Some Issues and Proposals about Reconstruction and Extension of Expressway Embankment on Soft Ground
Proposals have been put forward for some issues about reconstruction and extension of embankment on soft ground basing on many expressway reconstruction and extension practice.Embankment whose ground improvement can't be constructed in pools should be improved by deep-mixing piles or should be designed as embankment supported by rigid piles.The working platform for ground improvement under existing slope should be formed by sharpening of slope or supported by steel piles.Steps shouldn't be set when stability along surface between extension embankment and existing embankment meets requirements.Step wall should be slanting and step platform should be horizontal or inclined outward slightly for extension embankment with ordinary soil.Loose zone will form near step wall when height of vertical-wall step is more than 44cm.The loose soil should be compacted by hydraulic compactor or impact roller.The loose soil should be cemented by grouting when height of vertical-wall step is more than 2m.Extension embankment with light soil can't be used as retaining wall and drainage facilities easy to construct should be designed to avoid water collecting behind light soil.Only the traffic load over the slanting surface should be considered and for stability analysis of extension embankment with light soil.Only the beam between caps of piles constructed by long screw should be designed.
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