Comprehensive Analysis and Rehabilitation of a Slow-Moving Landslide in Vietnam Using Laboratory and Field Measurements

Abstract

Landslides govern the evolution of landforms and pose a serious threat across the globe, especially in mountainous areas. In the northwestern area of Vietnam, a slow-moving landslide occurred near an important economic road corridor in Caumay Ward, Sapa Town, Laocai Province. In December 2019, some serious cracks were observed at a construction site near this landslide. Since this phenomenon could cause not only loss of life but also damage to the properties located downhill, the construction was abandoned until the slope was rehabilitated. Geological investigations, laboratory tests, and surface displacement monitoring were conducted to understand the failure mechanism. The analysis results showed that the anthropogenic activities associated with the rising groundwater level due to frequent rainfall events, owing to climate change, had contributed to the sliding of the sloping soil mass. The rehabilitation works at the failed area were conducted chronologically in two stages: (1) backfilling at the downhill area; demolishing two villas located within the sliding area to reduce surcharge; constructing an anchor system in the uphill area, and (2) constructing the anchored wall at the downhill area. During the rehabilitation works, the Caumay landslide was observed to initially undergo gradual movement and then stabilize at the end of the first stage of the rehabilitation works. The rehabilitation techniques adopted at the failed site were validated using both numerical analysis and field measurements. The anchor reinforcement methodology adopted in this study is expected to help agencies and the public in stabilizing landslide-prone areas for residential and other infrastructure construction.