Experimental study on mechanical properties of grout/ground interface of fully bonded anchors in cohesive soil layer

The results of load test and distributed optical fiber in Shenping Anchor Test show that the fully bonded anchor in the granite residual cohesive soil layer: (1) The effective and critical fixed length of anchor exceed 24m. (2) There is almost no stress concentration at grout/ground interface. (3) When the pulling force reaches the limit state in a single layer, the bond stress is distributed uniformly along the whole length of the anchor body. (4) There is a length effect on anchor fixed length, that is, the anchoring efficiency decreases with the increase of anchor fixed length after the length exceeds a certain value. (5) The bond stress of the first half of the anchor body will be transferred to the back half before the bond strength is reached. The anchor body will be transferred to the tail end of the anchor tendon for a short length and then increase to the bond strength in the whole length, while for a long length, the first half reaches the bond strength and then passes back to the tail end, and then the full length reaches the bond strength. (6) When the hard layer is distributed in the second half of the anchor body, its bond strength is usually difficult to give full play. (7)The axial distribution curve of grout tensile stress can be divided into four sections, namely, rapid increase, deceleration increase, gradual decrease and slow decrease.（8）The stiffness of anchor body is mainly reflected in the stiffness of anchor tendon, and the elastic modulus of anchor fixed length should not be calculated according to the weighted average method of the cross-sectional area of the elastic modulus of anchor tendon and grout