Experimental and numerical studies of a strip footing on geosynthetic-reinforced sand

Abstract

The behaviour of footings on geosynthetic-reinforced soils has been investigated by many researchers through experimental and numerical modelling under stress-controlled or strain-controlled conditions. It is believed that stress-controlled tests better represent the field conditions because the load applied to the footing increases as the super structure is being built. Therefore, a new experimental set-up was designed under a stress-controlled condition, with the application of particle image velocimetry (PIV) technique. A series of model footing tests were carried out using this equipment to investigate the behaviour of the geosynthetic-reinforced soil below a strip footing. The deformation inside the soil mass below the strip footing was determined using the PIV technique. The reinforcing performances of the single-layer and multi-layer geotextile and geogrid embedded at different depths were compared and discussed by analysing the load-settlement curves. The optimum embedment depth for the single-layer geosynthetic reinforcement is in the vicinity of 0.4B. It is found that there is a stepwise increase phenomenon in settlement under the stress-controlled condition. The ultimate bearing capacities were determined from the obtained stepwise load-settlement curves using three approaches, including the tangent intersection method, the tail linear method and the allowable settlement method. The three approaches were coded in a Python program in order to easily determine and compare the results. In addition, the experimental model footing tests were simulated using the finite element method (FEM) under the same stress-condition condition with good agreement for a settlement range within 0.1B.