Conventional quality control of compaction during construction is currently based on an in-situ determination of dry unit weight and moisture content via nuclear procedures, but because this is a localised procedure, poor compaction can often occur. Moreover, with older compacted embankments where few or no records of the control done during construction are available, there is no existing methodology that can help practising engineers assess their post-construction condition. This means that the scope of the nuclear method renders it as inadequate and alternative methods should be considered. The use of shear wave velocity (Vs) surveys (i.e. MASW) to assess the quality of larger, previously compacted surface areas and depths seems to be a promising method. Furthermore, shear wave velocity can be readily related to the soil modulus, which is a variable commonly used in construction design. Fills are placed on, at, or near the OMC (optimum moisture content) so the compacted soil is in an unsaturated condition at the time of construction and therefore a field determination of Vs should also include the evaluation of matric suction (ua-uw). In this study, a field application at Penrith Lake Development Corporation (NSW, Australia) was investigated. A silty sand material collected from the site, was compacted and subjected to different confining pressures. In each specimen the Vs and (ua-uw) were measured with Bender elements and the filter paper method, respectively. The laboratory results showed that Vs trends together with (ua-uw) or moisture content, could effectively predict the compaction characteristics of the soil.
Available at: http://works.bepress.com/crujikiatkamjorn/123/