Stress and stability analysis
Structural analyses of dam-foundation-reservoir systems are generally carried out:
- To interpret monitoring data and in-situ observations and to study damage mechanisms.
- To predict stability and identify failure mechanisms under different loading combinations (normal, unusual, extreme).
- To enable the development of rehabilitation methods and corrective actions to improve the safety of the structures.
Figure 191 indicates that during a stability assessment, the user must always correlate the physical reality of the current system under consideration (Figure 193A) with the assumptions adopted during the development of the structural model for the study of failure mechanisms (Figure 192) along with the uncertainties related to these models and the required input parameters. CADAM3D allows parametric analyses to be performed to develop a confidence level to make appropriate decisions regarding the safety of a particular structure and the need for corrective measures to increase safety, if necessary.
Routine application of dam safety guidelines (e.g., suggested values for material strength parameters) without questioning and acting (e.g., site visit) to confirm their validity, to ensure the applicability of the anticipated loading conditions and analytical method used, is dangerous.
Figure 191 Safety assessment of existing dams
Figure 192 Failure mechanisms of gravity dams (1-2 horizontal cracks, 3-4 curvilinear cracks, 5 vertical cracking of the foundation, 6 extension of a discontinuity in the rock foundation into the body of the dam, 7 sliding in the foundation, 8 buckling of thin, stratified geological layers.
Figure 193 Existing dam v/s analytical model