Settling And Consolidation Behaviour Of Dredged Cohesive Estuarine Soil Using Column Testing Apparatus

Consolidation testing on in situ normally or over consolidated cohesive soils is commonly used to assess engineering parameters such as C_v, C_c and C_α. However, the application of conventional consolidation tests to reconstituted soil slurries is often unachievable. A column testing method for assessing the settling and consolidation behaviour of dredged soils was devised and applied to five samples of estuarine soil in a brackish (somewhat salty) water environment sourced from the South Coast of N.S.W, Australia. Test results show that void ratio and bulk density values after the settling phase of the test were comparable with results of in situ soil at the initial stage of standard laboratory oedometer testing. Calculation of compressibility coefficients C_c and C_α after the loading stage of the test revealed similar results to oedometer testing on the soils in the in situ state. The testing method was assessed to provide results within a more reasonable timeframe with sample thicknesses of approximately 100 mm. It was assessed that soil thicknesses greater than 100 mm in the columns were influenced by simultaneous primary and creep settlement and that an unreasonable test duration would be required to achieve meaningful results in an economic timeframe.