Shear wave velocity monitoring of collapsible loessic brickearth soil
Gunn, David; Nelder, L.M.; Jackson, Peter; Northmore, Kevin; Entwisle, David; Mildowski, A.E.; Boardman, D.I.; Zourmpakis, A.; Rogers, C.D.F.; Jefferson, I.; Dixon, N.. 2006 Shear wave velocity monitoring of collapsible loessic brickearth soil. Quarterly, 39 (2). 173-188.Full text not available from this repository. (Request a copy)
Metastable loessic brickearth comprises a stiff fabric structure with inter-particle interactions different to those normally associated with clay-sized or silt-sized particle fabrics. Laboratory samples loaded near in situ moisture contents exhibited little consolidation and relatively high shear wave velocities, which changed in response to sample flooding. In situ hydro-collapse caused non-monotonic changes in the velocity of shear waves through loessic brickearth that was subjected to simple flooding and to flooding while under additional surface loading. Hydro-collapse in situ resulted in an overall reduction of up to 50% in the shear wave velocity. A conceptual model of brickearth structure based on SEM images is presented to explain the process of collapse and its effect on shear wave velocity. These indicate a transition from a relatively low-density, high-stiffness fabric to the higher-density, lower-stiffness fabric during structural collapse of the loessic brickearth. The collapse process disrupts clay bridge-bonds that hold individual and aggregated clay-coated silt sized particles in an open packed structure, and which are absent in a more closely packed collapsed structure. These studies provide information for geohazard research and the development of shear wave velocity and other geophysical tools to assess soil collapse potential in situ.
|Programmes:||BGS Programmes > Other|
|Additional Keywords:||Density, Engineering properties, Geophysics, Load tests, Shear-wave behaviour ; Soils|
|NORA Subject Terms:||Earth Sciences|
|Date made live:||16 Jul 2007 13:14|
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