Anna Szostak-Chrzanowski

Analysis of deformations of large earth dams

Safety of earth dams depends on the proper design, construction, and monitoring of actual behaviour during the construction and during the operation of the structure. The most critical factor in the assessment of the safety threshold value of any structure is the acceleration of its deformation. Therefore, the designed accuracy of monitoring surveys must fulfill requirements of detecting accelerations at critical locations of the investigated object. As an example, time dependant behavior of a large embankment dam during filling up the reservoir has been analyzed and verified by comparing monitoring results with the deterministic (prediction) model of the deformation. The geotechnical and geodetic monitoring besides providing a warning system in case of an abnormal behaviour of the dam, may be used as a tool for a verification of design parameters where geotechnical parameters are of the highest importance. Modeling of deformation of earth dams is a complex process in which one should consider the nonlinear behaviour of the construction material, interaction between the structure and the underlying foundation strata, influence of water load on the structure and on the foundation bedrock, and the effects of water saturation. Due to the uncertainty of the model parameters, careful monitoring of the dam and its surroundings are required in order to verify and enhance the model. In addition, with properly designed monitoring surveys, one may also determine the actual deformation mechanism. The finite element method may be useful tool in the proper design of the monitoring scheme by providing information on the locations and magnitude of the expected maximum displacements and velocites of movements. The discussed problems are illustrated by three types of earth dams located in California, U.S.A. and in Quebec, Canada.

Increasing public and environmental safety through integrated monitoring and analysis of structural and ground deformations

Any engineered or natural structure, when subjected to loading, undergoes deformation and/or rigid body movements. Once the deformation, its velocity and/or acceleration exceed critical values, the structure fails. The critical values are determined using failure criteria that are based upon either empirical formulae or principles of continuum mechanics. By providing continuous and properly designed deformation monitoring schemes, one may provide information about the new state of the deformation. This information can then be used to provide advance warning of imminent structural failure.

Design and analysis of a multi-sensor deformation detection system

Abstract Development of new technologies for monitoring structural and ground deformations puts new demands on the design and analysis of the multi-sensor systems. Design and analysis of monitoring schemes require a good understanding of the physical process that leads to deformation. Deterministic modelling of the load-deformation relationship provides information on the magnitude and location of expected critical deformations as well as delineates the deformation zone. By combining results of deterministic modelling with geometrical analysis, one can find the deformation mechanism and explain the cause of deformation in case of irregular behaviour of the investigated object. The concept is illustrated by four practical examples.