Soil Structure Interaction Studies with Use of Geosynthetics in Soils Beneath Footings

Abstract

The present study consists of two parts. In the first part, the effect of using a geomembrane (slip) layer in soil beneath footings under seismic excitations from shake table tests is being investigated. A triaxial shaker system is used to carry out the tests on a one-third scaled model of single storey, single bay RC space frame. The structure with different base conditions are subjected to sine sweep tests and simulated seismic excitation corresponding to the design spectrum for Zone III as per the Indian standard code (IS 1893 (Part 1): 2002). It is observed that the natural frequency of the structure decreases with increase in the flexibility of supporting soil In the second part, effects of using geosynthetic reinforced soil beneath footings of multistoried structures with tunneling operations beneath are being looked into. Numerical investigations on shallow depth tunnels like metro tunnels in granular soils, response due to tunneling itself (single and twin tunnels) and also their impact on the buildings above are carried out, using 3DEC software. Tunneling for metro causes innumerable changes in the form of distortion taking place in strata surrounding the tunnel, and also affect the member forces of framed structures on the surface. Height of superstructure and building eccentricities from the tunnel centre line are also varied. Results reveal that the presence of geosynthetic reinforcement in soil considerably reduces the displacements under footings.