N2 - In monitoring vertical displacements in elongated structures (e.g. bridges, dams)
by means of precise geometric levelling a reference base usually consists of two subgroups
located on both ends of a monitored structure. The bigger the separation of the subgroups,
the greater is the magnitude of undetectable displacement of one subgroup with respect to
the other. With a focus on a method of observation differences the question arises which of
the two basic types of computation datum, i.e. the elastic and the fixed, both applicable in
this method, is more suitable in such a specific base configuration. To support the analysis of
this problem, general relationships between displacements computed in elastic datum and in
fixed datum are provided. They are followed by auxiliary relationships derived on the basis
of transformation formulae for different computational bases in elastic datum. Furthermore,
indices of base separation are proposed which can be helpful in the design of monitoring
networks.
A test network with simulated mutual displacements of the base subgroups, is used
to investigate behaviour of the network with the fixed and the elastic datum being applied.
Also, practical guidelines are given concerning data processing procedures for such specific
monitoring networks. For big separation of base subgroups a non-routine procedure is
recommended, aimed at facilitating specialist interpretation of monitoring results.
JO - Geodesy and Cartography
L1 - http://journals.pan.pl/Content/105913/PDF/art1.pdf
L2 - http://journals.pan.pl/Content/105913
IS - No 2
KW - vertical displacements
KW - control networks
KW - partitioned bases
KW - elastic datum
KW - fixed datum
KW - base separation indices
ER -
A1 - Prószyński, Witold
PB - Commitee on Geodesy PAS
VL - vol. 59
JF - Geodesy and Cartography
T1 - Problem of partitioned bases in monitoring vertical displacements for elongated structures
UR - http://journals.pan.pl/dlibra/docmetadata?id=105913
DOI - 10.2478/v10277-012-0001-1