Analysis of reinforced cushions in high-strength concrete pile composite foundation based on large-scale static model tests

To study the mechanism of reinforced cushions and the method for calculating bar tensions, four groups of large-scale static model tests are carried out by means of a self-designed equipment system to control the differential settlement between piles and soil. The bar tensions in the reinforced cushions under different loading levels are tested. The variation rules of magnitude and distribution of tensions with the increasing loadings are analyzed. The test results show that the bare tension gradually increases with the increase of settlement differences between pile top and soil between piles, and that the maximum one occurs at pile top. With the coverage expanding of the pile cap, the bar tension in the soil between slowly decreases, and that at the pile top sharply changes, following a rule of increasing at the beginning and decreasing at the end of the settlement process. The failure mode of reinforced cushions is represented by the fracture of bar strip along the pile cap.