With the basic principle of polymer chemistry and physics as basis, the preparation technology of colored asphalt was proposed and main technological parameters and parameter level were selected. The influential technological parameters in different levels acting on the performance of cementing material were analyzed through range analysis. On this basis, the critical factors affecting the performance of cementing material and optimal technological parameters for cementing material preparation were found.

To explore the working mechanism of retaining a wall reinforced with denti-geogrids, the numerical simulation of a pullout test was performed, the working behavior and influencing factors were analyzed, a generalized model was suggested, and an ultimate pullout force calculation formula was proposed. The research obtains the following results. (1) The horizontal displacement of the inner segment of the geogrid is relatively small because of the denti-strips. (2) The displacement gradients of the denti-geogrid are evidently large, whereas the horizontal displacement core is approximately 25 cm outside the denti-strip. The peak value of the horizontal displacement is approximately 3 cm. (3) The pullout force peaks when the denti-strip is approximately 3 m from the lateral boundary. The effective span is extended, and the resistance of the denti-strip increases with denti-strip spacing. Denti-strip height is positively correlated with the pullout force, whereas the influence of thickness is insignificant. (4) The working mechanism of denti-geogrid can be roughly described by three processes, namely, compaction, detour flow, and convergence. (5) The calculation values of the ultimate pullout force obtained from the generalized model are close to the numerical test results. Thus, the applicability of the suggested model was verified.

In special situations, the treatment plan for embankment failure is hindered by cracking and sliding failure in highway embankment slopes. For example, the prestressed anchor cable or bolt frame beam is not suitable as the absence of a hard anchorage ground layer,or slip deformation embankment cannot be removed and rebuilt to protect the existing sub-grade. An ideal solution in this situation is to use grid-work girders of oblique steel pipe piles. The grouting of oblique steel pipe piles is a method that uses a composite foundation of steel pipe piles to reinforce slopes. Specifically, grout is embedded into steel pipe piles and passes through the sliding surface. Grouting can change deformable soil into composite soil and protect steel pipes from corrosion. Steel pipe piles serve as reinforcement by applying anti-slide force directly onto the soil. By means of a successful example of slope deformation treatment, this work discusses the scope of the application, the stress characteristics, the changes in slope stability, and the reinforcement effects after slope strengthening. The results would benefit engineering projects involving similar slope failure treatments.

To investigate the law that governs changes in excess pore water pressure during the sinking of a pipe pile with a group of holes, excess pore water pressure is monitored during the process of sinking a pile between a pipe pile without holes and three types of pipe pile with holes based on model test. The influences of the time-space dissipation of excess pore water pressure are analyzed by considering the factors of sinking pile sequence and disposal hole mode. The variation rules for excess pore water pressure dissipation with time, depth, radial distance, and sinking pile sequence are also established during the process of sinking the pile. On the basis of comparison and analysis, the pipe pile with holes, which are penetrated in a radial manner, achieves the lowest excess pore water pressure peak and the fastest dissipation rate, which are the most favorable conditions for reducing the squeezing effect of the pile, and the best pile driving effect is achieved. Moreover, the results can provide a reference for the application of pipe piles with holes in engineering practice.

Issues in the consolidation deformation of saturated clay have a close relationship with its permeability. In this work, a modified K₀ oedometer was used to conduct a variable water head permeability test. The changing law of the initial water head H₀, effective void ratio, and permeability and effective permeability coefficients were analyzed under various load degrees combined with the concept of efficient void ratio of saturated clay. Our study showed the following results. The initial water head of undisturbed soil could be divided into two stages:rapidly increasing and slowly increasing, the initial water head of disturbed soil was related to the change rate of the total water head. The efficient void ratio of undisturbed soil decreased with an increase in consolidation pressure. The change law of the void ratio of disturbed soil was similar to that of undisturbed soil. In addition, when the soil structure tended to fail, the structural differences tended to be consistent. If the efficient void ratio was large, then the permeability coefficient was also large. The permeability coefficient of clayey soil was related not only to soil structure but also to initial void ratio. Finally, the efficient void ratio and the water head and its change law had a considerable influence on consolidation.

