Abstract
Identification of a locking segment is crucial to assess the potential runout risk and the overall stability of a high-locality landslide. However, it is difficult to identify a locking segment through field surveys before a landslide failure due to their concealment. Taking the Tizicao landslide—a high-locality landslide in Southwest China—as a field example, this study aims to identify and analyze a locking segment of the landslide. Based on geomorphology and spatial–temporal deformation of the landslide, the characteristics for identifying the locking segment of the Tizicao landslide are analyzed, and the locations and area of the locking segment are determined based on the analytical results. Furthermore, the identification results are interpreted through fieldwork including the displacement monitoring of ground surface and deep parts, borehole drilling, and oblique photography using unmanned aerial vehicles. The results reveal that the locking segment of the Tizicao landslide lies at the southern slope toe and covers an area of approximately 4.69 × 104 m2, accounting for 15.2% of the total area of the landslide. Significantly different characteristics are observed in respect of surface displacement, deep displacement, surface cracks, and sliding zone soil between locking and non-locking segment.
Highlights
Locking segments, called rock bridges (Einstein et al 1983; Frayssines and Hantz 2006) or locked sections (Huang 2012; Chen et al 2018) in the rockslides, play a critical role in the occurrence of a highlocality landslide, and the overall stability of the landslides involved depends on the strength and deformation of the locking segments (Jennings 1970; Jaeger 1971; Pariseau et al 2008; Chen et al 2018)
The results show that the locking segment of the Tizicao landslide lies at the southern slope toe, which covers an area of about 4.69 × 104 m2, accounting for 15.2% of the total area of the landslide
It is concluded that the formation and evolution of the locking rock masses in the Tizicao landslide are closely related to the development of local folds and S-shaped river valleys, differential unloading due to river cutting, and earthquake-induced damage to rock masses in the landslide area
Summary
Called rock bridges (Einstein et al 1983; Frayssines and Hantz 2006) or locked sections (Huang 2012; Chen et al 2018) in the rockslides, play a critical role in the occurrence of a highlocality landslide, and the overall stability of the landslides involved depends on the strength and deformation of the locking segments (Jennings 1970; Jaeger 1971; Pariseau et al 2008; Chen et al 2018). A high-locality landslide with locking segments usually possesses huge potential energy. On June 5, 2009, a huge catastrophic rockslide with a rock mass barrier in the front took place at the crest of the Jiweishan Mountain in Wulong County, Chongqing, China, with a long runout distance of 1,500 m, and the landslide body about 7.0 × 106 m3 was moved towards the valley; as a result, about 0.47 km[2] of the residential area was buried, an iron ore mine was destroyed and 74 people were killed (Xu et al 2010; Yin et al 2011). On August 27, 2014, a similar large-scale landslide with one locking segment at its front toe occurred in Fuquan County, Guizhou province, China, which killed 23 people and destroyed 77 houses (Lin et al 2018). On June 24, 2017, a catastrophic landslide with locking masses in the front was triggered above the Xinmo Village, Maoxian County, Sichuan Province, China; it buried the whole Xinmo village (10 deaths, 73 people missing) and the sliding mass blocked over a distance of 1,300 m of the Songping River (Kang et al 2019; Wang et al 2019a)
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