Laboratory tests were performed to determine the most effective application of tuff minerals as an aggregate of asphalt mixture for expressway asphalt pavements. In the tests, the physical and mechanical characteristics of tuff, limestone, and basalt aggregates were compared. The high-temperature performance, low-temperature performance, and water stability of the asphalt mixture were also compared under the conditions involving different mixture types, different asphalts, and different mineral aggregate combinations. Test results indicate that (1) except for low-grade asphalt mixtures, tuff asphalt mixture achieves good road performance that meets Chinese specifications when the shape of the tuff aggregate is regular and clean. Moreover, (2) the comprehensive road performance of the asphalt mixture composed of tuff and other aggregates shows obvious improvement relative to the common aggregate asphalt mixture.

Nonlinear characteristics of road mineral material and the fractal dimension of grain size distribution, including D (fractal dimension of whole aggregate), D_c (fractal dimension of coarse aggregate) and D_f(fractal dimension of fine aggregate) are used as indexes to describe fractal characteristics. Additionally, the formula of fractal gradation theory is put forward, and the correlation with the performance of the mixture is evaluated. Results show that the fine aggregate of 2.36 mm size has a considerable influence on the physical and mechanical properties of cold recycled pavement base mixture with foamed asphalt. The fractal of the continuous-graded aggregate is one dimensional, while the fractal of the gap-graded aggregate is two dimensional. The fractal dimension of the aggregate volume has good applicability as the evaluation index of cold recycled pavement base with foamed asphalt. When the corresponding regression model is established, a strong correlation is also observed between the fractal dimension of the aggregate volume and the indexes of the physical, mechanical, and durable properties of the cold recycled pavement base with foamed asphalt. The fractal dimension of the aggregate volume is an important parameter with rich information content, and fractal is an essential character of the aggregate.

For improving the crack resistance of the semi-rigid base of an asphalt pavement and self-healing property to the base, the main materials (cement, fly ash, quartz sand, and polyvinyl alcohol) for a polyvinyl alcohol-engineered cementitious composite (PVA-ECC) were added to the regular materials for a new self-healing material for pavement base, i.e., PVA-ECC-stabilized crushed-stone mixture (PECR). Compressive strength tests were conducted on the base materials with various curing times to evaluate self-healing performance by comparing the strengths of standard specimens and specimens with cracking under different conditions (outdoor curing, laboratory curing, and dry-wet circulation). Results of the tests indicate that PECR has superior self-healing performance and that the compressive strength increases by 57.3% after self-healing. The compressive strength of PECR is higher than that of cement-stabilized crushed-tone mixture, and the peak compressive strength increases by 42%. The material that experienced dry-wet circulation has the highest compressive strength and the best self-healing performance.

A de-noising algorithm was designed on the basis of connectivity checking of pixel and crack block levels to remove isolated noises in pavement crack images and to retain the fine features of crack edges. This algorithm comprises three main parts, namely, (1) Pixel connectivity checking to eliminate pixels with poor connexity, (2) A de-noising algorithm to remove insular target regions, and (3) An 8×8 cracking block de-noising algorithm. The algorithm procedures and parameter selection issues were presented. Performance tests on the proposed algorithm and two commonly used methods (median filtering and the algorithm based on long line and black pixel percentage) were conducted using Visual Studio 2008 and OpenCV. Results indicated that the proposed algorithm could effectively remove isolated noises and maintain the continuity of cracking edges with higher precision(85.06%) and recall (85.80%) and better F₁ scores (0.74% to 19.19% and 0.20% to 12.06%) in comparison with the other two methods.

In order to evaluate the reliability of the deck system of concrete bridge reasonably, multi-index multilevel reliability assessment model of the bridge deck system was set up based on the extension assessment method according to engineering diseases and related bridge maintenance assessment specification, and the classification standards of underlying assessment index were given as well. Correlation function and correlative degree in the extension set were introduced into. The subsystems' extension assessment analysis of the bridge deck system was conducted by the comprehensive correlative degree size. The multi-index multilevel extension assessment method was combined with the improved AHP, and the overall reliability level of the deck system was determined by calculating the correlation degree. The results show that reliability status of the bridge deck system is third class but close to forth class. Some effective treatments are taken according to the assessment results and the development of the diseases. The rationality and validity of the assessment results and treatment methods are verified by load test. In the process of the extension assessment, every subsystem extension assessment results are given, which is contributed to analyzing the causes of the reliability declining and making the reasonable decisions on maintenance and rehabilitation.

