Reservoir slope stability under drawdown condition is always important for reservoir designs. During rapid drawdown, the water level is reduced which allows the excess pore pressure to be generated. Therefore, it is possible to cause the slope to be unstable. Conventionally, the Mohr-Coulomb failure criterion is the most commonly used failure criterion to estimate the factor of safety for reservoir slopes. Morgenstern produced some stability charts, which are used in practice to date. In this study, analyses of rock slope rapid drawdown are performed by using the limit analysis method, and the nonlinear Hoek-Brown failure criterion was used in the analysis. Limit analysis employs the lower bound and upper bound theorems to give rigorous bounds of the true solution. The finite element program OPTUM G2 was used to study the effects of rapid drawdown on a fully submerged rock slope, using the Hoek-Brown failure criterion. Various slope heights, unit weights were analysed using the Hoek-Brown parameters to find their lower bound solutions. The results obtained presented in the form of stability charts and tables.

Reservoir slope stability under drawdown condition is always important for reservoir designs. During rapid drawdown, the water level is reduced which allows the excess pore pressure to be generated. Therefore, it is possible to cause the slope to be unstable. Conventionally, the Mohr-Coulomb failure criterion is the most commonly used failure criterion to estimate the factor of safety for reservoir slopes. Morgenstern produced some stability charts, which are used in practice to date. In this study, analyses of rock slope rapid drawdown are performed by using the limit analysis method, and the nonlinear Hoek-Brown failure criterion was used in the analysis. Limit analysis employs the lower bound and upper bound theorems to give rigorous bounds of the true solution. The finite element program OPTUM G2 was used to study the effects of rapid drawdown on a fully submerged rock slope, using the Hoek-Brown failure criterion. Various slope heights, unit weights were analyzed using the Hoek-Brown parameters to find their lower bound solutions. The results obtained presented in the form of stability charts and tables.

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