First application of cast-in-place concrete large-diameter pipe (PCC) pile-reinforced railway foundation: A field study

© 2016, National Research Council of Canada. All Rights Reserved. Cast-in-place concrete large-diameter pipe (PCC) piles have been widely used in highway construction for foundation reinforcement, where soft ground was encountered, due to their fast on-site construction and high capacity, hence economics. This paper reports the performance of their first application in high-speed railway foundation reinforcement on soft soil ground. To satisfy the strict settlement requirement for railway design, PCC piles with large diameters (D = 1 m), thick pile wall thicknesses (t = 0.15 m), and close spacing (s = 2.5 m) were constructed. The foundation performance has been monitored by measuring in situ foundation settlement, excess pore pressure in soil, lateral displacement of soil, and tension in the geogrid during and after embankment construction. The measurements of this project have been compared with that of a previous project when PCC piles were used. It is found that the PCC pile arrangement in this project has performed as predicted and fulfilled the strict settlement requirement set by the Chinese design guidelines.