Negative skin friction and Neutral plan on the pile in collapsible soil:A Review Study

Abstract

The use of the pile in geotechnical engineering has become interesting due to the many challenges facing the installation process and the problems that may occur suddenly during construction if it is not taken into account. construction of piles in collapsing soil such as soft soil or gypsum soil leads to losses in the bearing capacity of the pile by creating an imaginary additional loading that is above the pile when the settlement of the surrounding soil is faster than the settlement of the pile itself.  Previous studies showed that if lateral displacement movement between the pile and soil at a specific level was equal to zero, this elevation represents the depth of the neutral plane at which the skin friction along the pile shaft was changed from the negative skin friction to the positive skin friction. This paper aims to provide an art review about the development of NSF on single and group piles. The effect of several factors has been studied on each of the development of negative friction and its value, as well as on the location or depth of the neutral plane such as the time of consolidation, soil and pile type, properties of the interface between pile-soil, stiffness of bearing soil and other factors.

Keywords: Negative skin friction, Neutral plane, collapse soil, Numerical Modeling, pile