Tests on bond strength between grout and tendon of soil anchors

The research results about the bond strength between anchor tendon and grout are few. The test results of 64 soil anchors in 3 projects show that: (1) The dispersion degree of the ultimate bond capacity between grout and tendon is tremendous, and its solitary-low phenomenon is widespread. The dispersion degree has nothing to do with the bond length and is related with the quantity of tendons and tension technique, so that of the calculated bond strength of grout-tendon is tremendous. (2) The bond strength of grout-tendon is not related with the in-situ conditions, grout techniques and quantity of tendons, but is able to be improved when drilling with casing pipes and improving the cleanliness of the hole. (3) The relationship between the grout-tendon bond strength and the grout design strength cannot be verified, neither is the effect of actual strength of grout and tendon sharp on the bond strength of grout-tendon. (4) The exerting degree of bond strength slightly decreases with the increase of bond length. (5) The characteristic values of bond strength of grout-tendon are 0.744~0.664 MPa under the bond length of 3~6 m. (6) The bond length of soil anchors should be more than 8 m. (7) The number of tendons in the single anchor should not be 2.