LIMIT STATES APPROACH FOR COUPLED SEEPAGE-DEFORMATION ANALYSIS OF EARTH EMBANKMENTS

摘要

The experience of past levee failures has proved that the use of "factor of safety" approach is not an effective indicator of the safety level pertinent to earth structures given uncertainties in loading, soil properties, and changes in geometry that can take place with time. An approach based on the definition of deformation-based limit states is proposed to assess the condition of embankment dams and levees as well as possible performance under future loading events. Compared to approaches based on the concept of factor of safety, the proposed approach utilizes simplified probabilistic analysis coupled with numerical modeling. The deformation-based performance limit states and their use as indicators of functionality levels are introduced and the probability of exceeding prescribed limit state is defined based on potential emerging failure zones. The effects of variation in hydraulic conductivity of the soil as well as the rate of rising water level in the reservoir are used to illustrate the concept of the limit states. Results on the lateral deformation response and the importance of utilizing transient loading conditions are presented and discussed.