Performance of stone columns with circumferential nails

Abstract

Stone columns are often used as an effective technique for improving the performance of soft ground. Stone columns derive their load-carrying capacity due to lateral confinement from the surrounding soil. Very soft soils offer very low lateral confinement, leading to large settlements and low load-carrying capacities. In this paper, an alternative method of enhancing the performance of stone columns in soft soils by reinforcing the stone columns with circumferential nails driven vertically is suggested. The method was developed in laboratory-scale model tests and a series of plate load tests were performed in unit cell tanks to investigate the performance of stone columns reinforced with circumferential nails. The investigation was carried out by varying the depth of nails below ground level, the number of nails and the diameter of nails with different diameter stone columns and area ratios (or spacing). It was found that the circumferentially reinforced stone columns have much higher load-carrying capacity with a significant reduction in settlement and less lateral bulging in comparison with plain stone columns.

Model Tests on Coir Geotextile-Encased Stone Columns with Tyre Crumb-Infilled Basal Coir Geocell

“…However, the results may be erroneous for peripheral columns due to the unsymmetric load distribution. The frictionless rigid boundaries of the unit cell simulate the passive resistance offered by the surrounding soil, which is the major influencing factor to the load carrying capacity of the stone column soil composite system [35,47].…”

“…After loading, a thin paste of plaster of Paris was poured into the stone column and left for 24 h, enabling the paste to dry and bind with the aggregates to form a rigid column [36,37,47,48]. The lubricated tank boundaries were then separated and the clay surrounding the stone column was carefully removed to reveal the deformed central stone column.…”

Editorial

“…The final paper by Nayak et al (2011) focuses on the use of stone columns with circumferential nails to enhance the strength of soft soils. Laboratory investigations were conducted in large tanks in which soft clays treated with stone columns reinforced with nails were fabricated.…”