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Title: The consolidation behaviour of soft clays
Author: Tonks, David M.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1978
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Increased understanding of engineering behaviour of soil requires sophisticated interplay between observation, theory and analysis. Interactive Graphics programs are presented to handle numerical extensions to Terzaghi Consolidation Theory, permitting multi-layer analysis, time-dependant loading, and governing parameters varying with effective stress. The capabilities of such analysis are explored. Problems arise with non-linear stress-strain behaviour and there is considerable evidence that strain rate is also a significant variable for soft clays. A model proposed by Bjerrum is investigated in detail. This suggests skeletal behaviour may be constituted of two relationships, termed Instantaneous Consolidation - comprised of stress-strain functions only, and Delayed Consolidation - relating only strain and time. These processes may be considered independent, but progress simultaneously. The mathematical model of such consolidation, and its solution, has been developed by Garlanger. Improved numerical solution techniques are presented. Some minor theoretical inconsistencies are resolved, and some major ones identified. Later work establishes the theoretical validity of the scheme. After clarification and modification this is rather better than originally claimed. The major modification is in treatment of the critical pressure, PC. It is suggested that a discontinuity of stress-strain function is superfluous; the phenomenon is adequately defined by inclusion of a compatible strain-time function. Experimental evidence for this and the general acceptability of Garlanger's scheme is based on some 30 consolidation tests of varying type, pressure, and prior delayed consolidation, on Grangemouth silty-clay. Other cases of laboratory and field behaviour are also considered. It is concluded that the modified Garlanger theory is the most satisfactory approach currently available, and is potentially of considerable value for analysis of the Consolidation of Soft Clays.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available