Evaluation of Soil Interaction with Laterally Loaded Minipiles Using Optic Fiber

Driven minipile foundations are becoming common due to merits such as lightweight, easy installation and suitability for reinforcing in-situ structures with limited access. However, their interaction with the surrounding soil especially in battered conditions is not fully understood. To develop a better understanding of the interaction of minipiles with the surrounding soil, they were instrumented with Fiber Bragg grating (FBG) sensors. Open-ended steel minipiles of 1600 mm length were then driven at a site with cohesive soil vertically and at positive and negative 25 ̊ angle with the vertical and were tested for three in-situ lateral static loading cases. The near-continuous strain profile along the minipile shaft was reported using FBG. This helped in identifying the deformation pattern and the impact of load magnitude on this profile. The lateral load capacity was found to be maximum for positive 25 ̊, which decreased for 0 ̊, followed by negative 25 ̊ batter angle.