Pullout resistance of bearing reinforcement embedded in marginal lateritic soil at molding water contents

Abstract

The effect of molding water contents (on dry and wet sides of optimum water content) on the pullout resistance mechanism of the bearing reinforcement embedded in a marginal lateritic soil is investigated in this paper. The total pullout resistance is contributed from the pullout friction and bearing resistances. The pullout friction resistance is approximated from the soil shear strength and interaction factor, α. The peak and residual interaction factors (αp and αr) are independent of molding water contents tested and are approximately 0.63 and 0.46, respectively. The bearing pullout resistance of a single isolated transverse member is dependent upon both shear strength and failure mode and can be approximated from the modified punching shear solution with various angles of transformation, β. The β values of the compacted soil at 0.67≤w/wOWC≤1.0 are essentially constant and equal to π/2 (where wOWC is the optimum water content). For 1.0<w/wOWC≤1.33, the β value decreases polynomial with an increase in w/wOWC. The failure mechanism of the bearing reinforcement is classified into three zones (block, interference and individual), depending upon spacing and dimension of transverse member, S/B ratio. The transverse member interference zone is independent of water content when 0.67≤w/wOWC≤1.0 and decreases as w/wOWC increases when 1.0<w/wOWC≤1.33. Based on a critical analysis of the test results, the pullout resistance equations in term of normal stress, shear strength parameters, S/B and molding water content are proposed. The proposed equations are useful for the internal stability analysis of bearing reinforcement earth walls during construction and at the end of construction.