Bearing Capacity Characteristics and Differential Settlement of Composite Foundation with Column-Hammered and Thrusted-Expanded Piles

The foundation bearing-capacity characteristics and differential settlement have become the vital issues of high-speed rail study. Because of the collapsibility around loess foundations, the bearing characteristics as well as differential settlement are significantly different from other soil foundations. At present, there are many studies on other types of soil foundations, while the bearing capacity characteristics and differential settlements of the column-hammered and thrusted-expanded pile (CHTEP) composite foundation in the collapsible loess area are rarely involved. Therefore, based on the current codes, field tests and finite-element method (FEM), the variation in the differential settlement and bearing capacity characteristics of composite foundations with CHTEP is studied in collapsible loess areas. This paper mainly obtains the changing law of pile body stress, pile-soil stress ratio, pile side-friction resistance, differential settlement about the pile, and the soil between the piles of the composite foundation with CHTEP during different construction conditions. The result also shows the bearing capacity and settlement about composite foundation with CHTEP is up to code. This paper can provide some important rule to the design or construction about composite foundations with CHTEP at collapsible loess areas or other similar cases.