The Tie Bar Connection Technology Research Of Old Cement Concrete Pavement Widening

The tie bar used in the joints between old and new concrete pavement caneffectively prevent widening of the joint, so as to ensure load transfer between joints.At present China’s specification did not specify the tie bar’s selection for pavementwidening. The determination of tie bar’s diameter, length and spacing is usually basedon engineering experience or refer to method used in new pavement construction.Current specification for the selection of tie bar is too simple, which only consideringthe slab thickness and the distance to the free edge. Therefore, the currentspecification is not suitable for the complicated situation of widening project. It isnecessary to carry out systematic research on setting method and mechanical analysisof the tie bar connection between old and new concrete pavement.This article uses the cohesive element to research the bonding properties betweentie bars and cement concrete slab. Three-dimensional finite element model of thepavement structure is established by ABAQUS finite element software, and finiteelement analysis of the tie bar connection between old and new concrete pavement iscarry out to analysis the uneven support between the old and new subgrade, and themechanical response of tie bars at different base types. The results of this study canprovide a theoretical basis for setting tie bar reasonably.The results show that the cohesive element setting between the concrete slab andtie bar could simulate the bond damage between concrete slab and tie bar effectively.Under the uneven support of subgrade, tensile stress concentration phenomenon at thebottom of slab and base appear near the longitudinal joint between old and newconcrete slab. The setting of tie bars can greatly reduce deflection difference betweenthe old and new slab. It shows it is necessary to set tie bar between the old and newpavement. The maximum longitudinal tensile stress of slab bottom, maximumdeflection difference between old and new concrete slab, maximum tensile stress andshear stress of tie bar decrease when base modulus and coefficient of friction at theslab-base interface increasing. The transverse and longitudinal tensile stress of lean concrete base is larger than that of graded aggregate base and cement stabilizedmacadam base.