On Numerical Modelling of Internal Erosion in Embankment Dams

摘要

Internal erosion in embankment dams is not a completely understood phenomenon.Dam failures,accidents and deterioration of dams caused by ageing effects do take place as a result of internal erosion.Even if dams generally should be considered as safe constructions,a large part of the present knowledge about problems associated with internal erosion is a result of studies of former dam incidents. This circumstance is almost inevitable since internal erosion processes are very complex and take place inside the embankment or foundation making the erosion transparency limited until it has progressed enough to be visible or detected by measurements. The research groups overall objective is to develop a numerical model that can capture the processes of internal erosion in a physically sound fashion in the simulation.In the paper a new innovative research program to accomplish this is presented.By utilizing e.g. The finite element method,based on a continuum approach,stresses,strains,deformations and pore pressures in an embankment dam can be theoretically analysed and conclusions drawn about initiation of internal erosion processes. Our approach,when initiation is established,is to interpret internal erosion numerically as a type of localisation and describe the constitutive behaviour with micromechanical models in localised zones.It is of considerable importance that the localisation model,the micromechanical model and the finite element model are mathematically consistent with each other.Such a final software,containing a model that simulates internal erosion could be useful for:an increase of the knowledge about internal erosion processes,evaluating the risk for dam incidents caused by internal erosion,estimating the time for progression of internal erosion and piping,studying self-healing of leaks,changes in filter behaviour subsequent to particle accumulation and aging effects in dams,analysing the amount of instrumentation needed in a dam and the proper location for monitoring and surveillance as well as designing dams to mention some examples.It is therefore apparent that the route suggested has a high potential to become a tool for future improvements regarding dam safety issues.