SHOULD GROUTED ANCHORS HAVE SHORT TENDON BOND-LENGTH

Field measurements associated with the behavior of ten low-pressure gr outed anchors installed with a hollow stern auger at the National Geot echnical Experimentation Site at Texas A&M University are presented. T he anchors were 0.3 m in diameter and embedded 13.8 m in a stiff to ve ry stiff clay. Six anchors had a tendon bond length of 4.6 m and four had a tendon bond length of 9.2 m. All anchors were load tested to nea r failure, some were subjected to creep tests, and some to long-term r elaxation tests. This study evaluates the load distribution in the soi l, grout, and steel tendon; the shear strength of the soil-grout inter face compared to engineering soil properties; the relationships betwee n the ultimate load, the creep failure load, the creep threshold load, and the design load; the creep movement rate under load; and the load loss as a function of time. The results show that anchors with shorte r tendon bond lengths have higher ultimate capacities and lower creep rates, and transfer the load further away from the supported structure .