Swelling and collapse of compacted soils to be used as earth dam cores

Abstract

The mechanical behaviour of fine-grained soil materials to be used as impermeable cores for earth dams has been extensively studied by numerous researchers. The required properties of these materials have also been very well described by standards and specifications. Yet, more than often it is required to assess their swelling/collapse potential, especially at various vertical stresses, as a means to estimate their volume changes upon inundation which is going to be caused by filling the dam reservoir. In the paper, experimental results of five different soils are presented. The soils tested ranged from non-plastic silty sands with clay to medium plasticity clayey silts that were compacted in conditions dry, at and wet of optimum moisture content as derived from standard compaction energy Proctor tests, then subjected to one-dimensional loading conditions and then inundated. The vertical stress was up to 7.6 MPa. The experimental results are categorized according to initial moisture content relative to Proctor optimum and indicate expected magnitudes of strains due to inundation for various grain-size distributions and plasticities.