The phenomenon known as the ‘arching effect’ occurs when a portion of granular mass yields relative to an adjacent stationary region. The movement is resisted by shearing stresses which act to reduce the pressure on the yielding support and increase the pressure on the adjacent stationary supporting zones. Arching is widely observed in both natural and man-made structures such as piled embankments, tunnelling, and above mine works and sinkholes. In this research the arching effect is recreated in the increased gravity environment of a geotechnical centrifuge where the pressure distribution across both the yielding and supporting soil masses is measured and the resulting soil displacements observed. A motor driven ‘trapdoor’ apparatus was built inside a plane strain container to model the yielding support. Both the trapdoor and an adjacent support were instrumented to measure the force (and derived pressure) distribution. Soil and trapdoor displacements are determined by analysis of digital images taken in-flight through a Perspex wall of the container. One method of increasing soil shear strength and its resistance to deformation is the reinforcement of soil with randomly distributed discrete fibres. The degree of improvement has been shown to be directly related to the fibre content in the soil, the fibre aspect ratio, orientation and mechanical properties. In this research the effect of fibre reinforcement on the arching process and resulting deformation is examined by variation of fibre parameters such as fibre aspect ratio and volumetric content of fibre. The influence of fibre and model scale effects were investigated by conducting a modelling of models exercise whereby trapdoor scale and effective stress were varied whilst maintaining a constant cover depth to structure width ratio, and compaction effort. The results were compared directly with those obtained for unreinforced soil trapdoor tests in order to determine the extent of improvement offered by fibre-reinforcement.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:635136 |
| Date | January 2014 |
| Creators | Cox, Craig Mark |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://eprints.nottingham.ac.uk/28020/ |
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