Evaluation of rainfall-induced landslide and subsequent debris flow using physically based models | |
| Author | Gaviola, John Christian Leorna |
| Call Number | AIT Thesis no.GE-23-01 |
| Subject(s) | Landslides--Mathematical models Debris avalanches--Phillippines |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Geotechnical and Earth Resources Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | The Philippines encounters substantial challenges with landslides, leading to destructive impacts on human lives, property, and the economy. This study focuses on understanding these hazards, particularly in Leyte, Philippines, which has experienced severe landslides, exacerbated by the increasing number of typhoons, emphasizing the timely need for effective landslide hazard assessment and mitigation strategies. This study employs physically based models to analyze the significant landslide event in Kantagnos Village that occurred during Typhoon Megi in 2022. It utilizes the TRIGRS model to simulate the transient infiltration effects of a 4-day continuous rainfall of varying intensity, evaluating changes in total pressure head and the response of the factor of safety. Following this, the DEBRIS-2D model is utilized to simulate the motion of the unstable mass and assess hazard zones. The parametric analysis shows that a friction angle of 16ยบ, cohesion of 32 kPa, initial water table depth of approximately 20% of the soil thickness, and other parameters determined through laboratory testing yielded the most realistic conditions in predicting the spatiotemporal change of the factor of safety during landslide initiation, with a modeling accuracy of 79.23% assessed using receiver operating characteristic analysis and validated through area under its curve. It was found that the main triggering factor of the failure was the oversaturation of the slope due to the rise of the groundwater table as a result of prolonged rainfall infiltration. Moreover, the study reveals that the application of area zoning based on the orientation of the bedding plane relative to the slope aspect has increased the accuracy of the result by 8.23%. Meanwhile, the DEBRIS-2D was able to simulate the actual debris flow motion and the area and depth of deposition, which were validated by actual observations. The combined use of TRIGRS and DEBRIS-2D has proven effective in delineating the hazard zone of a real landslide case, in which 93.97% of the area within the debris flow boundary was correctly predicted. These results would be a valuable benchmark study to formulate a framework for the analysis and risk management of slope disasters in Leyte, Philippines |
| Year | 2024 |
| Type | Thesis |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Geotechnical and Earth Resources Engineering (GTE)/Former name = Geotechnical Engineering (GE) |
| Chairperson(s) | Chao, Kuo Chieh |
| Examination Committee(s) | Avirut Puttiwongrak |
| Scholarship Donor(s) | DOST-SEI Foreign Graduate Scholarships;AIT Scholarships |
| Degree | Thesis (M. Sc.) - Asian Institute of Technology, 2024 |