G MS THESIS_final version_Maxim Prokudin.pdf - Digital Repository ...

37full depth of the consolidated layer of the soil. If the piles are only extended to the quarterdistance of the full depth of a soil layer, then an even closer spacing does not significantlyimpact the reduction in the amount of settlement for a certain group of piles. Also, it wasfound that as the column penetration was to increase from 50 to 100 percent, the moduluswas found to increase proportionally by 50 percent.Having performed the study at a theoretical or empirical level, the verification was neededthrough laboratory and field testing. The interaction between reinforcing sand column andsoft soil was concluded to be extremely complex based on the parameters included in thecorrelations.Case 7 – Hughes and Withers, 1974 – Reinforcing of Soft Cohesive Soils with Stone Columns(Cambridge, United Kingdom)The study was performed on scaled stone columns at Cambridge in United Kingdom. Theresearch involved placement of stone columns composed of Leighton Buzzard sand in kaolinclay. The columns were scaled to 1/10 th scale and, therefore, were built at 12.5 mm to 38 mmdiameter and 150 mm length. The kaolin clay was one dimensionally consolidated and keptat a constant stress. For the purpose of consolidation of the clay material, the laboratory 225mm by 160 mm consolidometer was used. Also, a scaled vibroflot was utilized to form acavity in the soil. To measure displacement of a column in the soil, a radiograph of lead shotmarkers was used.The investigation revealed a significant amount of displacement developed within the matrixsoil at the distance of one and a half times the diameter of the column. The ultimate strengthof the column was found to be governed by the lateral reaction in the bulging zone. At thesame time, no movement was found at the distance of four times the diameter of the columnbelow the surface. For columns deformed through bulging the degree of bulging was foundto be dependent on the cohesion of the matrix soil. During the entire process of loading the