Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.600749
Title: Rate effects in fine grained soils
Author: Quinn, Turlough
Awarding Body: University of Dundee
Current Institution: University of Dundee
Date of Award: 2013
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Abstract:
The strain rate dependent behaviour of fine grained soils is an important aspect of geotechnical engineering. During dynamic or rapid events such as earthquakes and rapid pile testing, a fine grained soil will display significantly different behaviour than may be observed over the long life span of a structure. There is currently little understanding of the factors which influence the behaviour of fine grained soils during dynamic events (extremely high strain rates), making their response difficult to predict. This research investigates the behaviour of fine grained soils subjected to a wide range of constant strain rates in monotonic triaxial compression testing. Each test is conducted under drained conditions to observe the behaviour of soils as they transition from a drained response at lower strain rates, through to an undrained or viscous response at higher strain rate tests. Where the response of soils is drained or partially drained, higher strain rate tests measure a decrease in strength. The point of transition from partially drained to undrained behaviour corresponds to the lowest strain rate dependent strength. Further tests at higher strain rates measure consistently greater strength. The strain rate dependence of three fine grained soils is investigated, enabling a comparison of strain rate effects with soil index properties. The influence of initial state on the strain rate dependence of these Kaolin based model soils is also evaluated. The drained to partially drained response of the soils to strain rate increase is controlled by the coefficient of consolidation. Tests at high strain rates show the undrained or viscous strain rate effect on strength is related to liquidity index. Local strain instrumentation allowed comparison of strain rate effects on small strain stiffness. At higher strain rate the soils display increasingly linear behaviour. At non-linear elastic strains, liquidity index appears to control the magnitude of the strain rate effects on stiffness.
Supervisor: Brown, Michael Sponsor: Engineering and Physical Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.600749  DOI: Not available
Keywords: Strain rate effect ; High strain rate triaxial testing ; Fine grained soils ; Liquidity index ; Linear elastic threshold strain ; Volumetric threshold strain ; Strain rate coefficient
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