Geomechanics and Engineering, Vol. 10, No. 4 (2016) 405-422 DOI: http://dx.doi.org/10.12989/gae.2016.10.4.405 Copyright © 2016 Techno-Press, Ltd. http://www.techno-press.org/?journal=gae&subpage=7 ISSN: 2005-307X (Print), 2092-6219 (Online) Behaviour of geocell reinforced soft clay bed subjected to incremental cyclic loading A. Hegde 1 , and T.G. Sitharam 2 1 Department of Civil and Environmental Engineering, Indian Institute of Technology, Patna 801103, India 2 Department of Civil Engineering, Indian Institute of Science, Bangalore 560012, India (Received January 22, 2015, Revised December 07, 2015, Accepted December 31, 2015) Abstract. The paper deals with the results of the laboratory cyclic plate load tests performed on the reinforced soft clay beds. The performances of the clay bed reinforced with geocells and geocells with additional basal geogrid cases are compared with the performance of the unreinforced clay beds. From the cyclic plate load test results, the coefficient of elastic uniform compression ( C u ) was calculated for the different cases. The C u value was found to increase in the presence of geocell reinforcement. The maximum increase in the C u value was observed in the case of the clay bed reinforced with the combination of geocell and geogrid. In addition, 3 times increase in the strain modulus, 10 times increase in the bearing capacity, 8 times increase in the stiffness and 90% reduction in the settlement was observed in the presence of the geocell and geogrid. Based on the laboratory test results, a hypothetical case of a prototype foundation subjected to cyclic load was analyzed. The results revealed that the natural frequency of the foundation-soil system increases by 4 times and the amplitude of the vibration reduces by 92% in the presence of the geocells and the geogrids. Keywords: geocells; cyclic plate load test; coefficient of elastic uniform compression; natural frequency; bearing capacity 1. Introduction The foundation beds are often subjected to cyclic loads due to many circumstances, such as earthquakes, traffic loads, and the machine vibrations in the case of the machine foundations. These cyclic loads are generally smaller as compared to the static loads; but are repetitive. As a result of these cyclic forces, the soil bed may undergo large settlements and subsequently may fail to support the superstructure above. In order to resist the cyclic stresses, generally, stiffness of the soil is increased. Out of many available techniques, soil reinforcement technique using geosynthetics is the most sought after technique to increase the stiffness of the soil (Dash et al. 2001a, Sitharam and Sireesh 2004, Hegde and Sitharam 2015a). Earlier days, geogrids were used to reinforce the soil. However, more effective and promising way of reinforcing the soil is to use the geocells (Hegde and Sitharam 2013, Hegde and Sitharam 2015b). Geocells are 3-dimensional expandable panels made up of ultrasonically welded high strength Corresponding author, Assistant Professor, E-mail: amarnathhegde@gmail.com a Professor, E-mail: sitharam@iisc.ernet.in 405