Peat Stabilization via Stone Column Integration

Peat poses major construction challenges due to high water content, low density, and poor strength. However, rapid urbanization and exponential population growth have necessitated constructional activities on peatlands. In this context, the present study involves collecting peat samples from a site in Silchar to assess physical, chemical, and strength parameters. Strength parameters were evaluated by consolidated undrained triaxial (CUTX) tests, where cohesion (c) and angle of internal friction (ϕ) varied from 4 kN/m2 to 10 kN/m2 and 4° to 10° respectively. Apart from that, PWP development was also noticed to range from 55 to 155 kN/m2. Such low strength values are highly inappropriate to carry out any sort of construction. To overcome such shortcomings, peat samples were reinforced with stone columns (SC) in both cased and uncased forms at altering length (L) to diameter (D) ratios. At varying L and D ratios, CUTX tests were carried out to assess change in c and ϕ values, where c value ranged from 22.35 to 28.02 kN/m2 in case of uncased stone columns (USC) and 26.22 to 35.66 kN/m2 for cased stone columns (CSC), showcasing a two- to three-fold increase and ϕ value varied from 0.90° to 13°. Results derived from analysis indicated cased samples to possess higher c and lower ϕ, primarily attributed to the fact that encasing provides resistance against lateral spreading, enhancing stability with low PWP development. Thus analysis from the present study concludes that CSC encased with geotextile significantly enhances stability and strength providing lateral support, reducing lateral spreading, improving c and ϕ while reducing PWP, an effective technique for reinforcing weak peat and enabling safer construction.