外文翻譯---土石壩的特征及筑壩技術(shù)控制-文庫吧資料
2025-01-23 23:07本頁面
【正文】 sed. Substantial organic content should not exist in the soils. Lignite sufficiently scattered through the fill to prevent the danger of spontaneous bustion, is not objectionable. Fat clays with high liquid limits may prove difficult to work and should be avoided.8. Compaction requirementsThe strength of the impervious and semiimpervious soils depends upon the pacted densities. These depend in turn upon the water content and weight of the pacting equipment. The design of the embankment is thus influenced by the water content of the borrow soils and by the practicable alternations to the water content either prior to placement of the fill or after placement but prior to rolling. If the natural water content is too high, then it may be reduced in borrow area by drainage, or by harrowing. If the soil is too dry it should be moistened in the borrow area either by sprinkling or by ponding and then permitted to stabilize the moisture content before use. The range of placement water content is generally between 2 percent dry to 2 or 3 percent wet of the standard Porter optimum water content. Pervious soils should be pacted to at least 80 percent of relative density.If necessary, test fills should be constructed with variations in placement water content, lift thickness, number of roller passes and type of rollers. For cases of steep abutment, the fill must be placed in thin lifts and pacted by mechanical hand tampers. All overhangs should either be removed or filled with lean concrete prior to fill placement.9
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