Summary
The efficiency of tension piles pulled from the bottom for TLP is based on the hypothesis that: (1) the capacity of the pile depends on the skin friction alone, as the upward load applied to it does not mobilize the end bearing capacity, (2) the pile loaded from the bottom is working in compression and thus uses the grout curtain in a more efficient way. (3) since the pile is being compressed, the Poisson ratio effect leads to a lateral expansion, thus increasing the skin friction and the capacity of the pile.
In the present project the advantages expected from the drilled and grouted piles pulled from the bottom will be investigated by using three methods. In a first step, the capacity under static loading of different types of piles and of soils will be computed with BMCOL76, a finite difference program that will use the friction capacity recommended in the APIRP2a (1990) for piles in clay. In a second step, a finite element program, ABAQUS, will be used to show the behavior of the pile and the stress distribution in the pile and in the soil with a linear elastic analysis, a situation far from the failure process. Finally, an idealized model of the pile under compression and under tension, and a study lead by Randolph (1993), will be used to find a relationship that clarifies the load transfer process from the pile to the soil.