To address the lack of a solar thermal gradient in a PK section concrete girder without pavement in highway bridge regulation and the limited research on this topic both local and abroad, an ANSYS model for the right branch cable-stayed bridge concrete girder without pavement of the Maanshan Yangtze River Expressway is built to calculate the temperature field. Results agree well with the measured values. The parameter analysis of the concrete girder without pavement shows that absorptivity significantly influences the maximum vertical temperature difference of the girder, and wind speed is another important factor. A vertical maximum gradient temperature model under the worst environment and its exponential function in the course of bridge construction are calculated. The distribution trend of the gradient temperature obtained from our research basically tallies with those from existing specifications of different countries. The values of the gradient temperature differ because of the effect of geography. Therefore, improving the specification for the gradient temperature of concrete girders without pavement in Chinese highway bridge regulations is suggested.

Finite element models of integrated (IPSS) and separate (SPSS) pile-anchor supporting structures are built by using ABAQUS software, and differences in the mechanical performance of these structures are analyzed. The influences of pile diameter, embedding depth, top-beam size, anchor bolt number, and prestress on the supporting structures are investigated. Results show that:(1) the displacements of IPSS and SPSS decrease from the ends to their middle portion, the moments and shear forces of these structures increase from the ends to their middle portion, and the loads and displacements of the middle portion of these structures remain unchanged; (2) the moments and shear forces of the two anti-slide piles at the end of the supporting structures should be multiplied by adjustment coefficients of 1.35 and 1.2, respectively, when the structures are designed; (3) the maximum IPSS displacement is smaller by at least 20% that of the SPSS, the largest moment of the former is at least 3% smaller than that of the latter, and the largest shear force of the former is at least smaller 6% than that of the latter; (4) enlarging the diameter of the anti-slide pile decreases the displacements and moments of the two structures; (5) increasing the embedding depths of the piles would diminish the displacements of the structures but increase their moments; (6) enlarging the top-beam size improves the stiffness and anti-deforming capability of the IPSS and SPSS but the function of which is limited; and (7) increasing the number of anchor bolts and prestressing could obviously decrease the displacements and moments of the supporting structures and change the distributional patterns of the displacements and moments on the piles. The influences of changes of the factors described above on IPSS are much smaller than those on SPSS.

Mechanical properties such as stress, deformation, and plastic zone distribution of the middle-rock-wall, along with the mechanical characteristics of the preliminary lining under different spacings, are particularly important for guiding the design and construction of small spacing tunnels. A three-step excavation numerical analysis model of the tunnel excavation is established, simulating the following conditions:D/B=0.5, 0.75, 1, 1.5, 1.25, 2. The mechanical behavior of a middle-rock-wall was analyzed after multiple disturbances through the digging of another tunnel. The stress and deformation analysis of the middle-rock-wall changes resulting from different intervals showed that when the middle-rock-wall thickness is less than 0.75B, the plastic zone expands rapidly and connects to the upper part of the middle-rock-wall. This result indicates that the latter digging of the tunnel has great influence on the force and deformation of the middle-rock-wall and on the force of the initial structure of the advance tunnel. Under the unfavorable situation of D/B=0.5, grouting can be used to reinforce the middle-rock-wall; furthermore, grouting can also greatly reduce initial support force and improve the stability of the surrounding rock. Analysis results further show that the maximum axial force can be reduced by 49.1%, and that the maximum bending moment can be reduced by 29.1%. Thus, the stability of the surrounding rock is greatly improved through grouting reinforcement.

Wave force effects vary with regular waves on different sections of bridge piers of different sizes in deep water. To solve this problem, this study calculates the wave forces in deep water piers under different wave parameter conditions, as well as the value of wave forces in the different sections of piers, using the computational fluid dynamic numerical analysis method. Results show that in the case of other conditions being the same, the section sizes and wave force are large. With increasing wave length and wave height, wave forces basically multiply. On the free surface at the pier bottom, wave forces gradually decrease to zero. Wave forces are loaded on piers with different sizes. The maximum displacement at the pier top is small, and the maximum stress increases at the pier bottom. The natural frequency is high.

At present, chemical admixtures are usually added in concrete mixtures when all ingredients are mixed together either by one-time input or in batches for various purposes. The present study proposes a new method for lightweight aggregate (LWA) concrete or combined aggregate concrete, wherein porous and hydrophilic LWA are presoaked in chemical admixture solution with the appropriate concentration. Poly carboxylic acid-based-super plasticizer and setting retarder were prepared and added individually in combined aggregate concrete in different ways, as follows:(1) one-time direct admixing into a concrete mixer; (2) blending in concrete mixture in batches; and (3) absorbing into LWA particles in advance. Time-dependent slump and setting times of concrete mixtures were investigated, which proved that chemical admixtures can be stored in porous aggregate particles beforehand by means of presoaking. LWA, with the internal pores as sustained-release capsules, become temporary carriers of water and chemical admixtures. Once relative humidity in the concrete mixture falls, the molecules of chemical admixtures gradually move out with water migration to play a persistent part in, for example, successful slump loss reduction or setting time adjustment.

