Influences of bearing capacity of piles on stability of embankment with rigid pile composite foundation

The influences of bearing capacity and cap of rigid piles on the stability of embankment with rigid pile composite foundation cannot be taken into account in the methods recommended by the existing Chinese codes. Some embankments with rigid pile composite pile foundation slid owing to that the factor of safety gotten by those methods is much larger than the real value. To avoid the defects of the existing methods, the interactions between the piles and the soil among piles during sliding are analyzed, and the mechanism of improving the embankment stability by rigid piles is analyzed by analyzing the causes of slides. Then the revised density method is improved to be the revised weight method by analyzing the defects of the existing stability methods. Finally, the influences of the length, distance, enlarged base and cap of rigid piles on the embankment stability are studied by use of the revised weight method, and the influences of their bearing capacity on embankment stability are evaluated. The analysis results of different methods are compared. Some design proposals for the embankment with rigid pile composite foundation are put forward. It is shown that the influences of bearing capacity of piles on the stability of embankment with dense pile composite foundation are little but great on the embankment with sparse pile composite foundation. Increasing the bearing capacity of piles is more reasonable than decreasing the distance of piles. The belled piles are more efficient than those increasing their length. The rigid piles with large bearing capacity can play an important role to increase the stability of embankment only if most loads of embankment are transferred to the piles by pile caps and soil arch. The hanging piles should not be used if the strength of soft clay increases little along depth. The rigid pile composite foundation under embankment should be designed as the sparse pile composite foundation with large bearing capacity and pile cap.