Differential Settlement of Cement Fly-Ash Gravel and Cement–Soil Compacted Piles

Due to the special characteristics of loess, the foundation of a high-speed railway is easy to compress and settle, and reasonable treatment of the foundation can reduce the settlement of the foundation. Based on the test section of Yinxi high-speed Railway and the finite element method, the differential settlement problem of CFG (cement fly-ash crushed stone) pile + cement–soil compacted pile composite foundation in a collapsible loess area is studied. The results show that: (1) The soil settlement between the cement–soil compacted pile and pile is synchronized, and the soil settlement between the embankment center line and pile can reach 18 mm. The soil settlement difference between CFG pile and pile is large, and the maximum settlement of the roadbed center line is ± 0.000 m. (2) The soil settlement between piles is the largest at the center line of the embankment, the settlement away from the center line of the embankment gradually decreases, and the settlement at the same observation point decreases with the increase in depth. (3) The loading test results show that the settlement of the CFG pile and soil–cement compacted pile is small, and the settlement of the CFG pile is smaller than that of the soil–cement compacted pile, both meet the requirements of the code.