Using FBGS to estimate the horizontal response of a monopile in a geotechnical centrifuge

Abstract

A 50-mm-diameter circular aluminium tube was instrumented with two optical fibres that consist of 13 Fibre Bragg Grating sensors (FBGS) for each. The performance of the FBGS was evaluated by applying a series of increasing transversal loads at 1×g level and comparing the strains measured by FBGS with those calculated from the Euler-Bernoulli beam theory. Centrifuge test was then conducted at 100×g to estimate the transversal response of the calibrated model pile that had been jacked 450 mm into saturated sand and horizontally loaded at 500 mm above the ground. The profiles of the normal strain, bending moment, soil reaction and pile deflection were measured or determined, allowing to construct the soil reaction-pile deflection (P-y) curves. The results confirmed the reliability of the FBGS at 100×g by giving satisfactory measurements on bending moments and coherent measurements on shear force at the ground level.

Impact driving of monopiles in centrifuge: effect on the lateral response in sand

“…▪ During horizontal loading, the compressive and tensile normal strains were asymmetric, as has been reported by Li et al (2020). Furthermore, the asymmetry was more significant at the monopile base.…”

“…Moreover, the recommended use of inclinometers in field tests along the embedded depth (Burd et al, 2020a;Byrne et al, 2020;McAdam et al, 2020) was not possible in the centrifuge. This is why the procedure developed by Li et al (2020) was implemented: The centre of rotation of the monopile was used to infer its horizontal displacement and rotation at the ground level. This method is detailed in the next sub-section as it involves strain measurements along the embedded depth of the monopile.…”

“…After calibration of the FBGs (Li et al, 2020), bending moments at different depths of the monopile were calculated, as shown in Equation 3, based on the average values of the tensile and compressive strains Ɛavg by using Euler-Bernoulli beam theory:…”

Dataset for centrifuge modelling of laterally monotonic loaded monopiles in saturated dense sand

“…Prior to testing in the centrifuge, the two instrumented piles had been calibrated by applying a set of incremental lateral loadings at 1 × g . The calibrating results are now available in [2] .…”

Test and Study of Pipe Pile Penetration in Cohesive Soil Using FBG Sensing Technology

“…Due to the small size of the model pipe pile and the small pressure on the pile, the size and sensitivity of the sensor were required to increase, and electrical sensors could not meet the test requirements. Fiber Bragg grating sensors have been applied to the model test due to their strong anti-electromagnetic interference ability, small size, light weight, and remote measurement [25][26][27][28][29][30][31][32][33].…”