Abstract
On August 29 and 30, 2012, local extreme rainfalls struck the construction area of the Jinping I Hydropower Station, Xichang, China, and triggered many geohazards. The upper region of the left valley slope 200 m downstream of the dam failed and slid, exposing the D‐pile of the G1002 electricity pylon and threatening the entire power transmission line. Therefore, guaranteeing the stability of the residual soil masses in the rear area of the main scarp and the safety of the G1002 electricity pylon became a primary emergency task. Geological field surveys, topographical mapping, study of the failure mechanisms, and stability evaluations were carried out from October 12, 2012, to November 7, 2013. It is revealed that the failure mechanism of the G1002 electricity pylon landslide is flood‐induced tractive sliding along the interlayer between the colluvium and the bedrock, significantly influenced by heavy precipitation and frequent blasting activities during the dam construction. The residual soil masses around the G1002 electricity pylon foundation are unstable under rainfall conditions. In order to ensure the stability of the residual soil masses and pylon foundation, a mitigation measure of the anchor cables combined with lattice frame beams was proposed and applied in practice. This paper provides insights into the problems associated with the selection of the locations of electricity pylons in ravine regions as well as mitigation strategies for similar landslides.
Highlights
Landslide hazards due to increasing population density and infrastructure development in canyon areas are inevitable
Established initiation models for debris flows, such as coupled hydraulics and soil mechanics models [17], surface runoff model [6], and runoff threshold model [13] mainly refer to the channel bed erosion rather than the lateral erosion. us, geological investigations and design stages should focus on the lateral erosion of accumulative deposits by floods and preliminary protection measures for the same
Instead of focusing on the mitigation of the G1002 electricity pylon landslide (EPL) itself, the protection of the G1002 electricity pylon was considered to be more important for the main stakeholder—China Power Engineering Consulting (Group) Corporation
Summary
Landslide hazards due to increasing population density and infrastructure development in canyon areas are inevitable. In unconsolidated soil with a wide grading and loose structure, the factors triggering debris flows are floods or large runoff, in addition to strong rainfall [13, 14]. It has been emphasized that 13.9% of the landslides were caused by erosion [15], the effects of floods and torrential runoff in mountainous areas, which are significant disaster factors for debris flows or landslides, remain unclear. Established initiation models for debris flows, such as coupled hydraulics and soil mechanics models [17], surface runoff model [6], and runoff threshold model [13] mainly refer to the channel bed erosion rather than the lateral erosion. Instead of focusing on the mitigation of the G1002 electricity pylon landslide (EPL) itself, the protection of the G1002 electricity pylon was considered to be more important for the main stakeholder—China Power Engineering Consulting (Group) Corporation. Considering the object to be protected, cost, and implementation, anchor cables combined with lattice frame beams and crack sealing were proposed as mitigation measures, which provide reference for similar events
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