摘要: In order to study the two kinds of instability failures between asphalt overlay and old cement slab such as black and white interlaminar horizontal shear slippage and interfacial bonding instability, the influence rules of vehicle speed, road adhesion coefficient, vertical load, interlaminar contact coefficient, loading rate, temperature and the spraying amount of viscous oil on interlaminar extreme stress and strain, shear strength and pull-out strength were revealed through the elastic theoretical calculation of composite structure, MATLAB programming, interlaminar shear test and pull-out test.The function relationships among interlaminar shear strength and normal stress, shear rate, temperature, and among pull-out strength and pull-out rate, temperature, the spraying amount of viscous oil were established respectively.Analysis result shows that the descending order of pull-out failure interface occurrence probabilities at 15 ℃ is cement slab surface, tack coat, asphalt membrane, the descending order at 45 ℃ is tack coat, cement slab surface, asphalt membrane, and average interlaminar bonding strength increases with the descending of above order.In order to reduce interlaminar instability failure, vehicle speed should be increased appropriately, vehicle axle load should be controlled, the clean and rough surface conditions of old cement slab should be kept, the spraying amount of viscous oil should be chosen appropriately, liquid petroleum asphalt is 0.20-0.40 L·m-2, and emulsified asphalt is 0.48-0.60 L·m-2.The average pull-out strength of core sample and interface failure position are recommended as distinguishinging bases for the construction quality of asphalt overlay.更多>
摘要: In order to eliminate the influence of fire smoke on people in single highway tunnel with subtended traffic, a fire numerical calculation model was established.The theory of fuzzy control was introduced into the control of fire smoke, and the reciprocating motion of smoke in the area of 200 m between two groups of jet fans in the tunnel was simulated.By changing the wind velocities and directions of jet fans in tunnel, the distribution and influence law of smoke within the control area were studied when smoke diffusion times were 180 and 360 s, and wind velocities were 1.0 and 1.5 m·s-1.Calculation result shows that after jet fans on both sides of fire source are started respectively, the smoke is basically controlled at the positions of 50-80 m on both sides of fire source, and its motion belongs to small amplitude motion when the start interval of jet fans is 30 s and wind velocity is 1.0 m·s-1.When the interval is 60 s and the speed is 1.5 m·s-1, the smoke is basically controlled at the positions of 80-100 m, and its motion is large amplitude motion.The small amplitude motion is superior to large amplitude motion.更多>
摘要: Based on urban road network, the feasibility and effectiveness of complex network theory application were analyzed.By using Dijkstra shortest path algorithm and Space L method, the initial topology network was built, and the characteristic index models of the degree of node, the degree of edge and the road impedance of node were set up.Under the premise of reflecting the reality of road network function, the initial topology network was optimized, and empirical analysis was carried out by using road traffic data in a central urban area.Analysis result shows that in the initial topology network, the average node degree is 2.850 0 and the standard deviation of node degree is 0.670 8.The average road impedance of node is 84.680 0 s and the standard deviation is 11.768 8 s.While in the optimal topology network, the average node degree is 38.750 0 and the standard deviation of node degree is 24.683 0.The average road impedance of nodes is 91.780 0 s and the standard deviation is 18.862 8 s.The average degree of east-west road section is 42.00, the average degree of north-south road section is 29.86, the average degree of internal section is 55.00, and the average degree of external road section is 28.33.In the optimal topology network, when the node with large degree is not stable, the road impedance of shortest path will increase in non-crowded state, and the road network will be paralyzed in crowded state.The node with higher degree is accord with the importance degree of intersection in real road network, and the difference of importance degree for intersection can be more reflected.更多>
