A series of pullout tests is presented in this paper and is used to identify the kinematics of failure and the uplift response of circular anchor plates embedded in sand-cement stabilized layers at distinct normalized embedment depths (H/D), where H is the thickness of the treated layer and D is the diameter of the anchor plates. Experimental results show that the uplift capacity of anchor plates embedded in sand backfill layers increases considerably after mixing 3% cement with the backfill material. Distinct failure mechanisms observed for anchor plates embedded in both sand and cement-stabilized backfills are shown to be a function of H/D. The addition of cement to the sand backfill leads to an increase in uplift capacity of 9 times for an H/D ratio of 1.0 and of 13 times for an H/D ratio of 2.0. For sand backfill with H/D 5 1:0, the failure surface had a truncated cone shape with a vertical inclination of 22°, whereas for H/D of 1.5 and 2.0, radial cracking was observed, and final failure surfaces had inclinations of 26 and 30°, respectively. Pullout of anchor plates in cement-stabilized backfills at H/D ratios ranging from 1.0 to 2.0 exhibit two distinct characteristics: (a) a linear elastic deformation response at small pullout displacements and (b) a later stage where radial fracturing of the stabilized backfill leads to hardening just prior to failure. Radial cracks starting at the top of the layer near the center of the anchor plates start to propagate only at about 90% of the final uplift failure load, irrespective of H/D.
The addition of a soil–cement reinforcement layer is an alternative to improve the bearing capacity of shallow foundations on weak soils. Recent research with small-scale tests highlighted the influence of the soil–cement layer's geometry and tensile strength in bearing capacity prediction of footings resting on treated layers. This work presents the evaluation of field static load tests of circular steel footings resting on soil–cement layers above a weak residual soil. Results showed on the one hand that traditional methods for predicting bearing capacity in homogeneous soils could be applied when the foundation and reinforcement layer are expected to punch together into the weakly bonded residual soil, without the failure of the reinforcement layer until some prescribed load. On the other hand, methods for continuous double-layer systems could be used where the reinforcement layer is expected to fail before reaching the prescribed load. The failure mode could be predicted by calculating the maximum tensile stress at the bottom of the reinforcement layer at the prescribed foundation load. An equation for this purpose was suggested and successfully tested against real-size field test results. Finally, analytical solutions for determining the bearing capacity were effective in foreseeing the field values.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.