Estimation of Time Rate of Settlement for Multilayered Clays Undergoing Radial Drainage

This paper demonstrates how the finite difference technique can be used to estimate the time rate of settlement for soft, compressible clayey soils treated with prefabricated vertical drains at sites where primary consolidation settlement is occurring in a multilayered system at varying rates. Semiempirical methods based on surface settlement monitoring have typically been used to estimate the progression of primary consolidation settlement. However, interpretation of such methods can be problematic for multilayered soil profiles. For such sites, it is crucial to obtain a reasonable characterization of the foundation soils’ horizontal drainage properties and include these estimates in the time rate of settlement projections. Field monitoring of subsurface instrumentation is extremely valuable in providing additional information about the consolidation behavior of different layers. When subsurface field measurements are coupled with the proposed numerical method, far more reliable projections are obtained. This paper focuses on how to integrate field and laboratory data with projections of time rate of settlement obtained from semiempirical and finite difference methods to predict more accurately the time rate of consolidation behavior of multilayered foundation soils.