Construction Technology and Pull-out Test of Underreamed Anchor in Expansive Soil

To enlarge anchorage diameter and to make a change in shape of anchorage body are critical methods to improve bearing capacity of anchor directly. In the expansive soil, the mechanical extruding reaming process was used to construct the multi section underreamed anchors, and the multi-stage cyclic loading test was carried out. According to the load-displacement curve, the failure mode of the anchor is determined as the failure of the bonding interface between the rod and the anchorage body. The test result shows that the construction technology of underreamed anchor in expansive soil layer is feasible. The uplift bearing capacity is one time higher than general anchorage. The bearing capacity value of underreamed anchors increases with decreasing anchor spacing, but the increase range is rarely. The test results could provide reference for the study of the influencing factor of anchorage bearing capacity and failure mechanism of anchorage.