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

138some major conclusion were made regarding plunging, bulging and combination of twomechanisms of pier failures.As previously outlined, the aggregate pier testing at this phase of the research includedpartial cementing of the top and bulb portions of the aggregate piers. The obtained resultshave shown a significant amount of stiffness improvement provided by cementing the topportion of the long 610 mm aggregate pier. The amount of stress imposed on the partiallycemented versus non-cemented aggregate pier increased by a factor of almost two at ultimateload condition. The long aggregate pier was expected to have a significant amount of bulgingupon failure and, therefore, the collected data has provided evidence for reduction in pierbulging when using partial cementing technique. However, it must be noted that theaggregate pier was still observed to fail by bulging, though in the area beneath the cementedportion.At the same time by cementing the bulb portion of the pier it was anticipated to have areduction in the amount of plunging to occur for short 305 mm aggregate pier. However, noadditional confinement was observed to develop within the pier and, therefore, no significantimprovement was noticed in pier stiffness or load capacity. Therefore, no definitiveconclusion can be made in regard to how the process of cementing bulb portion of the piercan benefit the overall loading or stiffness capacities of the short aggregate pier.Overall, the tell-tale displacement data has shown no great impact when cementing top orbottom potions of the aggregate piers. As per Table 24, the ratio δ tell-tale / δ top was observed tobe relatively small for uncemented aggregate piers, short aggregate pier with cemented bulband long aggregate pier with cemented top of the pier, thus, suggesting the failure mechanismto occur through bulging. In case with long aggregate pier with cemented bulb and shortaggregate pier with cemented top 100 mm, a greater amount of plunging was recorded,however could be better described as combination of bulging and plunging.