Abstract
In recent years, rock scouring or erosion downstream of dams has become an increasing dam safety concern. Several theoretical, semi-theoretical, semi-analytical and numerical methods can be used to assess the rock erosion in hydraulic structures. Semi-theoretical approaches determine the correlation between the erosive intensity of fluid flow and the resistive capacity of rock. Such approaches establish the scour thresholds as a function of erosive intensity of water and several rock mass indices by using in situ data and a curve-fitting approach. In some studies, the excavatability index, initially developed for rock mass stability analysis, was used to analyse the rock mass resistance in hydraulic erodibility analysis. The effectivity and weight of the geomechanical parameters used are yet to be determined on the basis of the erodibility phenomenon. The semi-analytical methods are developed on the basis of the mechanical and hydraulic interaction of rock mass and water. Four methods developed by Bollaert et al. are important in determining the erodibility in the plunge pool, but they are not applicable in the case of spillways. They used the comprehensive fracture mechanics for closed-end joints, quasi-steady impulsion, and dynamic impulsion (DI) for blocky rock erosion. The application of these methods to each site is necessary to identify constants that are difficult to determine. Few numerical methods are available to assess the rock mass erosion in hydraulic structures. In the case of numerical methods, the erosive agent is indistinct, and the hydraulic hazard parameter on the spillway surface is almost challenging to apply. This study comprehensively reviews the mechanism of erosion and the methods for assessing the risk of potential rock mass erosion downstream of dams and hydraulic structures. The advantages and disadvantages of all methods are discussed and the potential future research directions in this domain are proposed.
Highlights
The risk of rock scouring or erosion in hydraulic structures increased the concern about dam safety
The terms ‘erodibility’, ‘scour’, and ‘hydraulic erosion’ are considered synonymous technical words to explain critical centralised erosion that occurs when the erosive intensity of fluid surpasses the resistive capacity of the rock mass
Dissipationthreshold to scouring, which is determined by the erodibility index, rock mass erosion index (RMEI), or geological strength index (GSI)
Summary
The risk of rock scouring or erosion in hydraulic structures increased the concern about dam safety. The terms ‘erodibility’, ‘scour’, and ‘hydraulic erosion’ are considered synonymous technical words to explain critical centralised erosion that occurs when the erosive intensity of fluid surpasses the resistive capacity of the rock mass. Van Schalkwyk assumed the erosion condition as a function of erosion depth (Table 1) [29]. Methodsto the same concept of the study of Van Schalkwyk and the depth of erodedofarea according added information extentcondition of the eroded area If the conditions should be simultaneously considered, it might result in a problem, for example, whether class 1 or 2 should be considered for the maximum depth of 0.5 m and the general of 8 m3/100 m2
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