Characteristics and Remedy Solutions for a New Mong Sen Deep-Seated Landslide, Sapa Town, Vietnam

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 deep-seated landslide occurred near the new Mong Sen bridge in Trung Chai commune, Sapa town, Laocai province. In October 2020, some serious cracks were observed above a natural slope near a road, which was under construction to connect the Noi Bai-Laocai highway to Sapa town. The crack area was divided into two zones. Since this phenomenon could not only cause loss of life but also damage to the properties located downhill, the construction was stopped until the slope was rehabilitated. In this study, geological investigations, laboratory tests, and stability analysis were conducted to understand the failure mechanism. The analysis results showed that cutting activities during the construction of the road contributed to the sliding of the sloping soil mass. The following rehabilitation works at the failed area were conducted: (1) removing the soil above the natural slope; and (2) constructing the retaining system, including ground anchors and soil nails to retain the remaining slope. Results of stability analysis demonstrated that the retained slope would be stable after treatment.

A comparison of countermeasures against landslide on the road No.152, Sapa Town, Lao Cai Province, Vietnam

“…Moreover, according to this analysis, ground anchor work is the best method in these cases for stability of this slope failure. The result is consistent with previous research [5,7]. Only retaining wall method can't prevent the deep-seated landslide due to soil is going to collapse in surface.…”

“…The retaining wall and the concrete beam frames were simulated as plate elements with interfaces. Some researchers have been published utilizing the PLAXIS 2D program [5][6][7]10]. 3.6.1.…”

“…In recent years, several landslides have occurred on new expressways, including the Ha Noi-Lao Cai, Bac Giang-Lang Son, and Halong-Vandon expressways. In July 2018, a deep-seated landslide occurred, the biggest one in terms of its debris volume and sliding surface depth, on the Ha Long-Van Don expressway, in Quang Ninh province [5] Especially, landslides and slope failures in the Lao Cai province which have occurred due to its topographic characteristics and geographic position [6,7].…”

“…They studied the rainfall-induced slope failure, the stability assessment of the slope, and the prediction of the landslide block. Besides, many researchers have already published on the application of the Finite Element Method (FEM) (PLAXIS 2D) for slope stability [5][6][7]10]. They studied the sliding failures, the landslide slip surface, and remedies against the landslide.…”