The traditional design method for semirigid materials is unsuitable for the design and construction of modern road recycled building materials due the high water absorption property of construction waste recycling aggregates. Therefore, this study compares the mix design results of the traditional and rotary compaction methods of recycled aggregate cement-stabilized gravel. Test results indicate that the optimum water content obtained using the rotary compaction method is smaller than that obtained using the traditional method, and the dry density index of 80 compaction times complies with the design results of the traditional method, whereas the strength of the specimen is higher than that of the hydrostatic specimen. When cement content exceeds 7%, the strength of the material is mainly influenced by the cement, and the forming method minimally affects strength. The rotary compaction method is more suitable for the design of cement-stabilized recycled aggregates. The optimum water content and the maximum dry density of the cement-stabilized aggregates have a stable number of compaction.

Two 3D finite element models are established to analyze the mechanical response of road construction and solve the problem in which the actual fatigue life of the overlay is significantly shorter than the designed value. The first model is composite pavement with multiple overlays, whereas the second model is pavement overlaid with the same thickness of asphalt concrete. Calculation result indicates that interlaminar bonding condition significantly affects shear stress and tensile strain, and the value calculated by the second model is smaller than that calculated by the first model, which may lead to unsafe design. The following conclusions can be drawn based on the tendency of interlayer shear to form along the direction of road depth. (1) The interlaminar shear of old pavement decreases when overlaid with asphalt concrete, whereas maximum shear stress always occurs at the bottom of the surface layer. (2) When pavement overlay frequency is increased, the interlaminar shear value of the surface layer will be increased. The value of interlayer shear stress mutation increases with the frequency of overlay. The simulation results show that the service life of asphalt overlay decreases with the frequency of overlay, which indicates that overlaying asphalt cannot improve the stress state of the surface layer. By contrast, the comprehensive influences of interlaminar bonding condition and composite load will increase surface stress, which may eventually intensify surface damage.

The effects of environment and fatigue on the electrical resistance and piezoresistivity of the carbon nanotube/cement composite is investigated under a service environment using a four-probe method. The main influencing factors include temperature (20, 30, 40℃, and 50℃), water content (0%-6.4%), temperature and water content coupling, and number of fatigue cycles (20, 40, 60, 110, 160, and 240×10³). Test results showed that environment and fatigue considerably affected resistivity and piezoresistivity. The resistivity of the composite decreased as water content increased. When water content changed from 1.3% to 5.8%, resistivity was reduced 43%. By contrast, piezoresistivity and change in resistance initially increased and then decreased as water content increased. Temperature substantially affected resistivity and piezoresistivity. As temperature increased, resistivity decreased but piezoresistivity increased. Electrical resistance and change in resistivity exhibited a strong linear relationship with temperatures ranging from 20℃ to 50℃ with an R2 of over 0.99. As temperature increased from 20℃ to 50℃, resistivity decreased 35% and change in resistivity increased 84%, thereby indicating improved piezoresistivity. Piezoresistive sensitivity to temperature demonstrated a strong negative linear relationship with water content with an R2 of 0.915. Electrical resistance and piezoresistivity increased as the number of cycles increased. The major causes of changes in resistivity and piezoresistivity are a change in tunneling conduction and the development of micro-cracks.

To study the combination principles of structural design and material design in asphalt pavement with semi-rigid bases, the software BISAR3.0 was used to analyze the load responses in asphalt pavement with two layers of semi-rigid base courses, and its inversed structure. Then composite beam specimens composed of two kinds of cement-treated macadam with different cement contents were then fabricated, and four-point bending strength and fatigue tests were conducted. Results indicated that the lower semi-rigid base layer (lower base) undertakes greater tensile stress than the upper semi-rigid base layer (upper base), and the fatigue life of the pavement structure is dependent on the lower base. Therefore, using inferior materials for the lower base and superior materials for the upper base is unreasonable. The inversed structure can fully utilize each material, and its bearing capacity and fatigue resistance were considerably improved. Thus, pavement structural design should be combined with material design according to the tensile stress state in pavement layers.

This study aims to establish an appropriate method to calculate the bearing deformation of large-diameter bored piles in alluvial deposits with soils characterized mainly by medium-dense to dense silt, fine sand, and plastic to hard plastic silty clay in the middle and lower reaches of the Yellow River. According to the field measurement results of 18 large-diameter bored piles in six sites of the third-ring expressway project in Zhengzhou, this study discusses the action laws of pile shaft friction with pile-soil shear displacements and pile tip resistances with pile end displacements. A pile shaft load transfer model and pile tip bearing model are then established for large-diameter bored piles. The calculation parameter values are also given. The feasibility and rationality of the calculation method are verified by an engineering example. According to the engineering example and by changing the parameters of the pile diameter and pile length, the properties of bearing capacities and deformations of the large-diameter bored piles under this site condition are further analyzed. Results show that the inflection point of the pile Q~s curve is obvious for large pile diameters. The pile bearing capacity and deformation property are significantly improved by increasing the pile diameter under a small load. The increase amplitude of the pile bearing capacity and deformation property obviously decreases with the increase in pile length. This result indicates that the improvement of the pile bearing capacity and deformation property by increasing the pile length is not effective. The pile without grouting shows an obvious puncture damage model. Moreover, the settlement of the pile without grouting is small with a large pile diameter or short pile length. The effective length and bearing capacity of a large-diameter bored pile can be greatly increased by pile tip post grouting. The increased value of the pile bearing capacity is high with a large pile diameter and pile length under pile tip post grouting conditions.

