G MS THESIS_final version_Maxim Prokudin.pdf - Digital Repository ...

137Stiffness, kPa/mm600500400300200100Stiffness, kPa/mm600500400300200100Cone HeadTruncated Head00305mm RAPs610mm RAPsFigure 90: Stiffness comparison at 10mm of settlement for aggregate piers compactedvia cone and truncated cone headsThe amount of difference in stress imposed on aggregate pier compacted via cone andtruncated cone beveled heads was evaluated at 2 mm, 5 mm and 10 mm of top of the pierdisplacements, and was observed to be on the order of 50 percent on average. The resultswere found to be consistent for both short and long piers, where longer piers had a tendencyto develop a slightly higher level of stiffness and load resistance. Therefore, one of the majorconclusions was made, where the cone head was capable of delivering twice the amount ofenergy than the truncated cone head and, thus, was of a greater benefit for stiffening thepiers.Single Piers of Various MixesStress-SettlementThe stress-settlement data collected for the tested single piers of various compositions wassummarized in Figure 70. The results were grouped by length and the stiffness anddisplacement results were summarized in Table 24. The piers tested at this stage of theresearch were equipped with the tell-tale plates installed at the tip of the piers and, therefore,