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UNREINFORCED COLUMNNO COLUMNREINFORCED COLUMN31Case 3 – Black et al., 2007a – Reinforced Stone Columns in Weak Deposits: LaboratoryModel Study (Northern Ireland)The research investigation was carried out on 1/8 th scale stone columns in Northern Ireland.The columns were built at 75 mm in diameter and composed of quarried basalt rock crushedto 6 mm in diameter. The testing of the columns was performed in a chamber 1.75 m inwidth, 2.0 m in height. Soil was described as peat, obtained at Donganon Ireland (64 kmfrom Belfast), placed between two layers of sand located at top and the bottom of the testingchamber (Figure 15). Peat was characterized to have density of 1,080 kN/m 3 andcompression index of 5.6. Sand material was found to be uniformly graded with d 10 = 0.07mm and d 60 = 0.15 mm.SUPPORT FRAMEWORKINVERTEDTRIAXIALMACHINEWATER TABLESAND2mPEATSAND240mm1.75mFigure 15: Testing box (Black et al., 2007a)The compaction of the stone column basalt rock aggregate was performed in even size liftswithin a premade soil cavity. The aggregate compaction tool consisted of a steel rod withtamper head attachment on one end and platform for striking the rod with a 5 kg mass, on theother. In order to avoid collapse of the cavity walls, the hollow tube was inserted in the