Influence of Fiber-Reinforced Polymers on Pile–Soil Interface Strength in Clays

Abstract

A series of direct shear tests were carried out in order to characterize the pile–soil interface strength for various pile materials including steel, concrete, and grout and to investigate the influence of fiber-reinforced polymer (FRP) materials on the pile–soil interface strength in soft clay. The study investigated both pile–soil interface friction and interface adhesion by simulating drained and undrained conditions. The results among the traditional pile materials indicated the superior performance of grout and concrete relative to steel. FRP interfaces were shown to perform at a level the same as or higher than that of traditional steel piling under both drained and undrained conditions in clays. The FRP–clay interface friction angles were 5 % to 19 % greater than those in traditional steel–clay interfaces and 12 % to 23 % smaller than that of concrete. In addition, FRP interface adhesion was observed at between 86 % and 135 % of the interface adhesion of steel and between 65 % and 75 % of the interface adhesion of concrete.

Axial and lateral load transfer of fibre-reinforced polymer (FRP) piles in soft clay

“…This is believed to be a consequence of the higher surface roughness of the CFRP compared to steel and GFRP. Pile surface texture plays a significant role in the development of the shaft resistance; a similar behaviour was observed shearing different FRP fabrics against a soft clay in a shear box (Giraldo and Rayhani 2013). Based on the results shown here, it appears that CFRP pile presents a significant improvement over traditional steel piles in terms of geotechnical performance in soft clays.…”

Enhancement of Shaft Capacity of Cast-in-Place Piles Using a Hook System

“…A direct shear box device was employed to simulate the shear behaviour between the cast-in-place-pile surface versus surrounding clay and sandy soils. Similar approach has previously been used to investigate the pile-soil interface strength for different materials (e.g., Giraldo and Rayhani, 2014). Although the box size of 60 mm square seems to be a little small for interface investigation, but the data generated from these tests were shown to be reliable as per previous findings in the literature (e.g., O'Rouke et al, 1990).…”

“…(Figure 2.15). Polymer surface texture and fiber orientation were shown to significantly affect the FRP-soil interface resistance (Giraldo and Rayhani, 2014). The type of FRP materials have also shown to affect the pile performance.…”

“…More recently, Taha (2010) explored the influence of several parameters such as interface roughness, degree of saturation, over consolidation ratio, dry density and clay salt content on interface behaviour of pile-clay surfaces. Giraldo and Rayhani (2014) have investigated the pile-soil interface behaviour for traditional piling materials as well as fiber reinforced polymer piles.…”

“…Leda Clay and Sand grain size distributionTable 3.1: Index properties of soil samples(Giraldo and Rayhani, 2014) = bulk density; w = moisture content; wopt, optimum moisture content; ρd(max), maximum dry density; cv = coefficient of consolidation; Su = undrained shear strength; c = cohesion when sheared at 2mm/min. );  = friction angle when sheared at 2mm/min.…”