Need an research paper on historical development of the equations used for the design of cfa piles in granular soils. Needs to be 7 pages. Please no plagiarism. Continuous flight auger (CFA) can be considered to be present between driven piles and drift shaft, an idea that has a primary attribute towards different lateral stress changes during times of installation of the various types of piles.
According to Brown in the book Design and Construction of Continuous Flight Auger Piles Final, it is relatively important to note that the estimated static CFA capacity is achieved through methods that are developed for specific objects including drilled shafts and driven piles, mainly because the behavior of CFA piles’ load-settlement are same (2007, p.226). Several methods are specifically meant for CFA piles which take modification form that is made to the methods that were previously developed purposefully for drilled shafts, as well as driven piles (Brown, 2007, p.226).
Additionally, Lord and Hayward in the book Shaft Friction of CFA Piles in Chalk, state that there is the growth of End-Bearing Resistance and Side-Shear with Pile Displacement, which carries similar characteristics to other kinds of deep foundations. In this case, the overall axial compressive resistance (RT) of an identified CFA pile is achieved through the calculations of combining the side-shear resistance (RS) with the end-bearing resistance (RE).
While calculating the total side-shear resistance requires a division of the pile length into N pile sectors. Then side resistance of a specific pile segment “I” is achieved through the multiplication of the surface area of the pile with the achieved unit side-shear resistance of the segment (Lord and Hayward, 2003, p.345).
However, some methods presented use specifically an average unit side-shear for the pile length just instead of totaling individual pile segments. This is evident in the book Numerical modeling of soil-pile axial load transfer mechanisms in granular soils by Aguiar, Sofia, and Arézou Modaressi. For this case, the formula for the total side-shear resistance is: RS = fs-ave π DL where D is for the average diameter of the pile, and L represents the pile total embedment length.