EXPERIMENTAL STUDY ON PERFORMANCE OF VERTICAL GEO DRAIN ON KAOLINITE USING LARGE SCALE MODEL CONSOLIDATION TEST

Abstract

Soft marine clay deposits exhibit low bearing capacity and high compressibility characteristics. Using sand
drains or vertical Geo-drains is now well established ground improvement technique with wide theoretical base. The
objective of present research work is to evaluate compressibility characteristics of kaolin clay in large sized model
consolidometer having aspect ratio 1.0:0.635 (H:D) using vertical drain with ‘n’ (re
/rw) value of 10. Two materials viz.
sand and LLDPE Plastic granules were used as filler for vertical drain based on their permeability characteristics. The
results were compared with equal strain theory of ‘Barron’ with inward radial drainage based on settlement
measurements. The soil used here in the present case is kaolinite procured from Bhavnagar city (Gujarat).The highlight
of this study is to use large size consolidometer of size 25.4 cm diameter and 40cm height, specially designed and
fabricated at Applied Mechanics department, L.D. College of Engineering using 10mm thick steel plate. The difference
between conventional Oedometer test and present set-up is in their aspect ratio. In the present case aspect ratio of
1.0:0.635 is adopted. Barron’s equal strain theory is more popular and widely adopted in field for inward radial flow.
Referring to many theoretical models and their assumptions for evaluating consolidation characteristics it was found
that this theory’s hold good even for large thick samples. So this study is an attempt to validate experimental results for
large size consolidation parameters by measuring settlement readings. Pre and post vane shear strength are recorded
and shear strength results are compared with virgin clay.