An example of a project on an oversized box culvert jacked into highway subgrade in Guangdong area was investigated to determine the mechanical behavior of shallow soil-covered super-long box culvert in the jacking construction process. On the basis of 3D finite element simulation, the law for stress-strain change and the effective construction area of the box were studied by considering different lengths and thicknesses and drag reduction versus non-drag reduction of overburden soil. Result shows that under the same working condition, the stress-strain of the roof and bottom plate exhibits an "armchair" change shape with an increase in jacking length, whereas the side wall presents a "trapezoid" shape in the box culvert jacking process. The thickness and characteristics of the covered soil (on top of the box culvert) exert considerable influences on the stress-strain of the box culvert structure. If the covered soil is thick and dense, then the stress-strain of the structure will be high. The pavement (on top of the box culvert) settlement ranges from 7.0-17.1 mm due to the effect of vibrations produced during box culvert jacking construction, and the scope of the disturbed roadbed and road surface is 23-30 m along the jacking direction. The drag reduction effect of the paraffin oil mixture is more effective than that of slurry drag reduction. The research results will play a significant guiding role in the design and construction of similar projects.

Compared with traditional cast-in place piers, prefabricated piers have many advantages and been applied in an increasing number of bridge structures in recent years. However, inferior seismic performance hinders the development of these innovative piers. Improvement methods for the seismic performance of prefabricated piers have thus been studied. However, systematic discussions on the advantages and disadvantages, applicability, and concepts of these methods are limited. Thus, this study comprehensively compares and analyzes improvements in the seismic performance of prefabricated piers. The background of the problem is first discussed. The main measures for improving the seismic performance of these structures are then summarized and classified into four categories. Furthermore, concepts and methods relevant to these measures are analyzed. Finally, main issues that warrant further study are proposed. This work provides reference for the future research and engineering practice of prefabricated bridge piers.

Sand excavations at river beds have compromised the safety of several bridges in recent years. An expressway that connects a huge line bridge is selected as the research object in this study.The phenomenon of the excessive digging of river sand under a bridge is considered, and the influence of the development of bridgeson bridge carrying capacity and safety is studied through theoretical analysis, numerical simulation, and field test.Research results show that dredging under the bridge has reduced the bearing capacities of pile tip soil and single pile, but has less effect on the deflection and bending moment of the pier studand the mid-span deflection on the girder. When test vehicles run on the bridge, the increase in the vertical and portrait dynamic displacements of the sand excavation bridge pier top is less than that of the sand bridge pier. Braking will result in a significant increase in dynamic displacement compared with the working car test data. Experimental data on passing cars are considerably larger than those on the traction test vehicle, and passing cars are seriously overloaded. Under the action of test vehicles and passing cars,the dynamic deflection change of the girder mid-span is not evident. Vehicle weight is the main factor that influences the vertical displacement of the pier top.When avehicle brakes, longitudinal braking force is the main factor that influences the portrait displacement of the pier top. Braking on the bridge is highly detrimental.Therefore, measures, such as speed limit, weight limit, and reinforcement,should be taken to avoid water scouring and to ensure the safety of the bridge structure.

A model experiment is performed to test the rockfall impact force applied to frame shed tunnels under the protection of different types of cushions embedded on tunnel roof slabs. The changing rule of impact force induced by rockfall is analyzed according to different impact energies and types of cushions embedded on shed tunnels. An enlargement coefficient reflecting the relationship between average impact force and maximum impact force is presented using experimental data and theoretical analysis. The improved method for calculating rockfall impact force can consider the many factors that affect this phenomenon. For a particular rockfall impact energy, the rockfall impact force with different types of cushion properties is affected by the cushion property function f~(h,E,μ,γ). A large f value equates to the minimal discreteness of the expansion coefficient of rockfall impact force under different types of cushion, and vice versa.

