Centrifuge modelling of the ground reaction curve of fibre reinforced soil

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, tunnels, and above mine works and sinkholes. One method of increasing soil shear strength and its resistance to deformation is through the use of 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 arching effect is recreated in a geotechnical centrifuge model using a 'trapdoor' apparatus within a plane strain container and the effect of fibre reinforcement on results is examined. Both the trapdoor and an adjacent support were instrumented to measure the force (and derived pressure) distribution. Soil and trapdoor displacements were determined using digital image analysis. The influence of fibre content is examined whilst maintaining constant fibre length, applied compactive effort, and soil height.