Calculation method for earth pressure and stability of high submerged toe walls of concrete faced rockfill dams

High submerged toe walls are important hydraulic structures in many concrete face rockfill dams. The surface load exerted upon the backfilled rockfill materials is the hydraulic pressure， which is neither evenly distributed nor vertically downward. This load condition is evidently different from that given by designing codes of the retaining walls， in which the surface load is generally vertically downward and evenly distributed. Therefore， evaluating the earth pressure according to such designing specifications may give improper results. In this study， based on Coulomb′s earth pressure theory， the methods for evaluating the active earth pressure and the passive earth pressure on the high submerged toe walls are discussed. The necessity of numerical calculation of the earth pressures by changing the inclination angle of the slipping mass over its possible range is clarified by simple case studies. Two specific conditions that require further stability analysis for the high toe walls are also fixed， namely the horizontal water pressure is less than the horizontal component of the active earth pressure or more than the horizontal component of the passive earth pressure on the high toe walls (the sliding resistance stability problem doesn′t exist when the horizontal water pressure is between the horizontal component of the active earth pressure and the horizontal component of the passive earth pressure on the high toe walls). Moreover， the problems regarding the evaluation of the overturn moment of the high toe walls and the feasible approach to solve the problems are pointed out in the paper.