The thickness of the loose circle of surrounding rock is an important index in tunnel support parameter design and rock mass stability evaluation. Accurate and rapid determination of thickness is critical to ensure the safety of underground chamber construction. Field test is the most intuitive and accurate method for thickness determination. Acoustic method is also widely used because of its high precision, low cost, and simple operation. However, existing discriminative standards for analysis of test results are ambiguous and subjective; as such, a uniform standard that defines a loose circle has not been established yet. In this study, the complete degree of rock and loose rock mass is quantitatively analyzed by introducing the concept of and the calculation formula for the integrity coefficient of broken rock (R_v) and the integrity coefficient of loose circle (L_v). According to the formation principle of loose circle, the criteria and test method for surrounding rock loose circle are proposed on the basis of the integrity coefficient. The integrity coefficient of the loose circle (R_v) is assumed to be approximately equal to that of the broken rock (L_v) in chamber excavation. In the test of the surrounding rock loose circle in the Shimen tunnel at Baohan highway, the integrity coefficient (R_v) of the rock of the grade Ⅲ gneiss was 0.53 according to the combined indoor and field tests. The thickness of the type Ⅲ surrounding rock loose circle was 0.55-1.35 m, and the distribution along the circumference was not uniform. The arch shoulder was thick, and the wall was thin, consistent with the initial stress state of the surrounding rock. Comparison with the results of the original acoustic wave loosening test showed that the new discriminant method based on the integrity coefficient is more accurate and reliable. The proposed method could be used for the design and construction of tunnels.

To express information on construction project risks comprehensively and precisely and to improve the accuracy of the results of the ranking of construction project risk factors, we use the interval grey degree to express grey characteristics of information. The membership degree is used to express fuzzy characteristics of information. An uncertain linguistic variable is used to express linguistic descriptive characteristics of information. A ranking model for construction project risk factorsis proposed to identify the main risk factors on the basis of the interval grey fuzzy uncertain linguistic set and the continuous interval argument ordered weighted averaging (C-OWA) operator. We take the Weft Three-Road Cross-River Tunnel in Nanjing as a case to verify the feasibility of the proposed model.. Research results show that compared with fuzzy sets that can only use membership degree to express fuzziness, the interval grey fuzzy uncertain linguistic set can express the grey, fuzzy, and linguistic descriptive characteristics of practical construction project risk information simultaneously. The proposed model based on the theory helps to improve the comprehensiveness and authenticity of risk information expression, as well as the accuracy of risk factor rankings. The results of this work could assist project managers in determining main risk factors and thereby provide a theoretical basis for taking pre-control measures.

A model of a parallel-type acceleration lane length based on the dynamic merging process is established in this study to determine the need for parallel-type acceleration lane length of merging vehicles. The model considers road operation and design attributes, driver attributes, vehicle attributes, and several random attributes in the insertion process, and sets random attributes as the breakthrough point. Furthermore, Monte Carlo simulation is used to solve the model. The case study introduces the use of the model and proves its applicability.

An original method is used to analyze the topology structure of a road network and two indexes of road network performance, namely, connectivity and network efficiency, are used to evaluate road network robustness in medium measure and thus quantify the variety of urban road network vulnerability caused by unexpected congestion. Then, a variety of road network impedances is set as the vulnerability identification index and a network traffic flow model with a link queuing capacity constraint is established, considering such constraint on unexpected congestion condition. Finally, a Lagrange dual algorithm is designed to solve the model, whose accuracy is subsequently tested by an example. Results show that the model based on the vulnerability index can accurately recognize road network vulnerability. Invalid links caused by unexpected congestion lead to changes in road network impedance, thereby directly affecting the robustness of the entire road network.

In charging station services, user charging requirements limit the layout optimization of charging stations to realize total cost minimization. By combining the k-center algorithm and cloud model particle swarm algorithm, this study puts forward a method to improve the global search ability of the adaptive parameter adjustment strategy. A simulation is performed accordingly. Results show that when solving the layout optimization problem for charging stations, the improved adaptive hybrid algorithm that combines the k-center and cloud model particle swarm algorithm outperforms the original cloud model particle swarm algorithm and the basic particle swarm optimization algorithm. The improved algorithm is thus effective.

Choice-making in diverging in an interchange is affected by multiple external factors. Along with an analysis of the characteristics of drivers' choice-making in expressway interchanges, this study settles many other fundamental variables, including the selection tree, utility function, speed of vehicles on the main line, accelerated speed, hourly traffic volume of the ramp, time headway in the deceleration lane, and type of vehicle, etc. The two-level nested-logit probability model for drivers accepting ramp diverging and drivers' diverging choice behaviors modes is established. Based on the radar tracking data of part of diverging areas of interchanges in Guanghe expressway, the model parameters are estimated by the phased estimation method.According to t-test result, the influence degree of the characteristic variables is judged and the model is optimized. Results suggest that the choice behaviors of diverging at interchange is affected by multiple factors comprehensively, the two-layer nested logit probability model is featured by a higher prediction accuracy.