Simulation of a Rapid and Long-Travelling Landslide Using 2D-RAPID and LS-RAPID 3D Models

Abstract

In this study, two process-based computer numerical models for simulating the generation and propagation of landslide are developed by integrating the initiation process triggered by rainfalls and/or earthquakes and the development process to a rapid motion due to strength reduction and the entrainment of deposits in the runout path. Among them, the 2D-RAPID model is a two dimensional model and LS-RAPID 3D Model is a three dimensional model. Both of them were developed from the geotechnical model for the motion of landslides and its improved simulation model and new knowledge obtained from a new dynamic loading ring shear apparatus. The aim of this study is to validate and compare these two models. For this purpose, the two models were applied in a rapid and long-traveling landslide, which occurred on 17 February 2006 in the southern part of Leyte Island, Philippines and caused 154 confirmed fatalities, and with an additional 990 people missing in the debris. For comparison, all the parameters used in the 2D landslide model are using the same values used in the 3D landslide model. As simulation results, the application of these two simulation models could reproduce well the initiation and the rapid long runout motion of the Leyte landslide. However, for the deposition area, the 2D landslide model resulted in a higher and narrower mass volume than the 3D landslide model. Moreover, the 2D-RAPID shows a simple process to handle the input and output database, which is easily understood and can be used in engineering application. In addition, the LS-RAPID 3D Model shows an excellent interface for rainfall or/and earthquake induced landslide with spatially distributed complex topographic data. The distributional information of soil parameter can be set and the 3D view of the calculated landslide initiation and runout can be successfully achieved in LS-RAPID 3D Model. Thus, each of these different dimensional landslide models has its respective advantages and disadvantages depending on the target study area and the type of the area.