Page 69 - Microsoft Word - 20120528 Unesco study

Glossary

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Cohesion Attraction between soil particles (usually fine), by which they
are maintained in a fixed mass without the application of
external forces.
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Collapse Occurrence of inadmissible large deformations of a structure,
such that it loses coherence
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Correlation Measure of the extent to which a change in one variable tends
to correspond to a change in another variable. One measure of
linear dependence in the correlation coefficient.
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Cracking Loss of coherence for layer or element intended to be
coherent.
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Dependence Extent to which one variable depends on another variable.
Dependence affects the likelihood of two or more thresholds
being exceeded simultaneously. When it is not known whether
dependence exists between two variables or parameters,
guidance on the importance of any assumption can be
provided by assessing the fully dependent and independent
cases (correlation).
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Deterministic process Method or process that adopts precise, single values for all
variables and input values, giving a single value output.
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Discount rate Represents the opportunity costs associated with the
investment available in other (public) projects. This can be
different for different infrastructure sectors.
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Embankment Bank formed artificially from (usually local) materials to
exclude water from a given area. The main embankment
structure provides mass obstruction against water. The
embankment “outward face” is exposed directly to water, and
the “inward face” is on the landward side and hence not
normally exposed directly to water. The “embankment crest” is
the top of the embankment, typically flat and (ideally) several
meters wide.
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Erosion Processes of wearing a way of land or defense surface by
mechanical action (e.g. water, wind, ice)
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Failure Inability to achieve a defined performance threshold (response
given loading). “Catastrophic” failure describes the situation
where the consequences are immediate and severe, whereas
“prognostic” failure describes the situation where the
consequences only grow to a significant level when additional
loading has been applied and/or time has elapsed.
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Failure cause Reason why a component fails
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Failure mechanism The way in which a structure collapses (shearing, piping,
erosion), or fails to retain water (flood defense failure
mechanism).
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Flood A temporary covering of land by water outside its normal
confines.

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