Model tests on single and groups of stone columns with different geosynthetic reinforcement arrangement

ABSTRACT: Stone columns have proved to be a useful technique for supporting flexible structures resting on soft soils. However, in the case of very soft soils, stone columns have encountered excessive settlements due to insufficient lateral resistance offered by the soft soil against bulging of the columns upon loading. The bulging may be reduced to a great extent by reinforcing the columns either by encasing them with geosynthetics or by placing horizontal circular discs of geosynthetics within the columns at a regular interval. In the present study, model tests have been carried out on long floating and end-bearing single and groups of columns with and without reinforcement to evaluate the relative improvement in the failure stress of the composite ground due to different types of reinforcement. The exhumed deformed column shapes were used to understand the failure mechanism for different types and configurations of reinforcement. The geogrid was the best geosynthetic type for encasement for end-bearing columns; for floating columns, geotextile and geogrid were equally good for horizontal circular discs and encasement configurations.