Fibre-reinforced backfills for retaining structures

The shear strength of inferior backfill materials can be considerably improved by mixing them randomly with fibres. The increase in shear strength decreases the active soil pressures and increases the passive soil pressures, eventually leading to economy in the design of retaining structures. In the present study, a backfill material such as fine sand is mixed with coir fibre at different fibre contents and aspect ratio of the fibre. Triaxial tests established the marked gain in shear strength resulting from fibre inclusions. A table-top retaining wall apparatus, capable of simulating six modes of wall movements, was fabricated and tests were conducted in it with the above backfill in which wall deformations and thrusts were measured and the rupture figures delineated under all the above modes. Analytical studies by the Finite Element Method confirmed the experimental findings. The studies establish the advantage of using fibre-reinforced backfills for retaining structures.