Advanced Materials Research Vols. 671-674

Abstract: Foundation settlement of high-speed turnouts has a significant impact on its security serve status. Based on the general finite element software ABQUS, a vehicle-turnout-roadbed coupled dynamic model was built, and the dynamic properties of NO.18 movable-point turnout were analyzed in this paper. The result shows that: the acceleration of switch rail and nose rail is larger than that of track in common section under foundation settlement; large vibration and deformation of the track structure arise when the vehicle is going through, meanwhile the peak of foundation lateral vibration response is higher than that of vibration caused by the vehicle passing switch rail. The derailment coefficient, rate of rail load reduction, the acceleration and displacement of track plate and foundation all increase with the settlement of foundation. On the contrary, they reduce as the length of subtense. Also, the dynamic response of high-speed turnout grows along with the speed of the increasing under foundation settlement.

Abstract: Concrete pavement joints are an important part of the cement concrete pavement, and joints are the weak link of the concrete pavement. It is also one of the main causes of early diseases and failure of cement concrete pavement. This paper summarizes the outcome of the predecessors, introduces the research status of the joints, and analysis the joint destruction and its cause from the point of view of the stress.

Abstract: Longitudinal crack is one of the main subgrade diseases of qinghai-tibet highway and has large scale.While the existing treatment technology cannot completely solve the problem,especially cannot limit crack propagation,so the driving safety and road life will have huge influenced by the disease.In order to solve this problem,a new solution technology that the flexible beam combined with tenon type geomembrane bag is proposed in this paper.Through field implement,this new method which can effectively reduce and prevent crack diseases is verified.

Abstract: In this paper, a composite pavement stress absorbing layer is researched. Through the creation of the finite element analysis model of the composite pavement, the paper analyzed the shear stress and influencing factors such as a different level of force, the contact between the different layer, shear stress conditions, the surface layer modulus and thickness, base thickness, soil base resilient modulus. At last, the optimum thickness of the composite pavement structure layers is put forward.

Abstract: There are a lot of methods to improve the subgrade stability in permafrost regions. The scope of application and the advantages and disadvantages of the five methods including heat stick, insulation method, sunshade awning, particle improved method and ventiduct subgrade were analyzed. It can provide reference value for subgrade construction and diseases lot maintenance.

Abstract: CRTS I and CRTS II as well as two-layer two-way pre-tensioned prestressing ballastless track slabs were tested to compare their stiffness and strength. Midspan load-displacement curve was used to analyze the results. Based on the test results, the following conclusions can be obtained: The two-layer two-way pre-tensioned prestressing ballastless track slab has better performances than the other two kinds of ballastless track slabs in terms of both stiffness and strength.

Abstract: Crack of asphalt pavement is one of the major destruction in pavement engineering. The bending test of small beam at low-temperature is often applied to evaluate the resisting crack for asphalt mixture. In this paper, based on J-integral theory in elastic-plastic fracture mechanics, performance of resisting crack of asphalt mixtures is analyzed in cases of different temperatures and contents of Styrene Butadiene Styrene (SBS) by bending tests of small beam. It is shown that the optimal condition for anti-cracking of asphalt mixtures is SBS contents of 4.2%~5.0% at 10°C using flexural tensile strain and stiffness modulus and the highest flexural tensile strengths of mixture occur at 0°C. Ductile fracture toughness of mixture with SBS modifier may be more sensitive to temperature from -10°C to 0°C and may be more useful to analysis elastic-plastic formation energy and energy releasing rate of asphalt mixture.

Abstract: Since the asphalt overlay of freeway in Hubei Province was opened, it appeared undue early diseases. The diseases mainly appeared in the surface layer. Through the disease investigation, construction data lookups and on-site samplings of SMA-13 surface layer, the three main reasons of early diseases are indicated. They are unclean raw materials, loose control of mixture proportion and unreasonable construction site management. This paper analyzed the generation mechanism of diseases in SMA pavement from every involved respect. At last, the suggestions about construction control measures were put forward to prevent early diseases．

Abstract: The location technology of Truck Escape Ramp(TER) is the important guarantee for fully developing the TER actions and ensuring operation safety of heavy vehicles on long-steep downgrade. In order to improve the precision of TER location, this paper thoroughly analyzed the influence factors of TER location from the view of traffic accidents statistical data, road conditions and vehicle status. Expounded the theory of fuzzy rough set. Put forward the method of highway TER location based on fuzzy rough set. Used this method to evaluate the running safety of the unit sections on the long-steep downgrade. Calculated the comprehensive safety index values of sample sections and made ones with high comprehensive safety index values as the candidate sections for TER. Determined the accurate positions of the TER based on comparison of the comprehensive safety index value of adjacent candidate sections. Setting effect shows that the TER position determined by the method are scientific and rational.

Abstract: Combining with a mountain highway retaining wall earth pressure measured data, carried out a detailed study of the of multiple retaining wall back soil pressure distribution law, based on multi-level retaining wall measured horizontal earth pressure data mountainous retaining wallshorizontal earth pressure formula is derived, summed up the horizontal earth pressure with filling height variation.