This paper proposes a method for increasing the efficiency of identifying key nodes in a road network, especially in large-scale complex ones. The method was established based on spatial weighted degree and local improved structural hole (LISH) models by using node degrees fused with traffic characteristics. The node degree was redefined, and the traffic characteristics of a road network were integrated into the LISH model. The proposed method for calculating key nodes was validated using the backbone road network of Shaanxi Province. Result confirms the feasibility and rationality of the model. The improved LISH model is also more effective than existing models in identifying key nodes in the road network. This study provides a technical basis for determining key nodes of large-scale complex road networks by using GIS.

The traditional four-step traffic demand forecast model is limited by the long processing time and high cost of OD matrix investigation. A dynamic traffic assignment model is difficult to establish for a large-scale network. To obtain the traffic character and quickly search the shortest path of different zones for dynamic route guidance, we analyze travel distance and travel time using taxi GPS data, fit the travel time and stop time relation curve, and propose a method of traffic analysis using the two-fluid curve. We find that the bandwidth of the two-fluid curves is valuable for traffic operation and guidance. Subsequently, we analyze the relationship between unit distance travel time and unit distance stop time of different zones. The results verify that the sensitivity of different traffic zones varies. Finally, matrix iteration is used to calculate the shortest travel time path under different unit distance stop times, and the OD travel time matrix is analyzed. The findings indicate that the two-fluid method can be used for dynamic route guidance.

To prevent traffic signs from appearing in different degrees of geometric distortion in complex environments, the invariant moment, which includes translation, rotation, and scaling invariance characteristics, is used in image recognition. First, images are pre-processed. Second, the Zernike and Hu invariant moments of the images are extracted to establish the corresponding feature datasets. Third, the data set is inputted into a support vector machine (SVM) for target classification. Real-time-collected images and the recognition image database in German traffic sign recognition benchmark are used in the experiment. Compared with extracting the Hu invariant moment, extracting the Zernike invariant moments and using SVM recognition both demonstrate a higher real-time recognition rate for traffic signs in a complex environment.

In the downhill braking process, the high temperature of the service brake of heavy-duty trucks can lead to braking failure. To solve this problem, a brake heating model for heavy-duty trucks equipped with auxiliary brake systems is investigated. On the basis of coasting test, engine braking test, exhaust braking test, and eddy current retarder braking test, the model is established according to vehicle dynamics theory, energy conversion principle, and energy dissipation principle. Road tests are conducted to verify the accuracy of the model. Results demonstrate that the model accurately reflects the heating characteristics of the brake. Using this model to predict the brake temperature in different combined brake conditions is important to prevent traffic accidents caused by heat fading.

Currently, courier delivery is not efficient enough because of synchronization requirements of time and location between the courier and customer. To solve this problem, a new express delivery mode based on automatic parcel machine (APM) is proposed. Under the new delivery mode, a mathematical programming model is established to minimize the number of delivery vehicles and total vehicle mileage, considering constraint conditions such as vehicle loading capacity and specific driving order requirements for vehicles from customer demand points to their subordinate APMs. Based on the complexity of the problems and advantages and disadvantages of genetic algorithm (GA) in solving this kind of problems, the cellular genetic algorithm (CGA) is proposed. An analysis of examples shows that CGA is superior to the normal GA in terms of searching ability and efficiency, and it can solve large-scale express vehicle delivery routing problems based on APM.

With the industrial modernization in China, dangerous goods (DG) play an increasingly important role in the entire industrial system. The relevant laws, technologies, and management systems have progressed to some degree, but many problems that cause DG Transportation accident vemain. The explosion in the Rui-hai DG Logistics Corporation at the Tianjin Port threatened the safety of residents and properties and caused pollution and damage to the ecological environment. DG transportation must depend on special assets. However, this type of asset is not adequately available in the country, and certain unknown troubles exist. For example, staff members have no sufficient abilities and are inefficient, specific material assets are limited, and specialized assets are restricted and not environmental friendly enough. To solve the problems in DG transportation, we should intensify the construction of legal and standardized systems, implement overall management and supervision in every aspect, widely promote intelligent management and tracking, and effectively practice professional operation and management on the basis of advanced experience. By doing so, we can ensure the safety, efficiency, and quality of DG transportation.