I discussed a doctoral thesis at the College of Engineering at the University of Basrah (studying the effect of negative surface friction on single piles and aggregates of piles in Basrah Governorate)

The thesis submitted by the student

Jassim Mohsen Yasser Al-Battat

Extensive factor study regarding the effect of pile cross section dimensions, surface friction coefficient and burial thickness.

The most common hammering piles were analyzed, under the influence of structural loads and pulling forces due to recent burial.

The results reflected a significant decrease in the negative surface friction stress and in the pile length that is affected by the phenomenon due to the shedding of structural loads for the first scenario. A decrease in drag forces of up to 44% was recorded for the hammering piles and 74% for the drilling piles in some locations, while rates of up to 86% were diagnosed for the drilling piles. And 96% for the drilling pillars for the second scenario

The thesis aims to examine the ability of the finite element method to represent the behavior of deep foundations subjected to negative surface friction in the soil of Basra.

The thesis concluded that the central piles showed a maximum decrease of 50% for the hammering piles and 44% for the drilling piles to study the effect of the interval between piles.

A range is adopted that ranges from three times the width or diameter to six times the width or diameter regardless of the position of the pillar within the set.

It was also concluded that the pulling force is directly proportional to the interval between the piles for the hammering piles and inversely with the interval for the drilling piles.