BEHAVIOUR OF FIBRE REINFORCED CLAY UNDER DYNAMIC LOADING

Abstract

Various soil improvement methods have been developed to improve the soil properties. Fibre reinforcement of soil is considered as an effective ground improvement technique because of its cost effectiveness, easy adaptability and reproducibility. Reinforcement of soil using, randomly distributed fibres is known to significantly improves the mechanical and dynamic properties of the soil In the present experimental study, an attempt has been made to investigate the effect of randomly distributed fibres on the behaviour of clay under dynamic loading. Clay samples of size 60mm x 60mm and height 25mm were tested under dynamic loading conditions using an oscillatory shear box. Clay samples with fibre contents of 0%, 0.1%, 0.2% and 0.3% were studied in the testing programme. Fibre content was calculated as a percentage of dry weight of the clay sample. Three different fibre lengths of 6mm, 10mm and 20mm were also investigated in the test programme. Proctor compaction tests have been conducted on the soil with different fibre lengths, 6mm, 10mm and 20mm and fibre contents of 0.0% 0.1%, 0.2% and 0.3%. From the compaction tests, it was observed that (i) with an increase in fibre content, the maximum dry density increases whereas the optimum moisture content decreases. (ii) with an increase in fibre length, the maximum dry density increases upto a fibre length of 10mm after this the maximum dry density decreases. From the oscillatory shear tests, it was observed that (i) dynamic shear modulus increases with an increase in fibre content, for a given normal stress and fibre length. (ii) dynamic shear modulus increases with fibre length upto a fibre length of 10 mm, however at a fibre length of 20mm the dynamic shear modulus value decreases, for a given normal stress and fibre content. To investigate the relationship between fibre length and soil sample size (60mm x 60mm in this study) further research