In order to prevent the appearance of these vertical cracks, the authors analyze different factors affecting the behavior of the abutment backwall, including horizontal crack-control reinforcement, pile foundation rigidity, concrete age difference between the pile cap and abutment backwall, and the inclusion of a postcast strip.
Horizontal Crack-Control Reinforcement. Keeping the reinforcement ratio and 20 cm stirrup interval fixed, the change in abutment backwall cracking with the change in diameter and interval of horizontal crack-control reinforcement was evaluated.
The data provided in Table 6 suggest that, for the same reinforcement ratio, the maximum crack width increases with the increasing diameter and interval of horizontal crack-control reinforcement. In other words, the arrangement of horizontal crack-control reinforcement in a "thin but dense" manner most successfully controls the appearance of vertical cracks on the abutment during construction.
In the process, the stress mechanisms in the abutment body under the effects of concrete shrinkage and various temperature changes are summarized, and influencing factors on the abutment are analyzed, including the parameters of horizontal crack-control reinforcement, the pile rigidity, the difference in age of the pile cap and abutment backwall concrete, and the inclusion of a postcast strip in the abutment backwall.
Holding the reinforcement ratio for a horizontal crack-control reinforcement constant, a "thin but dense" arrangement is more favorable for controlling the growth of vertical cracks on the abutment backwall.