Experimental investigation and discrete element method simulation on mechanical properties and failure mechanism of polymer-stabilized sand

Natural sand can be heavily eroded due to its weak internal cohesion, and most solutions are reinforced by recovering particle connections regardless of their environmental impact. In view of this, our study focuses on an organic polymer reinforcement (PU) and investigates the strength, failure behavior, and energy evolution. Unconfined compressive tests are conducted, and the DEM method is used to establish corresponding numerical models, which contains the various polymer contents and densities. The results indicate that the compressive strengths are strongly improved with increasing polymer content and specimen density. The polymer has significant impacts on mechanical strength, failure behavior, and energy evolution. The failure pattern of the specimens with various polymer contents is changed from single to multiple path cracks. The specimens of various densities, however, only have difference in path extension. The failure process of the polymer-stabilized sand distinctly depends on the bond breakage state. Its increment curves can be divided into compaction phase, slow expansion phase, fast propagation phase, and stability phase. The instability microstructure of force chains is transformed by polymer effects, which causes force-chain reconstruction, micro-cracks redistribution, and energy increment. The level of energy averages and releasing rates are both improved with the polymer content. The insights from the physical and numerical tests are expected to help understand the possible reinforcement mechanisms of polymer and the potential relations between cracks development and energy evolution.