Field testing study on bearing behavior of full-length bonding anti-floating anchor in rocks
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Abstract:
Anti-floating anchors have a broad engineering application prospect, due to their excellent properties including good stratum adaption, high anchorage force, low energy consumption, and short construction period. Four sets of ultimate tensile load experiment for thirteen rock anti-floating anchors were conducted. One of the anchors was installed fiber grating strain sensors in order to monitor the anchor stress, and all of the anchors were loaded until the failure status. The aspects of load-anchor head displacement curve, axial and shear stress distribution of anchor rod, and interface bonding strength were analyzed. The experimental results show that there are three types of failure modes of test anchor, i.e. the shear-slip failure at the rod-anchorage body interface, the shear-slip failure at the anchorage body-surrounding rock interface, and the fracture failure of the anchor rod. Under the experiment conditions, the ultimate tensile load of the anti-floating anchors with a 2.0 m bonding length is 240 kN, and the ultimate load of the anchors with the bonding length exceeded 3.0 m is more than 320 kN. The properties of the experimental anchor including high bearing capacity and small deformation meet the engineering requirements. The axial force of the anchor rods reduces from the anchor head to anchor bottom, and the anchor rods bear tiny force after reaching the depth of three meters. Hence, the suggesting design value of the bonding length of anti-floating anchors embedded in moderately weathered granite is from 3.5 m to 4.0 m. The rod shear stress presents a trend of increasing firstly and then decreasing, the position of the maximum shear stress is located at the depth of 0.45 m and its value is approximate 2.7 MPa. In addition, the average bonding strengths of the rod-anchorage body interface and anchorage body-surrounding soil interface are 1.14-1.36 MPa and 0.28-0.37 MPa, respectively.
