Abstract: This paper presents a case history of gravity anchorage for a special bridge in Guizhou Province. To study the joint bearing characteristics of a notched sill gravity anchorage and rock foundation, model tests and numerical simulations of two different options including a 1/4 depth and a 1/2 depth of notched sill gravity anchorage were conducted. The displacement, stress distribution, and failure evolution characteristics at the interface between the anchorage and the foundation under different cable forces were also analyzed. The synergistic action mechanism of anchorage and foundation, bearing capacity transmission and distribution were obtained. The results show that: 1) during the step-by-step loading process, the horizontal displacement curve of the anchor exhibits an evolution pattern of “gentle linearity, nonlinear bending and sharp growth”;  2) The overturning of the anchorage leads to the continuous transfer of contact force between the anchor and the foundation to the forward notched sill, resulting in a significant decrease in contact stress at the base and limited friction. The shear resistance is mainly provided by the normal stress of the notched sill and the rock mass in front (depending on the depth of the anchor); 3) Under the ultimate bearing state, the notched sill bears almost all the vertical loads. The horizontal load sharing ratios of the foundation and notched sill of first scheme are 79% and 21%, while the horizontal load sharing ratios of the base, notched sill, and front rock mass of second scheme are 25%, 15%, and 60%. As the burial depth of the anchorage increases, its horizontal bearing capacity shifts from being dominated by foundation friction to being dominated by rock mass shear resistance.

Key words: Gravity Anchorage, Rock Foundation, Bearing Characteristics, Load Sharing Ratio