Small scale model test on lateral behaviors of pile group in loose silica sand

Abstract

The accurate predictions of load- deflection response of the pile group are necessary for a safe and economical design. The behavior of piles under the lateral load embedded in soil, is typically analyzed using the Winkler nonlinear springs method. In this method, the soil-pile interaction is modeled by nonlinear p-y curves in a way that the single pile p-y curve is modified using a p-multiplier (Pm) for each row of piles in the group. The average Pm is called the group reduction factor. The Pm factor depends upon the configuration of pile group and the pile spacing (S). The present study was conducted to investigate the effects of various parameters, such as the pile spacing in the group, different layouts and the lateral load angle (Ѳ) change as a new parameter on the Pm factor and group efficiency based on the 1-g model test. The Pm factor is well comparable with the results of the full-scale test on pile group. However, based on the results, the calculated values of the Pm factor for 3×3 pile groups under 2.5-diameter spacing was estimated about 0.38 and under 3.5-diameter spacing was estimated about 0.52, so the calculated values at S/D=3, obtained from interpolation the values of group reduction factor at S/D=2.5 and S/D=3.5, are close to the AASHTO recommendation.

An Improved Winkler Foundation Modulus for a Beam in a Full Space

“…Underground structures, such as tunnels, are subject to free-field deformation. The displacement of the free field is assumed to be wf from Equation (8). The contact force at the interface of the beam and foundation has the form ( )…”

“…Dash et al [7] carried out 12 centrifuge tests to obtain the nonlinear Winkler foundation spring of liquefiable soil. Vakili et al [8] conducted a 1 g model test to obtain the Winkler nonlinear spring of the pile group under the lateral load. Moreover, the nonlinear spring applicable to CFA and Franki piles was proposed [9,10] based on the test method.…”