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

139In case with the piers consisting of loess as a main component, the addition of fibers to themixture has proven to significantly reduce pier strength at the level of service load. A similareffect was noticed for the piers composed of loess and cement type I, where addition of thefibers has shown reduction in load bearing capacity of the fiber containing pier at bothservice and ultimate levels of load.Another set of remarkable observations and findings was obtained for the piers composed ofloess and cement. The loess and cement composition 305 mm pier has shown the higheststiffness results at ultimate load conditions among all the piers tested at this stage of study.The long 610 mm pier has shown a tendency to outperform other single piers at the initialportion of the stress-settlement curve, however a steep decline in load support was observedat 2.5 mm level of settlement. After reaching a total displacement of 12 mm and uponexcavation of the tested piers, the short and long loess and cement composition piers werediscovered cracked at the top portion. The shear planes, as well as, point of failure can beobserved from the stress-settlement curves in Figure 64. The figures confirm a very brittletype of failure and support earlier stated observation of steep loss in load bearing.As one would anticipate, the tell-tale plate movement represented by the δ tell-tale / δ top ratiowas observed to be relatively small for 305 mm loess and fiber mix piers, as well as, longloess and cement composition pier (Table 24). This would suggest a bulging type of failurefor loess and fiber composition pier, while no tip movement for loess and cementcomposition pier would support brittle failure and shearing observations. On the other hand,significant movement at the bulb of the short cement, loess and loess, cement, fibercomposition piers suggests a plunging type of failure.Finally, the piers main components of which were cement type I and K were also evaluatedon the basis of stress-settlement performance. The compositions have shown improvement inpier stiffness where mixture of cement type I and K was used, whereas addition of NS7component has shown no consistent results. While having NS7 component to have negativeeffect on pier stiffness at the level of ultimate load, the opposite effect was noticed at the