Stone Columns with Vertical Circumferential Nails: Laboratory Model Study

Abstract

This paper presents results from a series of laboratory plate load tests carried out in unit cell tanks to investigate the improvement in stiffness, load carrying capacity and resistance to bulging of stone columns installed in soft soils. A new method of reinforcing the stone columns with vertical nails installed along the circumference of the stone column is suggested for improving the performance of these columns. Tests were carried out with two types of loading (1) the entire area in the unit cell tank loaded, to estimate the stiffness of improved ground and (2) only the stone column loaded, to estimate the limiting axial capacity. It is found that stone columns reinforced with vertical nails along the circumference have much higher load carrying capacity and undergo lesser compression and lesser lateral bulging as compared to conventional stone columns. The benefit of vertical circumferential nails increases with increase in the diameter, number and depth of embedment of the nails. The improvement in the performance of stone column was found to be more significant, even with lower area ratio. It is found that reinforcing stone column with vertical circumferential nails at the top portion to a depth equal to three times the diameter of stone columns, will be adequate to prevent the column from excessive bulging and to improve its load carrying capacity substantially.

Experimental and Numerical Analysis of Geosynthetic-Reinforced Floating Granular Piles in Soft Clays

“…Many authors [24][25][26][27] performed field scale load tests on vertical encased granular piles; however no literature is available on in situ tests carried out on granular piles reinforced with horizontal strips. Shivashankar et al [28] investigated granular piles reinforced with vertical nails and found higher load carrying capacity and lesser bulging as compared to ordinary granular piles. Kumar et al [29] studied combined effect of vacuum consolidation and geosynthetic encased granular piles and observed that both stiffness and load carrying capacity of the piles increase significantly after the application of vacuum.…”

Behavior of Compacted Lime — (Well-graded) Soil columns: Large scale tests and numerical modelling

“…Stone columns are installed in wide variety of soils, ranging from loose sands to soft compressible clays (Shivashankar et al, 2010). The beneficial effects of stone columns on their loadsettlement characteristics of reinforcing soft clay deposits have been widely demonstrated by several researchers (Engelhardt et al, 1974;DiMaggio, 1978;Han and Ye, 2001;McKelvey et al, 2004;Castro and Karstunen, 2010;Murugesan and Rajagopal, 2010;Cimentada et al, 2011;Deb et al, 2011;Fattah et al, 2011).…”

The Experimental Design of Stone Columns' Modelling using Small-Scale Unit Cells: A Review

“…Although the column diameter and the unit cell diameter can affect the Ar, the studies with variable D e values concentrated on the effect of SC spacing, while those with variable d values concentrated on the effect of the SC diameter. [37] 158, 283 750 720 D, d Subramaniyan and Masoodhu [38] 280 310 310 60 Sudheer et al [39] 210 280 210 50 Suriya et al [40] 150 220 220 -Tallapragada et al,2011 [41] 100 300 300 -…”

“…Inserting nails vertically along the perimeter of the SC is suggested as a form of reinforcement [17,37]. For the geosynthetic fabrics, the tensile strength, the aperture size, the thickness and, the weight per unit length can usually be provided by the manufacturer.…”