Research on Alleviating Vertical Curve and Service Length in Old Road Reconstruction Project
In order to improve the quality of longitudinal section alignment in old road reconstruction projects and reduce the unnecessary and expensive asphalt underlying lining materials,the alleviating vertical curve and its service basis are studied.Firstly,the"human-vehicle-road"dynamic calculation model and the alleviating vertical curve evaluation criteria are determined.Through dynamic calculation and analysis,the multiple parabolas are determined as the research direction of alleviating vertical curve.And the method of undertermined coefficients are used to deduce a family of equations of 8-degree parabola alleviating vertical curves.Secondly,the methods for determining the alleviating vertical curves under different engineering conditions are classified and discussed.And through the dynamic calculation,the 7-degree parabola is determined as the minimum vibration alleviating vertical curve.Thirdly,the dynamic calculation analysis is used to determine the minimum radius of vertical curve without alleviating vertical curve at each design speed.Finally,based on dynamic calculations,the relationship between the basic parameters of the alleviating vertical curve and the evaluation indicators of vehicle vibration is established.Combined with the vehicle vibration perception standards,the minimum length of the alleviating vertical curve is determined.The above research forms the basic conditions and relevant service foundations for the design of alleviating vertical curve,which can be selected in the design of old road reconstruction projects.
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