Please use this identifier to cite or link to this item: https://hdl.handle.net/11681/20558
Title: Pore pressures in soft ground under surface loading : interpretation of field records
Authors: University of Cambridge.
Parry, R. H. G. (Richard Hawley Grey)
Wroth, Peter.
Keywords: Clays
Clay soils
Soft soils
Embankments
Soil deformation
Soil mechanics
Pore pressure
Publisher: Soils and Pavements Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Description: Contract Report
Abstract: Most soft clays in their natural state exhibit a small degree of overconsolidation resulting from changes in ground water level, delayed consolidation, or other causes. The overconsolidation ratio is commonly in the range of 1.0 to 2.5. Under surface loading, pore pressures in such a deposit will develop as for an elastic material until the effective stresses reach a yield condition or failure condition. In the latter case the soil can continue to carry additional total stresses within confined zones and pore pressures in these zones will continue to increase. In the former case the soil will continue to deform plastically until it reaches failure, showing, in general, different pore pressure responses in these two phases. Thus pore pressure response at any point in a soft clay deposit under increasing surface loading may show two or three distinct phases, although in some cases the plastic and failure responses may be almost indistinguishable. In this report three published field records are examined. One of these, a circular embankment loading on sensitive clay, is studied in some detail and it is found that at the end of the initial elastic phase, contained failure occurs with a distinct change in pore pressure response with further loading. The plastic phase is absent. In the second case, again a circular embankment but on soft clay of comparatively low sensitivity, the pore pressure response under loading is distinctly three-phased. In the final case record studied, a road embankment loading on Boston blue clay, a distinct change in pore pressure response occurs at the end of the elastic phase, followed by a phase in which plastic yielding if it occurs is not clearly distinguishable from the contained failure response.
URI: http://hdl.handle.net/11681/20558
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