Abstract
Effects of compaction on the undrained shear strength of saturated earth-fill dam materials are presented. Poorly and well compacted saturated soils may exhibit undrained shear strengths, respectively, significantly lower and higher than corresponding drained shear strength and this trend is amplified as the undrained strength deteriorates by preceding undrained cyclic loading. These features are implemented in a new simplified seismic analysis to evaluate residual deformation of earth-fill dams. The analysis consists of: 1) a modified Newmark sliding block analysis; and 2) a pseudo-static non-linear FEM analysis, both formulated in a unified framework based on the cumulative damage concept, total stress earthquake response analysis and a direct total stress modelling of undrained monotonic and cyclic stress-strain behaviours obtained by triaxial tests. The analysis simulates very well the collapse of an earth-fill dam by the 2011 Off the Pacific Coast of Tohoku Earthquake, Japan, and indicates a substantially higher seismic stability under the same conditions of the newly restored dam completed in 2017. Paramount effects of soil compaction on the seismic stability of earth-filled dam are demonstrated.
Highlights
Around 2,000 of the 12,500 irrigation earth-fill dams in Iwate, Miyagi and Fukushima Prefectures in Japan were seriously damaged during the 2011 Off the Pacific Coast Tohoku Earthquake [1]
In particular with the old main dam, the compaction of the sandy top fill was very poor, which resulted in a very low initial undrained shear strength that largely deteriorated by undrained cyclic loading (UCL) during a long earthquake motion [2]
A series of undrained triaxial compression (TC) tests were performed on specimens compacted to the field densities and those compacted looser or denser
Summary
Around 2,000 of the 12,500 irrigation earth-fill dams in Iwate, Miyagi and Fukushima Prefectures in Japan were seriously damaged during the 2011 Off the Pacific Coast Tohoku Earthquake (magnitude M=9.0) [1]. In particular with the old main dam, the compaction of the sandy top fill was very poor, which resulted in a very low initial undrained shear strength that largely deteriorated by undrained cyclic loading (UCL) during a long earthquake motion [2]. To reach these conclusions, dry densities of the fills remaining after the collapse were evaluated and laboratory compaction tests were performed on samples retrieved from the field. The results of the seismic stability analysis of the new main dam evaluated by the same analysis method and under otherwise the same conditions as the analysis of the collapsed old main dam are reported below
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
