Identification, Monitoring, and Assessment of an Active Landslide in Tavan-Hauthao, Sapa, Laocai, Vietnam – A Multidisciplinary Approach
Manh Duc Nguyen*1,, Nguyen Van Thang*2, Akihiko Wakai*2, Go Sato*3, Jessada Karnjana*4, Hoang Viet Hung*5, Lanh Si Ho*6,*7, Indra Prakash*8, Hoc Tran Quang*9, and Binh Thai Pham*6
*1University of Transport and Communications
No.3 Cau Giay Street, Lang Thuong Ward, Dong Da District, Hanoi, Vietnam
*2Gunma University, Gunma, Japan
*3Teikyo Heisei University, Tokyo, Japan
*4National Electronics and Computer Technology Center, Pathum Thani, Thailand
*5Thuyloi University, Hanoi, Vietnam
*6University of Transport Technology, Hanoi, Vietnam
*7Civil and Environmental Engineering Program, Graduate School of Advanced Science and Engineering,
Hiroshima University, Hiroshima, Japan
*8Geological Survey of India, Gandhinagar, India
*9University of Transport and Communications, Hanoi, Vietnam
The active landslide located in the Tavan-Hauthao, Sapa district, Laocai province, Vietnam was investigated using geophysical methods (2D Electrical Resistivity and Tomography), geotechnical investigations, and a ground survey to assess the geologic condition of the sliding block and surrounding ground. Landslide displacement was measured using 15 surface monitoring points. Numerical modeling was done to assess the behavior of an active landslide. This multi-disciplinary approach helped in interpreting landslide stratigraphy, geotechnical characteristics of the sliding groundmass, depth, and nature of the sliding plane. The surface area of the slide is approximately 1200 m2. Studying this active landslide is important as it affects the road No. 152, which is an important road connecting the Sapa Ancient Rock Field. This study involved surface topographical survey, surface and sub-surface geological, and geotechnical investigations including Standard Penetration Test and Electrical Resistivity Tomography. Geologic and geotechnical data were used to characterize an active landslide block, which is composed of different soil layers underlaid by granitic rock. The surface electrical-resistivity measurements across the Sapa landslide resulted in inverted-resistivity sections with distinct resistivity contrasts that correlated well with the geology and geo-hydrology observed in boreholes.
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