Analysis of the pile skin resistance formation

Abstract

This paper introduces a method based on a static load test which is aimed to verify the mechanism of the piles soil–skin interaction. The authors base their analysis on detailed data from static load test with extensometers on CFA piles. The main goal of the research is to determine the proper method of examining how the skin of the pile and soil interacts and apply it to practical engineering practice. As the first stage of the research is limited to the available set of piles, the authors make assumptions that will be verified on later stages of research as more data become available. The authors attempt to formulate the boundary conditions for the formation of pile skin resistance formation using mathematical physics equations to describe the phenomena. Current research proves that it is possible, with the suitable for practical engineering calculations, to describe soil–pile interaction mechanism based on static load test results. Experimental research indicated that there is possibility, for practical engineering calculations purposes, to assume that skin resistance of the pile due to depth can be presented with linear graph. The description is made upon extensometer results, but is meant to be appropriate with the standard static load test results, which provide load–settlement curve of the pile.

Pile–Soil Interaction during Static Load Test

“…Instead, it considered the mechanism of the bending of the soil space around the pile according to Kirchhoff's principle, which allowed to consider the entire soil body. An analysis of the experimental results showed that the applied mathematical description validates the presented approach [28]. The verification of the static load test results showed a positive correlation between the calculation and the field investigation results [22].…”

“…An analysis of the experimental results showed that the applied mathematical description validates the presented approach [28]. The verification of the static load test results showed a positive correlation between the calculation and the field investigation results [22]. Multiple studies have been conducted on specific soil geotechnical parameters based on static load testing [9; 14; 15; 25; 33].…”

“…6. Displacement piles were used to determine whether previous calculations could be applied to other piling technologies, as previous work focused on CFA piles [22]. Tables 1 and 2 present the static load test results.…”

“…The solution to this equation can be expressed as follows: 𝜏𝜏𝜏𝜏(𝜏𝜏𝜏𝜏) = 𝐴𝐴𝐴𝐴 1 sinh(𝑎𝑎𝑎𝑎𝜏𝜏𝜏𝜏) + 𝐴𝐴𝐴𝐴 2 cosh(𝑎𝑎𝑎𝑎𝜏𝜏𝜏𝜏) (16) The boundary conditions of the solution are z=0; τ=τ 2 and z=h; τ=τ 1 . A detailed analysis of the solution presented in previous research [22] showed that the influence of the a coefficient, expressed in (2), does not have a carryover effect on the shear stress distribution. This verification confirms the possibility of applying such a simplification.…”

“…dN=πD•τdz (1) 2. Pile-soil interaction is described using Kirchhoff's principle [22] in accordance with the graph shown in Fig. 1.…”