Channel: http://www.gljtkj.com EN-US http://www.gljtkj.com/EN/current.shtml http://www.gljtkj.com 5 K-means algorithm is proposed. First, the asphalt pavement crack images obtained by road patrol inspection vehicle is wavelet de-noised, an adaptive threshold calculation method that changes with the number of wavelet decomposition layers is proposed, and the corresponding wavelet threshold function expression is determined. Then, the de-noised asphalt pavement crack images are segmented by using the K-means algorithm optimized by fruit fly. Finally, the small noises in the segmented images are removed by using mathematical morphology, and the cracks at the fracture are connected by using region growth operator. The result shows that (1) the improved wavelet threshold de-noising algorithm performs well as a whole, it has certain advantages in the evaluation parameters of peak signal-to-noise ratio, information entropy and contrast, and the de-noising effect is better than the those of dark channel prior algorithm and CLAHE algorithm; (2) the improved K-means algorithm has the advantages of faster convergence speed and smaller taste judgment value, the average calculation time for an image is 1.15 s; (3) the analysis of the accuracy of the algorithm shows that the new algorithm has a high accuracy-recall indicator, with the accuracy of 85.69 and the recall of 86.93, and the comprehensive evaluation coefficient of 86.31, which exceed those of the improved Sobel operator, maximum entropy segmentation algorithm and Otsu algorithm. To sum up, the proposed crack segmentation algorithm has the advantages of good image de-noising effect, high crack segmentation accuracy and short running time.]]> BPN₂₀), dynamic friction coefficient (DF₈₀), average sectional structural depth (MPD) in different aggregate types and grading types are discussed. The result shows that (1) The anti-sliding performance of GSAM and LAM under the action of abrasion has the same attenuation trend, which is basically divided into the attenuation period with fast and high attenuation rate and the stable period with slow attenuation rate, and GSAM has strong anti-skid performance. Under the same grading condition, LAM has large attenuation rate, while the final attenuation value of anti-skid indicator of GSAM is large. (2) There is a good correlation among the measured MPD, BPN₂₀ and DF₈₀ during the wearing process of asphalt mixture. The MPD can be used to calculate the BPN₂₀ and DF₈₀ of each asphalt mixture during the wearing process. (3) The logarithmic model in the empirical model can be used for regression analysis of the anti-skid durability of the asphalt mixture. Among the 3 indicators, the fitting effect of MPD on the attenuation rule of anti-skid performance is good, which can better reflect the relationship between pavement structure depth and abrasion times of the asphalt mixture.(4) The basic road performance of GSAM of the 2 gradations, such as high temperature stability, low temperature crack resistance and water stability, meet the requirements of the specification, and their overall performance are superior to those of the corresponding LAM.]]> 2/ZnO) and basalt fiber (BF) as the modifiers for composite modification of asphalt and mixture, and the dense graded TiO₂/Zno-BF composite modified AC-13C asphalt mixture is prepared. Based on the performance research of raw materials such as asphalt, TiO₂/ZnO, and basalt fiber, the composite modified asphalt is prepared. Through tests of softening point, ductility, rotational viscosity, thin-film oven, and temperature sensitivity analysis, etc., the effects of different dosages of TiO₂/ZnO and 6% basalt fiber on the performance of asphalt are evaluated. By mix design, the optimum asphalt-aggregate ratio of the mixture under different mixing combinations of TiO₂/ZnO and basalt fiber is determined. Relevant laboratory tests of high-temperature stability, low-temperature cracking resistance, water stability, and fatigue performance are carried out on the composite modified asphalt mixture to evaluate their road performance. The result shows that (1) With the increase of TiO₂/ZnO dosage, the softening point, rotational viscosity and the penetration ratio after aging increased gradually, while the penetration, ductility, temperature sensitivity, softening point increment after aging, and quality loss decreased gradually. The overall performance of the composite modified asphalt with 4%TiO₂/ZnO+6%BF is better than that of the matrix asphalt, and the recommended dosage of TiO₂/ZnO is 4%. (2) The addition of 6% basalt fiber and 4% TiO₂/ZnO can improve the high-temperature rutting resistance, low-temperature cracking resistance, moisture damage resistance and fatigue resistance of the mixture. Among them, the high temperature stability and water stability of the asphalt mixture with 4% TiO₂/ZnO is better than that of the asphalt mixture with 6% basalt fiber.]]