# A Multi-Segment Expanded Anchor for Landslide Emergency Management
## 1 Introduction  
The concealment and emergency of landslides tend to cause great losses of human life and production, which can be minimized by rapid and effective emergency response. As an important part of landslide emergency response, emergency management plays an instrumental role before or after landslides. However, a gap still exists between the actual control effects and the satisfactory and optimal solutions due to limited technical conditions. For example, a large-scale landslide occurred in Baige Village, Jiangda County, Changdu City, on 11 October 2018. Emergency investigation and monitoring [1] were implemented, but emergency management could not be conducted due to the limited technical and construction conditions. After 23 days, a high-altitude rock mass of about 215 \(\times\) 104 m\({}^{3}\) at the rear edge of the landslide collapsed and slid again, causing a disaster for 102,000 people, and the collapse of more than 3400 houses in Tibet, Sichuan, and Yunnan. Moreover, the landslide in Baige Village is still facing the risk of recurring and blocking the Jinsha River [2,3]. Therefore, it is a challenge for geologists to take effective measures and provide decision-makers with new tools for landslide emergency management. As an effective means of active support, lattice anchors are widely used in the emergency management of severe landslides. Conventional anchors support loads using grouted bodies [4, 5, 6]. Fully grouted anchors are affected by anchor factors, grouting-related factors,stresses, anchor installation, and rock-mass conditions [7]. However, both the grouted bodies and the concrete lattice girders require a long curing time. Therefore, conventional anchors cannot fully meet the needs of landslide emergency management. For instance, 284 anchors were constructed for emergency reinforcement against the landslide in Danba County, Ganzi Tibetan Autonomous Prefecture, Sichuan Province, in early February 2005; however, the first anchor was not tensioned for about one month and the whole anchoring project was completed in June, missing the scope of emergency rescue date [8; 9]. In 2019, a landslide in the Jiulao section of the Gedan Highway was reinforced using sloping and fully grouted anchors. The landslide mass was greatly deformed again before anchor tensioning within a 7-day grouting curing. Consequently, the anchors were tensioned with a U-steel reaction support [10]. Many studies have been conducted to reduce the construction period of anchorages. To facilitate the rapid construction of lattice girders, precast concrete lattices and steel anchor piers can be used to improve construction efficiency and environmental friendliness [11; 12; 13]. One method for achieving the rapid load bearing of anchors is to reduce the time difference between the initial and final setting of mortar. For instance, the time difference of self-expanding anchors can be reduced by 78% by using expanding cement grout [14; 15]. The other method to achieve rapid load bearing with anchors is to adopt special structures to improve the initial bearing capacity. For example, many new anchors have gradually emerged in recent decades, such as mechanically underreamed anchors [16], self-burying anchors [17], earth anchors with squibbing [18], under-reamed ground anchors with capsules [19; 20; 21], umbrella-shaped anchors [22], and high-pressure jet grouting (HPJG) anchors [23]. However, some of these anchors have insufficient tonnages, and others still rely on mortar strength, resulting in a lengthy construction period. For instance, mechanically underreamed anchors have a pullout resistance of 250 kN, are based on grouted bodies, and are suitable for soft soil; self-expanding anchors have a pullout resistance of about 116 kN and can be used for rocks; umbrella-shaped anchors have a tensile resistance of 100 kN, and HPJG anchors are based on grouted bodies. Therefore, these new anchors cannot meet the emergency management requirements for severe rockslides. In this study, a MSEA with a sliding mechanism was proposed.