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GDS CSWS |
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What is it? |
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The Continuous Surface Wave System (CSWS)
enables a shear stiffness-depth profile to be determined to depths
between 10m (in clays) and 30m (in some granular soils and weak
rocks) without the need to provide a borehole. It provides on-line
data processing such that the stiffness-depth profile may be viewed
as the test is in progress. This allows the operator to assess the
quality of the data before moving to another location. These
profiles enable geotechnical engineering predictions of surface
settlement. |
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Download full
specification datasheet as
pdf
[282kb] |
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| What are its
uses |
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Traditionally, geophysics has been used only as an indirect means of
targeting and dimensioning sub-surface features. This application
has its origins in oil and mineral exploration. The CSWS is set up
on the ground surface and propagates Rayleigh waves which are
constrained within a zone which is, approximately, one wavelength in
depth. In ground where the stiffness changes with depth, these
elastic waves are dispersive in nature, which means that they travel
at a velocity which is dependent upon frequency and wavelength.
The CSWS uses a frequency controlled vibrator to regulate the
frequency of these surface waves, thus permitting a dispersion curve
(velocity against frequency or wavelength) to be readily determined
(see Fig. 1). By using the theory of elasticity, shear wave velocity
and shear modulus G can be determined from these velocity
measurements. |
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| GDS
Instruments is an ISO 9001:2000 credited company. |
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