Shaking table tests on the influence of geosynthetic encasement stiffness on the shear reinforcement effect of GESC composite foundation

Abstract

This paper presents an experimental study of shaking table tests on two geosynthetic encased stone columns (GESC) composite foundation models with different geosynthetic encasement stiffness to investigate the influence of geosynthetic encasement stiffness on the shear reinforcement effect. The reduced-scale GESC composite foundation models were designed according to the similitude relationships by scaling the model geometry, geosynthetic encasement stiffness, and input motions for shaking table tests in a 1 g gravitational field. The GESC composite foundation models were constructed using poorly graded sand, gravel, and geotextile encasement, and then were excited using a series of sinusoidal input motions with increasing peak acceleration. The acceleration amplification factors for the GESC composite foundation model with higher geosynthetic encasement stiffness are larger than those of the lower geosynthetic encasement stiffness model due to the increased stiffness of the composite foundation. The higher geosynthetic encasement stiffness composite foundation has smaller settlements and lateral displacements under the same input motions compared to the lower geosynthetic encasement stiffness composite foundation. The incremental geosynthetic encasement tensile strains increase with increasing input acceleration for both models. The longitudinal tensile effect of geosynthetic encasement plays an important role on the shear reinforcement mechanism of GESC.