KEYWORDS: Diseases and disorders, Asphalt pavements, Random forests, Data modeling, Roads, Machine learning, Dimension reduction, Decision trees, Principal component analysis, Education and training
To construct an automatic discrimination method for the causes of pavement diseases, the typical characteristics of different types of asphalt pavement diseases of the Inner Ring Expressway in Chongqing, which was taken as an engineering example, were analyzed, and the feasibility of data dimension reduction analysis was determined based on the correlation characteristics of different types of damage. Then, numerous state information data were subjected to dimension reduction through the principal component analysis (PCA), followed by the automatic cause analysis of pavement diseases using the random forest algorithm. The results show that the cause conclusions acquired through machine learning model training basically accord with the actual field survey conclusions. Thus, it can be deemed that the intelligent discrimination method based on machine learning is reliable, to some extent, for the cause analysis of pavement diseases and can serve as an automatic discrimination method for the follow-up development of an intelligent maintenance decision system.
In order to solve the problem of the long repair time of bridge expansion joints that may result in long road closure periods and reduced vehicle traffic efficiency, a rapid-curing cement-based mortar material was prepared in this paper on the basis of special cement material through the adjustment of formulation and mineral admixture. The optimum mortar mix proportion obtained through research is as follows: cement-sand ratio is 1:1.1, water reducer is 0.2%, and the ratio of silica fume, mineral powder, and fly ash to cement is 6%, 2%, and 2% respectively. The 2h flexural strength and 2h compressive strength of the material obtained with the optimum formula reached 7 MPa and 24 Mpa respectively. Moreover, it has good fluidity and setting time properties without an obvious decrease in long-term strength, so it is an ideal rapid repair material for bridge expansion joints.
In this study, we used the SEM electron microscope to observe the morphological characteristics of each phase interface in the mixture, focusing on the effects of gradation, cement content, curing age, and mixing method on the unconfined compressive strength and splitting strength of the cold recycled mixture, to optimize the material composition design of cement composite recycled mixture. The results showed that dry shrinkage cracks and cement aggregates appeared on the surface of the three aggregates formed by conventional mixing, while the old cement that was not closely connected on the RBP surface of the mixture fell off using the vibration mixing method. The cement on the surface of all kinds of aggregates was evenly coated, with a reduced interface strength variability. The strength of the mixture increased with age was in line with the law of cement strength growth; The increase in cement content could increase the unconfined compressive strength and splitting strength of the mixture; The strength of the mixture increased and then decreased with the increase of RAP content. The unconfined compressive strength and splitting strength of the mixture were increased by 32.4% and 44.3%, and the coefficient of variation was reduced by 27.1% and 31.0%, respectively, by using vibration mixing compared with conventional mixing.
KEYWORDS: Shape memory alloys, Resistance, Roads, Minerals, Particles, Raw materials, Kinematics, Interfaces, Information and communication technologies, Absorption
For the mix proportion design of bituminous mixture, gap graded SMA-13 is selected and 4‰ of basalt fiber is added to it. Moreover, its pavement performance is compared with that of the ordinary SMA-13 bituminous mixture with the same amount of lignin fiber, so as to study the effect of the basalt fiber on the pavement performance of the SMA-13 bituminous mixture. The test results show that compared with the ordinary SMA-13 asphalt mixture, the bitumen aggregate ratio of the SMA-13 bituminous mixture with basalt fiber is reduced, and the high-temperature stability and low-temperature crack resistance are improved, while the water stability is improved to a limited extent.
KEYWORDS: 3D modeling, Visual process modeling, Bridges, Data modeling, Computer aided design, Roads, Visualization, Systems modeling, 3D visualizations, Virtual reality
Through the application of building information modeling (BIM) technology in the Xiaowan Interchange project, this paper reviewed the idea and the correct process of the establishment of the whole complex municipal interchange BIM model in detail, studied the technology application of earthwork adjustment, collision detection, visual distance detection and headroom detection based on BIM technology, and finally tried BIM mapping and VR display. The research shows that the application of BIM technology in the design of municipal interchange can effectively optimize the linear shape, longitudinal section, structure, and position of the intersection; and the use of the BIM model to carry out a statistical review of engineering quantities and 3D mapping can improve the quality of design documents and express the design intention with a better visualization.
To study the anti-sliding performance of the two-component epoxy resin thin layer, a combination of accelerated loading test and mechanical test was used to focus on the influence of different aggregate types on its anti-sliding performance. SMA-10 and modified emulsified asphalt micro-surface were selected as a control group, accelerated loading test were carried out, the law of BPN value, TD value, and aggregate wear mass loss rate with wear time were analyzed; and the logarithmic formula was used to make a fitting regression of the attenuation law of anti-sliding performance. Through shear test and pull-out test, the influence of different aggregate types and asphalt on its mechanical properties was analyzed. The test results showed that the anti-sliding performance of the two-component epoxy resin anti-sliding layer was better than that of SMA-10 and the modified emulsified asphalt micro-surface; within 3h after the start of the accelerated loading test, the anti-sliding performance decayed rapidly, and the later decay rate was slow and showed a slow decreasing trend. Besides, the relationship between the TD value and the BPN value with abrasion time had a good correlation with the logarithmic formula. In addition, the shear strength and bonding strength between the anti-sliding thin layer and the asphalt concrete base surface are strong, and the failure surfaces of the specimens all appear inside the asphalt layer.
With the expansion of the road maintenance market, there is an increasing demand for road maintenance materials, especially high-performance emulsified asphalt materials. In this paper, a new type of waterborne epoxy modified emulsified asphalt cementitious material was prepared. Through laboratory tests, its material ratio, mixing process and epoxy content were studied in detail, and performance indicators such as adhesion, viscosity, and bond strength were investigated. Finally, the influence factors and the strength formation mechanism of the solidified materials were explored and studied by microstructure analysis methods.
In order to select the construction period of expressways with heavy traffic flow reasonably, this paper builds a mixed integer optimization model based on the in-depth analysis of various economic and social benefits and the constructional and organizational costs. Then the algorithm for the optimization model is studied and coded by Excel VBA. Finally, by the example of Ningbo-Taizhou-Wenzhou Expressway, the application method of the optimization model is demonstrated through concrete case analysis. The method proposed by this study can support the decision-making of the optimal allocation during the construction period of expressways with heavy traffic flow, and can effectively reduce the economic loss of expressway reconstruction or extension construction.
KEYWORDS: Roads, Safety, Space operations, Communication engineering, Analytical research, Natural surfaces, Lithium, Information and communication technologies, Facility engineering, Data analysis
In order to further optimize the traffic organization designing process and methods during the road-occupying construction of expressways with heavy traffic flow, based on the in-depth analysis of the basic traffic operation conditions of expressways with heavy traffic flow, this paper put forward the general principles of traffic organization during the road-occupying construction. The general process of the design work and the specific methods of each stage are defined. Finally, by taking the Ningbo-Taizhou-Wenzhou Expressway as an example, a specific case was analyzed. The research results of this paper can provide reference for the research and formulation of traffic organization schemes during the road-occupying construction of expressways with heavy traffic flow.
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