This study evaluated the characteristics of temperature field distribution of the concrete box girder based on the middle bridge of Xiaosha River, and the effects of temperature in severely cold area were determined through experiments and finite element model (FEM) analysis. An FEM model of the concrete box girder considering the temperature field was established based on heat transfer theory to verify the accuracy of the model. Moreover, the calculation of the vertical temperature distribution and the temperature distribution along the web plate was conducted. The distribution along the through-thickness direction of the bottom plate and the temperature drop caused by cold waves was evaluated. Results suggest that the published codes and guidebooks were relevant. The effect of the most unfavorable condition of temperature load was also calculated. The result drawn from this research shows that the distribution of temperature field at the cross sections in the severely cold area differed greatly from that in the current code. However, the temperature difference in the top flange was not evident, whereas it was much larger in the bottom flange. The temperature in the web was higher than that in the top flange under solar radiation and was lower during cooling. The results of the temperature effect were much more critical than the result calculated using the vertical temperature gradient in the current code. The tensile stress produced by temperature load may cause cracks. Consequently, sufficient attention should be paid to the damage of thermal effects when calculating the concrete box girder in the northwest of the severely cold area.

The settlement of tunnel vault, which is a complicated process that includes combined actions of multiple factors together, is difficult to calculate accurately with mathematical model. In the actual construction process, the surrounding rock often changes, so we must strictly control the tunnel vault settlement to meet design requirements. Traditional prediction models can obtain only a rough estimate of the vault settlement by using the monitoring data to fit and forecast its changes. To solve the problem, this paper constructs a time-series model, GM (1, 2) model, and BP model with input variables to predict the settlement of the vault. The effectiveness of the model is verified by examples, which show that the GM (1,1) prediction model of a single variable is completely ineffective. To avoid the lower prediction accuracy of single model and use the complementary advantages of different models, this paper establishes an integrated prediction model based on the above three models, and its weighting coefficient is determined by the application of the entropy method. The model is applied to Baimiaozi Tunnel for testing, which provides high-speed travel from Baoji to Hanzhong (two cities in Shanxi Province). The integrated model is effective in practice and has a high prediction accuracy.

To study the physical and mechanical properties of tunnel lining concrete under high temperature combustion, concrete specimens were developed by consulting the concrete proportioning in Xiangan subsea tunnel lining. After combusting the specimens under high temperature, two types of cooling methods were used, namely, natural cooling and water spraying. The thermal expansion and deformation characteristics, compressive strength, elastic modulus, and anti-permeability of concrete after high temperature were analyzed. Results were as follows:(1) Water spray cooling had a significant effect on the thermal expansion of concrete at high temperature, and natural cooling greatly influenced the elastic modulus and anti-permeability level. (2) If the axial strain was the same, then the transverse strain increased with the increase in temperature when the temperature was below 600℃. However, when the temperature was higher than 600℃, the transverse strain decreased with the increase in temperature. (3) With the increase in temperature, a linear relationship existed between the compressive strength of concrete and the temperature under natural cooling condition. However, under the water spray cooling condition, a nonlinear relationship was observed.

This study combined the coordinated control and time-of-day strategy to improve the stability and benefit cost ratio of the control strategy in the context of China's traffic condition. The coordination boundary was determined by the coordinatability model of intersections. The traffic volumes of intersections in the research area were dealt with the mixed clustering method to obtain the corresponding time-of-day strategies. On the basis of the previous study, the multiple-objective particle swarm optimization is used for the average delay to find the best switching time for time-of-day control. Relevant simulation indicates that when compared with current traffic control plans and mixed clustering optimization, the proposed strategy shows more advantages in termsof bandwidth of traffic control plan and delay optimization. After minimizing the disturbance caused by switching traffic control plans, the resulting decrement rate of average vehicle delay is 12.63% for the current traffic control plan and 2.45% for the mixed clustering optimization; the increasing bandwidth rates of the traffic control plan are 0.98% and 23.51%, respectively.

