Compressibility characteristics of peaty soils

In Singapore, high organic content soils are generally known as peaty soils. Peaty soils have organic contents ranging from 10% to 30% and their water contents are generally greater than 90%. They are acidic as their pH are generally less than 7. The peaty soils are generally considered to have high compressibility and low shear strength. There is a lack of research and existing literature on the engineering behaviour of the Singapore peaty soils, therefore, a study of the compressibility of the peaty soils is presented in this paper. One-dimensional incremental loading (IL) and constant rate of strain (CRS) consolidation tests were conducted on the peaty soils collected from several locations in Singapore. A comparison was made between the IL and CRS consolidation tests and a suitable strain rate for the CRS consolidation tests was selected on the basis of the comparison. Compressibility parameters obtained include compression index, recompression index and secondary compression index. The test results indicate that the compressibility of the Singapore peaty soils is comparable to the marine clay, another soft soil deposit in Singapore, and good agreement is obtained between the IL and CRS consolidation tests when a suitable strain rate was selected in the CRS consolidation test.