The particle size effect on the uplift capacity of shallow circular plate anchors in sand using DEM

Abstract

To address the inherent particle size effect (PSE) in physical and DEM modeling, 3D DEM models of shallow circular plate anchors in sand were developed using PFC3D. Following validation against centrifuge data, the influence of the effective plate diameter-to-mean particle size ratio ( d w / d 50 ) on uplift behavior was systematically investigated by scaling anchor dimensions under corresponding gravitational fields. Results indicate: (1) The macroscopic uplift response exhibits a stage-dependent PSE. For d w / d 50 > 14.17, the PSE is negligible. Below this threshold, ultimate uplift capacity and failure displacement increase nonlinearly, accompanied by pronounced load-displacement curve fluctuations. (2) End-bearing and shaft friction exhibit distinct PSE sensitivities. The artificial increase in overall uplift capacity is primarily governed by overestimated plate end-bearing (critical threshold d w / d 50 = 14.17). Shaft friction presents a lower threshold ( d w / d 50 = 12.14) with limited magnitude enhancement, yet its response stability is highly susceptible to particle size variations. (3) Microscopic analyses of displacement fields and force chain networks reveal that at lower d w / d 50 ratios, the mobilized soil zone expands and load transfer paths become highly concentrated. Enhanced particle interlocking, wedging, and local arching fundamentally drive the artificially higher ultimate uplift capacity and intensified macroscopic load fluctuations.