PROGRESSIVE CONSOLIDATION SETTLEMENT OF NATURALLY DEPOSITED CLAYEY SOIL UNDER EMBANKMENT LOADING

• NODA TOSHIHIRO

  Department of Civil Engineering, Nagoya University

• ASAOKA AKIRA

  Department of Civil Engineering, Nagoya University

• NAKANO MASAKI

  Department of Civil Engineering, Nagoya University

• YAMADA EIJI

  Department of Civil Engineering, Nagoya University

• TASHIRO MUTSUMI

  Department of Civil Engineering, Nagoya University

Abstract

In a naturally deposited soil foundation subject to embankment loading, a delayed settlement can often be observed after the embankment's completion, sometimes also showing acceleration over time. Frequently in such cases the soil exhibits an increase rather than a dissipation of excess pore pressure in some of its parts, a phenomenon which cannot be explained by conventional elasto-plastic consolidation theory. In this paper the possible mechanism for this kind of delayed settlement is investigated numerically using a soil-water coupled elasto-plastic computation under plane strain conditions. It is assumed that the soil section contains a medium dense sand layer and highly structured clay layers. A Super/subloading Yield Surface Cam-clay model is used to describe the elasto-plastic behavior of both the sand and the clay with respect to soil structure, overconsolidation and anisotropy. It is found that the delayed settlement behavior occurs under a certain constant embankment load, and persists over a period of 40 years, with increases in the settlement rate accompanied by both dissipation and a rise in excess pore pressure. The cause of this is the softening that co-occurs with the plastic compression of the soil skeleton. In other words, consolidation settlement can be considered as an example of “progressive consolidation with decay of structure”. Some typical characteristics of this delayed settlement behavior are also numerically examined with reference to the height and weight of the embankment, and to soil improvements using sand drains. When the embankment is much lower, the foundation does not undergo delayed consolidation, and when it is higher, the foundation becomes subject to circular slip failure. Soil improvement with sand drains can effectively shorten the length of time up to final settlement.

Journal

• SOILS AND FOUNDATIONS

  SOILS AND FOUNDATIONS 45 (5), 39-51, 2005

  The Japanese Geotechnical Society

Keywords

• clay
• delayed consolidation
• overconsolidation
• sand
• soil structure
• soil-water coupled analysis
• super/subloading surfaces (IGC : D6/E2)

Details

• CRID: 1390282679588070912
• NII Article ID: 110003983964
• NII Book ID: AN10496056
• DOI: 10.3208/sandf.45.5_39
• NDL BIB ID: 7717851
• ISSN: 13417452
• ISSN: http://id.crossref.org/issn/00380806
• Web Site: http://id.ndl.go.jp/bib/7717851
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I7717851
• Web Site: https://www.jstage.jst.go.jp/article/sandf1995/45/5/45_39/_pdf
• Web Site: http://dl.ndl.go.jp/info:ndljp/pid/10424313
• Text Lang: en
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • NDL-Digital
  • CiNii Articles
• Abstract License Flag: Disallowed