抄録
A high speed railway foundation with a thick top sand layer overlying a thick muck layer was treated with three methods respectively: both the sand layer and muck layer being treated by pre-stressed concrete pipe pile with a geogrid on pile top (PP foundation), only the muck layer being treated by jet grouting pile (JP foundation), and the sand layer being treated by dynamic compaction (DC foundation). Based on in-suit test data measured during construction of the railway embankment, settlement characteristics of the foundation were analysed. The results show that when choosing treatment method, not only the load level and foundation geological feature should be paid attention to, but also treatment aim must be considered; treatment method suitable for buildings to control total settlement might not be effective for embankment only to control post-construction settlement (PCS). DC foundation could only eliminate settlement of the sand within effective depth of dynamic compaction treating, so it was not suitable for the case whose treatment aim was controlling PCS. JP foundation, whose settlement during construction was large while the PCS was close to that of PP foundation, was efficient for the case with treatment aim of controlling PCS but might not be effective for the case that needs to control total settlement. PP foundation, whose settlement during construction and PCS were both small, as compared with JP foundation, just increased the project cost by increasing pile length to treat the sand layer for controlling PCS, and whose long-term stability of settlement depending on the durability of the geogrid is less reliable because the sand layer still remained loose.
