Model Test Study on Bearing Characteristics of Pile Foundation in Red Clay

The physical and mechanical properties of red clay have a significant influence on the bearing characteristics of pile foundations. Therefore, this paper conducted model tests to study the influence of different red clay water content (16~−20%) and different compaction degrees (88~−92%) on the bearing characteristics of pile foundations. The results show that the load–displacement curves of the test pile generally exhibit a steep type. The ultimate bearing capacity of the test pile increases gradually with the compaction degree from 86% to 92%. However, the ratio of load borne by the side of the pile increases from 54.8% to 67.8%, while the ratio of load borne by the end decreases from 45.2% to 32.2%. The ratio of load borne by the pile end to that borne by the pile side also decreases gradually from 0.825 to 0.476. The ultimate bearing capacity of the test pile decreases gradually with the moisture content from 17% to 26%, showing a decreasing trend. However, the ratio of load borne by the pile side decreases from 69.5% to 51.9%, while the ratio of load borne by the end increases from 30.5% to 48.1%. The ratio of load borne by the pile end to that borne by the pile side also increases gradually from 0.439 to 0.927. This indicates that increasing the compaction degree or reducing the moisture content has a more significant effect on increasing the side resistance. In this paper, the ultimate bearing capacity of test piles are calculated by the Mohr–Coulomb criterion (M-CC) and Duncan–Chang hyperbolic model (D-CHM), respectively. The results show that M-CC and D-CHM methods can accurately calculate the bearing capacity of the pile foundation in red clay. The conclusion of this study can provide a reference for the design and construction of pile foundations in red clay areas.