> 2 photocatalyst on automobile exhaust is studied. TiO₂ photocatalyst has certain photocorrosion resistance and catalytic activity. The samples are prepared by adding different amounts of TiO₂ photocatalyst (0, 30%, 50%, 70%, 100%) instead of mineral powder into the macroporous asphalt mixture. The cumulative degradation rates of the macroporous asphalt pavement samples under different porosities, different amounts of TiO₂ photocatalyst, and different reaction time are measured, and the change rule and the change of pavement performance of the mixture are analyzed. The result shows that (1) The higher the porosities of the asphalt mixture, the better the effect of adding TiO₂ photocatalyst, and the stronger the degradation capacity of automobile exhaust. (2) The analysis of the automobile exhaust degradation efficiency shows that the optimal mixing amount range is 50% to 70%. Within this range, the maximum degradation efficiency of CH, NO, CO reaches 0.039 75%/10 min, 0.083 93%/10 min and 0.032 73%/10 min respectively. (3)The analysis of reaction time shows that the cumulative degradation efficiency increases with the increase of reaction time after adding TiO₂ photocatalyst, and the growth rate slows down after 50 minutes. Adding TiO₂ photocatalyst can effectively degrade vehicle exhaust. (4) Especially for replacing mineral powder with the same content of TiO₂ photocatalyst, it will not affect the water stability and high temperature stability of the macroporous asphalt mixture. On the contrary, with the increase of the content, the anti-flying ability of the macroporous asphalt mixture will be improved, but the low temperature performance will be reduced to a certain extent. Therefore, the content of supported TiO₂ photocatalyst can be comprehensively considered according to actual needs.]]> 3 and the optimum moisture content of 4.4%. (2) The test curing temperature is 60 鈩�, the curing time is 2 d, and the curing target moisture content is 1.4%. (3) When the moisture content is smaller than the target value, the CBR value of the material reaches more than 250%, meeting the requirements of relevant specification. (4) When the optimum content of water-based polymer is 0.5%, the uniaxial penetration strength of the material is 0.91 MPa, which is higher than the general value of the uniaxial penetration strength of ordinary asphalt mixture (0.7 MPa). The change rate of the unit content of water-based polymer reaches the peak value, and the cost-performance ratio for the strength improvement of each ton of macadam material reaches 0.002 64 MPa/yuan. The engineering cost-performance of the material is also the best while meeting the road performance. (4) The composition design method of water-based polymer stabilized macadam based on penetration strength is more timely than the traditional CBR value design method, and the uniaxial penetration strength can directly reflect the bearing capacity of water-based polymer stabilized macadam base under load, which is more consistent with the flexible material characteristics of water-based polymer stabilized macadam base.]]> Standards for Technical Condition Evaluation of Highway Bridges (JTG5210鈥�2018), the technical condition of selected roads is evaluated by PQI index, the causes and formation mechanism of road frost damage in Ningxia are analyzed. The result shows that (1) the spatio-temporal variation characteristics of temperature, precipitation and other related factors in the seasonally frozen regions of Ningxia are highly regional; (2) there are differences in diseases in different regions of Ningxia, but cracks are the main diseases, and roads show different forms of cracks; (3) the overall pavement performance of roads in different regions of Ningxia is mainly excellent, and the service performance in the northern and central regions is slightly better than that in the south region; (4) the road diseases in different regions of Ningxia are mainly caused by frost damage, the changes of temperature field, the cyclic freeze-thaw effect and the traffic load interact with each other, leading to the occurrence of road frost damage. The result will provide reference for road construction, reasonable design and operation in the engineering practice in the seasonally frozen regions of Ningxia, and have important significance for the prevention of road diseases in the seasonally frozen regions.The research will provide reference and reference for the road construction and operation in Ningxia region, and is of great significance to the prevention of road diseases in the seasonal frozen soil area.]]> 2 crystals will be adsorbed around the lime-soil particles, increasing the porosity of lime-soil, and part swelling deformation of the lime-soil will fill these pores, resulting in the swelling of the 3锛�7 lime-soil is smaller than that of the 2锛�8 lime-soil.]]> T₂ spectrum of the sample are measured, and the mechanisms of disintegration and cracking of red-bed mudstone under dry-wet cycles is discussed. The result shows that (1) In the water absorption stage of the sample, the cracks are mainly generated along the bedding direction, and the length and width of the cracks increase with the increase of water absorption time after 5-6 h. The fractures in the direction perpendicular to the bedding of the sample are occurred and concentrated at the initial stage of dehydration for 0.5 h. After the capillary water is lost, the mineral shrinks due to water loss and gradually closes as the dehydration continues. (2) After the 6th dry-wet cycle, the disintegrated particles gradually transitioned from being dominated by large particles with diameter of >10 mm to being dominated by small particles with particle diameter of <10 mm, and the disintegrated particles became increasingly close to square rather than elongated particles. (3) There is a redistribution of water in pelitic siltstone. The water contained in the mudstone sample is mainly mineral bound water, which provides the source of water for a large number of swelling minerals in the mudstone to absorb water. (4) The disintegration and deterioration process of mudstone under the action of dry-wet cycles is: existence of primary defects in mudstone 鈫� primary defects of water infiltration 鈫� generation of surface cracks 鈫� enhancement of water-rock interaction area 鈫� crack expansion and penetration 鈫� dry-wet cycle action 鈫� mudstone continues to disintegrate to massive and granular shape 鈫� end of disintegration finally. The research can provide a reference for the engineering application of pelitic siltstone as roadbed filler, with significant engineering application value.]]