Optimization of compaction zoning in loess embankments

Abstract

Extensive centrifuge model tests were carried out to investigate optimum compaction density zones within loess embankments 30 and 63.8 m high. In these tests, water infiltration into the slopes and upstream storm water ponds were modelled to simulate the most unfavourable working conditions. Displacement contours in the cross sections were measured and crest settlements were monitored during the tests. Finally, the optimum compaction zoning was analysed based on the comprehensive evaluation of the total crest settlement, the postconstruction settlement, and the slope stability of the embankments. It was indicated that a properly designed high loess embankment could perform satisfactorily with the lower part compacted looser than the conventional code requirements. In terms of total crest settlement and embankment cracking, the degree of compaction K of loess fills should not be less than 0.85 for 30 m high embankments and not less than 0.90 for 63.8 m high embankments. In terms of the postconstruction settlement (<0.2-0.3 m) and construction feasibility, it is expedient to compact the lower one third to K = 0.85, and the top two thirds to K = 0.90 for 63.8 m high embankments. For 30 m high embankments, the bottom zone with K = 0.85 can make up two thirds of the height.Key words: Key words: embankment, centrifuge test, compaction, settlement, stability, loess.