Abstract:When one freeway goes through uneven soft soil area with great depth in the Pearl River Delta,sand pile,sand bed course and geogrid are adopted firstly to consolidate the soft soil groundsill. During the loading process,the speed of filling was faster than the allowable one,but the sand pile is without shear strength. So cracks were found on the surface of subgrade filling. In order to keep the stability of groundsill,prestressed concrete tube pile with steel geogride were then used to consolidate the soft soil after the filling was unloaded. The vertical drainage function of sand soil and transverse drainage function of sand bed course were brought to reduce the excessive pore water pressure during the prestressed concrete tube pile was driven into the soft soil. After using tube pile,the stability of groundsill was enhanced,and the filling speed was expedited to guarantee subgrade construction completion before rainy season. With the settlement analysis,the lateral deformation,in-situ pore water pressure,and the invalidation reason of sand pile are achieved. The conclusions that sand pile without shear strength is not suitable for deep soft soil treatment at slope foot and that the measurement with certain shear strength can be adopted are acceptable. In order to guarantee the stability of groundsill,rotational folium loading shall be adopted during loading process.