The Research On The Key Technologies Of Constraint-interchange

There are more than ten years of mountain freeway construction history,and now is at the peak period. Compared with the plain area of freeway,mountain freeway has significant feature of low route indicators,more long- steep longitudinal slope,widespread high filling and dig deep subgrade,many bridge and tunnel,etc. Interchange,as an important part of freeway,inevitably affected by the main line,the layout of the interchange will be restricted by the above conditions.Based on the above constraints,put forward the concept of Constraint-Interchange, Constraint-Interchange means the Interchange restricted by the topography,geology,surface features, the main line standard or continuous bridges, tunnels, service facilities, etc,and difficult to meet the standard requirements if according to conventional design . Constrained interchange in very common in Chongqing mountain roads. The papers relying on the transportation technology projects "Group Urban Belt Freeway Planning and technical standards" and the scientific and technological projects of Chongqing Transportation Committee "Mountain Freeway Interchange planning and technical standards", based on the Interchanges have been built on Chongqing expressway, analyse the characteristics and constraints, initially established the type and system of constraint-interchange. For the Spacing-constrained Interchange, The start from the factors that affect the interchange spacing, to explore ways to shorten the spacing between interchange, preliminary research the appliance of"Secondary reduction theory"in constrained-interchange, and in accordance with theoretical method to determine the minimum spacing and experience of interchange spacing at home and abroad, proposed interchange reasonable spacing and measures of small spacing interchange in constraint conditions; for the longitudinal Constraint-Interchange, study from the way to overcome the height, proposed route-development-interchange and it's several forms; finally, explored the programs of plane constraint-interchange.