THESIS
2013
xii, 95 pages : illustrations ; 30 cm
Abstract
Fibre addition may help to increase the strength of sand and improve its resistance to
liquefaction. In this thesis, an experimental study was carried out to investigate the
behavior of fibre-reinforced sand. Polypropylene fibre was chosen to examine its
reinforcement of Toyoura sand based on conventional triaxial compression tests. A
total of 36 sets of tests were performed under either drained or undrained monotonic
shear. The influences of fibre content, soil density, confining stress and drainage
condition on the macroscopic behavior of fibre-reinforced sand, including shear
strength, volumetric change/dissipation of excess pore water pressure, mobilized
friction angle and final failure pattern (if observable), were thoroughly investigated
and compared. The addition of fi...[
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Fibre addition may help to increase the strength of sand and improve its resistance to
liquefaction. In this thesis, an experimental study was carried out to investigate the
behavior of fibre-reinforced sand. Polypropylene fibre was chosen to examine its
reinforcement of Toyoura sand based on conventional triaxial compression tests. A
total of 36 sets of tests were performed under either drained or undrained monotonic
shear. The influences of fibre content, soil density, confining stress and drainage
condition on the macroscopic behavior of fibre-reinforced sand, including shear
strength, volumetric change/dissipation of excess pore water pressure, mobilized
friction angle and final failure pattern (if observable), were thoroughly investigated
and compared. The addition of fibre was demonstrated to be an effective way for
improvement of shear strength for sand without obvious loss of post-peak strength.
Only a small amount of fibre addition to Toyoura sand (0.25% to 0.5% of weight
fraction) may help an otherwise liquefiable loose sand to gain adequate shear strength
to avoid liquefaction. Depending on drainage condition and confining pressure, the
increase of shear strength amounts to 50% to 100% with 0.25% of fibre addition, and
can reach 100% to 300% with 0.5% of fibre addition. Higher fibre content than 0.5%
however cannot significantly improve the shear strength of sand any more. It is also
found that less than 0.1% fibre addition cannot adequately serve the purpose of soil
reinforcement. Compared to pure sand case, the initial stiffness may be slightly
reduced for fibre-reinforced sand for the undrained tests.
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