Analysis of the Influence Factors of a Hydraulic Compactor to Reinforce the Subgrade on the Back of an Abutment

To study the dynamic influence of hydraulic compactor reinforcing the subgrade on the back of abutment, based on the subgrade filling project of abutment back in the transition section of the high-speed bridge and tunnel, the interaction model of rammer, subgrade and abutment is established by ABAQUS. The accuracy of the model is verified by full-scale ramming test. In the process of simulation, the maximum dynamic displacement and maximum dynamic strain of abutment are taken as evaluation indexes. The influence of factors such as the dropping distance, the distance between tamping point and abutment, the initial compactness of subgrade, the strength grade of abutment concrete and the top support conditions of abutment on the abutment deformation were analyzed. The results show that (1) The error between the measured value and the simulated value is less than 10%, and the variation trend of abutment dynamic displacement and dynamic strain along the abutment height is in line with the convention, and the simulation model is reliable. (2) The maximum dynamic displacement and strain of abutment increase linearly with the increase of dropping distance and increase exponentially with the decrease of distance between tamping point and abutment. (3) When the initial compactness of subgrade increases from 75% to 95%, the maximum dynamic displacement and the maximum dynamic strain of abutment are basically the same, and the initial compactness of subgrade has little effect on the deformation of abutment. (4) The improvement of concrete strength grade of abutment has significant effect on the reduction of abutment deformation. (5) When there is no expansion joint at the top of the abutment, the maximum dynamic displacement and the maximum dynamic strain are reduced by 75% and 24% compared with those with expansion joint. In the process of reinforcement, the method of temporary blocking of bridge expansion joint can be used to change the stress form of abutment.