Effects of berms on the factor of safety of an embankment.

摘要

The objective of this investigation and the accompanying analyses, were to determine the effectiveness of one of the most common corrective measures for improving the safety factor against slope failure in embankment dams; specifically, by adding a berm. Since this measure is among the most commonly used corrective actions, the analyses in this thesis were designed to serve as an aid in decision making during the design phase, before construction of the dam.; An embankment dam was assumed with base case parameters for the end of construction case such that the value of the factor of safety against sliding was found to be one using the PCSTBL5 computer program. To improve the factor of safety, a berm was added downstream at the toe of the dam. The effects of the berm were evaluated for different widths, heights and slope. For example: the berm slope was flattened from 2H; IV; and berms with a range of geometry, but having the same slope as the embankment dam, were added.; There were some trends seen in the increases of safety factors associated with increasing cohesion values and the angle of internal friction. But soil properties of the berm were not as important as berm geometry. While some of the analyses of these increases are not directly used in the conclusions, they may be applied to further study. The results of the analyses showed that addition of a berm would be comparatively cheaper than slope flattening given suitable berm dimensions to achieve a desired factor of safety. Widening a berm typically increased the factor of safety up to an optimum width, but further increases in width did not change stability.