Dip-slope failure assessment based on Discrete numerical simulation - example from Formosa highway

• Main Authors: Ho-Shyang Chang, 張賀翔
• Other Authors: 張國楨
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/rfb8qa

碩士 === 國立臺北科技大學 === 土木與防災研究所 === 100 === It is because that frequent and intense of the plate movement in Taiwan make it so inconvenient to construct transportation system, and thus transportation is restricted to develop on the dip-slope which would impair the toe of slope leading to instability during construction. Accordingly, if the new-built construction cannot bear the weight of toe of slope, tremendous disaster will occur.Four people passed away on April 25th 2010 as a result of a landslide in Formosa Freeway. It was astonishing that under legitimate regulation the design of the construction still caused great casualty of public security. This research applied the Digital Terrain Model (DTM) featuring specific three dimensional coordinate, combines Particle Flow Code (PFC3D) which could simulate great deformation and analyze the landslide formation. First of all, builds up DTM based on the aerial photos before and after landslide. The different point from other cases is that there is no separation between slide block and slide slope result in difficult to acquire its slide slope. Using slide slop on upper part of exposed strata to obtain completed slide slop through interpolation method.Second, via calculation, the slide block is approximately 150 thousand cubic meters. In the PFC3D part, the topographic surface, based on pre-disaster and post-event DTM, serve as sliding surface of the numerical simulations models. To begin with, particle clusters production that the isotropic stress and porosity should take into account. To ensure the production range should cover the entire slid mass from the source area. Besides that, to transpose the particle clusters to the numerical model where the source is. Moreover, keep the particles which the positions are situated within the slide block confined by the upper and lower surface of the DTM before and after landslide, or eliminate from the clusters. According to the geological map, the particles of slide block can be divided into two parts: 1) interbedded sandstone and shale which soften by water 2) upper part of sandstone. Furthermore, set up a layer of particles to simulate ground anchor. In the end, the model is ready for simulation. The advantages of DTM collocate PFC3d are that real terrain can be represented on the model, and can be simulated the complete landslide process dynamically. Comparing with other finite element analysis software that only provides state of instability but by using this method we can know the dynamical process of sliding include trajectory, velocity change, sliding distance and also accumulation patterns after stopping and know the effect areas from the disaster event.