68 research outputs found
Sampling disturbance effects in the Bothkennar laminated facies
Sample disturbance effects in the laminated facies at the Bothkennar soft clay research
site are examined by comparing the results of laboratory tests on specimens obtained
from three fixed piston tube samplers. A significant feature of the results is that the
sampling process associated with the conventional piston tube used in the UK and Ireland
appears to increase the post yield stiffness and the CAUC triaxial undrained strength,
reduce the preconsolidation stress, the pore pressure coefficient at failure and induce a
strong tendency for dilatant behaviour post peak when compared to tests on specimens
from a sampler with a modified (sharper) cutting edge angle. It is reasoned that these
findings are caused by material destructuration during the sampling process with the
conventional tubes. Increased densification of these specimens caused both by sampling
and during anisotropic consolidation may also contribute to these effects. The results are
supported by reference to recent analytical work and data for three other soils. It is
recommended that the use of these conventional thin walled tubes with a crude cutting
edge is abandoned and that some with improved cutting edge geometry replaces them.Other funderEnterprise IrelandBritish Counci
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