No abstract is provided for this article.
No abstract is provided for this article.
Cracks are always a serious concern in the stability analysis of gravity dams. One of the main reasons for the initiation of cracks is overflows. In evaluating dam safety under flood conditions, it is crucial to consider the balance between the strength of the dam body and the propagation of cracks. In this context, simplified equations serve as valuable tools in dam design as they offer a quick and efficient way to estimate the behavior of the dam structure. In this study, firstly using a polygonal material-based model (P-MBM), which is improved in considering the softening behavior of joints, the micro-crack propagation in masonry material is investigated. Then, based on performing 81 numerical simulations in a parametric study on the geometrical and geotechnical properties of the dam subjected to overflow, a great database of the behavior of different dams is investigated. Then, using the genetic algorithm, a set of equations is proposed, and their accuracy is validated through UDEC simulations and some theoretical methods from existing literature. For all models, the crack tends to be horizontal at the initial phase. Then, due to increasing the compressive stresses on the downstream side, the fractures tend to the dam toe. The results also indicate that the proposed equations can reasonably determine the behavior of gravity dams and the development of cracks in the dam body. The outcomes highlighted the considerable effects of geometry and geotechnical properties on dictating the trajectory of crack growth.
No abstract is provided for this article.
Studies carried out to analyse the risks of levees must include an evaluation of the probabilities of occurrence of different failure mechanisms. The probabilistic quantitative evaluation of these mechanisms remains difficult due to often insufficient data, the natural variability of the materials, structures that are very long, and the unavailability of mechanical models for certain failure mechanisms. This makes it necessary to call for expert judgement to evaluate the probabilities of failure. However, expert judgement generally has qualitative and subjective dimensions, and it includes biases that are liable to impair the capacities of an expert to elicit their evaluations. This article proposes an approach to processing expert judgement that includes the modalities of I ndividual e xpert E licitation, C alibration, A ggregation, and D ebiasing of expert judgement ( IeCAD ). This IeCAD approach has been developed for river levees in view to correcting biased expert evaluations in the case of evaluating the failure probability of structures.
No abstract is provided for this article.
No abstract is provided for this article.
No abstract is provided for this article.
Diagnosis and risk analysis are essential to ensure the safety of dams. Dam specialist engineers have useful methods available to help them in their task: physical modelling for assessing dam stability, statistical analysis of dam monitoring data, and, more recently, functional modelling for operational safety analysis. However, an expert's judgment is necessary when the works are complex and unique, when data are imprecise or insufficient, and when preliminary diagnosis or detailed analysis are being made. Using their experience and knowledge, dam specialist engineers are able to provide recommendations to address specific problems. The authors propose methods to support expert diagnosis and risk analysis that capitalize on the expert's knowledge and feedback. Their approach is threefold: (i) an ageing functional model based on the failure mode and effect analysis (FMEA) method using a causal graph representation of ageing scenarios leading to loss of functions; (ii) a qualitative method of describing dam ageing historical data and representing trends in performance loss; and (iii) qualitative methods to assess the risk of performance loss of dams and their components. In terms of practical applications, our research has produced a knowledge database on dam mechanisms. Also, an ageing historical database was compiled from dams that have experienced deterioration. Finally, we are developing computer aids to assist engineers in diagnosis and risk analysis tasks.Key words: dam, diagnosis, risk analysis, ageing, criticality.
Standard practice in dam engineering is to consider only the maximum reservoir level governing the maximum hydraulic loading. This article presents a probability method for modelling reservoir level and the corresponding load on the dam. It uses multiple randomly-generated flood hydrographs to investigate the effect of reservoir level variability. The method was tried on three operational dams to assess its utility as an operational dam safety analysis method.
Based on a previous experimental study that we conducted on granite joint replicas including thirty direct shear tests, this article proposes to integrate the joint roughness in the Mohr-Coulomb shear behaviour model (MC). The model integrates joint roughness into constitutive stress-displacement relationships describing mechanical behaviour of rock joint. The shear strength of rock joint is assessed by the MC shear criterion that takes into account the apparent cohesion. This MC model integrating rock joint roughness component is validated against other experimental results from the literature. It is able to accurately predict the peak shear strength of an unbounded rock joint with an average relative error of 7.9%. It is finally used to assess the role of joint roughness on the shear behaviour of a gravity dam foundation.
