An Experimental Study on the Failure Mechanism of Load Distributive Compression Anchors in Residual Soil

Abstract

The use of Load Distribution Compression Anchors (LDCAs), known for their high bearing capacity and removable strands after construction, has grown recently. Unlike conventional anchors, LDCAs have multiple anchor bodies along their length, presenting unique pull-out behaviors that remain insufficiently understood. This study aimed to investigate the failure mechanisms of LDCAs through physical model tests conducted in residual soil with a 90% relative density, adjusting variables such as anchor length, the number of anchor bodies, and the spacing between these bodies. To assess the effect of the surrounding soil on these mechanisms, the results of the experiment were compared with those from experiments conducted at a 70% relative density. Findings revealed that anchor body-grout tensile failure occurred during the initial loading stage. The tensile failure was determined by the grout strength itself rather than the effect of the surrounding soil. After anchor body-grout tensile failure, each anchor body behaves independently. However, when the spacing between the anchor bodies was small, local grout-ground interface failure occurred at both 70% and 90% relative density conditions, resulting in the overlapping of grout axial loads. Lastly, it was confirmed that the ultimate bearing capacity of LDCAs (multiple anchor bodies) can be less than that of compression-type anchors (single anchor body). The shear field developed by each anchor body in LDCAs overlapped and reduced the grout-ground shear strength. The reduction in ultimate bearing capacity was more pronounced in the dense soil condition and narrow anchor body spacing condition.