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143Some of the loess composition piers were also not investigated for the bearing capacityparameter. Loess and cement composition piers were excluded from the bearing capacityinvestigation due to the brittle mechanism of failure at the top portion of the piers. The pierscomposed of loess and fiber, on the other hand, were not included in bearing capacitycalculations either, due to the unknown angle of frictional resistance of the composedmaterial in spite of the anticipated mechanism of failure through bulging.Overall, the bearing capacity results were generated for aggregate piers, sand piers, as wellas, loess, cement, fiber and cement type I and K component piers. According to the stresssettlementinformation gathered for aggregate piers and sand piers, the long 610 mmaggregate pier and both 305 mm and 610 mm sand piers were subjected to bulging failure asconfirmed in Figure 61 and Figure 69. Since the bulging failure of the long aggregate pierand short and long sand piers was mainly dependent on the angle of friction of the pieraggregate, the ultimate bearing capacity values were estimated as follows: 1.0x10 3 kPa,0.7x10 3 kPa and 0.8x10 3 kPa respectively for long aggregate pier, short sand pier and longsand pier.On the other hand, piers composed of loess, cement, fiber, as well as, cement type I, K andNS7 composition piers were deemed to fail by plunging due to little to no internal materialdeformation. Therefore, the bearing capacity for short 305 mm cementitious compositionpiers was estimated at 1.6x10 3 kPa on average, while the long 610 mm piers had averagebearing capacity values at 2.1x10 3 kPa. The short 305 mm aggregate was also deemed to failby plunging and, therefore, the bearing capacity was found at 1.7x10 3 kPa.Additionally, a reference bearing capacity value for the unreinforced matrix soil wascalculated using Terzaghi’s bearing capacity coefficients and estimated at 0.7 kPa.Therefore, a conclusion was made that cementitious composition piers had a greatimprovement in bearing capacity by factor of 2-3. The long sand and aggregate piers werealso proven to increase bearing capacity of the matrix soil, however by a much lesser margin– by factor of 1.1-1.4.