Re-Evaluation of the Lower San Fernando Dam. Report 3. The Behavior of Undrained Contractive Sand and Its Effect on Seismic Liquefaction Flow Failures of Earth Structures
Abstract
Soil test results are analyzed from 2 complementary viewpoints: the shear strength behavior of the soil (including steady-state lines, effective stress conditions at triggering of flow failure, and the pore water pressure needed for triggering) for both monotonic and cyclic loading; and the pore water pressure buildup and number of straining cycles needed for triggering during cyclic loading. The influence of several parameters is investigated, including: void ratio, minor effective consolidation stress, coefficient of anisotropic consolidation, cyclic torsional shear strain, sand fabric, and sand type. A conceptual framework is proposed for evaluating seismic flow failure of specific engineering projects, including the possibility of undrained and partially drained mechanisms. This procedure is applied to the upstream slope slide induced in the Lower San Fernando Dam by the 1971 earthquake. It is concluded that the hydraulic fill sand in the dam was contractive prior to the earthquake, which means that a purely undrained evaluation using the techniques proposed here would have predicted the 1971 upstream failure, as well as the good performance of the downstream slope, which had a local factor of safety close to unity after triggering. Earthquakes, Earth dams. (EDC)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1989
- Accession Number
- ADA215417
Entities
People
- Andres Vasquez-herrera
- Ricardo Dobry