To study the advance distance of guide signs of expressway exit, we divide driving behavior in expressway exit into five processes according to the characteristics of the driving psychology principle and drivers' response to signs. A model of guide signs of expressway exit is built to calculate the advance distance of guide signs that meets safety and comfort requirements. The proposed model is established on the basis of the insertion gap travel distance model and isokinetic deviation sine curve model of vehicle lane changing distance. Through the analysis of the setting mode of guide signs, we calculate a reasonable distance for guide signs under different road conditions and different driver characteristics. The proposed model is developed with the UC-win/road and simulated by the Forum8 driving simulator. Simulation results show that only the distance of the advance signs of a two-way four-lane expressway exit is close to the specified value of Road Traffic Signs and Markings, which is reasonable; while for expressway with six lanes and above, the specified value is small.

To optimize the supplier selection and order allocation procedures of purchasing management and improve their efficiency, this study employs mathematical statistics theory and optimization algorithm in building a two-stage analysis method implemented in MATLAB and LINGO software. Specifically, the AHP-EM and TOPSIS methods are used to select the suppliers in phase 1. The weights produced in stage 1 are applied to the multi-objective mixed-integer programming model to study the order allocation in phase 2. On the basis of an example, the impact of information sharing rate on supplier selection, order allocation, and total cost is determined. Finally, the solution to this problem under the Total just-in-time environment is found to be better than that in the general environment. The study of this issue offers important theoretical and practical significance by extending supply chain management theory, improving the enterprise supply chain management level, and enhancing the core competitiveness of enterprises.

Highway passenger travel demand forecasting provides an important basis for travel planning. Considering the relationships among travel modes (highway, railway, and aviation) is necessary to accurately predict travel demand. On the basis of such relationships, influencing factors, including population, gross regional product, highway kilometers, high-speed rail construction, and aviation facility accessibility, are selected to construct a dummy variable model for forecasting highway passenger travel demand. On the basis of the chosen dummy variables (high-speed rail construction and aviation facility accessibility), model formation includes the following four conditions:no high-speed rail construction and low aviation facility accessibility; high-speed rail construction and low aviation facility accessibility; no high-speed rail construction and high aviation facility accessibility; and high-speed rail construction and high aviation facility accessibility. We measure these conditions using panel data at the city and provincial levels of China for the years 2000-2014. The error analysis between the forecasting results and accurate data collection at the National Bureau of Statistics of China verify that the model formation is correct. Results show the travel demand differences under various conditions. The elasticity coefficients among the influencing factors of travel demand explain the co-opetition relationships among travel modes. These results provide valuable guidance to the sustainable development of a passenger transportation system.

To research and study the topology of a hazardous material transportation (HMT) network, we analyze the properties of path choice models and their problems and build an appropriate normative and standard frame. We present a case study on the HMT network of Chengdu City. In accordance with the created pattern, we use ArcGIS and MATLAB software to initially design and construct the topology network of HMT and calculate the necessary and related topology data. A same-size random network is then generated for comparison with the HMT network of Chengdu City. Comparison result shows that the topology of the HMT network has stochastic properties. First, the frequency of node degrees follows a Poisson distribution. Second, through linear, Gaussian, and power law fitting, the cumulative probability of node degrees follows a Poisson distribution if the R2 is a decision-making condition. Finally, the degree distribution of nodes is concentrated on node degrees 2-4, and the average node degree is 2.968 2. According to these results, the related government department and the transport company can determine a scientific and effective method of designing an HMT network in urban cities.

Overload and oversize transport not only causes serious damage to highway, but also brings about irreparable traffic accidents. WIM technology can control the overload and oversize of vehicles and provide a reliable basis for the heavy truck toll collection. The main existing WIM equipment includes bending-plate (weighing part wheel load), single-scale-platform (weighing load of single-axle), double-scale-platform (weighing load of single-axle), axis-group-scale (weighing weight of axis-group), and vehicle-scale (weighing total weight of vehicle). They have many advantages and disadvantages in cost, installation, maintenance, traffic efficiency and accuracy of WIM. The WIM accuracy is one of the key indicators considered in application of technology governance, toll by weight, and traffic investigation. The carrier length of WIM system increases gradually with the increase of WIM accuracy, which leads to the construction cost and time increase also. In order to ensure the WIM accuracy, considering the economy of the carrier length, based on the vibration characteristics of the vehicle and the scale, the mathematical model of the WIM signal is established by means of moving average filtering and B spline least square method, and the vibration disturbance of low frequency dynamic load is effectively eliminated. The test result shows that (1) the weight error is less than 0.5% if test vehicles pass through the 0.8 m and 1.6 m long scales in the speed range of 0-5 km/h and 0-12 km/h, which meets the national standard about Class 1 scale; (2) if test vehicles pass through the 2.6 m and 3 m long scales with the theoretical limit speed of 20.7 km/h and 24.3 km/h, the statistical weight error is less than 0.5%. The research not only provided a theoretical basis for design the length of the scale, but also has important reference value for improvement of the WIM accuracy of the existing installed single scale and double scales.