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

147Another observation was made, where the trend of reduction of the group efficiency withincreasing amount of load was noticed (Table 27). Therefore, piers and groups of piersfeatured greater group efficiency at service load conditions and much lesser efficiency atfailure. As a result, it was concluded that the group efficiency became smaller as the loadimposed on a group of piers approached critical or ultimate condition.Group efficiency values obtained for all 305 mm groups of piers at 5 mm and 10 mm levelsof settlement were observed to consistently vary within the margin of 2.0-2.8 for groupefficiency calculated in terms of single pier. Therefore, short groups of piers at 5 mm and 10mm levels of settlement had a consistent group efficiency value ranging between two andthree independently of the number of piers within the group. Similarly, the long 610 mmgroups of piers featured consistent group efficiency values ranging between 1.0 and 1.9 at 5mm and 10 mm levels of settlement. Thus, the group efficiency for groups of long piersvaried between 1 and 2 at the level of 5 mm and 10 mm levels of settlement independently ofthe number of piers contained within the group.For the groups efficiency calculated in terms of unit cell, the values were found to beconsistently lower than 1.0 for most of the groups of piers. Consistently with Table 27 groupefficiency results, the piers within the short groups of piers were found to be more efficiencythan in long groups of piers. No particular trend was noticed with respect to group efficiencyrelated to the amount of pier settlement.C(I) + C(K) - Stress-SettlementAs outlined in Figure 89, the stress-settlement curves were plotted and grouped by length.The relative position of the plotted data points for the groups of piers was observed to behavein the expected manner, where the greatest amount of stress was carried by the group of sixpiers and the least by the group of two. As one would expect, the groups of shorter 305 mmpiers were also observed to support less load than long piers at the same amount ofsettlement. However an anomaly was notices where the unit cell has shown to outperformed