Analysis of CFG Composite Foundation Settlement of Beijing-Shanghai High-Speed Railway

Abstract

For the cement fly ash gravel (CFG) pile reinforced section of Beijing-Shanghai high-speed railway with typical geological characteristics, numerical method was used to simulate the embankment filling and to calculate the settlement of CFG pile reinforced subgrade. During analysis, the CFG pile and soil were considered separately. By contrast with the tested results, it was shown that the model was rational. Effect of the different pile length and spacing on subgrade settlement was studied. On base of subgrade settlement, the rational length and spacing of CFG pile was obtained. The results show that settlement will decrease with the increase of pile length, but when pile toe is placed in better rock stratum, its effect becomes less. The pile length was obtained under the premise of settlement control, at the same time, geologic data and economic factors were considered. The results also show that pile spacing, as the main controlling factor of replacement rate of CFG composite foundation, has comparatively weaker influences on settlement with the decrease of pile spacing.