The HYDRODRIL research program is grouped into five Work Packages (WP1-WP5). Each work package has a scientific focus lead by an assigned academic person who will take responsibility for execution and reporting deliverables (Table 2). Within and between the Work Packages we will establish a communication platform for administration and scientific exchange. WP1: Monitoring of hydrologically-driven landslides Monitoring is essential to predict the behavior of landslides and forecast which storms can trigger landslides. Accordingly, HYDRODRIL conducts remote monitoring of precipitation as well as pore-water pressure at a particular depth to obtain useful data for modeling and analysis, especially for the understanding of landslide triggering mechanisms such as rainfall induced landslide. SITE IN CHINA: (Xintan-landslide), Lian Ziya-rockslide sliding belt WP2: Triggering mechanisms of hydrologically-driven landslides Despite decades of an extensive development of slope stability models, the fundamental controls connecting the hydrological and geotechnical processes triggering slope failure are still not well quantified. This lack of understanding is a direct result of the simplified physics in current models, omitting the effect of partial saturation. This work package will include unsaturated conditions to performed numerical simulations. WP3: Multiscale modeling of landslides We will conduct concept-unification simulations designed to better understand the significance of the continuum slope stability indicators in relation to the factor of safety calculated by limit equilibrium analysis methods. Limit equilibrium methods are universally used not only in the classroom but also in practice to predict the occurrence of a slip surface in a slope; however, it cannot predict the initiation of debris flow. Hence, we will focus the concept-unification study on hydrologically-driven slip surface initiation in 2D. We envision running a coupled solid-deformation/fluid-flow FE analysis on a 2D unsaturated saturated slope model and using the calculated pore pressure response as input into a limit equilibrium analysis. For a given hydrologic response the factor of safety obtained from the limit equilibrium simulation will be compared with continuum failure indicators, such as the determinant of the acoustic tensor, obtained from the FE simulation. The limit equilibrium analysis will be carried out using software developed in our institute in Vienna, which is based on the modified Bishop method and has been frequently used in teaching, research and consulting. WP4: GIS based risk assessment The assessment of landslide hazard and risk has become a topic of major interest for both geoscientists and engineering professionals as well as for the local administrations in many parts of the world. Landslide hazard assessment plays an important role in developing land utilization regulations, which aimed to minimize the loss of lives and damage to property. A variety of approaches has been used in landslide assessment and these can be classified into qualitative factor overlay, statistical models, geotechnical process models, etc. However, there is little work on the satisfactory integration of these models with Geographic Information Systems (GIS) to support slope management and landslide hazard mitigation. Manipulation, analysis, and graphic presentation of the risk and hazard data can be done within a GIS system, and because these data have associated location information which is also stored within the GIS, their spatial interrelationships can be determined and used in computer based risk assessment models. This assessment can be used by insurance companies to help them make decisions on their insurance policy rates, by land developers to make decisions on the feasibility of project sites, and by government planners for better disaster preparedness. Numerous applications of GIS have been used to assess slope stability, but there is not a standard or agreement to use them to predict landslide risk. Based on a survey of recent GIS applications to model landslide risk, it has been found that models need to be systematically incorporated into a GIS application to make the prediction maps somewhat more helpful and suitable for engineers, policy-makers, and developers choosing appropriate locations to carry out hazard mitigation. WP5: Mitigation measures The purpose of landslide mitigation is to minimize the potential occurrence of the phenomenon by means of various structures and interventions which are generally subdivided into: geometric methods (in which the geometry of the hillside is changed), hydrogeological methods (in which the groundwater level is lowered or the water content of the material is reduced), chemical and mechanical methods (which attempt either to increase the shear strength of the soil or to anchor the unstable soil mass to the stable substratum). Not all the above delineated methods are pertinent and thus effective in the case of hydrologically-induced landslides; our concern is therefore mainly about drainage of the percolated water. As part of the risk assessment of hydrologically-driven slope failures, we will review and assess various measures adopted to mitigate such kind of failures. Different case studies on hydrologically-driven slope failures will be included to evaluate the effectiveness of various mitigation measures adopted in the real life. The mitigation measures under different scenario shall be analyzed by the limit equilibrium method as well as coupled finite element analysis. Based on this study, a recommendation regarding the most suitable mitigation measures for hydrologically-driven slope failures shall be suggested.
