Study On The Deformations And Stresses Of Manhole Under Traffic Loads

As the Society develops rapidly, both of the scale and quality of cities' construction need to be promoted. So the constructions of urban roads and municipal pipe network must be followed up. Manholes are important parts of urban roads and municipal pipe network. Some common phenomena, such as sinking of manholes and cracking of asphalt concrete, seriously effect the safety and comfort of driving and the beauty of the city environment. In order to specifically investigate the damage causation of manholes and damage mechanism, this dissertation did some work as follow:(1) Investigating manholes in some roads in Hangzhou. It was found that traffic load was most likely the factor to cause sinking of manholes and cracking of asphalt concrete, according to the comparison between the damages of manholes in vehicle lanes and non-motor vehicles lanes.(2)Establishing calculating methods of vehicle impact loads onto manholes and residual deformations. Computational analysis indicated that residual deformations of brick masonry caused by traffic load were not noticeable. So the residual deformations of brick masonry were not the main factor causing manholes sinking.(3)Adopting three-dimensional finite element method to simulate manholes" superstructure. Computational analysis indicated that cushions of manhole covers and vertical section of asphalt concrete connecting to brick masonry's outer edge undergone repeated shear loads. Under this repeated shear stresses, cushions of manhole covers and asphalt pavements might easily give in to fatigue failure, which caused manholes sinking and neighboring pavements cracking.(4)Using axisymmetrical finite element model to calculate and deformation and stress of manholes under traffic loads, and to analyze the influence of magnitude and duration of loads, and material properties on the stress of manholes. The analysis demonstrated that the load duration had little effect on manholes' peak stress and deformation. Under dynamic load, tensile and compressive stresses occurred by turns on the cover plates of manholes. The traffic loads' effect on the manholes became less from the top to the bottom. Therefore, traffic loads' effect is limited in the lower part of manholes. For this reason, manholes' damages mostly occur in the superstructure...