Comparative research on penetration resistance of jacked tapered piles and uniform section piles

Based on the cavity expansion theory of Vesicc and the effect of penetration depth on expansion pressure, an iterative algorithm is developed for expansion pressure. By analyzing the differences between taperd piles and uniform section piles in view of penetration resistance, condidering the utmost sliding friction betweem piles and soil, a method for the penetration resistance of both types of jacked piles is deduced. In order to validate the feasibility of the proposed approach, laboratory model tests on penetration of traped piles and uniform section piles are performed. The above method is used to analyze them. The test and theoretical results indicate that the penetration resistance of uniform section piles rises rapidly at the primary stage and slowly at the later stage, and that of traped piles steadily increases during the entire stage of penetration. The final penetration resistance of uniform section piles is much smaller than that of taperd piles which have equal average section radius with uniform section piles. The traped piles may save costs of materials and reduce their consumption.