A Multi-Segment Expanded Anchor for Landslide Emergency Management

Abstract

Conventional mortar cemented anchors cannot meet the needs for landslide emergency management, as they can withstand loads only after mortar curing for 14–28 days. This study developed a multi-segment expanded anchor (MSEA) that expands using a sliding mechanism and rapidly bears loads using multiple load-bearing bodies by the frictional drag along the perforated wall, and the reaction force of the underreams’ platforms. Field tensile tests without grouting and the secondary tensile tests of six MSEAs, each with a length of 23 m, were carried out. The field tests show that the installed load-bearing bodies expanded steadily when the MSEAs were tensioned without grouting. In hard sandstones, the initial tensile force of each load-bearing body exceeded its design value of 150 kN, and the initial bearing capacity of each MSEA was greater than 300 kN, which exceeded the bearing capacity of the existing anchors regardless of grouting. The secondary tensile tests of the MSEAs were conducted after they were grouted for three days, and their lock-off load was greater than their design value of 600 kN. Based on the elastic mechanics and the stress process of the MSEAs, this study derived the theoretical equations of the ultimate bearing capacity of the MSEAs without grouting. The results calculated using the theoretical equations were roughly consistent with the field test results of the ultimate bearing capacity.