Applied Mechanics and Materials Vols. 405-408

Abstract: Fatigue crack is one of the main road damage forms of asphalt pavement structure, and serious impact the asphalt pavement performance and service life. Asphalt mixture has typical viscoelastic,and can get Burgers model and viscoelastic parameters form creep test. Using finite element method of fracture mechanics, simulation under dynamic loading, research crack extending behavior of common asphalt concrete pavement and mixed with 0.2% of sisal fiber asphalt concrete pavement. From the results, it can find out that when mixed with sisal fiber, the anti-fatigue cracking performance is obvious enhancement.

Abstract: mi-rigid base on crack resistance, using orthogonal experimental design method, arranged 16 groups of orthogonal test and conducted the water content test and drying shrinkage test that aimed at various ages from 5d to 50d respectively. The results indicated that with the increasing of waste asphalt content, the shrinkage gradually increasing and the maximum reached when the dosage of waste asphalt concrete was 55%, since then, with the increasing of waste asphalt content, the shrinkage gradually decreasing and the range was largely. Fiber has little effect on moisture loss and shrinkage, with the increasing of fiber content, the moisture loss of materials with different ages increased gradually and the maximum loss rate reached when the dosage of fiber was 4, then the moisture loss decreased gradually after that. As for shrinkage, it reached minimum value when the dosage of fiber was 2.5. Mixing waste asphalt concrete and fiber in reasonable dosage can improve the crack resistance of materials.

Abstract: A newly developed skid resistance measurement system ViaFriction is studied, which can detect the skid resistance under conditions with a variable slip rate, just like the braking process with an anti-lock braking system (ABS). Until now there is still no evaluation framework on the testing results from this test system. In the scope of this paper, the impact from the temperature of the ambient air, the road surface, the tire and the water for the test as well as the influence of the driving speed of the test vehicle on the testing results of the ViaFriction was identified and transferred to a correction function. This total correction algorithm for the measurement results of the ViaFriction allows a comparative analysis of the friction coefficients at different speeds and under different testing temperatures.

Abstract: The pier longitudinal horizontal stiffness is the key technical parameter of rigid frame bridge and the continuous welded rail. Both the distribution of longitudinal force and the relative displacement between the beam and rail are rely on the longitudinal horizontal stiffness of the pier. This passage takes the symmetrical arrangement of different span rigid frame bridge in ballast track as an example to study the value of pier top longitudinal horizontal rigidity, using the finite element method. The analysis show that when the amplitude of rail temperature variation is less than 50 °C and the nominal temperature span within a certain range, the minimum value of pier longitudinal horizontal rigidity depends largely on the braking conditions. However, as the further increasing of the span, the pier longitudinal horizontal rigidity is restricted by the expansion conditions. Therefore, the small resistance fastening system should be taken into consideration. Especially, if the temperature of rail reaches above 50°C, laying rail expansion adjuster is needed in order to satisfy the requirement of the continuous welded rail temperature on bridge.

Abstract: Through indoor simulation test of double-block ballastless track sleeper loose hydrodynamic pressure, this paper study the variation laws of hydrodynamic pressure of different position, different load and frequency variation. The results show: The location of the biggest hydrodynamic pressure is in the middle of the crack and near the not void area. The amplitude and frequency of load have obvious influence on the hydrodynamic pressure. When the load amplitude is more than 30kN or load frequency exceeds 10HZ, the effect on the hydrodynamic pressure is particularly notable.

Abstract: Warm mix asphalt (WMA) is a new type of asphalt mixture that uses a special additive to reduce mixing temperature and compaction temperature to realize energy saving and environmental protection purpose. Laboratory tests are conducted to study that, at different compaction temperatures, the air void rate, dynamic stability and change rule of flexural-tensile strain of the Sasobit WMA of 3 matrix asphalts (Liaohe70#, Liaohe90#, Karamay90#). The results show that when compaction temperature rises, air void rate decreases and the degree of decrease turns slow. At the same temperature, WMA of Karamay90# added with 3% of Sasobit (K90S) has the least air void rate. Along with the rising of the compaction temperature, dynamic stability increases in linearity. At the same temperature, WMA of Liaohe90# added with 3% of Sasobit (L90S) has the best dynamic stability. 115°C is the optimal compaction temperature for L70S and K90S to keep relatively high flexural-tensile strain. At the same compaction temperature, difference of flexural-tensile strain is small among 3 matrix asphalts.

Abstract: With the development of the high-speed railway (HSR) and metro, the metro crossing the HSR in operation usually happened in metropolis. Considering the stability of railway bridge foundation is very critical to the safety of HSR in operation, it is very important to monitor the influence of the construction of metro tunnel. The no.6 metro line of Nanjing city is crossing the railway bridge group, including three HSR lines, Beijing-Shanghai HSR, Nanjing-Anqing intercity railway, and Shanghai-Wuhan-Chengdu railway. A real-time deformation system using sensors with high accuracy and wireless network is designed to monitor the bridge piers, which are adjacent to the metro tunnel and may be affected in the bridge group. The tilt and settlement of bridge piers and horizontal displacement of pier head are considered in this system. The monitoring results show the feasibility of the system and grantee the operation and bridge engineerings safety.

Abstract: To analyze the earth pressure of corrugated steel culvert under high fill embankment, a field test was taken and the change law was got with the filling height increasing, the force state when geotechnical grilles were laid on the top of corrugated steel culvert was compared to that of reinforced concrete slab culvert. Results show that the pressure on the top of corrugated steel culvert is smaller than that on the external in same level when test points are near to culvert, the values of test points above and below geotechnical grilles are close, and the pressure of corrugated steel culvert is smaller than that of reinforced concrete slab culvert when filling height is above 7.3 m. So analysis indicates corrugated steel culvert spreads the upper load better, the geotechnical grille can reduce the pressure effectively through earth pressure redistribution, and the mechanical property of corrugated steel culvert is better than reinforced concrete slab culvert under high fill embankment.

Abstract: established the evaluation index according to the influencing factors (the road grade, traffic volume, road conditions, the strength of pavement, pavement performance and anti-sliding ability, etc) of highway asphalt pavement maintenance scheme. According to the interrelation of the various indexes, I put forward a set of method about the maintenance of the highway asphalt pavement.

Abstract: The CRTSⅡ slab track is one of the major ballastless tracks in China. Factors of the design, the construction, the train load and the service environment lead to the wide juncture cracking. The beam-solid model on the elastic foundation was established to carry out the mechanics analysis. Theoretical analysis was made on the influence of the depth and the length of the cracking on mechanical properties of the CRTS Ⅱ slab track. The train load and temperature load can make the increase of the warping of the slab that cause the irregularity of the slab track. When the wide juncture crack completely, the sudden chill can make the slab track crack and effect the quality of ballastless tracks.