Steel slag and wasted rubber tire are both solid wastes which are high production and difficult to dispose. Steel slag-rubber asphalt mixture (SSRAM) was prepared by using steel slag which replaced part of coarse aggregate and rubber asphalt. In order to study the regularity of gradation, steel slag content and binder property on the road performance of SSRAM, three kinds of coarse aggregate fractal dimension values (Dc) and two kinds of fine aggregate fractal dimension values (Df) were selected according to fractal theory. The performance of SSRAM in three-level orthogonal scheme with three factors (Dc steel slag content and rubber content) was analyzed and the performance of the mixture under two kinds of Df was compared. The results show: In the selected levels, Dc is the main factor affecting the high temperature stability and anti-freezing and thawing performance of SSRAM. With the decrease of Dc, aggregate gradation becomes coarser the dynamic stability of the mixture increases and the predicted permanent deformation decreases, but the anti-freezing and thawing performance decreases; the content of steel slag is the main factor affecting the optimal asphalt-aggregate ratio and low temperature bending strain of SSRAM. With the increase of steel slag content, the optimal asphalt-aggregate ratio increases and the low temperature bending strain of the mixture also increases; compared with base asphalt, rubber asphalt shows better performance, but the rubber content has little effect on the performance of the mixture. All SSRAM with different composition have good volume stability. For the better road performance, SSRAM composition with Dc=2.1, Df=2.55, steel slag content 60% and rubber content 21% is recommended.
With the development of the freight platform market, the problem of asymmetric information between vehicles and consignors has been effectively alleviated, and there is still room for improvement in the satisfaction of car owners and consignors, vehicle loading rate, and the cost-borne by consignor. In the context of transportation capacity supply exceeding freight demand, the satisfaction of the consignor becomes the key factor affecting vehicle-cargo matching and platform competitiveness. To make the solution of vehicle-cargo matching more desirable to the requirement of the matching party and attract more customers, a new model is proposed by considering the consignor. The two parties to the vehicle-cargo matching are regarded as the customer side and the service provider involved in logistics services according to the definition of a logistics streamline network. Considering the closeness between the consignor’s requirements for cargo integrity, time and cost of transportation, and the motorists’ actual service of transportation, the matching degree is defined. Then, a matching satisfaction model is constructed to maximize the matching satisfaction, and an improved genetic algorithm is designed and solved using Python. Three different models of vehicle-cargo matching are compared on the data of the platform. The result shows that the average vehicle loading rate of the proposed model is 31.2% higher than the one of the one-to-one matching model, and the cost of the consignor is 4.3% lower. Compared with the one-to-many vehicle-cargo matching model with transportation cost as the target, the average consignor satisfaction increased by 16.2%, and the cost borne by the consignor decreased by 2.9%. It reduces the total cost borne by the consignor and maintains a high consignor satisfaction and vehicle loading rate while being more in line with the actual scenario.
Long-distance passenger lines exceeding 800 kilometers are a crucial component of highway passenger transport. This paper analyzes the causes of traffic accidents on long-distance passenger routes exceeding 800 kilometers from 2014 to 2020. This paper conducts a causal analysis and researches accident-prone scenarios for long-distance passenger lines exceeding 800 km. It selects key characteristics to establish an index system based on human factors, road conditions, and the environment. This paper analyzes the characteristics of humans, roads, and the environment in the traffic system when accidents occur. The Decision Tree model is utilized to investigate the internal relationships among key factors in accident scenarios, such as operating time, human factors, weather, quarter, accident region, holidays, spring transportation, road alignment, and road condition. The results show that the run time, human factors, and weather conditions are important influencing factors for accidents on long-distance passenger lines over 800 km. They have a coupling relationship with factors such as quarter, accident region, road alignment, and road condition. Holidays, spring transportation, highway technical grade, and highway administrative grade are not the important factors affecting the occurrence of accidents on long-distance passenger lines over 800 km. This paper provides a theoretical basis for reducing the potential for accidents and promoting safety within enterprises operating long-distance passenger lines over 800 km. In the future, road transport management departments and road transport enterprises should strengthen safety management, standardize drivers' safe driving behavior, and promote defensive driving knowledge in accident-prone situations.
The disorderly emission and poor treatment effect of asphalt mixture fume in asphalt mixing stations have caused huge harm to the natural environment and human health. Based on the gravimetric method, self-designed and assembled fume generation-enrichment device that was suitable for the mixing state of asphalt mixture in the plant, and conducts research on the fume release rules during asphalt mixture mixing. Four kinds of petroleum asphalt were selected to consider the conditions of asphalt fume generation in the field mixing station. The mixing temperature, aggregate specific surface area and mixing frequency were determined as the key factors affecting the release of fume. The exposed area of the aggregate was calculated by the measured modified specific surface area calculation method, and the influence of each key factor on the smoke release of the plant-mixed asphalt mixture was analyzed. The results show that the self-designed and assembled fume generation-enrichment device has good stability and can ensure the accuracy of the experimental results. The magnitude of the light components in the fume under different mixing conditions is much lower than that of the heavy components, and the fume release after the base asphalt is modified by SBS is reduced. Mixing temperature is the most critical factor that determines the amount of fume release. The amount of fume release shows an obvious growth trend with the increase in temperature. Fume production has strong temperature sensitivity, and release varies significantly under different mixing temperatures. 160 ℃ and 170 ℃ are the jumping nodes of fume release. The amount of fume produced by the asphalt mixture is directly proportional to the specific surface area of the aggregate. The specific surface area of the aggregate directly affects the amount of fume released by determining the exposed area of the asphalt. The amount of fume release is positively related to the mixing frequency. Compared with the heavy components of the fume, the release amount of the light components of the fume is less affected by the mixing frequency. The research results can provide theoretical and technical support for the release and disposal of fume in mixing plants.
Taking the carbonaceous slate of Zhuokeji tunnel on the Wenchuan-Ma, erkang expressway as the research subject, triaxial compression creep tests were conducted under various freeze-thaw cycles to analyze the creep strain characteristics and long-term strength of the carbonaceous slate. Assuming that the aging damage of rock under load follows the Weibull probability density distribution, the loaded damage variable is defined. The freeze-thaw damage variable is defined according to the phenomenological theory of damage mechanics. Considering the coupling effect of freeze-thaw and stress, a total damage variable for freeze-thaw and load is constructed. Based on the creep behavior of carbonaceous slate, the structure of the H-H|N-N|S creep model is determined. Based on this, the damage evolution is carried out, and a new creep damage model that can reflect the coupling of freeze-thaw and stress is obtained, which is extended to a three-dimensional stress state. The solution method for model parameters is provided, and the damage evolution law is analyzed. The creep characteristics of carbonaceous slate are identified using the established model. A traditional model is introduced for comparison, and the simulation comparison curve is analyzed to verify the feasibility and rationality of the new model.
