application of the criteria for liquefaction judgment of 168 fine-grained soil samples collected in Dhaka，Bangladesh and surrounding cities，the rationality of each judgment process and criteria was evaluated comprehensively.Finally，a set of judgment processes and result criteria for fine-grained soil liquefaction integrating all criteria were put forward.