Isolation Prospects of Geosynthetics Reinforced Soil Beds Subjected to Vibration Loading: Experimental and Analytical St
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ORIGINAL PAPER
Isolation Prospects of Geosynthetics Reinforced Soil Beds Subjected to Vibration Loading: Experimental and Analytical Studies Hasthi Venkateswarlu . A. Hegde
Received: 17 October 2019 / Accepted: 28 June 2020 Springer Nature Switzerland AG 2020
Abstract The study discusses the potential use of geosynthetics in isolating the ground vibration emanated from the vertical mode dynamic excitation. A field study was conducted to investigate the screening efficacy of reinforced foundation beds. In the field study, vibration was generated using a mechanical oscillator. Four different cases, namely, unreinforced, single layer geogrid, two layers of geogrid, and geocell reinforced cases were considered. The isolation efficacy was studied in terms of peak particle velocity and amplitude reduction ratio. The resonance response of different reinforced conditions was studied by varying the dynamic force, and frequency of the excitation. The effectiveness of the reinforced soil system was examined by comparing the performance of the reinforced system with the unreinforced system. From the field test results, a significant reduction in ground vibration was observed in the presence of
H. Venkateswarlu A. Hegde (&) Department of Civil and Environmental Engineering, Indian Institute of Technology Patna, Patna 801106, India e-mail: [email protected] H. Venkateswarlu e-mail: [email protected]
geosynthetics. Maximum reduction was observed in the case of geocell reinforced condition as compared to other cases. In the presence of geocell, peak particle velocity and resonant amplitude were reduced by 48% and 61% respectively, as compared to the unreinforced condition. Similarly, 98% improvement in the stiffness of the foundation bed was observed in the presence of geocells. Further, the dynamic response obtained from the field study was compared with the mass spring dashpot analogy. The dynamic response predicted from the analytical study has shown reasonable agreement with the field test results. From the analytical comparison, 2.6 times improvement in the damping ratio of the foundation bed was noticed due to the inclusion of geocell reinforcement. Keywords Geosynthetics Field vibration test MSD analogy Peak particle velocity Damping ratio List of symbols A Contact area of the footing with the soil mass (m2) Ar Displacement amplitude of reinforced condition (mm) Aun Displacement amplitude of unreinforced condition (mm) Arf Amplitude reduction factor b Width of the reinforcement (m) B Width of the footing (m) C Damping coefficient (dimensionless)
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D Dr e fnz Fd Fo Fif Fr Fu g G h H IE K M m me MSD N o PPV t ti u uc € Z; _ and Z Z;
W x xn Z m h k
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Damping ratio in percentage Radiation damping in percentage Eccentric distance between center of mass and the center of rotation (m) Natural frequency of the foundation soil system (Hz) The dynamic force excited over the footing in a vertical mode (N) Total dynamic force (N) Frequency
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