Applied Mechanics and Materials Vols. 256-259

Abstract: Subgrade settlement is a complex process system. Commonly used single-point prediction models can’t consider the correlation between the discrete deformation monitoring points, which doesn’t adequately reflect the overall deformation law of subgrade. A multivariable grey model (MGM(1,n)), which is an expansion of the single-point GM(1,1) model for multiple variables, is introduced to resolve the above problem. Aiming at the drawback of background value in the traditional MGM(1,n) model, the functions with non-homogeneous exponential law are used to fit the accumulated sequences for every variable, reconstruct the calculating formula of background value, and gets a new MGM(1,n) model based on optimized background value (OMGM(1,n)). A case study shows that the forecast result of the proposed model is more precise and effective than these of the single-point GM(1,1) model and the traditional MGM(1,n) model for predicting subgrade settlement.

Abstract: In this paper, subsidence diseases of the semi-filling and semi-excavating subgrade in Shao-huai expressway are taken as an example. And the causes of disease of subgrade subsidence are analyzed. The pertinent scheme of grouting reinforcement is designed. According to the subgrade subsidence, the grouting technology of vertical and horizontal porous tube is proposed innovatively. The FWD means of non-destructive testing is used to evaluate the effect of grouting. The results of the evaluation show that the technology of grouting reinforcement by porous tube can achieve the good grouting effect and solve the treatment problem of subgrade subsidence effectively.

Abstract: According to the statistical analysis of the accident data about 490 km of expressways, the safety of shoulder width was studied and the relationship between the shoulder width and the total accident rate and the mortality rate was analyzed. Researches indicate that the impacts of shoulder width on the total accident rate and the mortality rate are not always the same. Overall, wider shoulder can raise the safety of expressways, which provides basis for rebuilding the expressways whose shoulder widths don’t meet requirements and regulations in China.

Abstract: Based on three expressway in hunan province，through site investigation and laboratory test，mainly according to the characteristics and causes of subgrade failure，the subgrade failure in the work area were divided in to 10 types. The influence mechanism of moisture content，degree of compaction，soil property and so on were analyzed in detail. The conclusion can provide reference for the prevention and treatment of subgrade failure.

Abstract: When a truck passes on the expansion joint of an expressway bridge, the tire spring vibration of the truck is generated by short wavelength road roughness. Moreover, environmental vibration problems, such as infrasound and ground vibration, occur as a result of the impact force of the tire spring vibration. Then, IRI_10 analysis using a quarter car model was carried out using short wavelength road roughness in the expansion joints of Japanese expressways. This study proposed the IRI_10 value '7 mm/m' and an estimation method for repairing short wavelength road roughness.

Abstract: As vehicle flow on arterial highway in Inner Mongolia sharply increased, the originally designed natural increase rate of 8% per year has been exceeded on the vehicle flow in some sections. According to statistics, monthly average vehicle flow on major section of G6 expressway has reached a standard flow of 67478 vehicles per day and night, of which in 70-80% are large ones for coal transportation. Therefore, pavement load and road capacity have exceed the designed expressway load capacity. At present, semi-rigid base asphalt pavement structure is still widely used for high-grade highway pavement in Inner Mongolia. With years of construction for such pavement structure, a great deal of valuable experience has been gained on construction technology. However, there are still a few deficiencies in the quality of raw materials, gradation control of asphalt mixture and adjustment of equipment, etc. Hohhot circle expressway connects with the G6 and G7 expressways, suffering from problems such as large vehicle flow and load overweight. This paper introduced a key technique that should be properly controlled during construction of such pavement structure, emphasized technique control and management of the following aspects, i.e. ballast sizes and gradation control, asphalt concrete mixture, adjustment of pavers, validation of mixing proportion in production and reasonable arrangement of process, and summarized corresponding technical measures taken during construction of asphalt pavement in this project.

Abstract: Based on the real-time settlement monitoring of embankment on-site, Hyperbola method and Index curve method are used in the prediction of embankment settlement and the prediction results were compared to verify the feasibility and the potential engineering value of the prediction of embankment settlement. The calculation results showed that the relative error of the results calculated by the above methods was controlled within 2%. The accuracy of early settlement prediction of Index curve method was lower than the accuracy of later settlement prediction, but the predicting result met the needs of the engineering accuracy. The accuracy of settlement prediction of Hyperbola method was significantly higher than Index curve method. Through the comparing and analyzing of the prediction results of embankment settlement, the final settlement value calculated by Hyperbola method was higher than the real-time monitoring on-site, and the final settlement value calculated by Index curve method was lower than the real-time monitoring on-site, Hyperbola method is more suitable for the estimation to the subsidence of actual embankment engineering construction.

Abstract: Absolute measuring principle of the high-speed rail was introduced to the measurement of existing speed rail. The line parameter reconstruction and long-wave smooth management is implemented. CPIII control points are laid along existing speed rail. Using the track fine-adjustment instrument, the center geodetic coordinates of midline of track were measured precisely. By least squares fitting method, parameters of straight line between curves was calculated. Plane curve were reconstructed based on measured geodetic coordinates of the continuous rail. The optimization results were used for the theoretical basis, and smoothness of 30 meters chord and 300 meters chord of rail were analyzed, and adjustments of plane curve were calculated to meet the long-wave smooth of rail.

Abstract: The factors of asphalt-aggregate adhesion were studied. Based on the expression of the adhesion work between the asphalt and mineral aggregates, several factors concerning the influence laws on asphalt-aggregate adhesion were analysed. The adhesion work of compatibility among the preparation temperature, aggregate types, and asphalt quality were calculated. The preparation temperature is found to be inversely related to the adhesion work. Among the four kinds of asphalts, the styrene-ethylene/butylene-styrene-modified one has the optimal adhesion with the mineral aggregates. Among the three kinds of aggregates, limestone has the best adhesion with the asphalts.

Abstract: The thermal stress of asphalt pavement is one of important factor that bring pavement destruction. This dissertation using large-scale finite element analysis software-ABAQUS built the model of asphalt pavement thermal stress field with continuous temperature changing. It analyzed the effect of the change of asphalt pavement material parameters on thermal stress. The results indicate that temperature-dependent elastic modulus, property of temperature contraction and Poisson ratio can influence thermal stress, especially when the three parameters changing with temperature at the sametime, it has greater influence.