Initiation mechanism and deformation tendency of a high-position landslide at Ningnan County, China. Issue 6 (October 2021)

• Record Type: Journal Article
• Authors: He, Kun; Hu, Xiewen; Liu, Bo; Zhou, Ruichen; Xi, Chuanjie
• Is Part Of: IOP conference series. Volume 861:Issue 6(2021)
• Publication Date: 2021-10
• Subjects: Earth sciences -- Periodicals; Environmental sciences -- Congresses; Environmental sciences -- Periodicals; 550.5
• DOI: 10.1088/1755-1315/861/6/062006
• Languages: English
• ISSNs: 1755-1307

Abstract

Abstract: High-position landslides mainly occur in the upper part of the steep slope wherein the shear outlet is much higher than the toe of the slope. It often transforms into the rapid and long-runout debris flow, causing severe loss of life and property. This paper describes a high-position landslide that occurred on the right bank of the Heishui River in Songxin Town, Ningnan County, southwestern China, on June 28 and August 16, 2012, resulting in five deaths. Based on the field investigations, borehole drilling, in situ, and laboratory experiments, the initiation mechanism of the landslides are unraveled. Detailed crack surveys are conducted to identify the deformation tendency of this landslide in the future. The Baishuihe landslide originated on a 310 m-high hillslope, which provided a favorable free surface for the landslide occurrence. The Baishuihe landslide is located in the influence zone of the Zemuhe fault, and the active fault activities dramatically contribute to the fragmented stratigraphic structures and well-developed minor structures. The initiation of the June 28 landslide is considered a long-term creep under the inner and outer integrations, while the consequent bedding slope and persistent precipitation are the primary factors. The failure of the August 16 landslide is analyzed using the retrogressive slide in the source area of the first landslide. The sustaining deformation of the landslide is controlled via cracks on the surface of the main deformation zone and hydraulic influences induced by rainfall. The slip process follows creep deformation and can be aggravated under rainfall. Based on the crack distribution, the potential instability volume is calculated as 1.66 × 10 4 m 3 ∼ 54 × 10 4 m 3 . The Baishuihe landslide provides a crucial case study for evaluating high-position landslide and zoning risk areas in mountainous areas.