Dynamic Response of Model Footing on Hair Fiber-Reinforced Sand

Abstract

Free vibration tests were conducted on scaled model footing resting on unreinforced and hair fiber-reinforced sand to determine the dynamic characteristics of the soil-foundation system. The sand was reinforced with the random mixing of unsorted human hair fibers collected from barber shops and compacted to a relative density (RD) of 80% in the model test tank. The percentage of fiber inclusion was varied up to 1.0% by dry weight of sand. The reinforced sand was prepared with an initial moisture content of about 2–3% to obtain the consistent uniform mixing. The sand bed was filled in eight layers of 10 cm each in loose condition. Each layer was compacted using a calibrated plate vibrator to achieve the desired relative density before filling the next layer. The free vibration tests were conducted in model test tank by varying the depth of fiber reinforcement (dr) and the width of the fiber reinforcement (wr) for different percentage of fiber inclusions, viz., 0.5%, 0.75%, and 1.0%. The results demonstrated that addition of even 0.5% human hair fiber with the sand can help in shifting the natural frequency of the soil-foundation system.