Advanced Materials Research Vols. 594-597

Abstract: To solve the early destruction problems occurred when overlaying asphalt pavement structure containing semi-rigid base on broken cement concrete pavement, finite element software is used to compare the stress characters between the repaving pavement and ordinary pavement, and analyze the repaving structures under different loads and different road transverse grade. It shows that the value of compressive stress at the top of base of repaving pavement is significantly higher than that of ordinary pavement, meanwhile, its value of tensile stress of base bottom is lower; the asphalt surface and new base top of repaving pavement need to bare a high value of shear stress and compressive stress under overload, so it’s prone to splitting failure in the base. With the increase of transverse grade, both the shear stress difference of road surface and maximum vertical compressive at top of the base increase in a lower position, but the situation is opposite in the higher position.

Abstract: Structural integrity of Subway station is a very important indicator when the earthquake happens as it is a densely populated venue. Time-history analysis of Tianjin metro line 3 based on the theory of coupling seismic load was done with the finite-element software ANSYS. Consequently, numerical expression of the equivalent load was fixed and the procedure of seismic check of subway station structure gets further simplified and necessary theoretical basis.

Abstract: Cement concrete pavement as a common form of the road has been widely used because of its high strength, stiffness, and good durability characteristics. In order to explore failure modes and the strength control factors of the cement concrete pavement in the region, site investigation and the orthogonal test method in laboratory are used. Test combination design for the main control factors of the cement concrete strength was executed based on orthogonal test method. Strength of concrete specimen was determined by using indoor pressure test machine. The results show that the chiefly control parameter of affecting concrete strength is water cement ratio and the following are sand ratio and the coarse aggregate grading.

Abstract: Safety performance of rural signalized intersections is critical for identifying high-risk sites and predicting the hazardousness. This paper aims to develop a predictive model that will describe the safety of rural signalized intersections based on various input variables. Data are examined from 124 rural signalized intersections over three states, and Poisson log-linear regression model is presented, which connected traffic number and the average traffic volumes, geometric characteristics and signalization characteristics variables together. The model and associated data analysis reveal that average daily traffic, media width, speed limit, degree of horizontal curvature and left-turn lane are the factors that have greatest overall effect on safety. The results show that the Poisson log-linear regression model is able to describe the rural signalized intersection safety accurately. Using this model, effective countermeasures can be applied for improving traffic safety.

Abstract: The pavement-subgrade interaction is an important issue in the concrete pavement design.The present study focuses on the analysis of the dynamic deflection and the velocity response of airport concrete pavements to impact loading. The pavement-subgrade interaction is simplified as a linear viscoelastic model, in which the subgrade is composed of two layers (a base layer and a soil layer). The subgrade’s synthetical modulus and damping coefficient are obtained by the method of weighed mean. Through the Fourier and the Laplace transform the solution of the equilibrium equation of the pavement-subgrade system is deduced and the dynamic deflection solution of the pavement-subgrade system is obtained. In this study, an impact aircraft landing load increasing proportional to the aircraft vertical landing acceleration is considered. A Matlab program is compiled based on the solution to assess the influence of various system parameters (slab thickness h, slab size, subgrade reaction modulus Ks and subgrade damping factor C0) on the dynamic deflections of the pavement slab. The influence of h and Ks on the dynamic velocity response of the slab is also discussed. The results show that changing the damping factor and the subgrade reaction modulus has only a small influence on the deflection of the slab and the deflection, while the amplitude of velocity response and the frequency of velocity responses all decrease with the increase of the slab thickness. If the pavement slab size is decreased, the deflection at the center of the slab will decrease. A nonlinear relationship can be established between h and the maximum deflection, while linear relationships exist between C0 and the maximum deflection, as well as Ks and the maximum deflection.

Abstract: In order to overcome the weakness of semi-rigidity base layer，the road performance of the SRX(Solution Road RomixSoilfix) stabilized base material and the mechanics response of asphalt pavement with the base layer stabilized by SRX have been studied in this paper. The CBR value and resilient modulus of SRX stabilized base material were given by indoor test. Based on the multiple layer elastic theory, both the mechanical responses of asphalt pavement structure with the SRX stabilized base and semi-rigid base were given, and according to the calculation results, the two kinds of pavement structure fatigue life were analyzed. The results have shown that the CBR value of SRX flexible material is greater than that of graded crushed stone; the SRX stable material can be used as pavement base layer, but the fatigue performance of SRX flexible base materials should be paid much attention.

Abstract: Nine test lab comparative test indexes of asphalt and asphalt mixtures are analyzed by consistent statistic analysis method of ASTM E691 and Robust statistical analysis method, analysis results indicate that two methods are basically in consistent with each other, but dubious analysis index is added in Robust statistical method, and reliability is possibly enhanced on data analysis. Combined with advantages and disadvantages of two methods, the paper suggests that two statistical method can associated with each other in statistical data analysis.

Abstract: Evaluation for traffic safety is very important to improve traffic safety. First analyzes high grade highway security characteristic, then according to grey characteristics of traffic safety system, proposed high grade highway grey clustering evaluation model, and carries on the model to Henan province high grade highway's safe condition status evaluation, thus confirms this method the validity. The research showed that this model is a effective way which measure high grade highway transportation degree of security.

Abstract: In order to eliminate the harm of salt heaving, the gravelly substructure was used to replace the tradition concrete stabilized grit substructure. And the construction technology was strictly controlled. Finally, the technology is testified by practice to avoid the salt heaving availably.

Abstract: Composite foundation is commonly used to control the soft soil subgrade settlement. Considering that post-construction settlement of high speed railway is strictly controlled, it’s supposed to use jet grouting pile to strengthen the existed composite foundation and it’s necessary to analyse the effectiveness. Take a line as an example, analyse embankment settlement regularity of the original design mixing pile reinforcement and jet grouting pile reinforcement, evaluate the effect of the jet grouting pile reinforcement. The results show that the jet grouting pile reinforcement on the basis of original design does not have obvious effect on the embankment surface and ground surface settlement control, but effectively controls horizontal displacement at toe of slope and improves the foundation stability.