> 2 when the wind speed is smaller than 5 m/s, and the rotation acceleration should not be larger than 0.59(°)/s² when the wind speed is 5-10 m/s.]]> F-test method and the coefficient of determination R². Finally, the parameters of the objective function are optimized by using Particle Swarm Optimization (PSO) algorithm, and the optimal parameters of viscous damper are obtained. The result shows that (1) There are some differences in the seismic response and damping effects on different side structural key parts of asymmetric suspension bridge with different parameter combinations of viscous damper. The seismic responses of the parts on the side with larger mass are more obvious, while the seismic damping effects of the parts on the side with smaller mass are better. (2) The fitted model of the relationship between viscous damper parameters and seismic responses of structures based on the response surface method has high fitting accuracy and good predictability. (3) After optimization, the adaptation degree of objective function is significantly reduced, and the differences in seismic response on different side structures are effectively reduced. The magnitudes of optimization of internal force responses are more obvious than those of displacement responses, and the optimization ratios are all above 10%. (4) Optimizing the parameters of viscous damper on asymmetric long-span suspension bridge by using the response surface method and PSO algorithm can improve the whole bridge鈥檚 forces and damping effect of dampers, and has important reference for anti-seismic analysis and damping design of similar suspension bridges.]]> 3; (2) the water quality of the fissure water from the surrounding rock at different locations varies greatly, with a high concentration of HCO₃^- in the water exuding from the tunnel face; (3) the Ca²⁺ concentration, OH^- concentration and pH of the water passing through the initial support concrete are generally higher; (4) the water quality of the outlet of the longitudinal drainage pipe can be divided into 2 categories, one with low pH, the other with high pH, and the water with high pH is more prone to crystallization; (5) the contents of salt ion and SO₄^2- are related to the strength of the interaction between the shotcrete and the karst water; (6) the crystallisation process of fissure water mainly includes three stages: dissolution of carbonate rock, the reaction between shotcrete and fissure water, and crystallisation and blockage of fissure water in the drainage pipe, the crystallisation is mainly due to the easy absorption of CO₂ by high pH water, which generates carbonate ions that combine with calcium ions in the fissure water to produce calcium carbonate crystals; (7) the flow mechanism of the fissure water will cause the surrounding rock debris and sediment to enter into the drainage pipe, which is also one of the reasons for the serious crystallisation and blockage of the drainage system.]]> 3, it contributes less to the growth of consolidated undrained strength of the grout, while the content is more than 100 kg/m³, the growth of strength is promoted, and the mineral water content always contributes to the growth of the consolidated undrained strength. (4) When the bound water content is less than 124 kg/m³ and the mineral water content is less than 10 kg/m³, the effective cohesion of the grout is mainly affected by the bound water content. When the water contents of the 2 forms are more than the above mentioned 2 values respectively, the effective cohesion of the grout is affected by the bound water content, and strengthened by the mineral water content in addition. (5) The strength of the early-age inert grout mainly comes from the contact and friction among the particles, and the strength of hard grout mainly comes from the reinforcement of filling and cementation in the pores among the grout particles by cement hydration products.]]> MAE) of the trajectory in the straight section extracted by camera is 0.19 m, and the mean absolute percentage error (MAPE) of speed is 3.27 %; (2) the MAE of the trajectory in curve section is 0.17 m, and the MAPE of speed is 4.38 %; (3) the MAE of trajectory in intersection is 0.16 m, and the MAPE of speed is 3.38 %. On the whole, the average trajectory error is less than 0.2 m, and the average speed error is less than 2 km/h. This method effectively improved the accuracy of obtaining the vehicle trajectory from traffic surveillance video.]]> R² values of modified models are greater than 0.8, which is highly explanatory. On the basis of this temperature rise model, the corresponding reliability model for continuous downhill is constructed. With 260 鈩� as the limit temperature, combining with the distribution parameters of truck loading and driving speed, the reliabilities of high-grade highway and low-grade highway with different slope-length combinations are calculated respectively. With 85% and 95% as the safety reliability thresholds of different graded highways, the slope-length combinations for continuous downhill at high-altitude are calculated. The result shows that (1) the design indicators of continuous downhill in the current design specification is conservative; (2) the downhill indicators obtained based on the reliability theory can provide reasonable theoretical basis for the designers to design the alignment for continuous downhill at high altitude.]]>